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1. Prog Biophys Mol Biol. 2018 Jul;135:11-15. doi: 10.1016/j.pbiomolbio.2018.01.003. Epub 2018 Jan 11.

Quantum Mechanics predicts evolutionary biology.

Torday JS(1).

Author information: (1)Department of Pediatrics, Harbor-UCLA Medical Center, 1224 W.Carson Street, Torrance, CA 90502, United States. Electronic address: jtorday@ucla.edu.

Nowhere are the shortcomings of conventional descriptive biology more evident than in the literature on Quantum Biology. In the on-going effort to apply Quantum Mechanics to evolutionary biology, merging Quantum Mechanics with the fundamentals of evolution as the First Principles of Physiology-namely negentropy, chemiosmosis and homeostasis-offers an authentic opportunity to understand how and why physics constitutes the basic principles of biology. Negentropy and chemiosmosis confer determinism on the unicell, whereas homeostasis constitutes Free Will because it offers a probabilistic range of physiologic set points. Similarly, on this basis several principles of Quantum Mechanics also apply directly to biology. The Pauli Exclusion Principle is both deterministic and probabilistic, whereas non-localization and the Heisenberg Uncertainty Principle are both probabilistic, providing the long-sought after ontologic and causal continuum from physics to biology and evolution as the holistic integration recognized as consciousness for the first time.

DOI: 10.1016/j.pbiomolbio.2018.01.003 PMID: 29337208 [Indexed for MEDLINE]

2. Heliyon. 2019 Dec 4;5(12):e02579. doi: 10.1016/j.heliyon.2019.e02579. eCollection 2019 Dec.

Quantum-classical mechanics as an alternative to quantum mechanics in molecular and chemical physics.

Egorov VV(1).

Author information: (1)Russian Academy of Sciences, FSRC "Crystallography and Photonics", Photochemistry Center, 7a Novatorov Street, Moscow, 119421, Russian Federation.

In quantum mechanics, the theory of quantum transitions is grounded on the convergence of a series of time-dependent perturbation theory. In nuclear and atomic physics, this series converges because the dynamics of quantum transitions (quantum jumps) are absent by definition. In molecular and chemical physics, on the contrary, the dynamics of "quantum" transitions, being determined by the joint motion of a light electron (or electrons) and very heavy nuclei, are present by definition, and the series of time-dependent perturbation theory becomes singular. An exception is the dynamic problem for stationary states in the Born-Oppenheimer adiabatic approximation, when the electronic subsystem turns out to be "off" from the general dynamic process and therefore is not dynamically full-fledged: it only forms an electric potential in which the nuclei oscillate. Removing the aforementioned singularity can be accomplished in two ways. The first method was consisted of introducing an additional postulate in the form of the Franck-Condon principle into molecular quantum mechanics, in which the adiabatic approximation is used. The second method was proposed by the author and consisted of damping the singular dynamics of the joint motion of an electron and nuclei in the intermediate (transient) state of molecular "quantum" transitions by introducing chaos. This chaos arises only during molecular quantum transitions and is called dozy chaos. Formally, the damping is carried out by replacing an infinitely small imaginary addition in the spectral representation of the complete Green's function of the system with its finite quantity. The damping chaos (dozy chaos) leads to the continuity of the energy spectrum in the molecular transient state, which is a sign of classical mechanics. Meanwhile, the initial and final states of the molecule obey quantum mechanics in the adiabatic approximation. Molecular quantum mechanics, which takes into account the chaotic dynamics of the transient state of molecular "quantum" transitions, can be called quantum-classical (dozy-chaos) mechanics. The efficacy of the damping for the aforementioned singularity was previously shown by dozy-chaos mechanics of elementary electron transfers in condensed matter, which is the simplest case of dozy-chaos mechanics, and its applications to a whole number of problems, especially to the optical spectra in polymethine dyes and their aggregates. This paper provides a regular exposition of this dozy-chaos (quantum-classical) mechanics of the elementary electron transfers. The main results of its applications presented in the introduction are also described.

DOI: 10.1016/j.heliyon.2019.e02579 PMCID: PMC6909101 PMID: 31872096

3. Sci Rep. 2018 Sep 6;8(1):13305. doi: 10.1038/s41598-018-31481-8.

A Relational Formulation of Quantum Mechanics.

Yang JM(1).

Author information: (1)Qualcomm, 5775 Morehouse Drive, San Diego, CA, 92121, USA. jianhao.yang@alumni.utoronto.ca.

Non-relativistic quantum mechanics is reformulated here based on the idea that relational properties among quantum systems, instead of the independent properties of a quantum system, are the most fundamental elements to construct quantum mechanics. This idea, combining with the emphasis that measurement of a quantum system is a bidirectional interaction process, leads to a new framework to calculate the probability of an outcome when measuring a quantum system. In this framework, the most basic variable is the relational probability amplitude. Probability is calculated as summation of weights from the alternative measurement configurations. The properties of quantum systems, such as superposition and entanglement, are manifested through the rules of counting the alternatives. Wave function and reduced density matrix are derived from the relational probability amplitude matrix. They are found to be secondary mathematical tools that equivalently describe a quantum system without explicitly calling out the reference system. Schrödinger Equation is obtained when there is no entanglement in the relational probability amplitude matrix. Feynman Path Integral is used to calculate the relational probability amplitude, and is further generalized to formulate the reduced density matrix. In essence, quantum mechanics is reformulated as a theory that describes physical systems in terms of relational properties.

DOI: 10.1038/s41598-018-31481-8 PMCID: PMC6127378 PMID: 30190533

Conflict of interest statement: The author declares no competing interests.

4. J Chem Phys. 2018 Jan 7;148(1):014102. doi: 10.1063/1.5006810.

Quantum mechanics/coarse-grained molecular mechanics (QM/CG-MM).

Sinitskiy AV(1), Voth GA(1).

Author information: (1)Department of Chemistry, James Franck Institute, and Institute for Biophysical Dynamics, The University of Chicago, Chicago, Illinois 60637, USA.

Numerous molecular systems, including solutions, proteins, and composite materials, can be modeled using mixed-resolution representations, of which the quantum mechanics/molecular mechanics (QM/MM) approach has become the most widely used. However, the QM/MM approach often faces a number of challenges, including the high cost of repetitive QM computations, the slow sampling even for the MM part in those cases where a system under investigation has a complex dynamics, and a difficulty in providing a simple, qualitative interpretation of numerical results in terms of the influence of the molecular environment upon the active QM region. In this paper, we address these issues by combining QM/MM modeling with the methodology of "bottom-up" coarse-graining (CG) to provide the theoretical basis for a systematic quantum-mechanical/coarse-grained molecular mechanics (QM/CG-MM) mixed resolution approach. A derivation of the method is presented based on a combination of statistical mechanics and quantum mechanics, leading to an equation for the effective Hamiltonian of the QM part, a central concept in the QM/CG-MM theory. A detailed analysis of different contributions to the effective Hamiltonian from electrostatic, induction, dispersion, and exchange interactions between the QM part and the surroundings is provided, serving as a foundation for a potential hierarchy of QM/CG-MM methods varying in their accuracy and computational cost. A relationship of the QM/CG-MM methodology to other mixed resolution approaches is also discussed.

DOI: 10.1063/1.5006810 PMID: 29306280

5. Rep Prog Phys. 2019 Jan;82(1):012002. doi: 10.1088/1361-6633/aae2c6. Epub 2018 Sep 20.

Making better sense of quantum mechanics.

Mermin ND(1).

Author information: (1)Laboratory of Atomic and Solid State Physics, Cornell University, Ithaca NY 14853-2501, United States of America.

We still lack any consensus about what one is actually talking about as one uses quantum mechanics. There is a gap between the abstract terms in which the theory is couched and the phenomena the theory enables each of us to account for so well. Because it has no practical consequences for how we each use quantum mechanics to deal with physical problems, this cognitive dissonance has managed to coexist with the quantum theory from the very beginning. The absence of conceptual clarity for almost a century suggests that the problem might lie in some implicit misconceptions about the nature of scientific explanation that are deeply held by virtually all physicists, but are rarely explicitly acknowledged. I describe here such unvoiced but widely shared assumptions. Rejecting them clarifies and unifies a range of obscure remarks about quantum mechanics made almost from the beginning by some of the giants of physics, many of whom are held to be in deep disagreement. This new view of physics requires physicists to think about science in an unfamiliar way. My primary purpose is to explain the new perspective and urge that it be taken seriously. My secondary aims are to explain why this perspective differs significantly from what Bohr, Heisenberg, and Pauli had been saying from the very beginning, and why it is not solipsism, as some have maintained. To emphasize that this is a general view of science, and not just of quantum mechanics, I apply it to a long-standing puzzle in classical physics: the apparent inability of physics to give any meaning to 'Now'-the present moment.

DOI: 10.1088/1361-6633/aae2c6 PMID: 30232960

6. Curr Top Med Chem. 2017;17(23):2663-2680. doi: 10.2174/1568026617666170707120609.

Quantum-Mechanics Methodologies in Drug Discovery: Applications of Docking and Scoring in Lead Optimization.

Crespo A(1), Rodriguez-Granillo A(1), Lim VT(2).

Author information: (1)Chemistry Modeling & Informatics, MRL, Merck & Co. Inc., Rahway, NJ 07065, United States. (2)Department of Chemistry, University of California, Irvine, CA, 92697,, United States.

The development and application of quantum mechanics (QM) methodologies in computer- aided drug design have flourished in the last 10 years. Despite the natural advantage of QM methods to predict binding affinities with a higher level of theory than those methods based on molecular mechanics (MM), there are only a few examples where diverse sets of protein-ligand targets have been evaluated simultaneously. In this work, we review recent advances in QM docking and scoring for those cases in which a systematic analysis has been performed. In addition, we introduce and validate a simplified QM/MM expression to compute protein-ligand binding energies. Overall, QMbased scoring functions are generally better to predict ligand affinities than those based on classical mechanics. However, the agreement between experimental activities and calculated binding energies is highly dependent on the specific chemical series considered. The advantage of more accurate QM methods is evident in cases where charge transfer and polarization effects are important, for example when metals are involved in the binding process or when dispersion forces play a significant role as in the case of hydrophobic or stacking interactions.

DOI: 10.2174/1568026617666170707120609 PMID: 28685695 [Indexed for MEDLINE]

7. Drug Des Devel Ther. 2017 Aug 31;11:2551-2564. doi: 10.2147/DDDT.S126344. eCollection 2017.

Quantum mechanics implementation in drug-design workflows: does it really help?

Arodola OA(1), Soliman ME(1)(2).

Author information: (1)Department of Pharmaceutical Chemistry, University of KwaZulu-Natal, Durban, South Africa. (2)Department of Pharmaceutical Organic Chemistry, Faculty of Pharmacy, Zagazig University, Egypt.

Erratum in Drug Des Devel Ther. 2017 Nov 08;11:3205.

The pharmaceutical industry is progressively operating in an era where development costs are constantly under pressure, higher percentages of drugs are demanded, and the drug-discovery process is a trial-and-error run. The profit that flows in with the discovery of new drugs has always been the motivation for the industry to keep up the pace and keep abreast with the endless demand for medicines. The process of finding a molecule that binds to the target protein using in silico tools has made computational chemistry a valuable tool in drug discovery in both academic research and pharmaceutical industry. However, the complexity of many protein-ligand interactions challenges the accuracy and efficiency of the commonly used empirical methods. The usefulness of quantum mechanics (QM) in drug-protein interaction cannot be overemphasized; however, this approach has little significance in some empirical methods. In this review, we discuss recent developments in, and application of, QM to medically relevant biomolecules. We critically discuss the different types of QM-based methods and their proposed application to incorporating them into drug-design and -discovery workflows while trying to answer a critical question: are QM-based methods of real help in drug-design and -discovery research and industry?

DOI: 10.2147/DDDT.S126344 PMCID: PMC5587087 PMID: 28919707 [Indexed for MEDLINE]

Conflict of interest statement: Disclosure The authors report no conflicts of interest in this work.

8. Philos Trans A Math Phys Eng Sci. 2018 Jul 13;376(2123):20170461. doi: 10.1098/rsta.2017.0461.

Exploring the boundaries of quantum mechanics: advances in satellite quantum communications.

Agnesi C(1), Vedovato F(1), Schiavon M(1), Dequal D(1)(2), Calderaro L(1), Tomasin M(1), Marangon DG(1), Stanco A(1), Luceri V(3), Bianco G(2), Vallone G(1), Villoresi P(4).

Author information: (1)Department of Information Engineering, University of Padova, 35131 Padova, Italy. (2)Matera Laser Ranging Observatory, Italian Space Agency, 75100 Matera, Italy. (3)e-GEOS SpA, 75100 Matera, Italy. (4)Department of Information Engineering, University of Padova, 35131 Padova, Italy paolo.villoresi@dei.unipd.it.

Recent interest in quantum communications has stimulated great technological progress in satellite quantum technologies. These advances have rendered the aforesaid technologies mature enough to support the realization of experiments that test the foundations of quantum theory at unprecedented scales and in the unexplored space environment. Such experiments, in fact, could explore the boundaries of quantum theory and may provide new insights to investigate phenomena where gravity affects quantum objects. Here, we review recent results in satellite quantum communications and discuss possible phenomena that could be observable with current technologies. Furthermore, stressing the fact that space represents an incredible resource to realize new experiments aimed at highlighting some physical effects, we challenge the community to propose new experiments that unveil the interplay between quantum mechanics and gravity that could be realizable in the near future.This article is part of a discussion meeting issue 'Foundations of quantum mechanics and their impact on contemporary society'.

DOI: 10.1098/rsta.2017.0461 PMCID: PMC5990660 PMID: 29807904

Conflict of interest statement: We declare we have no competing interests.

9. Ann N Y Acad Sci. 2015 Dec;1361:69-73. doi: 10.1111/nyas.12972.

Uncertain for a century: quantum mechanics and the dilemma of interpretation.

Frank A(1).

Author information: (1)Department of Physics and Astronomy, University of Rochester, Rochester, New York.

Quantum mechanics, the physical theory describing the microworld, is one of science's greatest triumphs. Remarkably, however, after more than 100 years it is still unclear what quantum mechanics means in terms of basic philosophical questions about the nature of reality. While there are many interpretations of the mathematical machinery of quantum physics, there remain no experimental means to distinguish between most of them. In this contribution, I wish to consider the ways in which the enduring lack of an agreed-upon interpretation of quantum physics influences a number of critical philosophical debates about physics and reality. I briefly review two problems affected by quantum interpretations: the meaning of the term universe and the nature of consciousness.

DOI: 10.1111/nyas.12972 PMID: 26767928 [Indexed for MEDLINE]

10. Biosystems. 2019 Apr;178:16-24. doi: 10.1016/j.biosystems.2019.01.010. Epub 2019 Jan 26.

Quantum biology and human carcinogenesis.

Bordonaro M(1).

Author information: (1)Geisinger Commonwealth School of Medicine, 525 Pine Street, Scranton, PA 18509, USA. Electronic address: mbordonaro@som.geisinger.edu.

Quantum-mediated effects have been observed in biological systems. We have previously discussed basis-dependent quantum selection as a mechanism for directed adaptive mutation, a process in which selective pressure specifically induces mutation in those genes involved in the adaptive response. Tumor progression in cancer easily lends itself to the adaptive evolutionary perspective, as the Darwinian combination of heritable variations together with selection of the better proliferating variants are believed to play a major role in multistep carcinogenesis. Adaptive mutation may play a role in carcinogenesis; accordingly, we propose that the principles of quantum biology are involved in directed adaptive mutation processes that promote tumor formation. In this paper, we discuss the intersection between quantum mechanics, biology, adaptive evolution, and cancer, and present general models by which adaptive mutation may influence neoplastic initiation and progression. As a potential theoretical and experimental model, we use colorectal cancer. Our model of "quantum cancer" suggests experiments to evaluate directed adaptive mutation in tumorigenesis, and may have important implications for cancer therapeutics.

DOI: 10.1016/j.biosystems.2019.01.010 PMID: 30695703 [Indexed for MEDLINE]

11. J Membr Biol. 2019 Oct;252(4-5):425-449. doi: 10.1007/s00232-019-00095-0. Epub 2019 Sep 30.

Quantum Mechanical and Molecular Mechanics Modeling of Membrane-Embedded Rhodopsins.

Ryazantsev MN(1), Nikolaev DM(2), Struts AV(3)(4), Brown MF(5)(6).

Author information: (1)Institute of Chemistry, Saint Petersburg State University, 26 Universitetskii pr, Saint Petersburg, Russia, 198504. (2)Saint-Petersburg Academic University - Nanotechnology Research and Education Centre RAS, Saint Petersburg, Russia, 194021. (3)Department of Chemistry and Biochemistry, University of Arizona, Tucson, AZ, 85721, USA. (4)Laboratory of Biomolecular NMR, Saint Petersburg State University, Saint Petersburg, Russia, 199034. (5)Department of Chemistry and Biochemistry, University of Arizona, Tucson, AZ, 85721, USA. mfbrown@u.arizona.edu. (6)Department of Physics, University of Arizona, Tucson, AZ, 85721, USA. mfbrown@u.arizona.edu.

Computational chemistry provides versatile methods for studying the properties and functioning of biological systems at different levels of precision and at different time scales. The aim of this article is to review the computational methodologies that are applicable to rhodopsins as archetypes for photoactive membrane proteins that are of great importance both in nature and in modern technologies. For each class of computational techniques, from methods that use quantum mechanics for simulating rhodopsin photophysics to less-accurate coarse-grained methodologies used for long-scale protein dynamics, we consider possible applications and the main directions for improvement.

DOI: 10.1007/s00232-019-00095-0 PMID: 31570961 [Indexed for MEDLINE]

12. Sci Rep. 2019 Dec 27;9(1):19984. doi: 10.1038/s41598-019-56357-3.

Quantum Mechanics can be understood through stochastic optimization on spacetimes.

Lindgren J(1), Liukkonen J(2).

Author information: (1)Aalto University, Department of Mathematics and Systems Analysis, Espoo, Finland. jussi.lindgren@aalto.fi. (2)Nuclear and Radiation Safety Authority, STUK, Helsinki, Finland.

The main contribution of this paper is to explain where the imaginary structure comes from in quantum mechanics. It is shown how the demand of relativistic invariance is key and how the geometric structure of the spacetime together with the demand of linearity are fundamental in understanding the foundations of quantum mechanics. We derive the Stueckelberg covariant wave equation from first principles via a stochastic control scheme. From the Stueckelberg wave equation a Telegrapher's equation is deduced, from which the classical relativistic and nonrelativistic equations of quantum mechanics can be derived in a straightforward manner. We therefore provide meaningful insight into quantum mechanics by deriving the concepts from a coordinate invariant stochastic optimization problem, instead of just stating postulates.

DOI: 10.1038/s41598-019-56357-3 PMCID: PMC6934697 PMID: 31882809

Conflict of interest statement: The authors declare no competing interests.

13. Expert Opin Drug Discov. 2015 Oct;10(10):1047-57. doi: 10.1517/17460441.2015.1076389. Epub 2015 Aug 8.

Simulation with quantum mechanics/molecular mechanics for drug discovery.

Barbault F(1), Maurel F(1).

Author information: (1)a Univ Paris Diderot, Sorbonne Paris Cité, ITODYS, UMR CNRS 7086 , 15 rue J-A. de Baïf, Paris, France florent.barbault@univ-paris-diderot.fr.

INTRODUCTION: Biological macromolecules, such as proteins or nucleic acids, are (still) molecules and thus they follow the same chemical rules that any simple molecule follows, even if their size generally renders accurate studies unhelpful. However, in the context of drug discovery, a detailed analysis of ligand association is required for understanding or predicting their interactions and hybrid quantum mechanics/molecular mechanics (QM/MM) computations are relevant tools to help elucidate this process. AREAS COVERED: In this review, the authors explore the use of QM/MM for drug discovery. After a brief description of the molecular mechanics (MM) technique, the authors describe the subtractive and additive techniques for QM/MM computations. The authors then present several application cases in topics involved in drug discovery. EXPERT OPINION: QM/MM have been widely employed during the last decades to study chemical processes such as enzyme-inhibitor interactions. However, despite the enthusiasm around this area, plain MM simulations may be more meaningful than QM/MM. To obtain reliable results, the authors suggest fixing several keystone parameters according to the underlying chemistry of each studied system.

DOI: 10.1517/17460441.2015.1076389 PMID: 26289577 [Indexed for MEDLINE]

14. Nat Commun. 2017 Nov 3;8(1):1306. doi: 10.1038/s41467-017-01375-w.

Quantum mechanics as classical statistical mechanics with an ontic extension and an epistemic restriction.

Budiyono A(1)(2), Rohrlich D(3).

Author information: (1)Edelstein Center, Hebrew University of Jerusalem, Jerusalem, 91904, Israel. agungbymlati@gmail.com. (2)Department of Physics, Ben-Gurion University of the Negev, Beersheba, 8410501, Israel. agungbymlati@gmail.com. (3)Department of Physics, Ben-Gurion University of the Negev, Beersheba, 8410501, Israel. rohrlich@bgu.ac.il.

Where does quantum mechanics part ways with classical mechanics? How does quantum randomness differ fundamentally from classical randomness? We cannot fully explain how the theories differ until we can derive them within a single axiomatic framework, allowing an unambiguous account of how one theory is the limit of the other. Here we derive non-relativistic quantum mechanics and classical statistical mechanics within a common framework. The common axioms include conservation of average energy and conservation of probability current. But two axioms distinguish quantum mechanics from classical statistical mechanics: an "ontic extension" defines a nonseparable (global) random variable that generates physical correlations, and an "epistemic restriction" constrains allowed phase space distributions. The ontic extension and epistemic restriction, with strength on the order of Planck's constant, imply quantum entanglement and uncertainty relations. This framework suggests that the wave function is epistemic, yet it does not provide an ontic dynamics for individual systems.

DOI: 10.1038/s41467-017-01375-w PMCID: PMC5670234 PMID: 29101341

Conflict of interest statement: The authors declare no competing financial interests.

15. Ann Transl Med. 2019 Oct;7(20):585. doi: 10.21037/atm.2019.09.09.

The finer scale of consciousness: quantum theory.

Li T(1), Tang H(1), Zhu J(1), Zhang JH(2).

Author information: (1)Department of Neurosurgery, Fudan University Huashan Hospital, National Key Laboratory of Medical Neurobiology, the Institutes of Brain Science and the Collaborative Innovation Center for Brain Science, Shanghai Medical College, Fudan University, Shanghai 200040, China. (2)Center for Neuroscience Research, Loma Linda University School of Medicine, Loma Linda, CA, USA.

Consciousness is a multidisciplinary problem that has puzzled all human beings since the origin of human life. Being defined in various pointcuts by philosophers, biologists, physicists, and neuroscientists, the definitive explanation of consciousness is still suspending. The nature of consciousness has taken great evolution by centering on the behavioral and neuronal correlates of perception and cognition, for example, the theory of Neural Correlates of Consciousness, the Global Workspace Theory, the Integrated Information Theory. While tremendous progress has been achieved, they are not enough if we are to understand even basic facts-how and where does the consciousness emerge. The Quantum mechanics, a thriving branch of physics, has an inseparable relationship with consciousness (e.g., observer effect) since Planck created this subject and its derived quantum consciousness theory can perfectly fill this gap. In this review, we briefly introduce some consciousness hypotheses derived from quantum mechanics and focus on the framework of orchestrated objective reduction (Orch-OR), including its principal points and practicality.

DOI: 10.21037/atm.2019.09.09 PMCID: PMC6861790 PMID: 31807566

Conflict of interest statement: Conflicts of Interest: The authors have no conflicts of interest to declare.

16. Nat Commun. 2019 Mar 25;10(1):1361. doi: 10.1038/s41467-019-09348-x.

The measurement postulates of quantum mechanics are operationally redundant.

Masanes L(1), Galley TD(2)(3), Müller MP(4)(5).

Author information: (1)Department of Physics and Astronomy, University College London, Gower Street, London, WC1E 6BT, UK. (2)Department of Physics and Astronomy, University College London, Gower Street, London, WC1E 6BT, UK. tgalley1@perimeterinstitute.ca. (3)Perimeter Institute for Theoretical Physics, Waterloo, ON, N2L 2Y5, Canada. tgalley1@perimeterinstitute.ca. (4)Perimeter Institute for Theoretical Physics, Waterloo, ON, N2L 2Y5, Canada. (5)Institute for Quantum Optics and Quantum Information, Austrian Academy of Sciences, Boltzmanngasse 3, A-1090, Vienna, Austria.

Understanding the core content of quantum mechanics requires us to disentangle the hidden logical relationships between the postulates of this theory. Here we show that the mathematical structure of quantum measurements, the formula for assigning outcome probabilities (Born's rule) and the post-measurement state-update rule, can be deduced from the other quantum postulates, often referred to as "unitary quantum mechanics", and the assumption that ensembles on finite-dimensional Hilbert spaces are characterized by finitely many parameters. This is achieved by taking an operational approach to physical theories, and using the fact that the manner in which a physical system is partitioned into subsystems is a subjective choice of the observer, and hence should not affect the predictions of the theory. In contrast to other approaches, our result does not assume that measurements are related to operators or bases, it does not rely on the universality of quantum mechanics, and it is independent of the interpretation of probability.

DOI: 10.1038/s41467-019-09348-x PMCID: PMC6434053 PMID: 30911009

Conflict of interest statement: The authors declare no competing interests.

17. Theor Biol Forum. 2019 Jan 1;112(1-2):35-51. doi: 10.19272/201911402004.

When cancer meets quantum mechanics.

Laster M(1), Matouk IJ(2), Fellig Y(3), Hochberg A(1).

Author information: (1)Department of Biological Chemistry, Institute of Life Sciences, the Hebrew University of Jerusalem, Jerusalem 91904, Israel. (2)Department of Biological Chemistry, Institute of Life Sciences, the Hebrew University of Jerusalem, Jerusalem 91904, Israel. Department of Biological Sciences, Faculty of Science and Technology, Al-Quds University, Jerusalem. (3)Department of Pathology, Hadassah Hebrew University Medical Center, Jerusalem 91240, Israel.

To date, classical deterministic Newtonian physics has been used by biologists to describe living processes. However, it is increasingly appreciated that the probabilistic view offered by quantum mechanics more accurately describes the behavior of atoms and materials in all systems. Here, we discuss how the concepts of quantum mechanics can be applied to biological processes involved in cancer. We present a concise summary inspired by Heisenberg's Uncertainty Principle to describe our «Genetic Environmental Field Hypothesis». Combining the uncertainties of genetic changes as expressed by epigenetic changes and/or somatic mutations with the uncertainties of environmental changes, cells may become cancerous as a way to increase entropy. Throughout the paper we will utilize the H19 gene system as an example. Using the concepts of quantum mechanics to describe oncological processes may provide novel directions in our understanding of cancer.

DOI: 10.19272/201911402004 PMID: 32125350 [Indexed for MEDLINE]

18. Philos Trans A Math Phys Eng Sci. 2018 Jul 13;376(2123):20170322. doi: 10.1098/rsta.2017.0322.

What is quantum in quantum randomness?

Grangier P(1), Auffèves A(2).

Author information: (1)Laboratoire Charles Fabry, IOGS, CNRS, Université Paris Saclay, 91127 Palaiseau, France. (2)CNRS and Université Grenoble Alpes, Institut Néel, 38042 Grenoble, France alexia.auffeves@neel.cnrs.fr.

It is often said that quantum and classical randomness are of different nature, the former being ontological and the latter epistemological. However, so far the question of 'What is quantum in quantum randomness?', i.e. what is the impact of quantization and discreteness on the nature of randomness, remains to be answered. In a first part, we make explicit the differences between quantum and classical randomness within a recently proposed ontology for quantum mechanics based on contextual objectivity. In this view, quantum randomness is the result of contextuality and quantization. We show that this approach strongly impacts the purposes of quantum theory as well as its areas of application. In particular, it challenges current programmes inspired by classical reductionism, aiming at the emergence of the classical world from a large number of quantum systems. In a second part, we analyse quantum physics and thermodynamics as theories of randomness, unveiling their mutual influences. We finally consider new technological applications of quantum randomness that have opened up in the emerging field of quantum thermodynamics.This article is part of a discussion meeting issue 'Foundations of quantum mechanics and their impact on contemporary society'.

DOI: 10.1098/rsta.2017.0322 PMID: 29807899

19. Sci Rep. 2018 Oct 5;8(1):14878. doi: 10.1038/s41598-018-33023-8.

The Quantum Mechanics of a Rolling Molecular "Nanocar".

Fernandez OE(1), Radhakrishnan ML(2).

Author information: (1)Wellesley College, Department of Mathematics, Wellesley, MA, 02482, USA. ofernand@wellesley.edu. (2)Wellesley College, Department of Chemistry, Wellesley, MA, 02482, USA. mradhakr@wellesley.edu.

We formulate a mathematical model of a rolling "molecular wheelbarrow"-a two-wheeled nanoscale molecular machine-informed by experiments on molecular machines recently synthesized in labs. The model is a nonholonomic system (briefly, a system with non-integrable velocity constraints), for which no general quantization procedure exists. Nonetheless, we successfully embed the system in a Hamiltonian one and then quantize the result using geometric quantization and other tools; we extract from the result the quantum mechanics of the molecular wheelbarrow, and derive explicit formulae for the quantized energy spectrum. We also study a few variants of our model, some of which ignore the model's nonholonomic constraints. We show that these variants have different quantum energy spectra, indicating that in such systems one should not ignore the nonholonomic constraints, since they alter in a non-trivial way the energy spectrum of the molecule.

DOI: 10.1038/s41598-018-33023-8 PMCID: PMC6173740 PMID: 30291255

Conflict of interest statement: The authors declare no competing interests.

20. Sci Rep. 2019 Jan 24;9(1):470. doi: 10.1038/s41598-018-37535-1.

How Quantum Mechanics can consistently describe the use of itself.

Lazarovici D(1), Hubert M(2).

Author information: (1)Université de Lausanne, Section de Philosophie, Lausanne, 1015, Switzerland. dustin.lazarovici@unil.ch. (2)Columbia University, Department of Philosophy, New York, 10027, USA.

We discuss the no-go theorem of Frauchiger and Renner based on an "extended Wigner's friend" thought experiment which is supposed to show that any single-world interpretation of quantum mechanics leads to inconsistent predictions if it is applicable on all scales. We show that no such inconsistency occurs if one considers a complete description of the physical situation. We then discuss implications of the thought experiment that have not been clearly addressed in the original paper, including a tension between relativity and nonlocal effects predicted by quantum mechanics. Our discussion applies in particular to Bohmian mechanics.

DOI: 10.1038/s41598-018-37535-1 PMCID: PMC6346061 PMID: 30679739

Conflict of interest statement: The authors declare no competing interests.

21. Anal Biochem. 2017 Jul 15;529:65-78. doi: 10.1016/j.ab.2016.08.019. Epub 2016 Sep 3.

Optimization of metabolite detection by quantum mechanics simulations in magnetic resonance spectroscopy.

Gambarota G(1).

Author information: (1)Université de Rennes 1, LTSI, Rennes, F-35000, France; INSERM, UMR 1099, Rennes, F-35000, France. Electronic address: gambarota@gmail.com.

Magnetic resonance spectroscopy (MRS) is a well established modality for investigating tissue metabolism in vivo. In recent years, many efforts by the scientific community have been directed towards the improvement of metabolite detection and quantitation. Quantum mechanics simulations allow for investigations of the MR signal behaviour of metabolites; thus, they provide an essential tool in the optimization of metabolite detection. In this review, we will examine quantum mechanics simulations based on the density matrix formalism. The density matrix was introduced by von Neumann in 1927 to take into account statistical effects within the theory of quantum mechanics. We will discuss the main steps of the density matrix simulation of an arbitrary spin system and show some examples for the strongly coupled two spin system.

DOI: 10.1016/j.ab.2016.08.019 PMID: 27596743 [Indexed for MEDLINE]

22. Philos Trans A Math Phys Eng Sci. 2018 Jul 13;376(2123):20170311. doi: 10.1098/rsta.2017.0311.

Extracontextuality and extravalence in quantum mechanics.

Auffèves A(1), Grangier P(2).

Author information: (1)Institut Néel, BP 166, 25 rue des Martyrs, 38042 Grenoble Cedex 9, France. (2)Laboratoire Charles Fabry, IOGS, CNRS, Université Paris Saclay, 91127 Palaiseau, France philippe.grangier@institutoptique.fr.

We develop the point of view where quantum mechanics results from the interplay between the quantized number of 'modalities' accessible to a quantum system, and the continuum of 'contexts' that are required to define these modalities. We point out the specific roles of 'extracontextuality' and 'extravalence' of modalities, and relate them to the Kochen-Specker and Gleason theorems.This article is part of a discussion meeting issue 'Foundations of quantum mechanics and their impact on contemporary society'.

DOI: 10.1098/rsta.2017.0311 PMID: 29807891

23. Philos Trans A Math Phys Eng Sci. 2018 Jul 13;376(2123):20170320. doi: 10.1098/rsta.2017.0320.

Locality and quantum mechanics.

Unruh WG(1).

Author information: (1)CIfAR Cosmology and Gravity Program, Department of Physics, University of British Columbia, Vancouver, Canada V6T 1Z1 unruh@physics.ubc.ca.

It is argued that it is best not to think of quantum mechanics as non-local, but rather that it is non-realistic.This article is part of a discussion meeting issue 'Foundations of quantum mechanics and their impact on contemporary society'.

DOI: 10.1098/rsta.2017.0320 PMCID: PMC5990662 PMID: 29807897

Conflict of interest statement: I declare I have no competing interests.

24. Eur Phys J C Part Fields. 2016;76(4):227. doi: 10.1140/epjc/s10052-016-4079-8. Epub 2016 Apr 25.

Quantum mechanics of 4-derivative theories.

Salvio A(1), Strumia A(2).

Author information: (1)Departamento de Física Teórica, Universidad Autónoma de Madrid and Instituto de Física Teórica IFT-UAM/CSIC, Madrid, Spain. (2)Dipartimento di Fisica dell'Università di Pisa and INFN, Pisa, Italy ; Theory Division, CERN, Geneva, Switzerland.

A renormalizable theory of gravity is obtained if the dimension-less 4-derivative kinetic term of the graviton, which classically suffers from negative unbounded energy, admits a sensible quantization. We find that a 4-derivative degree of freedom involves a canonical coordinate with unusual time-inversion parity, and that a correspondingly unusual representation must be employed for the relative quantum operator. The resulting theory has positive energy eigenvalues, normalizable wavefunctions, unitary evolution in a negative-norm configuration space. We present a formalism for quantum mechanics with a generic norm.

DOI: 10.1140/epjc/s10052-016-4079-8 PMCID: PMC5320946 PMID: 28280424

25. J Phys Chem A. 2019 Oct 31;123(43):9420-9428. doi: 10.1021/acs.jpca.9b08882. Epub 2019 Oct 21.

Quantum Mechanics/Extremely Localized Molecular Orbital Method: A Fully Quantum Mechanical Embedding Approach for Macromolecules.

Macetti G(1), Genoni A(1).

Author information: (1)Université de Lorraine & CNRS , Laboratoire de Physique et Chimie Théoriques (LPCT) , UMR CNRS 7019, 1 Boulevard Arago , F-57078 Metz , France.

The development of methods for the quantum mechanical study of macromolecules has always been an important challenge in theoretical chemistry. Nowadays, the techniques proposed in this context can be used to investigate very large systems and can be subdivided into two main categories: fragmentation and embedding strategies. In this paper, by modifying and improving the local self-consistent field approach originally proposed for quantum mechanics/molecular mechanics techniques, we introduce the new multiscale embedding quantum mechanics/extremely localized molecular orbital (QM/ELMO) method. The new strategy enables treatment of chemically relevant regions of large biological molecules through usual methods of quantum chemistry while describing the remaining parts of the systems by means of frozen extremely localized molecular orbitals transferred from properly constructed libraries. Test calculations have shown the correct functioning and the high reliability of the new approach, thus anticipating its possible applications to different fields of physical chemistry, such as rational drug design and structural refinements of proteins.

DOI: 10.1021/acs.jpca.9b08882 PMID: 31539253

26. Proc Natl Acad Sci U S A. 2018 Nov 13;115(46):11730-11735. doi: 10.1073/pnas.1807554115. Epub 2018 Oct 22.

Completely top-down hierarchical structure in quantum mechanics.

Aharonov Y(1)(2)(3), Cohen E(4)(5), Tollaksen J(6)(2).

Author information: (1)Institute for Quantum Studies, Chapman University, Orange, CA 92866; yakir@post.tau.ac.il eli17c@gmail.com. (2)Schmid College of Science and Technology, Chapman University, Orange, CA 92866. (3)School of Physics and Astronomy, Tel Aviv University, Tel Aviv 6997801, Israel. (4)Physics Department, Centre for Research in Photonics, University of Ottawa, Ottawa, ON K1N 6N5, Canada; yakir@post.tau.ac.il eli17c@gmail.com. (5)Faculty of Engineering, Institute of Nanotechnology and Advanced Materials, Bar Ilan University, Ramat Gan 5290002, Israel. (6)Institute for Quantum Studies, Chapman University, Orange, CA 92866.

Comment in Proc Natl Acad Sci U S A. 2018 Nov 13;115(46):11661-11663.

Can a large system be fully characterized using its subsystems via inductive reasoning? Is it possible to completely reduce the behavior of a complex system to the behavior of its simplest "atoms"? In this paper we answer these questions in the negative for a specific class of systems and measurements. After a general introduction of the topic, we present the main idea with a simple two-particle example, where strong correlations arise between two apparently empty boxes. This leads to surprising effects within atomic and electromagnetic systems. A general construction based on pre- and postselected ensembles is then suggested, wherein the N-body correlation can be genuinely perceived as a global property, as long as one is limited to performing measurements which we term "strictly local." We conclude that under certain boundary conditions, higher-order correlations within quantum mechanical systems can determine lower-order ones, but not vice versa. Surprisingly, the lower-order correlations provide no information whatsoever regarding the higher-order correlations. This supports a top-down structure in many-body quantum mechanics.

DOI: 10.1073/pnas.1807554115 PMCID: PMC6243242 PMID: 30348797

Conflict of interest statement: The authors declare no conflict of interest.

27. Philos Trans A Math Phys Eng Sci. 2016 May 28;374(2068):20150236. doi: 10.1098/rsta.2015.0236.

Darwinism in disguise? A comparison between Bohr's view on quantum mechanics and QBism.

Faye J(1).

Author information: (1)Media, Cognition and Communication, University of Copenhagen, Copenhagen, Denmark faye@hum.ku.dk.

The Copenhagen interpretation is first and foremost associated with Niels Bohr's philosophy of quantum mechanics. In this paper, I attempt to lay out what I see as Bohr's pragmatic approach to science in general and to quantum physics in particular. A part of this approach is his claim that the classical concepts are indispensable for our understanding of all physical phenomena, and it seems as if the claim is grounded in his reflection upon how the evolution of language is adapted to experience. Another, recent interpretation, QBism, has also found support in Darwin's theory. It may therefore not be surprising that sometimes QBism is said to be of the same breed as the Copenhagen interpretation. By comparing the two interpretations, I conclude, nevertheless, that there are important differences.

DOI: 10.1098/rsta.2015.0236 PMID: 27091172

28. Acta Crystallogr D Struct Biol. 2018 Nov 1;74(Pt 11):1063-1077. doi: 10.1107/S2059798318012913. Epub 2018 Oct 29.

High-throughput quantum-mechanics/molecular-mechanics (ONIOM) macromolecular crystallographic refinement with PHENIX/DivCon: the impact of mixed Hamiltonian methods on ligand and protein structure.

Borbulevych O(1), Martin RI(1), Westerhoff LM(1).

Author information: (1)QuantumBio Inc., 2790 West College Avenue, State College, PA 16801, USA.

Conventional macromolecular crystallographic refinement relies on often dubious stereochemical restraints, the preparation of which often requires human validation for unusual species, and on rudimentary energy functionals that are devoid of nonbonding effects owing to electrostatics, polarization, charge transfer or even hydrogen bonding. While this approach has served the crystallographic community for decades, as structure-based drug design/discovery (SBDD) has grown in prominence it has become clear that these conventional methods are less rigorous than they need to be in order to produce properly predictive protein-ligand models, and that the human intervention that is required to successfully treat ligands and other unusual chemistries found in SBDD often precludes high-throughput, automated refinement. Recently, plugins to the Python-based Hierarchical ENvironment for Integrated Xtallography (PHENIX) crystallographic platform have been developed to augment conventional methods with the in situ use of quantum mechanics (QM) applied to ligand(s) along with the surrounding active site(s) at each step of refinement [Borbulevych et al. (2014), Acta Cryst D70, 1233-1247]. This method (Region-QM) significantly increases the accuracy of the X-ray refinement process, and this approach is now used, coupled with experimental density, to accurately determine protonation states, binding modes, ring-flip states, water positions and so on. In the present work, this approach is expanded to include a more rigorous treatment of the entire structure, including the ligand(s), the associated active site(s) and the entire protein, using a fully automated, mixed quantum-mechanics/molecular-mechanics (QM/MM) Hamiltonian recently implemented in the DivCon package. This approach was validated through the automatic treatment of a population of 80 protein-ligand structures chosen from the Astex Diverse Set. Across the entire population, this method results in an average 3.5-fold reduction in ligand strain and a 4.5-fold improvement in MolProbity clashscore, as well as improvements in Ramachandran and rotamer outlier analyses. Overall, these results demonstrate that the use of a structure-wide QM/MM Hamiltonian exhibits improvements in the local structural chemistry of the ligand similar to Region-QM refinement but with significant improvements in the overall structure beyond the active site.

open access.

DOI: 10.1107/S2059798318012913 PMCID: PMC6213575 PMID: 30387765 [Indexed for MEDLINE]

29. Phys Rev Lett. 2018 Nov 16;121(20):201602. doi: 10.1103/PhysRevLett.121.201602.

Small Magnetic Charges and Monopoles in Nonassociative Quantum Mechanics.

Bojowald M(1), Brahma S(2), Büyükçam U(1), Guglielmon J(1), van Kuppeveld M(1).

Author information: (1)Department of Physics, The Pennsylvania State University, 104 Davey Lab, University Park, Pennsylvania 16802, USA. (2)Asia Pacific Center for Theoretical Physics, Pohang 37673, South Korea.

Weak magnetic monopoles with a continuum of charges less than the minimum implied by Dirac's quantization condition may be possible in nonassociative quantum mechanics. If a weakly magnetically charged proton in a hydrogen atom perturbs the standard energy spectrum only slightly, magnetic charges could have escaped detection. Testing this hypothesis requires entirely new methods to compute energy spectra in nonassociative quantum mechanics. Such methods are presented here, and evaluated for upper bounds on the magnetic charge of elementary particles.

DOI: 10.1103/PhysRevLett.121.201602 PMID: 30500233

30. Phys Chem Chem Phys. 2018 Dec 12;20(48):30076-30082. doi: 10.1039/c8cp06786d.

A perspective on quantum mechanics and chemical concepts in describing noncovalent interactions.

Clark T (1), Murray JS , Politzer P .

Author information: (1)Computer-Chemie-Centrum, Department of Chemistry and Pharmacy, Friedrich-Alexander-Universität Erlangen-Nürnberg, Nägelsbachstr. 25, 91052 Erlangen, Germany.

Since quantum mechanical calculations do not typically lend themselves to chemical interpretation, analyses of bonding interactions depend largely upon models (the octet rule, resonance theory, charge transfer, etc.). This sometimes leads to a blurring of the distinction between mathematical modelling and physical reality. The issue of polarization vs. charge transfer is an example; energy decomposition analysis is another. The Hellmann-Feynman theorem at least partially bridges the gap between quantum mechanics and conceptual chemistry. It proceeds rigorously from the Schrödinger equation to demonstrating that the forces exerted upon the nuclei in molecules, complexes, etc., are entirely classically coulombic attractions with the electrons and repulsions with the other nuclei. In this paper, we discuss these issues in the context of noncovalent interactions. These can be fully explained in coulombic terms, electrostatics and polarization (which include electronic correlation and dispersion).

DOI: 10.1039/c8cp06786d PMID: 30484786

31. Philos Trans A Math Phys Eng Sci. 2019 Nov 4;377(2157):20190025. doi: 10.1098/rsta.2019.0025. Epub 2019 Sep 16.

Quantum contextuality in the Copenhagen approach.

Jaeger G(1).

Author information: (1)Quantum Communication and Measurement Laboratory, Department of Electrical and Computer Engineering and Division of Natural Science and Mathematics, Boston University, Boston, MA, USA.

The origin and basis of the notion of quantum contextuality is identified in the Copenhagen approach to quantum mechanics, where context is automatically invoked by its requirement that the experimental arrangement involved in any measurements or set of measurements be taken into account while, in general, the outcome of a measurement may depend on other measurements immediately preceding or jointly performed on the same system. For Bohr, the specification of the experimental situation of any measurement is essential to its significance in light of complementarity and the omnipresence of the quantum of action in physics; for Heisenberg, the incompatibility of pairs of sharp measurements belonging to different situations coheres with both the completeness of the quantum state as an objective physical description and the principle of indeterminacy. Here, context in the Copenhagen approach is taken to be the equivalence class of experimental arrangements corresponding to a set of compatible measurements of quantum observables in standard quantum mechanics; the associated form of contextuality in quantum mechanics arises via the non-commutativity in general of sharp observables, proven by von Neumann, that can appear, providing different contexts. This notion is related to theoretical situations explored later by Bell, by Kochen and Specker, and by others in relation to the classification of hidden-variables theories and elsewhere in physics. This article is part of the theme issue 'Contextuality and probability in quantum mechanics and beyond'.

DOI: 10.1098/rsta.2019.0025 PMID: 31522644

32. Malays J Med Sci. 2019 Jan;26(1):147-156. doi: 10.21315/mjms2019.26.1.14. Epub 2019 Feb 28.

Understanding Neurobehavioural Dynamics: A Close-Up View on Psychiatry and Quantum Mechanics.

Latif WA(1), Ggha S(1).

Author information: (1)Cytogenetics and Molecular Toxicology Laboratory, Section of Genetics, Department of Zoology, Faculty of Life Science, Aligarh Muslim University, Aligarh, 202002, Uttar Pradesh, India.

Psychiatric disorders are prevalent throughout the world and causes heavy burden on mankind. Alone in US, billions of dollars are used for treatment purposes annually. Although advances in treatment strategies had witnessed recently, however the efficacy and overall outcome weren't quite promising. In neurobehavioural sciences, old problems survive through ages and with psychiatric disease, the phenomenon turns intensely complex. While our understanding of brain is mostly based on concepts of particle physics, its functions largely follow the principles of quantum mechanics. The current therapeutics relies on understanding of brain as a material entity that turns to be one of the chief reasons for the unsatisfactory therapeutic outcomes. Collectively, as mankind we are suffering huge loss due to the least effective treatment strategies. Even though we just begin to understand about how brain works, we also do not know much about quantum mechanics and how subatomic particles behave with quantum properties. Though it is apparent that quantum properties like particle and wave function duality coincides with the fundamental aspects of brain and mind duality, thus must share some common basis. Here in this article, an opinion is set that quantum mechanics in association with brain and more specifically psychiatry may take us towards a better understanding about brain, behaviour and how we approach towards treatment.

DOI: 10.21315/mjms2019.26.1.14 PMCID: PMC6419875 PMID: 30914902

Conflict of interest statement: Conflict of Interest The authors have no conflicts of interest to declare.

33. Phys Rev Lett. 2015 Nov 27;115(22):220402. doi: 10.1103/PhysRevLett.115.220402. Epub 2015 Nov 24.

Testing Nonassociative Quantum Mechanics.

Bojowald M(1), Brahma S(1), Büyükçam U(1).

Author information: (1)Institute for Gravitation and the Cosmos, The Pennsylvania State University, 104 Davey Lab, University Park, Pennsylvania 16802, USA.

Erratum in Phys Rev Lett. 2016 Aug 26;117(9):099901.

The familiar concepts of state vectors and operators in quantum mechanics rely on associative products of observables. However, these notions do not apply to some exotic systems such as magnetic monopoles, which have long been known to lead to nonassociative algebras. Their quantum physics has remained obscure. This Letter presents the first derivation of potentially testable physical results in nonassociative quantum mechanics, based on effective potentials. They imply new effects which cannot be mimicked in usual quantum mechanics with standard magnetic fields.

DOI: 10.1103/PhysRevLett.115.220402 PMID: 26650282

34. J Phys Chem A. 2020 Jan 9;124(1):141-147. doi: 10.1021/acs.jpca.9b09689. Epub 2019 Dec 24.

Multilevel Quantum Mechanics and Molecular Mechanics Study of the Double-Inversion Mechanism at Nitrogen: F(-) + NH(2)Cl in Aqueous Solution.

Niu X(1), Liu P(1), Wang D(1).

Author information: (1)College of Physics and Electronics , Shandong Normal University , Jinan , Shandong 250014 , China.

We employ a multilevel quantum mechanics and molecular mechanics method to investigate the double-inversion mechanism of the nucleophilic substitution reaction at the N center: the F- + NH2Cl reaction in aqueous solution. We find that the structures of the stationary points along the reaction path are quite different from the ones in the gas phase owing to the hydrogen-bond interactions between the solute and the surrounding water molecules. The atomic-level evolutions of the structures and charge transfer along the reaction path show that this double-inversion mechanism consists of an upside-down proton inversion process and a Walden-inversion process. The computed potential of mean force at the coupled-cluster singles and doubles with perturbative triples (CCSD(T))/molecular mechanics (MM) level of theory has the two-inversion barrier heights, and reaction free energy at 11.7, 29.6, and 12.6 kcal/mol, agreeing well with the predicted ones at 12.6, 32.5, and 12.2 kcal/mol obtained on the basis of the gas-phase reaction path and the solvation free energies of the stationary points.

DOI: 10.1021/acs.jpca.9b09689 PMID: 31820988

35. Phys Rev E. 2019 Sep;100(3-1):032207. doi: 10.1103/PhysRevE.100.032207.

Quantum mechanics and data assimilation.

Giannakis D(1).

Author information: (1)Center for Atmosphere Ocean Science, Courant Institute of Mathematical Sciences, New York University, New York, New York 10012, USA.

A framework for data assimilation combining aspects of operator-theoretic ergodic theory and quantum mechanics is developed. This framework adapts the Dirac-von Neumann formalism of quantum dynamics and measurement to perform sequential data assimilation (filtering) of a partially observed, measure-preserving dynamical system, using the Koopman operator on the L^{2} space associated with the invariant measure as an analog of the Heisenberg evolution operator in quantum mechanics. In addition, the state of the data assimilation system is represented by a trace-class operator analogous to the quantum mechanical density operator, and the assimilated observables by self-adjoint multiplication operators. An averaging approach is also introduced, rendering the spectrum of the assimilated observables discrete and thus amenable to numerical approximation. We present a data-driven formulation of the quantum mechanical data assimilation approach, utilizing kernel methods from machine learning and delay-coordinate maps of dynamical systems to represent the evolution and measurement operators via matrices in a data-driven basis. The data-driven formulation is structurally similar to its infinite-dimensional counterpart and shown to converge in a limit of large data under mild assumptions. Applications to periodic oscillators and the Lorenz 63 system demonstrate that the framework is able to naturally handle highly non-Gaussian statistics, complex state space geometries, and chaotic dynamics.

DOI: 10.1103/PhysRevE.100.032207 PMID: 31639900

36. Opt Lett. 2018 Jan 15;43(2):226-229. doi: 10.1364/OL.43.000226.

Equivalence principle and quantum mechanics: quantum simulation with entangled photons.

Longhi S.

Einstein's equivalence principle (EP) states the complete physical equivalence of a gravitational field and corresponding inertial field in an accelerated reference frame. However, to what extent the EP remains valid in non-relativistic quantum mechanics is a controversial issue. To avoid violation of the EP, Bargmann's superselection rule forbids a coherent superposition of states with different masses. Here we suggest a quantum simulation of non-relativistic Schrödinger particle dynamics in non-inertial reference frames, which is based on the propagation of polarization-entangled photon pairs in curved and birefringent optical waveguides and Hong-Ou-Mandel quantum interference measurement. The photonic simulator can emulate superposition of mass states, which would lead to violation of the EP.

DOI: 10.1364/OL.43.000226 PMID: 29328244

37. Chem Commun (Camb). 2018 Jul 12;54(57):7955-7958. doi: 10.1039/c8cc02850h.

Prediction and understanding of AIE effect by quantum mechanics-aided machine-learning algorithm.

Qiu J (1), Wang K , Lian Z , Yang X , Huang W , Qin A , Wang Q , Tian J , Tang B , Zhang S .

Author information: (1)School of Medicine, South China University of Technology, Guangzhou Higher Education Mega Center, Guangzhou 510006, China.

Significant effort has been devoted to the research of aggregation-induced emission (AIE); however, the discovery of new AIE materials is driven mainly by laborious trial-and-error. In this study, taking triphenylamine (TPA)-based luminophores as an example, we propose an efficient machine-learning scheme for predicting AIE-activity based on quantum mechanics.

DOI: 10.1039/c8cc02850h PMID: 29956696

38. Chaos. 2018 May;28(5):052101. doi: 10.1063/1.5026904.

Relativistic quantum chaos-An emergent interdisciplinary field.

Lai YC(1), Xu HY(1), Huang L(2), Grebogi C(3).

Author information: (1)School of Electrical, Computer and Energy Engineering, Arizona State University, Tempe, Arizona 85287, USA. (2)School of Physical Science and Technology, and Key Laboratory for Magnetism and Magnetic Materials of MOE, Lanzhou University, Lanzhou, Gansu 730000, China. (3)Institute for Complex Systems and Mathematical Biology, King's College, University of Aberdeen, Aberdeen AB24 3UE, United Kingdom.

Quantum chaos is referred to as the study of quantum manifestations or fingerprints of classical chaos. A vast majority of the studies were for nonrelativistic quantum systems described by the Schrödinger equation. Recent years have witnessed a rapid development of Dirac materials such as graphene and topological insulators, which are described by the Dirac equation in relativistic quantum mechanics. A new field has thus emerged: relativistic quantum chaos. This Tutorial aims to introduce this field to the scientific community. Topics covered include scarring, chaotic scattering and transport, chaos regularized resonant tunneling, superpersistent currents, and energy level statistics-all in the relativistic quantum regime. As Dirac materials have the potential to revolutionize solid-state electronic and spintronic devices, a good understanding of the interplay between chaos and relativistic quantum mechanics may lead to novel design principles and methodologies to enhance device performance.

DOI: 10.1063/1.5026904 PMID: 29857689

39. Angew Chem Int Ed Engl. 2018 Apr 9;57(16):4164-4169. doi: 10.1002/anie.201709686. Epub 2018 Mar 14.

Quantum Machine Learning in Chemical Compound Space.

von Lilienfeld OA(1).

Author information: (1)Institute of Physical Chemistry and National Center for Computational Design and Discovery of Novel Materials (MARVEL), Department of Chemistry, University of Basel, Klingelbergstrasse 80, 4056, Basel, Switzerland.

Rather than numerically solving the computationally demanding equations of quantum or statistical mechanics, machine learning methods can infer approximate solutions, interpolating previously acquired property data sets of molecules and materials. The case is made for quantum machine learning: An inductive molecular modeling approach which can be applied to quantum chemistry problems.

DOI: 10.1002/anie.201709686 PMID: 29216413

40. Sci Rep. 2017 Aug 10;7(1):7798. doi: 10.1038/s41598-017-08219-z.

Multi-level Quantum Mechanics and Molecular Mechanics Study of Ring Opening Process of Guanine Damage by Hydroxyl Radical in Aqueous Solution.

Liu P(1), Wang Q(2), Niu M(1), Wang D(3).

Author information: (1)College of Physics and Electronics, Shandong Normal University, Jinan, 250014, China. (2)College of Chemistry, Shandong Normal University, Jinan, 250014, China. (3)College of Physics and Electronics, Shandong Normal University, Jinan, 250014, China. dywang@sdnu.edu.cn.

Combining multi-level quantum mechanics theories and molecular mechanics with an explicit water model, we investigated the ring opening process of guanine damage by hydroxyl radical in aqueous solution. The detailed, atomic-level ring-opening mechanism along the reaction pathway was revealed in aqueous solution at the CCSD(T)/MM levels of theory. The potentials of mean force in aqueous solution were calculated at both the DFT/MM and CCSD(T)/MM levels of the theory. Our study found that the aqueous solution has a significant effect on this reaction in solution. In particular, by comparing the geometries of the stationary points between in gas phase and in aqueous solution, we found that the aqueous solution has a tremendous impact on the torsion angles much more than on the bond lengths and bending angles. Our calculated free-energy barrier height 31.6 kcal/mol at the CCSD(T)/MM level of theory agrees well with the one obtained based on gas-phase reaction profile and free energies of solvation. In addition, the reaction path in gas phase was also mapped using multi-level quantum mechanics theories, which shows a reaction barrier at 19.2 kcal/mol at the CCSD(T) level of theory, agreeing very well with a recent ab initio calculation result at 20.8 kcal/mol.

DOI: 10.1038/s41598-017-08219-z PMCID: PMC5552687 PMID: 28798372

Conflict of interest statement: The authors declare that they have no competing interests.

41. J Mol Model. 2015 Jun;21(6):138. doi: 10.1007/s00894-015-2681-6. Epub 2015 May 10.

A quantum mechanics-based halogen bonding scoring function for protein-ligand interactions.

Yang Z(1), Liu Y, Chen Z, Xu Z, Shi J, Chen K, Zhu W.

Author information: (1)Drug Discovery and Design Center, Key Laboratory of Receptor Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, 555 Zuchongzhi Road, Shanghai, 201203, China, zhuo.yang@sibcb.ac.cn.

A quantum mechanics-based scoring function for halogen bonding interaction, namely XBScore(QM), is developed based on 18,135 sets of geometrical and energetical parameters optimized at M06-2X/aug-cc-pVDZ level. Applying the function on typical halogen bonding systems from Protein Data Bank demonstrates its strong ability of predicting halogen bonding as attractive interaction with strength up to -4 kcal mol(-1). With a diverse set of proteins complexed with halogenated ligands, a systematic evaluation demonstrates the integrative advantage of XBScore(QM) over 12 other scoring functions on halogen bonding in four aspects, viz. pseudo docking power, ranking power, scoring power, and genuine docking power. Thus, this study not only provides a practicable scoring function of halogen bonding for high throughput virtual screening, but also serves as a benchmark for evaluating the performance of current scoring functions on characterizing halogen bonding.

DOI: 10.1007/s00894-015-2681-6 PMID: 25957658 [Indexed for MEDLINE]

42. J Chem Phys. 2018 Jul 28;149(4):044113. doi: 10.1063/1.5034771.

Red Moon methodology compatible with quantum mechanics/molecular mechanics framework: Application to solid electrolyte interphase film formation in lithium-ion battery system.

Fujie T(1), Takenaka N(1), Suzuki Y(1), Nagaoka M(1).

Author information: (1)Graduate School of Informatics, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601, Japan.

The Red Moon (RM) method [a hybrid Monte Carlo (MC)/molecular dynamics reaction method] is capable of realizing the practical atomistic simulation for complex chemical reaction systems beyond the range of application of the traditional molecular simulation techniques. In the RM method, the chemical reaction is treated stochastically based on the MC method. In the present study, to extend the applicability of the RM methodology, a new energy estimation method for the MC procedure has been proposed by using the quantum mechanics (QM)/molecular mechanics (MM) method. To validate its calculation reliability, we have examined it in a typical dimerization reaction in electrolytes of lithium-ion batteries (LIBs) and found that both solute internal energy and short-range solute-solvent interaction energy are significantly improved in comparison to the conventional energy estimation method using the MM method. As a practical application, we have dealt with the solid electrolyte interphase film formation in LIB, focusing on the bifurcation of dimerization reactions between the reduction products, and were able to reproduce the tendency similar to that in the experimental observations. It is concluded that the present RM methodology compatible with the QM/MM framework is expected to make a significant contribution to a variety of materials design and function development involved in various complex chemical reactions.

DOI: 10.1063/1.5034771 PMID: 30068180

43. Proc Math Phys Eng Sci. 2018 Sep;474(2217):20180264. doi: 10.1098/rspa.2018.0264. Epub 2018 Sep 12.

The minimally anisotropic metric operator in quasi-Hermitian quantum mechanics.

Krejčiřík D(1), Lotoreichik V(2), Znojil M(2).

Author information: (1)Department of Mathematics, Faculty of Nuclear Sciences and Physical Engineering, Czech Technical University in Prague, Trojanova 13, 12000 Prague 2, Czech Republic. (2)Department of Theoretical Physics, Nuclear Physics Institute, Czech Academy of Sciences, 25068 Řež, Czech Republic.

We propose a unique way to choose a new inner product in a Hilbert space with respect to which an originally non-self-adjoint operator similar to a self-adjoint operator becomes self-adjoint. Our construction is based on minimizing a 'Hilbert-Schmidt distance' to the original inner product among the entire class of admissible inner products. We prove that either the minimizer exists and is unique or it does not exist at all. In the former case, we derive a system of Euler-Lagrange equations by which the optimal inner product is determined. A sufficient condition for the existence of the unique minimally anisotropic metric is obtained. The abstract results are supported by examples in which the optimal inner product does not coincide with the most popular choice fixed through a charge-like symmetry.

DOI: 10.1098/rspa.2018.0264 PMCID: PMC6189602 PMID: 30333705

Conflict of interest statement: There are no competing interests related to this paper.

44. Phys Rev E. 2018 May;97(5-1):053311. doi: 10.1103/PhysRevE.97.053311.

Computational applications of the many-interacting-worlds interpretation of quantum mechanics.

Sturniolo S(1).

Author information: (1)Scientific Computing Department, STFC, Rutherford Appleton Laboratory, Harwell Campus, Didcot OX11 0QX, United Kingdom.

While historically many quantum-mechanical simulations of molecular dynamics have relied on the Born-Oppenheimer approximation to separate electronic and nuclear behavior, recently a great deal of interest has arisen in quantum effects in nuclear dynamics as well. Due to the computational difficulty of solving the Schrödinger equation in full, these effects are often treated with approximate methods. In this paper, we present an algorithm to tackle these problems using an extension to the many-interacting-worlds approach to quantum mechanics. This technique uses a kernel function to rebuild the probability density, and therefore, in contrast with the approximation presented in the original paper, it can be naturally extended to n-dimensional systems. This opens up the possibility of performing quantum ground-state searches with steepest-descent methods, and it could potentially lead to real-time quantum molecular-dynamics simulations. The behavior of the algorithm is studied in different potentials and numbers of dimensions and compared both to the original approach and to exact Schrödinger equation solutions whenever possible.

DOI: 10.1103/PhysRevE.97.053311 PMID: 29906823

45. Phys Rev E. 2016 Jun;93(6):066104. doi: 10.1103/PhysRevE.93.066104. Epub 2016 Jun 29.

Reply to "Comment on 'Fractional quantum mechanics' and 'Fractional Schrödinger equation' ".

Laskin N(1).

Author information: (1)TopQuark Inc., Toronto, Ontario, Canada M6P 2P2.

The fractional uncertainty relation is a mathematical formulation of Heisenberg's uncertainty principle in the framework of fractional quantum mechanics. Two mistaken statements presented in the Comment have been revealed. The origin of each mistaken statement has been clarified and corrected statements have been made. A map between standard quantum mechanics and fractional quantum mechanics has been presented to emphasize the features of fractional quantum mechanics and to avoid misinterpretations of the fractional uncertainty relation. It has been shown that the fractional probability current equation is correct in the area of its applicability. Further studies have to be done to find meaningful quantum physics problems with involvement of the fractional probability current density vector and the extra term emerging in the framework of fractional quantum mechanics.

DOI: 10.1103/PhysRevE.93.066104 PMID: 27415398

46. J Phys Condens Matter. 2019 May 15;31(19):195801. doi: 10.1088/1361-648X/ab0686. Epub 2019 Feb 12.

Manipulating quantum spins by spin-polarized current: an approach based upon [Formula: see text]-symmetric quantum mechanics.

Bou Comas A(1), Chudnovsky EM, Tejada J.

Author information: (1)Facultat de Física, Universitat de Barcelona, Diagonal 645, 08028 Barcelona, Spain.

We propose a quantum processor based upon single-molecule magnets and spin transfer torque described by [Formula: see text]-symmetric quantum mechanics. In recent years [Formula: see text]-symmetric Hamiltonians have been used to obtain stability thresholds of various systems out of equilibrium. One such problem is the magnetization reversal due to the spin transfer torque generated by a spin-polarized current. So far the studies of this problem have mostly focused on a classical limit of a large spin. In this work we are discussing spin tunneling and quantum dynamics of a small spin induced by a spin polarized current within a [Formula: see text]-symmetric theory. This description can be used for manipulating spin qubits by electric currents.

DOI: 10.1088/1361-648X/ab0686 PMID: 30754032

47. Curr Opin Drug Discov Devel. 2006 May;9(3):370-9.

Quantum mechanics in structure-based drug design.

Peters MB(1), Raha K, Merz KM Jr.

Author information: (1)University of Florida, Department of Chemistry, Quantum Theory Project, 2328 New Physics Building, PO Box 118435, Gainesville, FL 32611 USA.

In principle, quantum mechanics provides a more accurate representation of molecular systems than other modeling approaches. While this notion is not a matter of dispute, it has not yet been definitively demonstrated within the realm of structure-based drug design that the use of quantum mechanical methods over the use of classical modeling approaches is justified in consideration of the increase in expense associated with quantum mechanical methods. Demonstrating that quantum mechanics-based methods can be superior to simpler models, and resolving problems relating to estimating the effects of conformational entropy, will provide key areas of interest in the coming years for in silico structure-based drug design. Recent applications using quantum mechanical methods in structure-based drug design are reviewed herein, and applications ranging from scoring receptor-ligand interactions using quantum mechanics to the generation of quantitative structure-activity relationships using quantum mechanics-derived descriptors are discussed.

PMID: 16729734 [Indexed for MEDLINE]

48. Curr Top Med Chem. 2013;13(11):1257-72. doi: 10.2174/15680266113139990032.

A perspective on quantum mechanics calculations in ADMET predictions.

Bowen JP(1), Güner OF.

Author information: (1)Center for Drug Design, Department of Pharmaceutical Sciences, College of Pharmacy and Health Sciences, Mercer University, 3001 Mercer University Drive, Atlanta, GA 30341, USA. bowen_jp@mercer.edu

Understanding the molecular basis of drug action has been an important objective for pharmaceutical scientists. With the increasing speed of computers and the implementation of quantum chemistry methodologies, pharmacodynamic and pharmacokinetic problems have become more computationally tractable. Historically the former has been the focus of drug design, but within the last two decades efforts to understand the latter have increased. It takes about fifteen years and over $1 billion dollars for a drug to go from laboratory hit, through lead optimization, to final approval by the U.S. Food and Drug Administration. While the costs have increased substantially, the overall clinical success rate for a compound to emerge from clinical trials is approximately 10%. Most of the attrition rate can be traced to ADMET (absorption, distribution, metabolism, excretion, and toxicity) problems, which is a powerful impetus to study these issues at an earlier stage in drug discovery. Quantum mechanics offers pharmaceutical scientists the opportunity to investigate pharmacokinetic problems at the molecular level prior to laboratory preparation and testing. This review will provide a perspective on the use of quantum mechanics or a combination of quantum mechanics coupled with other classical methods in the pharmacokinetic phase of drug discovery. A brief overview of the essential features of theory will be discussed, and a few carefully selected examples will be given to highlight the computational methods.

DOI: 10.2174/15680266113139990032 PMID: 23675934 [Indexed for MEDLINE]

49. J Mol Model. 2018 Feb 1;24(2):46. doi: 10.1007/s00894-018-3589-8.

Biologically important conformational features of DNA as interpreted by quantum mechanics and molecular mechanics computations of its simple fragments.

Poltev V(1), Anisimov VM(2), Dominguez V(3), Gonzalez E(3), Deriabina A(3), Garcia D(3), Rivas F(3), Polteva NA(4).

Author information: (1)Autonomous University of Puebla, 72570, Puebla, Mexico. poltev@fcfm.buap.mx. (2)National Center for Supercomputing Applications, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA. (3)Autonomous University of Puebla, 72570, Puebla, Mexico. (4)Institute of Theoretical and Experimental Biophysics, Russian Academy of Sciences, Pushchino, 142290, Russia.

Deciphering the mechanism of functioning of DNA as the carrier of genetic information requires identifying inherent factors determining its structure and function. Following this path, our previous DFT studies attributed the origin of unique conformational characteristics of right-handed Watson-Crick duplexes (WCDs) to the conformational profile of deoxydinucleoside monophosphates (dDMPs) serving as the minimal repeating units of DNA strand. According to those findings, the directionality of the sugar-phosphate chain and the characteristic ranges of dihedral angles of energy minima combined with the geometric differences between purines and pyrimidines determine the dependence on base sequence of the three-dimensional (3D) structure of WCDs. This work extends our computational study to complementary deoxydinucleotide-monophosphates (cdDMPs) of non-standard conformation, including those of Z-family, Hoogsteen duplexes, parallel-stranded structures, and duplexes with mispaired bases. For most of these systems, except Z-conformation, computations closely reproduce experimental data within the tolerance of characteristic limits of dihedral parameters for each conformation family. Computation of cdDMPs with Z-conformation reveals that their experimental structures do not correspond to the internal energy minimum. This finding establishes the leading role of external factors in formation of the Z-conformation. Energy minima of cdDMPs of non-Watson-Crick duplexes demonstrate different sequence-dependence features than those known for WCDs. The obtained results provide evidence that the biologically important regularities of 3D structure distinguish WCDs from duplexes having non-Watson-Crick nucleotide pairing.

DOI: 10.1007/s00894-018-3589-8 PMID: 29392428 [Indexed for MEDLINE]

50. Methods Mol Biol. 2020;2114:339-353. doi: 10.1007/978-1-0716-0282-9_20.

What Next for Quantum Mechanics in Structure-Based Drug Discovery?

Bryce RA(1).

Author information: (1)Division of Pharmacy and Optometry, School of Health Sciences, University of Manchester, Manchester, UK. R.A.Bryce@manchester.ac.uk.

There is significant potential for electronic structure methods to improve the quality of the predictions furnished by the tools of computer-aided drug design, which typically rely on empirically derived functions. In this perspective, we consider some recent examples of how quantum mechanics has been applied in predicting protein-ligand geometries, protein-ligand binding affinities and ligand strain on binding. We then outline several significant developments in quantum mechanics methodology likely to influence these approaches: in particular, we note the advent of more computationally expedient ab initio quantum mechanical methods that can provide chemical accuracy for larger molecular systems than hitherto possible. We highlight the emergence of increasingly accurate semiempirical quantum mechanical methods and the associated role of machine learning and molecular databases in their development. Indeed, the convergence of improved algorithms for solving and analyzing electronic structure, modern machine learning methods, and increasingly comprehensive benchmark data sets of molecular geometries and energies provides a context in which the potential of quantum mechanics will be increasingly realized in driving future developments and applications in structure-based drug discovery.

DOI: 10.1007/978-1-0716-0282-9_20 PMID: 32016902

51. Food Chem. 2018 Jun 30;252:163-170. doi: 10.1016/j.foodchem.2018.01.091. Epub 2018 Jan 12.

Combined spectroscopic, molecular docking and quantum mechanics study of β-casein and p-coumaric acid interactions following thermal treatment.

Kaur J(1), Katopo L(1), Hung A(1), Ashton J(2), Kasapis S(3).

Author information: (1)School of Science, RMIT University, Bundoora West Campus, Plenty Road, Melbourne, VIC 3083, Australia. (2)Sanitarium Development and Innovation, Sanitarium Health and Wellbeing Company, Cooranbong, NSW 2265, Australia. (3)School of Science, RMIT University, Bundoora West Campus, Plenty Road, Melbourne, VIC 3083, Australia. Electronic address: stefan.kasapis@rmit.edu.au.

The molecular nature of interactions between β-casein and p-coumaric acid was studied following exposure of their solutions to ultra-high temperature (UHT at 145 °C). Interactions were characterised by employing multi-spectroscopic methods, molecular docking and quantum mechanics calculations. FTIR demonstrates that the ligand lies in the vicinity of the protein, hence inverting the absorbance spectrum of the complex. This outcome changes the conformational characteristics of the protein leading to a flexible and open structure that accommodates the phenolic microconstituent. Results are supported by UV-vis, CD and fluorescence quenching showing considerable shifts in spectra with complexation. Molecular docking indicates that there is at least a hydrogen bond between p-coumaric acid and the peptide backbone of isoleucine (Ile27). Quantum mechanics calculations further argue that changes in experimental observations are also due to a covalent interaction in the protein-phenolic adduct, which according to the best predicted binding pose involves the side chain of lysine 47.

DOI: 10.1016/j.foodchem.2018.01.091 PMID: 29478528 [Indexed for MEDLINE]

52. J Chem Phys. 2006 Dec 21;125(23):231103. doi: 10.1063/1.2400851.

Bohmian mechanics with complex action: a new trajectory-based formulation of quantum mechanics.

Goldfarb Y(1), Degani I, Tannor DJ.

Author information: (1)Department of Chemical Physics, The Weizmann Institute of Science, Rehovot, 76100 Israel.

Comment in J Chem Phys. 2007 Nov 21;127(19):197101, author reply 197102.

In recent years there has been a resurgence of interest in Bohmian mechanics as a numerical tool because of its local dynamics, which suggest the possibility of significant computational advantages for the simulation of large quantum systems. However, closer inspection of the Bohmian formulation reveals that the nonlocality of quantum mechanics has not disappeared-it has simply been swept under the rug into the quantum force. In this paper we present a new formulation of Bohmian mechanics in which the quantum action, S, is taken to be complex. This leads to a single equation for complex S, and ultimately complex x and p but there is a reward for this complexification-a significantly higher degree of localization. The quantum force in the new approach vanishes for Gaussian wave packet dynamics, and its effect on barrier tunneling processes is orders of magnitude lower than that of the classical force. In fact, the current method is shown to be a rigorous extension of generalized Gaussian wave packet dynamics to give exact quantum mechanics. We demonstrate tunneling probabilities that are in virtually perfect agreement with the exact quantum mechanics down to 10(-7) calculated from strictly localized quantum trajectories that do not communicate with their neighbors. The new formulation may have significant implications for fundamental quantum mechanics, ranging from the interpretation of non-locality to measures of quantum complexity.

DOI: 10.1063/1.2400851 PMID: 17190540

53. Philos Trans A Math Phys Eng Sci. 2015 Aug 6;373(2047):20140245. doi: 10.1098/rsta.2014.0245.

The geometric semantics of algebraic quantum mechanics.

Cruz Morales JA(1), Zilber B(2).

Author information: (1)Instituto Nacional de Matemática Pura e Aplicada, IMPA, Estrada Dona Castorina 110, Rio de Janeiro 22460-320, Brazil alekosandro@gmail.com jacruzm@impa.br. (2)Mathematical Institute, University of Oxford, 24-29 St Giles, Oxford OX1 3LB, UK.

In this paper, we will present an ongoing project that aims to use model theory as a suitable mathematical setting for studying the formalism of quantum mechanics. We argue that this approach provides a geometric semantics for such a formalism by means of establishing a (non-commutative) duality between certain algebraic and geometric objects.

DOI: 10.1098/rsta.2014.0245 PMID: 26124252

54. J Chem Phys. 2017 Oct 28;147(16):161732. doi: 10.1063/1.5006882.

Internal force corrections with machine learning for quantum mechanics/molecular mechanics simulations.

Wu J(1), Shen L(1), Yang W(1).

Author information: (1)Department of Chemistry, Duke University, Durham, North Carolina 27708, USA.

Ab initio quantum mechanics/molecular mechanics (QM/MM) molecular dynamics simulation is a useful tool to calculate thermodynamic properties such as potential of mean force for chemical reactions but intensely time consuming. In this paper, we developed a new method using the internal force correction for low-level semiempirical QM/MM molecular dynamics samplings with a predefined reaction coordinate. As a correction term, the internal force was predicted with a machine learning scheme, which provides a sophisticated force field, and added to the atomic forces on the reaction coordinate related atoms at each integration step. We applied this method to two reactions in aqueous solution and reproduced potentials of mean force at the ab initio QM/MM level. The saving in computational cost is about 2 orders of magnitude. The present work reveals great potentials for machine learning in QM/MM simulations to study complex chemical processes.

DOI: 10.1063/1.5006882 PMCID: PMC6910592 PMID: 29096448

55. Carbohydr Res. 2015 Feb 11;403:38-47. doi: 10.1016/j.carres.2014.06.017. Epub 2014 Jun 24.

Atomistic insight into the catalytic mechanism of glycosyltransferases by combined quantum mechanics/molecular mechanics (QM/MM) methods.

Tvaroška I(1).

Author information: (1)Department of Chemistry, Slovak Academy of Sciences, Bratislava, Slovakia; Department of Chemistry, Faculty of Natural Sciences, Constantine the Philosopher University, SK-949 74 Nitra, Slovakia. Electronic address: chemitsa@savba.sk.

Glycosyltransferases catalyze the formation of glycosidic bonds by assisting the transfer of a sugar residue from donors to specific acceptor molecules. Although structural and kinetic data have provided insight into mechanistic strategies employed by these enzymes, molecular modeling studies are essential for the understanding of glycosyltransferase catalyzed reactions at the atomistic level. For such modeling, combined quantum mechanics/molecular mechanics (QM/MM) methods have emerged as crucial. These methods allow the modeling of enzymatic reactions by using quantum mechanical methods for the calculation of the electronic structure of the active site models and treating the remaining enzyme environment by faster molecular mechanics methods. Herein, the application of QM/MM methods to glycosyltransferase catalyzed reactions is reviewed, and the insight from modeling of glycosyl transfer into the mechanisms and transition states structures of both inverting and retaining glycosyltransferases are discussed.

DOI: 10.1016/j.carres.2014.06.017 PMID: 25060837 [Indexed for MEDLINE]

56. Stud Hist Philos Sci. 2020 Apr;80:72-81. doi: 10.1016/j.shpsa.2019.03.006. Epub 2019 Mar 28.

Pluralism and anarchism in quantum physics: Paul Feyerabend's writings on quantum physics in relation to his general philosophy of science.

van Strien M(1).

Author information: (1)Bergische Universität Wuppertal, Interdisziplinäres Zentrum für Wissenschafts- und Technikforschung, Gaußstr. 20, 42219, Wuppertal, Germany. Electronic address: vanstrien@uni-wuppertal.de.

This paper aims to show that the development of Feyerabend's philosophical ideas in the 1950s and 1960s largely took place in the context of debates on quantum mechanics. In particular, he developed his influential arguments for pluralism in science in discussions with the quantum physicist David Bohm, who had developed an alternative approach to quantum physics which (in Feyerabend's perception) was met with a dogmatic dismissal by some of the leading quantum physicists. I argue that Feyerabend's arguments for theoretical pluralism and for challenging established theories were connected to his objections to the dogmatism and conservatism he observed in quantum physics. However, as Feyerabend gained insight into the physical details and historical complexities which led to the development of quantum mechanics, he gradually became more modest in his criticisms. His writings on quantum mechanics especially engaged with Niels Bohr; initially, he was critical of Bohr's work in quantum mechanics, but in the late 1960s, he completely withdrew his criticism and even praised Bohr as a model scientist. He became convinced that however puzzling quantum mechanics seemed, it was methodologically unobjectionable - and this was crucial for his move towards 'anarchism' in philosophy of science.

DOI: 10.1016/j.shpsa.2019.03.006 PMID: 32383675

57. Eur J Med Chem. 2017 May 5;131:152-170. doi: 10.1016/j.ejmech.2017.03.021. Epub 2017 Mar 14.

Systematic study of imidazoles inhibiting IDO1 via the integration of molecular mechanics and quantum mechanics calculations.

Zou Y(1), Wang F(1), Wang Y(2), Guo W(2), Zhang Y(1), Xu Q(3), Lai Y(4).

Author information: (1)State Key Laboratory of Natural Medicines, Jiangsu Key Laboratory of Drug Discovery for Metabolic Diseases, Center of Drug Discovery, China Pharmaceutical University, Nanjing 210009, PR China. (2)State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University, Nanjing 210093, PR China. (3)State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University, Nanjing 210093, PR China. Electronic address: molpharm@163.com. (4)State Key Laboratory of Natural Medicines, Jiangsu Key Laboratory of Drug Discovery for Metabolic Diseases, Center of Drug Discovery, China Pharmaceutical University, Nanjing 210009, PR China. Electronic address: yslai@cpu.edu.cn.

Indoleamine 2,3-dioxygenase 1 (IDO1) is regarded as an attractive target for cancer immunotherapy. To rationalize the detailed interactions between IDO1 and its inhibitors at the atomic level, an integrated computational approach by combining molecular mechanics and quantum mechanics methods was employed in this report. Specifically, the binding modes of 20 inhibitors was initially investigated using the induced fit docking (IFD) protocol, which outperformed other two docking protocols in terms of correctly predicting ligand conformations. Secondly, molecular dynamics (MD) simulations and MM/PBSA free energy calculations were employed to determine the dynamic binding process and crucial residues were confirmed through close contact analysis, hydrogen-bond analysis and binding free energy decomposition calculations. Subsequent quantum mechanics and nonbonding interaction analysis were carried out to provide in-depth explanations on the critical role of those key residues, and Arg231 and 7-propionate of the heme group were major contributors to ligand binding, which lowed a great amount of interaction energy. We anticipate that these findings will be valuable for enzymatic studies and rational drug design.

DOI: 10.1016/j.ejmech.2017.03.021 PMID: 28319781 [Indexed for MEDLINE]

58. Ann Appl Probab. 2016 Aug;26(4):2540-2555. doi: 10.1214/15-AAP1154. Epub 2016 Sep 1.

Convergence of empirical distributions in an interpretation of quantum mechanics.

McKeague IW(1), Levin B(1).

Author information: (1)Department of Biostatistics, Columbia University.

From its beginning, there have been attempts by physicists to formulate quantum mechanics without requiring the use of wave functions. An interesting recent approach takes the point of view that quantum effects arise solely from the interaction of finitely many classical "worlds." The wave function is then recovered (as a secondary object) from observations of particles in these worlds, without knowing the world from which any particular observation originates. Hall, Deckert and Wiseman [Physical Review X 4 (2014) 041013] have introduced an explicit many-interacting-worlds harmonic oscillator model to provide support for this approach. In this note we provide a proof of their claim that the particle configuration is asymptotically Gaussian, thus matching the stationary ground-state solution of Schrödinger's equation when the number of worlds goes to infinity. We also construct a Markov chain based on resampling from the particle configuration and show that it converges to an Ornstein-Uhlenbeck process, matching the time-dependent solution as well.

DOI: 10.1214/15-AAP1154 PMCID: PMC5542025 PMID: 28781498

59. Philos Trans A Math Phys Eng Sci. 2017 Nov 13;375(2106):20160393. doi: 10.1098/rsta.2016.0393.

Quantum mechanics: why complex Hilbert space?

Cassinelli G(1), Lahti P(2).

Author information: (1)Department of Physics, University of Genoa and INFN Genoa Unit, Genoa, Italy. (2)Department of Physics and Astronomy, University of Turku, Turku, Finland pekka.lahti@utu.fi.

We outline a programme for an axiomatic reconstruction of quantum mechanics based on the statistical duality of states and effects that combines the use of a theorem of Solér with the idea of symmetry. We also discuss arguments favouring the choice of the complex field.This article is part of the themed issue 'Second quantum revolution: foundational questions'.

DOI: 10.1098/rsta.2016.0393 PMID: 28971945

60. Phys Rev E Stat Nonlin Soft Matter Phys. 2015 Jul;92(1):013006. doi: 10.1103/PhysRevE.92.013006. Epub 2015 Jul 6.

Double-slit experiment with single wave-driven particles and its relation to quantum mechanics.

Andersen A(1), Madsen J(1), Reichelt C(1), Rosenlund Ahl S(1), Lautrup B(2), Ellegaard C(3), Levinsen MT(3), Bohr T(1).

Author information: (1)Department of Physics and Center for Fluid Dynamics, Technical University of Denmark, DK-2800 Kgs. Lyngby, Denmark. (2)Niels Bohr International Academy, The Niels Bohr Institute, Blegdamsvej 17, DK-2100 Copenhagen Ø, Denmark. (3)The Niels Bohr Institute, University of Copenhagen, Blegdamsvej 17, DK-2100 Copenhagen Ø, Denmark.

In a thought-provoking paper, Couder and Fort [Phys. Rev. Lett. 97, 154101 (2006)] describe a version of the famous double-slit experiment performed with droplets bouncing on a vertically vibrated fluid surface. In the experiment, an interference pattern in the single-particle statistics is found even though it is possible to determine unambiguously which slit the walking droplet passes. Here we argue, however, that the single-particle statistics in such an experiment will be fundamentally different from the single-particle statistics of quantum mechanics. Quantum mechanical interference takes place between different classical paths with precise amplitude and phase relations. In the double-slit experiment with walking droplets, these relations are lost since one of the paths is singled out by the droplet. To support our conclusions, we have carried out our own double-slit experiment, and our results, in particular the long and variable slit passage times of the droplets, cast strong doubt on the feasibility of the interference claimed by Couder and Fort. To understand theoretically the limitations of wave-driven particle systems as analogs to quantum mechanics, we introduce a Schrödinger equation with a source term originating from a localized particle that generates a wave while being simultaneously guided by it. We show that the ensuing particle-wave dynamics can capture some characteristics of quantum mechanics such as orbital quantization. However, the particle-wave dynamics can not reproduce quantum mechanics in general, and we show that the single-particle statistics for our model in a double-slit experiment with an additional splitter plate differs qualitatively from that of quantum mechanics.

DOI: 10.1103/PhysRevE.92.013006 PMID: 26274269

61. Integr Med Res. 2016 Dec;5(4):237-243. doi: 10.1016/j.imr.2016.08.003. Epub 2016 Aug 21.

The quantum universe: philosophical foundations and oriental medicine.

Kafatos MC(1), Yang KH(1).

Author information: (1)Center of Excellence in Earth Systems Modeling and Observations (CEESMO), Schmid College of Science and Technology, Chapman University, Orange, CA, USA.

The existence of universal principles in both science and medicine implies that one can explore their common applicability. Here we explore what we have learned from quantum mechanics, phenomena such as entanglement and nonlocality, the role of participation of the observer, and how these may apply to oriental medicine. The universal principles of integrated polarity, recursion, and creative interactivity apply to all levels of existence and all human activities, including healing and medicine. This review examines the possibility that what we have learned from quantum mechanics may provide clues to better understand the operational principles of oriental medicine in an integrated way. Common to both is the assertion that Consciousness is at the foundation of the universe and the inner core of all human beings. This view goes beyond both science and medicine and has strong philosophical foundations in Western philosophy as well as monistic systems of the East.

DOI: 10.1016/j.imr.2016.08.003 PMCID: PMC5390421 PMID: 28462124

62. J Asian Nat Prod Res. 2016;18(1):72-91. doi: 10.1080/10286020.2015.1134502.

Assignment of absolute stereostructures through quantum mechanics electronic and vibrational circular dichroism calculations.

Dai P(1), Jiang N(2), Tan RX(1).

Author information: (1)a State Key Laboratory of Pharmaceutical Biotechnology, Institute of Functional Biomolecules , Nanjing University , Nanjing 210093 , China. (2)b School of Pharmacy , Nanjing University , Nanjing 210029 , China.

Elucidation of absolute configuration of chiral molecules including structurally complex natural products remains a challenging problem in organic chemistry. A reliable method for assigning the absolute stereostructure is to combine the experimental circular dichroism (CD) techniques such as electronic and vibrational CD (ECD and VCD), with quantum mechanics (QM) ECD and VCD calculations. The traditional QM methods as well as their continuing developments make them more applicable with accuracy. Taking some chiral natural products with diverse conformations as examples, this review describes the basic concepts and new developments of QM approaches for ECD and VCD calculations in solution and solid states.

DOI: 10.1080/10286020.2015.1134502 PMID: 26880597 [Indexed for MEDLINE]

63. Front Chem. 2018 May 29;6:188. doi: 10.3389/fchem.2018.00188. eCollection 2018.

Quantum Chemical Approaches in Structure-Based Virtual Screening and Lead Optimization.

Cavasotto CN(1), Adler NS(1), Aucar MG(1).

Author information: (1)Laboratory of Computational Chemistry and Drug Design, Instituto de Investigación en Biomedicina de Buenos Aires, CONICET, Partner Institute of the Max Planck Society, Buenos Aires, Argentina.

Today computational chemistry is a consolidated tool in drug lead discovery endeavors. Due to methodological developments and to the enormous advance in computer hardware, methods based on quantum mechanics (QM) have gained great attention in the last 10 years, and calculations on biomacromolecules are becoming increasingly explored, aiming to provide better accuracy in the description of protein-ligand interactions and the prediction of binding affinities. In principle, the QM formulation includes all contributions to the energy, accounting for terms usually missing in molecular mechanics force-fields, such as electronic polarization effects, metal coordination, and covalent binding; moreover, QM methods are systematically improvable, and provide a greater degree of transferability. In this mini-review we present recent applications of explicit QM-based methods in small-molecule docking and scoring, and in the calculation of binding free-energy in protein-ligand systems. Although the routine use of QM-based approaches in an industrial drug lead discovery setting remains a formidable challenging task, it is likely they will increasingly become active players within the drug discovery pipeline.

DOI: 10.3389/fchem.2018.00188 PMCID: PMC5986912 PMID: 29896472

64. Methods Mol Biol. 2020;2114:207-229. doi: 10.1007/978-1-0716-0282-9_14.

Conformational Searching with Quantum Mechanics.

Habgood M(1), James T(2), Heifetz A(2).

Author information: (1)Evotec (UK) Ltd., Oxfordshire, UK. matthew.habgood@googlemail.com. (2)Evotec (UK) Ltd., Oxfordshire, UK.

Estimating the range of three-dimensional structures (conformations) that are available to a molecule is a key component of computer-aided drug design. Quantum mechanical simulation offers improved accuracy over forcefield methods, but at a high computational cost. The question is whether this increased cost can be justified in a context in which high-throughput analysis of large numbers of molecules is often key. This chapter discusses the application of quantum mechanics to conformational searching, with a focus on three key challenges: (1) the generation of ensembles that include a good approximation to a molecule's bioactive conformation at as prominent a ranking as possible; (2) rational analysis and modification of a pre-established bioactive conformation in terms of its energetics; and (3) approximation of real solution-phase conformational ensembles in tandem with NMR data. The impact of QM on the high-throughput application (1) is debatable, meaning that for the moment its primary application is still lower-throughput applications such as (2) and (3). The optimal choice of QM method is also discussed. Rigorous benchmarking suggests that DFT methods are only acceptable when used with large basis sets, but a trickle of papers continue to obtain useful results with relatively low-cost methods, leading to a dilemma that the literature has yet to fully resolve.

DOI: 10.1007/978-1-0716-0282-9_14 PMID: 32016896

65. Scand Stat Theory Appl. 2015 Jun 1;42(2):329-335. doi: 10.1111/sjos.12089.

A proof of Bell's inequality in quantum mechanics using causal interactions.

Robins JM(1), VanderWeele TJ(1), Gill RD(2).

Author information: (1)Departments of Epidemiology and Biostatistics, Harvard School of Public Health. (2)Mathematical Institute, Leiden University.

We give a simple proof of Bell's inequality in quantum mechanics using theory from causal interaction, which, in conjunction with experiments, demonstrates that the local hidden variables assumption is false. The proof sheds light on relationships between the notion of causal interaction and interference between treatments.

DOI: 10.1111/sjos.12089 PMCID: PMC4520697 PMID: 26236075

66. J Comput Chem. 2018 Jun 30;39(17):1068-1075. doi: 10.1002/jcc.24883. Epub 2017 Jul 27.

Contracted Schrödinger equation in quantum phase-space.

Frishberg C(1), Cohen L(2).

Author information: (1)Department of Chemistry, Ramapo College of New Jersey, 505 Ramapo Valley Rd, Mahwah, New Jersey, 07430. (2)Department of Physics, Hunter College of the City University, New York, New York, 10065.

The phase space formulation of quantum mechanics is equivalent to standard quantum mechanics where averages are calculated by way of phase space integration as in the case of classical statistical mechanics. We derive the quantum hierarchy equations, often called the contracted Schrödinger equation, in the phase space representation of quantum mechanics which involves quasi-distributions of position and momentum. We use the Wigner distribution for the phase space function and the Moyal phase space eigenvalue formulation to derive the hierarchy. We show that the hierarchy equations in the position, momentum, and position-momentum representations are very similar in structure. © 2017 Wiley Periodicals, Inc.

DOI: 10.1002/jcc.24883 PMID: 28749532

67. J Mol Model. 2018 Aug 29;24(9):257. doi: 10.1007/s00894-018-3795-4.

Quantum simulation of nanosized materials: 100 years of mystery is solved.

Tachibana A(1).

Author information: (1)Department of Micro Engineering, Kyoto University, Kyoto daigaku-Katsura, Nishikyo-ku, Kyoto, 615-8540, Japan. tachibana.akitomo.43s@st.kyoto-u.ac.jp.

Application of alpha-oscillator theory to quantum electrodynamics (QED) solves the mystery (as Feynman said) of the double-slit phenomenon involved in the foundation of quantum mechanics (QM). Even if with the same initial condition given, different spots on the screen can be predicted deterministically with no introduction of hidden variables. The general proof has already been published in Ref. [3] and "what is new in this paper" is the concrete numerical algorithm of the extended normal mode technique in section "Concrete numerical algorithm of the extended normal mode technique" and concrete trajectory of one electron in section "Current of one electron". The interference pattern is similar to, but cannot be reproduced quantitatively by, that of QM wave function, contrary to many-years-anticipation: a new prediction, awaiting experimental test over and above the Bohr-Einstein gedanken experiment. QED paves the way for the new generic quantitative theory of electronic structure and dynamics over and above QM. Alpha-oscillator theory presents new aspects of QED from basic physics to material sciences with mathematical rigor. Quantum simulation of nanosized materials is a realization of the new-generation quantum theory. A new era of quantum simulation of nanosized materials is realized. Correct theory of the double-slit phenomenon is QED. Correct quantum theoretical view of the double-slit phenomenon is relativistic quantum field theory (QFT).

DOI: 10.1007/s00894-018-3795-4 PMID: 30159609

68. Heliyon. 2019 Jul 27;5(7):e02130. doi: 10.1016/j.heliyon.2019.e02130. eCollection 2019 Jul.

A proposed mechanism for mind-brain interaction using extended Bohmian quantum mechanics in Avicenna's monotheistic perspective.

Jamali M(1)(2), Golshani M(1)(2), Jamali Y(3).

Author information: (1)Department of Physics, Sharif University of Technology, Tehran, Iran. (2)School of Physics, Institute for Research in Fundamental Sciences (IPM), Tehran, Iran. (3)Department of Applied Mathematics, School of Mathematical Sciences, Tarbiat Modares University, Tehran, Iran.

In quantum approaches to consciousness, the authors try to propose a model and mechanism for the mind-brain interaction using modern physics and some quantum concepts which do not exist in the classical physics. The independent effect of mind on the brain has been one of the challenging issues in the history of science and philosophy. In some recent mind-brain interaction models, the direct influence of mind on matter is either not accepted (as in Stapp's model) or not clear, and there have not been any clear mechanism for it (as in Penrose-Hameroff's model or in Eccles's model). In this manuscript we propose a model and mechanism for mind's effect on the matter using an extended Bohmian quantum mechanics and Avicenna's ideas. We show that mind and mental states can affect brain's activity without any violation of physical laws. This is a mathematical and descriptive model which shows the possibility of providing a causal model for mind's effect on matter. It is shown that this model guarantees the realistic philosophical constraints and respects the laws of nature. In addition, it is shown that it is in agreement with the Libet style experimental results and parapsychological data. To propose this model, we obtained a modified (non-unitary) Schrödinger equation via second quantization method which affects the particle through a modified quantum potential and a new term in the continuity equation. At the second quantized level, which is equivalent to quantum field theory level (QFT), we can use the path integral formalism of Feynman. We show that there are three methods to extend Bohmian QM via path integral formalism, which has different interpretations. By numerical simulation of trajectories in the two-slits experiment, we show their differences and choose one of these methods for our mind-brain model which can be the basis for explaining some phenomena which are not possible to explain in the standard Bohmian QM.

DOI: 10.1016/j.heliyon.2019.e02130 PMCID: PMC6667669 PMID: 31388577

69. J Phys Chem C Nanomater Interfaces. 2018 Oct 25;122(42):24488-24498. doi: 10.1021/acs.jpcc.8b08639. Epub 2018 Oct 9.

Polarizable Force Field for CO(2) in M-MOF-74 Derived from Quantum Mechanics.

Becker TM(1), Lin LC(2), Dubbeldam D(1)(3), Vlugt TJH(1).

Author information: (1)Engineering Thermodynamics, Process & Energy Department, Faculty of Mechanical, Maritime and Materials Engineering, Delft University of Technology, Leeghwaterstraat 39, 2628CB Delft, The Netherlands. (2)William G. Lowrie Department of Chemical and Biomolecular Engineering, The Ohio State University, 151 W. Woodruff Avenue, Columbus, Ohio 43210, United States. (3)Van't Hoff Institute for Molecular Sciences, University of Amsterdam, Science Park 904, 1098XH Amsterdam, The Netherlands.

On the short term, carbon capture is a viable solution to reduce human-induced CO2 emissions, which requires an energy efficient separation of CO2. Metal-organic frameworks (MOFs) may offer opportunities for carbon capture and other industrially relevant separations. Especially, MOFs with embedded open metal sites have been shown to be promising. Molecular simulation is a useful tool to predict the performance of MOFs even before the synthesis of the material. This reduces the experimental effort, and the selection process of the most suitable MOF for a particular application can be accelerated. To describe the interactions between open metal sites and guest molecules in molecular simulation is challenging. Polarizable force fields have potential to improve the description of such specific interactions. Previously, we tested the applicability of polarizable force fields for CO2 in M-MOF-74 by verifying the ability to reproduce experimental measurements. Here, we develop a predictive polarizable force field for CO2 in M-MOF-74 (M = Co, Fe, Mg, Mn, Ni, Zn) without the requirement of experimental data. The force field is derived from energies predicted from quantum mechanics. The procedure is easily transferable to other MOFs. To incorporate explicit polarization, the induced dipole method is applied between the framework and the guest molecule. Atomic polarizabilities are assigned according to the literature. Only the Lennard-Jones parameters of the open metal sites are parameterized to reproduce energies from quantum mechanics. The created polarizable force field for CO2 in M-MOF-74 can describe the adsorption well and even better than that in our previous work.

DOI: 10.1021/acs.jpcc.8b08639 PMCID: PMC6369669 PMID: 30774742

Conflict of interest statement: The authors declare no competing financial interest.

70. Phys Rev Lett. 2018 Feb 9;120(6):061602. doi: 10.1103/PhysRevLett.120.061602.

Phase Diagram of Planar Matrix Quantum Mechanics, Tensor, and Sachdev-Ye-Kitaev Models.

Azeyanagi T(1), Ferrari F(1)(2), Massolo FIS(2).

Author information: (1)Université libre de Bruxelles (ULB) and International Solvay Institutes Service de Physique Théorique et Mathématique Campus de la Plaine, CP 231, B-1050 Bruxelles, Belgique. (2)Center for the Theoretical Physics of the Universe Institute for Basic Sciences (IBS), Seoul 08826, Republic of Korea.

We study the Schwinger-Dyson equations of a fermionic planar matrix quantum mechanics [or tensor and Sachdev-Ye-Kitaev (SYK) models] at leading melonic order. We find two solutions describing a high entropy, SYK black-hole-like phase and a low entropy one with trivial IR behavior. There is a line of first order phase transitions that terminates at a new critical point. Critical exponents are nonmean field and differ on the two sides of the transition. Interesting phenomena are also found in unstable and stable bosonic models, including Kazakov critical points and inconsistency of SYK-like solutions of the IR limit.

DOI: 10.1103/PhysRevLett.120.061602 PMID: 29481232

71. J Mol Graph Model. 2019 May;88:11-22. doi: 10.1016/j.jmgm.2018.12.009. Epub 2018 Dec 28.

Adsorption and encapsulation of the drug doxorubicin on covalent functionalized carbon nanotubes: A scrutinized study by using molecular dynamics simulation and quantum mechanics calculation.

Kordzadeh A(1), Amjad-Iranagh S(1), Zarif M(2), Modarress H(3).

Author information: (1)Department of Chemical Engineering, Amirkabir University of Technology, Tehran, Iran. (2)Department of Physical and Computational Chemistry, Shahid Beheshti University, Tehran, Iran. (3)Department of Chemical Engineering, Amirkabir University of Technology, Tehran, Iran. Electronic address: hmodares@aut.ac.ir.

Adsorption of the drug doxorubicin (DOX) onto covalent functionalized carbon nanotubes (CNTs) as drug carriers was studied by employing molecular dynamics (MD) simulation. CNT was covalently functionalized by the chemical groups: amine, carboxyl and hydroxyl and the change in the electrostatic charge of CNT as a result of functionalization was investigated by quantum mechanics calculations. The drug adsorption onto the functionalized CNTs (f-CNT) was examined by analyzing the evaluated radial probability of the drug by MD simulation. Overall consideration of the results demonstrated that surface functionalization enhances the loading capacity of CNT for the drug encapsulation, also agglomeration of unprotonated drug molecules has increased encapsulation capacity. Analysis of the obtained results indicated that carboxyl and amine f-CNTs can act as a pH sensitive drug carrier where their protonation in acidic condition can decrease the electrostatic interactions of the loaded drug with the f-CNT and as a result can promote the drug release.

DOI: 10.1016/j.jmgm.2018.12.009 PMID: 30616088 [Indexed for MEDLINE]

72. Molecules. 2015 Oct 2;20(10):18107-27. doi: 10.3390/molecules201018107.

A Quantum-Based Similarity Method in Virtual Screening.

Al-Dabbagh MM(1), Salim N(2), Himmat M(3), Ahmed A(4)(5), Saeed F(6).

Author information: (1)Faculty of Computing, Universiti Teknologi Malaysia, Skudia 81310, Malaysia. mohamad.aldabbagh@protonmail.com. (2)Faculty of Computing, Universiti Teknologi Malaysia, Skudia 81310, Malaysia. naomie@utm.my. (3)Faculty of Computing, Universiti Teknologi Malaysia, Skudia 81310, Malaysia. barakamub@yahoo.com. (4)Faculty of Computing, Universiti Teknologi Malaysia, Skudia 81310, Malaysia. alikarary@gmail.com. (5)Faculty of Engineering, Karary University, Khartoum 12304, Sudan. alikarary@gmail.com. (6)Faculty of Computing, Universiti Teknologi Malaysia, Skudia 81310, Malaysia. faisalsaeed@utm.my.

One of the most widely-used techniques for ligand-based virtual screening is similarity searching. This study adopted the concepts of quantum mechanics to present as state-of-the-art similarity method of molecules inspired from quantum theory. The representation of molecular compounds in mathematical quantum space plays a vital role in the development of quantum-based similarity approach. One of the key concepts of quantum theory is the use of complex numbers. Hence, this study proposed three various techniques to embed and to re-represent the molecular compounds to correspond with complex numbers format. The quantum-based similarity method that developed in this study depending on complex pure Hilbert space of molecules called Standard Quantum-Based (SQB). The recall of retrieved active molecules were at top 1% and top 5%, and significant test is used to evaluate our proposed methods. The MDL drug data report (MDDR), maximum unbiased validation (MUV) and Directory of Useful Decoys (DUD) data sets were used for experiments and were represented by 2D fingerprints. Simulated virtual screening experiment show that the effectiveness of SQB method was significantly increased due to the role of representational power of molecular compounds in complex numbers forms compared to Tanimoto benchmark similarity measure.

DOI: 10.3390/molecules201018107 PMCID: PMC6331860 PMID: 26445039 [Indexed for MEDLINE]

Conflict of interest statement: The authors declare no conflict of interest.

73. Philos Trans A Math Phys Eng Sci. 2016 May 28;374(2068):20150237. doi: 10.1098/rsta.2015.0237.

Links between fluid mechanics and quantum mechanics: a model for information in economics?

Haven E(1).

Author information: (1)School of Management and IQSCS, University of Leicester, Leicester, UK eh76@le.ac.uk.

This paper tallies the links between fluid mechanics and quantum mechanics, and attempts to show whether those links can aid in beginning to build a formal template which is usable in economics models where time is (a)symmetric and memory is absent or present. An objective of this paper is to contemplate whether those formalisms can allow us to model information in economics in a novel way.

DOI: 10.1098/rsta.2015.0237 PMID: 27091173

74. Phys Rev Lett. 2020 Jul 24;125(4):041601. doi: 10.1103/PhysRevLett.125.041601.

Bootstrapping Matrix Quantum Mechanics.

Han X(1), Hartnoll SA(1), Kruthoff J(1).

Author information: (1)Department of Physics, Stanford University, Stanford, California 94305-4060, USA.

Large N matrix quantum mechanics is central to holographic duality but not solvable in the most interesting cases. We show that the spectrum and simple expectation values in these theories can be obtained numerically via a "bootstrap" methodology. In this approach, operator expectation values are related by symmetries-such as time translation and SU(N) gauge invariance-and then bounded with certain positivity constraints. We first demonstrate how this method efficiently solves the conventional quantum anharmonic oscillator. We then reproduce the known solution of large N single matrix quantum mechanics. Finally, we present new results on the ground state of large N two matrix quantum mechanics.

DOI: 10.1103/PhysRevLett.125.041601 PMID: 32794829

75. Methods Mol Biol. 2020;2114:231-255. doi: 10.1007/978-1-0716-0282-9_15.

User-Friendly Quantum Mechanics: Applications for Drug Discovery.

Kotev M(1), Sarrat L(1), Gonzalez CD(2).

Author information: (1)Global Research Informatics/Cheminformatics and Drug Design, Evotec (France) SAS, Toulouse, France. (2)Global Research Informatics/Cheminformatics and Drug Design, Evotec (France) SAS, Toulouse, France. Constantino.Diaz@evotec.com.

Quantum mechanics (QM) methods provide a fine description of receptor-ligand interactions and of chemical reactions. Their use in drug design and drug discovery is increasing, especially for complex systems including metal ions in the binding sites, for the design of highly selective inhibitors, for the optimization of bi-specific compounds, to understand enzymatic reactions, and for the study of covalent ligands and prodrugs. They are also used for generating molecular descriptors for predictive QSAR/QSPR models and for the parameterization of force fields. Thanks to the continuous increase of computational power offered by GPUs and to the development of sophisticated algorithms, QM methods are becoming part of the standard tools used in computer-aided drug design (CADD). We present the most used QM methods and software packages, and we discuss recent representative applications in drug design and drug discovery.

DOI: 10.1007/978-1-0716-0282-9_15 PMID: 32016897

76. J Chem Phys. 2018 Aug 21;149(7):074704. doi: 10.1063/1.5039476.

A combined molecular dynamics simulation and quantum mechanics study on the physisorption of biodegradable CBNAILs on h-BN nanosheets.

Torkzadeh M(1), Moosavi M(1).

Author information: (1)Department of Chemistry, University of Isfahan, Isfahan 81746-73441, Iran.

The nanoscopic structure of biodegradable choline-based naphthenic acid ionic liquids near the hexagonal boron-nitride (h-BN) surface was analyzed using quantum mechanics calculations and molecular dynamics simulations. The effects of the type of the ring (aliphatic or aromatic) and the size of the ring in the anion counterpart of the aliphatic ionic liquids (ILs) on the configurations, binding energies, orbital energies, density of states, charge transfer, and thermochemistry of adsorption of ILs on the h-BN surface were investigated. Also the significance of non-covalent interactions on the adsorption of ILs was disclosed from the quantum theory of atoms in molecule. The results of radial distribution functions, number density, and also charge density profiles showed the existence of a solid-like bottom layer in the vicinity of the surface. Angular distribution functions revealed that while the most probable orientation in aromatic anions is parallel to the h-BN sheet, the most probable orientation in aliphatic rings apparently is perpendicular to the surface. The mobility of cations and anions in the studied ILs with respect to the h-BN sheet was analyzed using their mean square displacements. For all ions near the surface, dynamics in the parallel direction were faster than those in the z-direction due to the structuring of the solid-like layer of ILs near the h-BN surface. Altogether, this study provides new insights into the physisorption of this new class of biodegradable ILs on h-BN nanosheets at the molecular level.

DOI: 10.1063/1.5039476 PMID: 30134711

77. J Chem Phys. 2015 Jun 28;142(24):244505. doi: 10.1063/1.4922938.

Investigation of the CH3Cl + CN(-) reaction in water: Multilevel quantum mechanics/molecular mechanics study.

Xu Y(1), Zhang J(2), Wang D(2).

Author information: (1)School of Science, Qilu University of Technology, Jinan 250353, China. (2)College of Physics and Electronics, Shandong Normal University, Jinan 250014, China.

The CH3Cl + CN(-) reaction in water was studied using a multilevel quantum mechanics/molecular mechanics (MM) method with the multilevels, electrostatic potential, density functional theory (DFT) and coupled-cluster single double triple (CCSD(T)), for the solute region. The detailed, back-side attack SN2 reaction mechanism was mapped along the reaction pathway. The potentials of mean force were calculated under both the DFT and CCSD(T) levels for the reaction region. The CCSD(T)/MM level of theory presents a free energy activation barrier height at 20.3 kcal/mol, which agrees very well with the experiment value at 21.6 kcal/mol. The results show that the aqueous solution has a dominant role in shaping the potential of mean force. The solvation effect and the polarization effect together increase the activation barrier height by ∼11.4 kcal/mol: the solvation effect plays a major role by providing about 75% of the contribution, while polarization effect only contributes 25% to the activation barrier height. Our calculated potential of mean force under the CCSD(T)/MM also has a good agreement with the one estimated using data from previous gas-phase studies.

DOI: 10.1063/1.4922938 PMID: 26133439 [Indexed for MEDLINE]

78. Phys Rev E Stat Phys Plasmas Fluids Relat Interdiscip Topics. 2000 Sep;62(3 Pt A):3135-45. doi: 10.1103/physreve.62.3135.

Fractional quantum mechanics.

Laskin N(1).

Author information: (1)Carleton University, 1125 Colonel By Drive, Ottawa, Ontario, Canada K1S 5B6.

A path integral approach to quantum physics has been developed. Fractional path integrals over the paths of the Levy flights are defined. It is shown that if the fractality of the Brownian trajectories leads to standard quantum and statistical mechanics, then the fractality of the Levy paths leads to fractional quantum mechanics and fractional statistical mechanics. The fractional quantum and statistical mechanics have been developed via our fractional path integral approach. A fractional generalization of the Schrodinger equation has been found. A relationship between the energy and the momentum of the nonrelativistic quantum-mechanical particle has been established. The equation for the fractional plane wave function has been obtained. We have derived a free particle quantum-mechanical kernel using Fox's H function. A fractional generalization of the Heisenberg uncertainty relation has been established. Fractional statistical mechanics has been developed via the path integral approach. A fractional generalization of the motion equation for the density matrix has been found. The density matrix of a free particle has been expressed in terms of the Fox's H function. We also discuss the relationships between fractional and the well-known Feynman path integral approaches to quantum and statistical mechanics.

DOI: 10.1103/physreve.62.3135 PMID: 11088808

79. J Am Chem Soc. 2015 Nov 25;137(46):14733-42. doi: 10.1021/jacs.5b08687. Epub 2015 Nov 12.

Reduction of α,β-Unsaturated Ketones by Old Yellow Enzymes: Mechanistic Insights from Quantum Mechanics/Molecular Mechanics Calculations.

Lonsdale R(1)(2), Reetz MT(1)(2).

Author information: (1)Max-Planck-Institut für Kohlenforschung , Kaiser-Wilhelm-Platz 1, 45470 Mülheim an der Ruhr, Germany. (2)Fachbereich Chemie der Philipps-Universität , Hans-Meerwein-Strasse, 35032 Marburg, Germany.

Enoate reductases catalyze the reduction of activated C═C bonds with high enantioselectivity. The oxidative half-reaction, which involves the addition of a hydride and a proton to opposite faces of the C═C bond, has been studied for the first time by hybrid quantum mechanics/molecular mechanics (QM/MM). The reduction of 2-cyclohexen-1-one by YqjM from Bacillus subtilis was selected as the model system. Two-dimensional QM/MM (B3LYP-D/OPLS2005) reaction pathways suggest that the hydride and proton are added as distinct steps, with the former step preceding the latter. Furthermore, we present interesting insights into the reactivity of this enzyme, including the weak binding of the substrate in the active site, the role of the two active site histidine residues for polarization of the substrate C═O bond, structural details of the transition states to hydride and proton transfer, and the role of Tyr196 as proton donor. The information presented here will be useful for the future design of enantioselective YqjM mutants for other substrates.

DOI: 10.1021/jacs.5b08687 PMID: 26521678 [Indexed for MEDLINE]

80. J Phys Chem Lett. 2019 Oct 3;10(19):5823-5829. doi: 10.1021/acs.jpclett.9b02318. Epub 2019 Sep 19.

Quantum Confinement Effects on Solvatochromic Shifts of Molecular Solutes.

Giovannini T(1), Ambrosetti M(2), Cappelli C(2).

Author information: (1)Department of Chemistry , Norwegian University of Science and Technology , 7491 Trondheim , Norway. (2)Scuola Normale Superiore , Piazza dei Cavalieri 7 , 56126 Pisa , Italy.

We demonstrate the pivotal role of quantum mechanics density confinement effects on solvatochromic shifts. In particular, by resorting to a quantum mechanics/molecular mechanics (QM/MM) approach capable of accounting for confinement effects we successfully reproduce vacuo-to-water solvatochromic shifts for dark n → π* and bright π → π* transitions of acrolein and dark n → π* transitions of pyridine and pyrimidine without the need of including explicit water molecules in the QM portion. Remarkably, our approach is also able to dissect the effects of the single forces acting on the solute-solvent couple and allows for a rationalization of the experimental findings in terms of physicochemical quantities.

DOI: 10.1021/acs.jpclett.9b02318 PMID: 31518133

81. Phys Rev Lett. 2019 Jan 11;122(1):011601. doi: 10.1103/PhysRevLett.122.011601.

Spectrum of Majorana Quantum Mechanics with O(4)^{3} Symmetry.

Pakrouski K(1), Klebanov IR(1)(2), Popov F(1), Tarnopolsky G(3).

Author information: (1)Department of Physics, Princeton University, Princeton, New Jersey 08544, USA. (2)Princeton Center for Theoretical Science, Princeton University, Princeton, New Jersey 08544, USA. (3)Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA.

We study the quantum mechanics of three-index Majorana fermions ψ^{abc} governed by a quartic Hamiltonian with O(N)^{3} symmetry. Similarly to the Sachdev-Ye-Kitaev model, this tensor model has a solvable large-N limit dominated by the melonic diagrams. For N=4 the total number of states is 2^{32}, but they naturally break up into distinct sectors according to the charges under the U(1)×U(1) Cartan subgroup of one of the O(4) groups. The biggest sector has vanishing charges and contains over 165 million states. Using a Lanczos algorithm, we determine the spectrum of the low-lying states in this and other sectors. We find that the absolute ground state is nondegenerate. If the SO(4)^{3} symmetry is gauged, it is known from earlier work that the model has 36 states and a residual discrete symmetry. We study the discrete symmetry group in detail; it gives rise to degeneracies of some of the gauge singlet energies. We find all the gauge singlet energies numerically and use the results to propose exact analytic expressions for them.

DOI: 10.1103/PhysRevLett.122.011601 PMID: 31012729

82. Proc R Soc Lond B Biol Sci. 1986 May 22;227(1249):411-28. doi: 10.1098/rspb.1986.0031.

Do mental events cause neural events analogously to the probability fields of quantum mechanics?

Eccles JC.

If non-material mental events, such as the intention to carry out an action, are to have an effective action on neural events in the brain, it has to be at the most subtle and plastic level of these events. In the first stage of our enquiry an introduction to conventional synaptic theory leads on to an account of the manner of operation of the ultimate synaptic units. These units are the synaptic boutons that, when excited by an all-or-nothing nerve impulse, deliver the total contents of a single synaptic vesicle, not regularly, but probabilistically. This quantal emission of the synaptic transmitter molecules (about 5000-10 000) is the elementary unit of the transmission process from one neuron to another. In the second stage this refined physiological analysis leads on to an account of the ultrastructure of the synapse, which gives clues as to the manner of its unitary probabilistic operation. The essential feature is that the effective structure of each bouton is a paracrystalline presynaptic vesicular grid with about 50 vesicles, which acts probabilistically in vesicular (quantal) release. In the third stage it is considered how a non-material mental event, such as an intention to move, could influence the subtle probabilistic operations of synaptic boutons. On the biological side, attention is focused on the paracrystalline presynaptic vesicular grids as the targets for non-material mental events. On the physical side, attention is focused on the probabilistic fields of quantum mechanics which carry neither mass nor energy, but which nevertheless can exert effective action at microsites. The new light on the mind-brain problem came from the hypothesis that the non-material mental events, the 'World 2' of Popper, relate to the neural events of the brain (the 'World 1' of matter and energy) by actions in conformity with quantum theory. This hypothesis that mental events act on probabilistic synaptic events in a manner analogous to the probability fields of quantum mechanics seems to open up an immense field of scientific investigation both in quantum physics and in neuroscience.

DOI: 10.1098/rspb.1986.0031 PMID: 2873576 [Indexed for MEDLINE]

83. Biochemistry. 2016 Oct 11;55(40):5764-5771. doi: 10.1021/acs.biochem.6b00267. Epub 2016 Sep 30.

Quantum Mechanics/Molecular Mechanics Study of the Sialyltransferase Reaction Mechanism.

Hamada Y(1), Kanematsu Y(1)(2), Tachikawa M(1).

Author information: (1)Division of Materials Science, Graduate School of Nanobioscience, Yokohama City University , Seto 22-2, Kanazawa-ku, Yokohama 236-0027, Japan. (2)Graduate School of Information Sciences, Hiroshima City University , Ozuka-Higashi 3-4-1, Asa-Minami-Ku, Hiroshima 731-3194, Japan.

The sialyltransferase is an enzyme that transfers the sialic acid moiety from cytidine 5'-monophospho-N-acetyl-neuraminic acid (CMP-NeuAc) to the terminal position of glycans. To elucidate the catalytic mechanism of sialyltransferase, we explored the potential energy surface along the sialic acid transfer reaction coordinates by the hybrid quantum mechanics/molecular mechanics method on the basis of the crystal structure of sialyltransferase CstII. Our calculation demonstrated that CstII employed an SN1-like reaction mechanism via the formation of a short-lived oxocarbenium ion intermediate. The computational barrier height was 19.5 kcal/mol, which reasonably corresponded with the experimental reaction rate. We also found that two tyrosine residues (Tyr156 and Tyr162) played a vital role in stabilizing the intermediate and the transition states by quantum mechanical interaction with CMP.

DOI: 10.1021/acs.biochem.6b00267 PMID: 27644888 [Indexed for MEDLINE]

84. Philos Trans A Math Phys Eng Sci. 2013 Mar 18;371(1989):20120523. doi: 10.1098/rsta.2012.0523. Print 2013 Apr 28.

PT quantum mechanics.

Bender CM(1), DeKieviet M, Klevansky SP.

Author information: (1)Department of Physics, Washington University, St. Louis, MO 63130, USA. cmb@wustl.edu

PT-symmetric quantum mechanics (PTQM) has become a hot area of research and investigation. Since its beginnings in 1998, there have been over 1000 published papers and more than 15 international conferences entirely devoted to this research topic. Originally, PTQM was studied at a highly mathematical level and the techniques of complex variables, asymptotics, differential equations and perturbation theory were used to understand the subtleties associated with the analytic continuation of eigenvalue problems. However, as experiments on PT-symmetric physical systems have been performed, a simple and beautiful physical picture has emerged, and a PT-symmetric system can be understood as one that has a balanced loss and gain. Furthermore, the PT phase transition can now be understood intuitively without resorting to sophisticated mathematics. Research on PTQM is following two different paths: at a fundamental level, physicists are attempting to understand the underlying mathematical structure of these theories with the long-range objective of applying the techniques of PTQM to understanding some of the outstanding problems in physics today, such as the nature of the Higgs particle, the properties of dark matter, the matter-antimatter asymmetry in the universe, neutrino oscillations and the cosmological constant; at an applied level, new kinds of PT-synthetic materials are being developed, and the PT phase transition is being observed in many physical contexts, such as lasers, optical wave guides, microwave cavities, superconducting wires and electronic circuits. The purpose of this Theme Issue is to acquaint the reader with the latest developments in PTQM. The articles in this volume are written in the style of mini-reviews and address diverse areas of the emerging and exciting new area of PT-symmetric quantum mechanics.

DOI: 10.1098/rsta.2012.0523 PMCID: PMC3638376 PMID: 23509390

85. Philos Trans A Math Phys Eng Sci. 2016 May 28;374(2068):20150238. doi: 10.1098/rsta.2015.0238.

Grounding the randomness of quantum measurement.

Jaeger G(1).

Author information: (1)Quantum Communication and Measurement Laboratory, Department of Electrical and Computer Engineering, Division of Natural Science and Mathematics, Boston University, Boston, MA 02215, USA gsjaeger@gmail.com.

Julian Schwinger provided to physics a mathematical reconstruction of quantum mechanics on the basis of the characteristics of sequences of measurements occurring at the atomic level of physical structure. The central component of this reconstruction is an algebra of symbols corresponding to quantum measurements, conceived of as discrete processes, which serve to relate experience to theory; collections of outcomes of identically circumscribed such measurements are attributed expectation values, which constitute the predictive content of the theory. The outcomes correspond to certain phase parameters appearing in the corresponding symbols, which are complex numbers, the algebra of which he finds by a process he refers to as 'induction'. Schwinger assumed these (individually unpredictable) phase parameters to take random, uniformly distributed definite values within a natural range. I have previously suggested that the 'principle of plenitude' may serve as a basis in principle for the occurrence of the definite measured values that are those members of the collections of measurement outcomes from which the corresponding observed statistics derive (Jaeger 2015Found. Phys.45, 806-819. (doi:10.1007/s10701-015-9893-6)). Here, I evaluate Schwinger's assumption in the context of recent critiques of the notion of randomness and explicitly relate the randomness of these phases with the principle of plenitude and, in this way, provide a fundamental grounding for the objective, physically irreducible probabilities, conceived of as graded possibilities, that are attributed to measurement outcomes by quantum mechanics.

DOI: 10.1098/rsta.2015.0238 PMID: 27091162

86. Philos Trans A Math Phys Eng Sci. 2013 Mar 18;371(1989):20120160. doi: 10.1098/rsta.2012.0160. Print 2013 Apr 28.

PT-symmetric quantum state discrimination.

Bender CM(1), Brody DC, Caldeira J, Günther U, Meister BK, Samsonov BF.

Author information: (1)Department of Physics, King's College London, Strand, London WC2R 1LS, UK.

The objective of this paper is to explain and elucidate the formalism of PT quantum mechanics by applying it to a well-known problem in conventional Hermitian quantum mechanics, namely the problem of state discrimination. Suppose that a system is known to be in one of two quantum states, |ψ(1)> or |ψ(2)>. If these states are not orthogonal, then the requirement of unitarity forbids the possibility of discriminating between these two states with one measurement; that is, determining with one measurement what state the system is in. In conventional quantum mechanics, there is a strategy in which successful state discrimination can be achieved with a single measurement but only with a success probability p that is less than unity. In this paper, the state-discrimination problem is examined in the context of PT quantum mechanics and the approach is based on the fact that a non-Hermitian PT-symmetric Hamiltonian determines the inner product that is appropriate for the Hilbert space of physical states. It is shown that it is always possible to choose this inner product so that the two states |ψ(1)> and |ψ(2)> are orthogonal. Using PT quantum mechanics, one cannot achieve a better state discrimination than in ordinary quantum mechanics, but one can instead perform a simulated quantum state discrimination, in which with a single measurement a perfect state discrimination is realized with probability p.

DOI: 10.1098/rsta.2012.0160 PMID: 23509387

87. Proc Natl Acad Sci U S A. 2019 Apr 16;116(16):7718-7722. doi: 10.1073/pnas.1821709116. Epub 2019 Mar 13.

Reaction intermediates during operando electrocatalysis identified from full solvent quantum mechanics molecular dynamics.

Cheng T(1)(2)(3), Fortunelli A(3)(4), Goddard WA 3rd(5)(3).

Author information: (1)Institute of Functional Nano & Soft Materials (FUNSOM), Jiangsu Key Laboratory for Carbon-Based Functional Materials & Devices, Joint International Research Laboratory of Carbon-Based Functional Materials and Devices, Soochow University, Suzhou, 215123, Jiangsu, PR China. (2)Joint Center for Artificial Photosynthesis, California Institute of Technology, Pasadena, CA 91125. (3)Materials and Process Simulation Center, California Institute of Technology, Pasadena, CA 91125. (4)Italian National Council for Research-Institute for the Chemistry of OrganoMetallic Compounds, Consiglio Nazionale delle Ricerche, Pisa 56124, Italy. (5)Joint Center for Artificial Photosynthesis, California Institute of Technology, Pasadena, CA 91125; wag@caltech.edu.

Comment in Proc Natl Acad Sci U S A. 2019 Apr 16;116(16):7611-7613.

Electrocatalysis provides a powerful means to selectively transform molecules, but a serious impediment in making rapid progress is the lack of a molecular-based understanding of the reactive mechanisms or intermediates at the electrode-electrolyte interface (EEI). Recent experimental techniques have been developed for operando identification of reaction intermediates using surface infrared (IR) and Raman spectroscopy. However, large noises in the experimental spectrum pose great challenges in resolving the atomistic structures of reactive intermediates. To provide an interpretation of these experimental studies and target for additional studies, we report the results from quantum mechanics molecular dynamics (QM-MD) with explicit consideration of solvent, electrode-electrolyte interface, and applied potential at 298 K, which conceptually resemble the operando experimental condition, leading to a prototype of operando QM-MD (o-QM-MD). With o-QM-MD, we characterize 22 possible reactive intermediates in carbon dioxide reduction reactions ([Formula: see text]RRs). Furthermore, we report the vibrational density of states (v-DoSs) of these intermediates from two-phase thermodynamic (2PT) analysis. Accordingly, we identify important intermediates such as chemisorbed [Formula: see text] ([Formula: see text]), *HOC-COH, *C-CH, and *C-COH in our o-QM-MD likely to explain the experimental spectrum. Indeed, we assign the experimental peak at 1,191 cm-1 to the mode of C-O stretch in *HOC-COH predicted at 1,189 cm-1 and the experimental peak at 1,584 cm-1 to the mode of C-C stretch in *C-COD predicted at 1,581 cm-1 Interestingly, we find that surface ketene (*C=C=O), arising from *HOC-COH dehydration, also shows signals at around 1,584 cm-1, which indicates a nonelectrochemical pathway of hydrocarbon formation at low overpotential and high pH conditions.

DOI: 10.1073/pnas.1821709116 PMCID: PMC6475413 PMID: 30867281

Conflict of interest statement: The authors declare no conflict of interest.

88. Chaos. 2000 Dec;10(4):780-790. doi: 10.1063/1.1050284.

Fractals and quantum mechanics.

Laskin N(1).

Author information: (1)Isotrace Laboratory, University of Toronto, 60 St. George Street, Toronto, ON M5S 1A7, Canada.

A new application of a fractal concept to quantum physics has been developed. The fractional path integrals over the paths of the Levy flights are defined. It is shown that if fractality of the Brownian trajectories leads to standard quantum mechanics, then the fractality of the Levy paths leads to fractional quantum mechanics. The fractional quantum mechanics has been developed via the new fractional path integrals approach. A fractional generalization of the Schrodinger equation has been discovered. The new relationship between the energy and the momentum of the nonrelativistic fractional quantum-mechanical particle has been established, and the Levy wave packet has been introduced into quantum mechanics. The equation for the fractional plane wave function has been found. We have derived a free particle quantum-mechanical kernel using Fox's H-function. A fractional generalization of the Heisenberg uncertainty relation has been found. As physical applications of the fractional quantum mechanics we have studied a free particle in a square infinite potential well, the fractional "Bohr atom" and have developed a new fractional approach to the QCD problem of quarkonium. We also discuss the relationships between fractional and the well-known Feynman path integral approaches to quantum mechanics. (c) 2000 American Institute of Physics.

DOI: 10.1063/1.1050284 PMID: 12779428

89. Curr Opin Struct Biol. 2001 Apr;11(2):217-23. doi: 10.1016/s0959-440x(00)00193-7.

New developments in applying quantum mechanics to proteins.

Gogonea V(1), Suárez D, van der Vaart A, Merz KM Jr.

Author information: (1)Department of Chemistry, 152 Davey Laboratory, The Pennsylvania State University, University Park, PA 16802, USA.

Algorithmic improvements of quantum mechanical methodologies have increased our ability to study the electronic structure of fragments of a biomolecule (e.g. an enzyme active site) or entire biomolecules. Three main strategies have emerged as ways in which quantum mechanics can be applied to biomolecules. The supermolecule approach continues to be utilized, but it is slowly being replaced by the so-called coupled quantum mechanical/molecular mechanical methodologies. An exciting new direction is the continued development and application of linear-scaling quantum mechanical approaches to biomolecular systems.

DOI: 10.1016/s0959-440x(00)00193-7 PMID: 11297931 [Indexed for MEDLINE]

90. J Chem Phys. 2017 Dec 28;147(24):244105. doi: 10.1063/1.5009820.

Optimization and benchmarking of a perturbative Metropolis Monte Carlo quantum mechanics/molecular mechanics program.

Feldt J(1), Miranda S(2), Pratas F(2), Roma N(2), Tomás P(2), Mata RA(1).

Author information: (1)Institut für Physikalische Chemie, Universität Göttingen, Tammannstrasse 6, D-37077 Göttingen, Germany. (2)INESC-ID/IST, Universidade de Lisboa, Rua Alves Redol, 1000-029 Lisboa, Portugal.

In this work, we present an optimized perturbative quantum mechanics/molecular mechanics (QM/MM) method for use in Metropolis Monte Carlo simulations. The model adopted is particularly tailored for the simulation of molecular systems in solution but can be readily extended to other applications, such as catalysis in enzymatic environments. The electrostatic coupling between the QM and MM systems is simplified by applying perturbation theory to estimate the energy changes caused by a movement in the MM system. This approximation, together with the effective use of GPU acceleration, leads to a negligible added computational cost for the sampling of the environment. Benchmark calculations are carried out to evaluate the impact of the approximations applied and the overall computational performance.

DOI: 10.1063/1.5009820 PMID: 29289129

91. FEBS Open Bio. 2017 Feb 5;7(3):391-396. doi: 10.1002/2211-5463.12188. eCollection 2017 Mar.

Identifying the receptor subtype selectivity of retinoid X and retinoic acid receptors via quantum mechanics.

Tsuji M(1), Shudo K(2), Kagechika H(3).

Author information: (1)Institute of Molecular Function Saitama Japan. (2)Japan Pharmaceutical Information Center Shibuya-ku Tokyo Japan. (3)Institute of Biomaterials and Bioengineering Tokyo Medical and Dental University Chiyoda-ku Japan.

Understanding and identifying the receptor subtype selectivity of a ligand is an important issue in the field of drug discovery. Using a combination of classical molecular mechanics and quantum mechanical calculations, this report assesses the receptor subtype selectivity for the human retinoid X receptor (hRXR) and retinoic acid receptor (hRAR) ligand-binding domains (LBDs) complexed with retinoid ligands. The calculated energies show good correlation with the experimentally reported binding affinities. The technique proposed here is a promising method as it reveals the origin of the receptor subtype selectivity of selective ligands.

DOI: 10.1002/2211-5463.12188 PMCID: PMC5337894 PMID: 28286734

92. Sci Rep. 2018 Mar 5;8(1):4010. doi: 10.1038/s41598-018-22336-3.

Disturbance-Disturbance uncertainty relation: The statistical distinguishability of quantum states determines disturbance.

Benítez Rodríguez E(1), Arévalo Aguilar LM(2).

Author information: (1)Facultad de Ciencias Físico Matemáticas, Benemérita Universidad Autónoma de Puebla, 18 Sur y Avenida San Claudio, Col. San Manuel, C.P: 72520, Puebla, Pue., Mexico. (2)Facultad de Ciencias Físico Matemáticas, Benemérita Universidad Autónoma de Puebla, 18 Sur y Avenida San Claudio, Col. San Manuel, C.P: 72520, Puebla, Pue., Mexico. larevalo@fcfm.buap.mx.

The Heisenberg uncertainty principle, which underlies many quantum key features, is under close scrutiny regarding its applicability to new scenarios. Using both the Bell-Kochen-Specker theorem establishing that observables do not have predetermined values before measurements and the measurement postulate of quantum mechanics, we propose that in order to describe the disturbance produced by the measurement process, it is convenient to define disturbance by the changes produced on quantum states. Hence, we propose to quantify disturbance in terms of the square root of the Jensen-Shannon entropy distance between the probability distributions before and after the measurement process. Additionally, disturbance and statistical distinguishability of states are fundamental concepts of quantum mechanics that have thus far been unrelated; however, we show that they are intermingled thereupon we enquire into whether the statistical distinguishability of states, caused by statistical fluctuations in the measurement outcomes, is responsible for the disturbance's magnitude.

DOI: 10.1038/s41598-018-22336-3 PMCID: PMC5838129 PMID: 29507359

Conflict of interest statement: The authors declare no competing interests.

93. Expert Opin Drug Discov. 2013 Mar;8(3):263-76. doi: 10.1517/17460441.2013.752812. Epub 2013 Jan 7.

The application of quantum mechanics in structure-based drug design.

Mucs D(1), Bryce RA.

Author information: (1)University of Manchester, School of Pharmacy and Pharmaceutical Sciences, Oxford Road, Manchester, UK.

INTRODUCTION: Computational chemistry has become an established and valuable component in structure-based drug design. However the chemical complexity of many ligands and active sites challenges the accuracy of the empirical potentials commonly used to describe these systems. Consequently, there is a growing interest in utilizing electronic structure methods for addressing problems in protein-ligand recognition. AREAS COVERED: In this review, the authors discuss recent progress in the development and application of quantum chemical approaches to modeling protein-ligand interactions. The authors specifically consider the development of quantum mechanics (QM) approaches for studying large molecular systems pertinent to biology, focusing on protein-ligand docking, protein-ligand binding affinities and ligand strain on binding. EXPERT OPINION: Although computation of binding energies remains a challenging and evolving area, current QM methods can underpin improved docking approaches and offer detailed insights into ligand strain and into the nature and relative strengths of complex active site interactions. The authors envisage that QM will become an increasingly routine and valued tool of the computational medicinal chemist.

DOI: 10.1517/17460441.2013.752812 PMID: 23289945 [Indexed for MEDLINE]

94. Phys Chem Chem Phys. 2018 Feb 14;20(7):4732-4738. doi: 10.1039/c7cp07673h.

Full-dimensional quantum mechanics calculations for the spectroscopic characterization of the isomerization transition states of HOCO/DOCO systems.

Ma D (1), Ren H , Ma J .

Author information: (1)Institute of Atomic and Molecular Physics, Sichuan University, Chengdu, Sichuan 610065, China. majianyi81@163.com.

Full-dimensional quantum mechanics calculations were performed to determine the vibrational energy levels of HOCO and DOCO based on an accurate potential energy surface. Almost all of the vibrational energy levels up to 3500 cm-1 from the vibrational ground state were assigned, and the calculated energy levels in this work are well in agreement with the reported results by Bowman. The corresponding full dimensional wavefunctions present some special features. When the energy level approaches the barrier height, the trans-HOCO and cis-HOCO states strongly couple through tunneling interactions, and the tunneling interaction and Fermi resonance were observed in the DOCO system. The energy level patterns of trans-HOCO, cis-HOCO and trans-DOCO provide a reasonable fitted barrier height using the fitting formula of Field et al., however, a discrepancy exists for the cis-DOCO species which is considered as a random event. Our full-dimensional calculations give positive evidence for the accuracy of the spectroscopic characterization model of the isomerization transition state reported by Field et al., which was developed from one-dimensional model systems. Furthermore, the special case of cis-DOCO in this work means that the isotopic substitution can solve the problem of the accidental failure of Field's spectroscopic characterization model.

DOI: 10.1039/c7cp07673h PMID: 29379927

95. J Comput Chem. 2019 Jan 15;40(2):316-327. doi: 10.1002/jcc.25600. Epub 2018 Oct 9.

New aspects of quantum electrodynamics on electronic structure and dynamics.

Tachibana A(1).

Author information: (1)Department of Micro Engineering, Kyoto University, Kyoto daigaku-Katsura, Nishikyo-ku, Kyoto 615-8540, Japan.

Application of Alpha-oscillator theory to quantum electrodynamics (QED) solves the mystery (Feynman) of the double-slit phenomenon involved in the foundation of quantum mechanics (QM). Even if with the same initial condition given, different spots on the screen can be predicted deterministically with no introduction of hidden variables. The interference pattern is similar to, but cannot be reproduced quantitatively by, that of the QM wave function, contrary to many-years-anticipation: a new prediction, awaiting experimental test over and above the Bohr-Einstein gedanken experiment. The general proof has already been published in Ref. [3a] and the concrete numerical algorithm of the extended normal mode technique for concrete trajectory of one electron in Ref. [3b]. In this article, (1) the new "interpretation" of the QED wave function is given in section "Interpretation of Wave Function in QED": the QED wave function used in the extended normal mode technique gives probability density distribution function of the initial values of trajectories. Moreover, (2) for the sake of demonstration of this new interpretation, the time-independent stationary state QM wave function is substituted to the QED wave function in section "Internal Self-Stress of Energetic Particles": the QED wave function is realized by internal self-stress revealed as energy density at the initial conditions. The renewed energy density is applied to study a unified scheme for generalized chemical reactivity. This is a new kind of chemical force acting in between electrons not in between nuclei. This paves a way for more advanced time-dependent simulation of electronic structure and dynamics in chemical reaction dynamics by tracing trajectories of many electrons. © 2018 Wiley Periodicals, Inc.

DOI: 10.1002/jcc.25600 PMID: 30299560

96. Found Phys. 2013;43:440-457. doi: 10.1007/s10701-012-9636-x. Epub 2012 Feb 29.

Quantum Blobs.

de Gosson MA(1).

Author information: (1)Faculty of Mathematics, University of Vienna, NuHAG, 1090 Vienna, Austria.

Quantum blobs are the smallest phase space units of phase space compatible with the uncertainty principle of quantum mechanics and having the symplectic group as group of symmetries. Quantum blobs are in a bijective correspondence with the squeezed coherent states from standard quantum mechanics, of which they are a phase space picture. This allows us to propose a substitute for phase space in quantum mechanics. We study the relationship between quantum blobs with a certain class of level sets defined by Fermi for the purpose of representing geometrically quantum states.

DOI: 10.1007/s10701-012-9636-x PMCID: PMC4267529 PMID: 25530623

97. Proc Natl Acad Sci U S A. 2016 Jan 19;113(3):532-5. doi: 10.1073/pnas.1522411112. Epub 2016 Jan 4.

Quantum violation of the pigeonhole principle and the nature of quantum correlations.

Aharonov Y(1), Colombo F(2), Popescu S(3), Sabadini I(2), Struppa DC(4), Tollaksen J(4).

Author information: (1)School of Physics and Astronomy, Tel Aviv University, Tel Aviv 69978, Israel; Schmid College of Science and Technology, Chapman University, Orange, CA 92866; Institute for Quantum Studies, Chapman University, Orange, CA 92866; aharonov@chapman.edu. (2)Dipartimento di Matematica, Politecnico di Milano, 20133 Milan, Italy; (3)Institute for Quantum Studies, Chapman University, Orange, CA 92866; H. H. Wills Physics Laboratory, University of Bristol, Bristol BS8 1TL, United Kingdom. (4)Schmid College of Science and Technology, Chapman University, Orange, CA 92866; Institute for Quantum Studies, Chapman University, Orange, CA 92866;

Comment in Proc Natl Acad Sci U S A. 2016 May 31;113(22):E3053. Proc Natl Acad Sci U S A. 2016 May 31;113(22):E3052.

The pigeonhole principle: "If you put three pigeons in two pigeonholes, at least two of the pigeons end up in the same hole," is an obvious yet fundamental principle of nature as it captures the very essence of counting. Here however we show that in quantum mechanics this is not true! We find instances when three quantum particles are put in two boxes, yet no two particles are in the same box. Furthermore, we show that the above "quantum pigeonhole principle" is only one of a host of related quantum effects, and points to a very interesting structure of quantum mechanics that was hitherto unnoticed. Our results shed new light on the very notions of separability and correlations in quantum mechanics and on the nature of interactions. It also presents a new role for entanglement, complementary to the usual one. Finally, interferometric experiments that illustrate our effects are proposed.

DOI: 10.1073/pnas.1522411112 PMCID: PMC4725468 PMID: 26729862

Conflict of interest statement: The authors declare no conflict of interest.

98. J Comput Aided Mol Des. 2017 Apr;31(4):365-378. doi: 10.1007/s10822-016-0003-4. Epub 2017 Feb 20.

Quantum probability ranking principle for ligand-based virtual screening.

Al-Dabbagh MM(1), Salim N(2), Himmat M(2), Ahmed A(3), Saeed F(2).

Author information: (1)Faculty of Computing, Universiti Teknologi Malaysia, Skudia, 81310, Malaysia. mohamad.aldabbagh@protonmail.com. (2)Faculty of Computing, Universiti Teknologi Malaysia, Skudia, 81310, Malaysia. (3)Faculty of Engineering, Karary University, Khartoum, 12304, Sudan.

Chemical libraries contain thousands of compounds that need screening, which increases the need for computational methods that can rank or prioritize compounds. The tools of virtual screening are widely exploited to enhance the cost effectiveness of lead drug discovery programs by ranking chemical compounds databases in decreasing probability of biological activity based upon probability ranking principle (PRP). In this paper, we developed a novel ranking approach for molecular compounds inspired by quantum mechanics, called quantum probability ranking principle (QPRP). The QPRP ranking criteria would make an attempt to draw an analogy between the physical experiment and molecular structure ranking process for 2D fingerprints in ligand based virtual screening (LBVS). The development of QPRP criteria in LBVS has employed the concepts of quantum at three different levels, firstly at representation level, this model makes an effort to develop a new framework of molecular representation by connecting the molecular compounds with mathematical quantum space. Secondly, estimate the similarity between chemical libraries and references based on quantum-based similarity searching method. Finally, rank the molecules using QPRP approach. Simulated virtual screening experiments with MDL drug data report (MDDR) data sets showed that QPRP outperformed the classical ranking principle (PRP) for molecular chemical compounds.

DOI: 10.1007/s10822-016-0003-4 PMID: 28220440 [Indexed for MEDLINE]

99. Chempluschem. 2013 Sep;78(9). doi: 10.1002/cplu.201380972.

Frontispiece.

[No authors listed]

The frontispiece shows the casein kinase 2 (CK2), cyclin-dependent kinase 2 (CDK2), HIV-1 protease (HIV-1 PR) and their inhibitors. Jindřich Fanfrlík and co-workers discuss the latest developments in modern quantum mechanics (QM)-based computer-aided drug design, especially using semiempirical QM methods in their Minireview on page 921 ff.

DOI: 10.1002/cplu.201380972 PMID: 31986715

100. Biosystems. 2003 Feb-Mar;68(2-3):107-18. doi: 10.1016/s0303-2647(02)00090-4.

Quantum mechanics in first, second and third person descriptions.

Matsuno K(1).

Author information: (1)Department of BioEngineering, Nagaoka University of Technology, Nagaoka 940-2188, Japan. kmatsuno@vos.nagaokaut.ac.jp

Although quantum mechanics in third person descriptions is certainly legitimate insofar as one is sure about what each energy quantum is all about, quantum mechanics in first person descriptions comes to the surface once one raises the issue of how each quantum transforms itself as measuring and interacting with the others of the similar nature. Each energy quantum is taken as the robust confinement of interactions, whose first person descriptions address the quantum involved in the process of measuring other quanta internally. In addition, the issue of how the robust confinement of interactions could come into being and develop is a matter of quantum mechanics in second person descriptions. Biological activities including cell motility and muscle contraction address the issue of quantum coherence accessible in quantum mechanics in second person descriptions.

DOI: 10.1016/s0303-2647(02)00090-4 PMID: 12595112 [Indexed for MEDLINE]

101. Phys Rev Lett. 2015 Apr 17;114(15):150601. doi: 10.1103/PhysRevLett.114.150601. Epub 2015 Apr 13.

Jarzynski Equality in PT-Symmetric Quantum Mechanics.

Deffner S(1), Saxena A(1).

Author information: (1)Theoretical Division and Center for Nonlinear Studies, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA.

We show that the quantum Jarzynski equality generalizes to PT-symmetric quantum mechanics with unbroken PT symmetry. In the regime of broken PT symmetry, the Jarzynski equality does not hold as also the CPT norm is not preserved during the dynamics. These findings are illustrated for an experimentally relevant system-two coupled optical waveguides. It turns out that for these systems the phase transition between the regimes of unbroken and broken PT symmetry is thermodynamically inhibited as the irreversible work diverges at the critical point.

DOI: 10.1103/PhysRevLett.114.150601 PMID: 25933299

102. Proteins. 2015 Nov;83(11):1973-86. doi: 10.1002/prot.24876. Epub 2015 Sep 22.

The determinants of bond angle variability in protein/peptide backbones: A comprehensive statistical/quantum mechanics analysis.

Improta R(1), Vitagliano L(1), Esposito L(1).

Author information: (1)Istituto di Biostrutture e Bioimmagini, Consiglio Nazionale delle Ricerche (CNR), Napoli, I-80134, Italy.

The elucidation of the mutual influence between peptide bond geometry and local conformation has important implications for protein structure refinement, validation, and prediction. To gain insights into the structural determinants and the energetic contributions associated with protein/peptide backbone plasticity, we here report an extensive analysis of the variability of the peptide bond angles by combining statistical analyses of protein structures and quantum mechanics calculations on small model peptide systems. Our analyses demonstrate that all the backbone bond angles strongly depend on the peptide conformation and unveil the existence of regular trends as function of ψ and/or φ. The excellent agreement of the quantum mechanics calculations with the statistical surveys of protein structures validates the computational scheme here employed and demonstrates that the valence geometry of protein/peptide backbone is primarily dictated by local interactions. Notably, for the first time we show that the position of the H(α) hydrogen atom, which is an important parameter in NMR structural studies, is also dependent on the local conformation. Most of the trends observed may be satisfactorily explained by invoking steric repulsive interactions; in some specific cases the valence bond variability is also influenced by hydrogen-bond like interactions. Moreover, we can provide a reliable estimate of the energies involved in the interplay between geometry and conformations.

DOI: 10.1002/prot.24876 PMID: 26264789 [Indexed for MEDLINE]

103. Spectrochim Acta A Mol Biomol Spectrosc. 2018 Jan 5;188:647-658. doi: 10.1016/j.saa.2017.07.058. Epub 2017 Jul 31.

A combined molecular dynamics simulation and quantum mechanics study on mercaptopurine interaction with the cucurbit [6,7] urils: Analysis of electronic structure.

Zaboli M(1), Raissi H(2).

Author information: (1)Department of chemistry, University of Birjand, Birjand 7761676334, Iran. Electronic address: zaboli_m@birjand.ac.ir. (2)Department of chemistry, University of Birjand, Birjand 7761676334, Iran. Electronic address: hraeisi@birjand.ac.ir.

In the current study, the probability of complex formation between mercaptopurine drug with cucurbit[6]urils and cucurbit[7]urils has been investigated. The calculations for geometry optimization of complexes have been carried out by means of DFT (B3LYP), DFT-D (B3LYP-D) and M06-2X methods. The Atoms In Molecules (AIM), Natural Bond Orbital (NBO), NMR, the density of states (DOSs) and frontier molecular orbital (MO) analyses have been done on the inclusion complexes. In addition, the UV-Vis spectra of the first eight states have been obtained by CAM-B3LYP/TD-DFT calculation. The obtained results of the complexation process reveal that CB[7]-DRG complexes are more favorable than that of CB[6]-DRG interactions. Furthermore, our theoretical results show that configurations III and I are the most stable configurations related to the CB[6]/DRG and CB[7]/DRG interactions, respectively. The positive ∇2ρ(r) and HC values at the bond critical points indicate that exist the weak H-bonds between CB[6] and CB[7] with H atoms of the drug molecule. The obtained negative binding energy values of CB[7]-DRG interaction in solution phase show the stability of these complexes in the aqueous medium. Also, all of the observed parameters of molecular dynamics simulation such as the number of contacts, hydrogen bonding, center-of-mass distance and van der Waals energy values confirm the encapsulation of mercaptopurine molecule inside the cucurbit[7]urils cavity at about 3.2ns.

DOI: 10.1016/j.saa.2017.07.058 PMID: 28793280 [Indexed for MEDLINE]

104. J Chem Phys. 2017 Oct 28;147(16):161401. doi: 10.1063/1.5008887.

Preface: Special Topic: From Quantum Mechanics to Force Fields.

Piquemal JP(1), Jordan KD(2).

Author information: (1)Laboratoire de Chimie Théorique, UMR 7616 CNRS, UPMC, Sorbonne Universités, 75252 Paris Cedex 05, France. (2)Department of Chemistry, The University of Pittsburgh, 219 Parkman Avenue, Pittsburgh, Pennsylvania 15260, USA.

This Special Topic issue entitled "From Quantum Mechanics to Force Fields" is dedicated to the ongoing efforts of the theoretical chemistry community to develop a new generation of accurate force fields based on data from high-level electronic structure calculations and to develop faster electronic structure methods for testing and designing force fields as well as for carrying out simulations. This issue includes a collection of 35 original research articles that illustrate recent theoretical advances in the field. It provides a timely snapshot of recent developments in the generation of approaches to enable more accurate molecular simulations of processes important in chemistry, physics, biophysics, and materials science.

DOI: 10.1063/1.5008887 PMID: 29096449

105. Heliyon. 2020 Jun 11;6(6):e04125. doi: 10.1016/j.heliyon.2020.e04125. eCollection 2020 Jun.

Quantum mechanics and 3D-QSAR studies on thienopyridine analogues: inhibitors of IKKβ.

Ul-Haq Z(1), Khan A(1), Ashraf S(1), Morales-Bayuelo A(2).

Author information: (1)Dr. Panjwani Center for Molecular Medicine and Drug Research, International Center for Chemical and Biological Sciences, University of Karachi, Karachi 75270, Pakistan. (2)Grupo de Investigaciones Básicas y Clínicas de la Universidad del Sinú (GIBACUS), Escuela de Medicina, Universidad del Sinú, Seccional Cartagena de Indias, Colombia.

Inhibitor of kappa B kinase subunit β (IKKβ) is a main regulator of nuclear factor kappa B (NF-κB) and has received considerable attention as an attractive therapeutic target for the treatment of lung cancer or other inflammatory disease. A group of diversified thienopyridine derivatives exhibited a wide range of biological activity was used to investigate its structural requirements by using DFT and 3D-Quantitative structure activity relationship. Comparative molecular field analysis (CoMFA) and comparative molecular similarity indices analysis (CoMSIA) were established using the experimental activity of thienopyridine derivatives. The cross-validation coefficient (q2) values for CoMFA and CoMSIA are 0.671 and 0.647 respectively, were achieved, demonstrating high predictive capability of the model. The contour analysis indicate that presence of hydrophobic and electrostatic field is highly desirable for biological activity. The results indicate that substitution of hydrophobic group with electron withdrawing effect at R4 and R6 position have more possibility to increase the biological activity of thienopyridine derivatives. Subsequently molecular docking and DFT calculation were performed to assess the potency of the compounds.

DOI: 10.1016/j.heliyon.2020.e04125 PMCID: PMC7298411 PMID: 32566780

106. Sci Eng Ethics. 2010 Sep;16(3):479-87. doi: 10.1007/s11948-009-9180-z.

Uncertainties.

Dalla Chiara ML(1).

Author information: (1)Department of Philosophy, University of Florence, Via Bolognese 52, 50139, Florence, Italy. dallachiara@philos.unifi.it

In contemporary science uncertainty is often represented as an intrinsic feature of natural and of human phenomena. As an example we need only think of two important conceptual revolutions that occurred in physics and logic during the first half of the twentieth century: (1) the discovery of Heisenberg's uncertainty principle in quantum mechanics; (2) the emergence of many-valued logical reasoning, which gave rise to so-called 'fuzzy thinking'. I discuss the possibility of applying the notions of uncertainty, developed in the framework of quantum mechanics, quantum information and fuzzy logics, to some problems of political and social sciences.

DOI: 10.1007/s11948-009-9180-z PMID: 19859828 [Indexed for MEDLINE]

107. Drug Discov Today. 2007 Sep;12(17-18):725-31. doi: 10.1016/j.drudis.2007.07.006. Epub 2007 Aug 31.

The role of quantum mechanics in structure-based drug design.

Raha K(1), Peters MB, Wang B, Yu N, Wollacott AM, Westerhoff LM, Merz KM Jr.

Author information: (1)Department of Chemistry, Quantum Theory Project, University of Florida, 2328 New Physics Building, P.O. Box 118435, Gainesville, FL 32611-8435, United States.

Herein we will focus on the use of quantum mechanics (QM) in drug design (DD) to solve disparate problems from scoring protein-ligand poses to building QM QSAR models. Through the variational principle of QM we know that we can obtain a more accurate representation of molecular systems than classical models, and while this is not a matter of debate, it still has not been shown that the expense of QM approaches is offset by improved accuracy in DD applications. Objectively validating the improved applicability and performance of QM over classical-based models in DD will be the focus of research in the coming years along with research on the conformational sampling problem as it relates to protein-ligand complexes.

DOI: 10.1016/j.drudis.2007.07.006 PMID: 17826685 [Indexed for MEDLINE]

108. J Comput Chem. 2013 Apr 5;34(10):862-9. doi: 10.1002/jcc.23209. Epub 2013 Jan 3.

Calculation of wave-functions with frozen orbitals in mixed quantum mechanics/molecular mechanics methods. II. Application of the local basis equation.

Ferenczy GG(1).

Author information: (1)MTA-SE Molecular Biophysics Research Group, Department of Biophysics and Radiation Biology, Semmelweis University, 1094 Budapest, Tűzoltó u. 37-47, Hungary. ferenczy.gyorgy@med.semmelweis-univ.hu

The application of the local basis equation (Ferenczy and Adams, J. Chem. Phys. 2009, 130, 134108) in mixed quantum mechanics/molecular mechanics (QM/MM) and quantum mechanics/quantum mechanics (QM/QM) methods is investigated. This equation is suitable to derive local basis nonorthogonal orbitals that minimize the energy of the system and it exhibits good convergence properties in a self-consistent field solution. These features make the equation appropriate to be used in mixed QM/MM and QM/QM methods to optimize orbitals in the field of frozen localized orbitals connecting the subsystems. Calculations performed for several properties in divers systems show that the method is robust with various choices of the frozen orbitals and frontier atom properties. With appropriate basis set assignment, it gives results equivalent with those of a related approach [G. G. Ferenczy previous paper in this issue] using the Huzinaga equation. Thus, the local basis equation can be used in mixed QM/MM methods with small size quantum subsystems to calculate properties in good agreement with reference Hartree-Fock-Roothaan results. It is shown that bond charges are not necessary when the local basis equation is applied, although they are required for the self-consistent field solution of the Huzinaga equation based method. Conversely, the deformation of the wave-function near to the boundary is observed without bond charges and this has a significant effect on deprotonation energies but a less pronounced effect when the total charge of the system is conserved. The local basis equation can also be used to define a two layer quantum system with nonorthogonal localized orbitals surrounding the central delocalized quantum subsystem.

DOI: 10.1002/jcc.23209 PMID: 23288700 [Indexed for MEDLINE]

109. J Chem Theory Comput. 2020 Sep 2. doi: 10.1021/acs.jctc.0c00751. Online ahead of print.

Density Functional Theory-based Quantum Mechanics/Coarse-grained Molecular Mechanics: Theory and Implementation.

Mironenko AV, Voth GA.

Quantum mechanics/molecular mechanics (QM/MM) is a standard computational tool for describing chemical reactivity in systems with many degrees of freedom, including polymers, enzymes, and reacting molecules in complex solvents. However, QM/MM is less suitable for systems with complex MM dynamics due to associated long relaxation times, the high computational cost of QM energy evaluations, and expensive long-range electrostatics. Recently, a systematic coarse-graining of the MM part was proposed to overcome these QM/MM limitations in the form of the quantum mechanics/coarse-grained molecular mechanics (QM/CG-MM) approach. Herein, we recast QM/CG-MM in the density functional theory formalism and, by employing the force-matching variational principle, access the method performance for two model systems: QM CCl4 in the MM CCl4 liquid and the reaction of tert-butyl hypochlorite with the benzyl radical in the MM CCl4 solvent. We find that DFT-QM/CG-MM accurately reproduces DFT-QM/MM radial distribution functions and 3-body correlations between QM and CG-MM subsystems. The free energy profile of the reaction is also described well, with an error < 1-2 kcal/mol. DFT-QM/CG-MM is a general, systematic, and computationally efficient approach to include chemical reactivity in coarse-grained molecular models.

DOI: 10.1021/acs.jctc.0c00751 PMID: 32877176

110. J Phys Chem A. 2017 Jul 20;121(28):5352-5360. doi: 10.1021/acs.jpca.7b04866. Epub 2017 Jul 11.

Quantum Molecular Trajectory and Its Statistical Properties.

Avanzini F(1), Moro GJ(1).

Author information: (1)Dipartimento di Scienze Chimiche, Università di Padova , via Marzolo 1, 35131 Padova, Italy.

Despite the quantum nature of molecules, classical mechanics is often employed to describe molecular motions that play a fundamental role in a wide range of phenomena including chemical reactions. This is due to the need of assigning well-defined positions to the atomic nuclei during the time evolution of the system in order to describe unambiguously the molecular motions, whereas quantum mechanics provides information on probabilistic nature only. One would like to employ a quantum molecular trajectory that defines rigorously the instantaneous nuclear positions and, simultaneously, guarantees the conservation of all quantum mechanics predictions unlike the classical trajectory. We argue that such a quantum molecular trajectory can be formally defined and we prove that it corresponds to a single Bohm trajectory. Our analysis establishes a clear correspondence between the statistical properties of the trajectory and the quantum expectation values. The obvious and undeniable benefit is that of dealing with a quantum methodology fully characterizing the molecular motions without any reference to classical mechanics.

DOI: 10.1021/acs.jpca.7b04866 PMID: 28650172

111. Living Rev Relativ. 2013;16(1):2. doi: 10.12942/lrr-2013-2. Epub 2013 Jan 29.

Minimal Length Scale Scenarios for Quantum Gravity.

Hossenfelder S(1).

Author information: (1)Nordita, Roslagstullsbacken 23, 106 91 Stockholm, Sweden.

We review the question of whether the fundamental laws of nature limit our ability to probe arbitrarily short distances. First, we examine what insights can be gained from thought experiments for probes of shortest distances, and summarize what can be learned from different approaches to a theory of quantum gravity. Then we discuss some models that have been developed to implement a minimal length scale in quantum mechanics and quantum field theory. These models have entered the literature as the generalized uncertainty principle or the modified dispersion relation, and have allowed the study of the effects of a minimal length scale in quantum mechanics, quantum electrodynamics, thermodynamics, black-hole physics and cosmology. Finally, we touch upon the question of ways to circumvent the manifestation of a minimal length scale in short-distance physics.

DOI: 10.12942/lrr-2013-2 PMCID: PMC5255898 PMID: 28179841

112. Phys Rev Lett. 2016 Mar 18;116(11):110403. doi: 10.1103/PhysRevLett.116.110403. Epub 2016 Mar 17.

Creating a Superposition of Unknown Quantum States.

Oszmaniec M(1), Grudka A(2), Horodecki M(3), Wójcik A(2).

Author information: (1)Center for Theoretical Physics, Polish Academy of Sciences, Aleja Lotników 32/46, 02-668 Warszawa, Poland and ICFO-Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology, 08860 Castelldefels, Barcelona, Spain. (2)Faculty of Physics, Adam Mickiewicz University, 61-614 Poznan, Poland. (3)Faculty of Mathematics, Physics and Informatics, University of Gdańsk, 80-952 Gdańsk, Poland and Institute of Theoretical Physics and Astrophysics, and National Quantum Information Centre in Gdańsk, 81-824 Sopot, Poland.

The superposition principle is one of the landmarks of quantum mechanics. The importance of quantum superpositions provokes questions about the limitations that quantum mechanics itself imposes on the possibility of their generation. In this work, we systematically study the problem of the creation of superpositions of unknown quantum states. First, we prove a no-go theorem that forbids the existence of a universal probabilistic quantum protocol producing a superposition of two unknown quantum states. Second, we provide an explicit probabilistic protocol generating a superposition of two unknown states, each having a fixed overlap with the known referential pure state. The protocol can be applied to generate coherent superposition of results of independent runs of subroutines in a quantum computer. Moreover, in the context of quantum optics it can be used to efficiently generate highly nonclassical states or non-Gaussian states.

DOI: 10.1103/PhysRevLett.116.110403 PMID: 27035290

113. Phys Rev Lett. 2019 Jun 21;122(24):240401. doi: 10.1103/PhysRevLett.122.240401.

Geometry of Einstein-Podolsky-Rosen Correlations.

Nguyen HC(1), Nguyen HV(2), Gühne O(1).

Author information: (1)Naturwissenschaftlich-Technische Fakultät, Universität Siegen, Walter-Flex-Straße 3, 57068 Siegen, Germany. (2)Institute of Physics, Vietnam Academy of Science and Technology, 10 Dao Tan, Hanoi, Vietnam.

Correlations between distant particles are central to many puzzles and paradoxes of quantum mechanics and, at the same time, underpin various applications such as quantum cryptography and metrology. Originally in 1935, Einstein, Podolsky, and Rosen (EPR) used these correlations to argue against the completeness of quantum mechanics. To formalize their argument, Schrödinger subsequently introduced the notion of quantum steering. Still, the question of which quantum states can be used for EPR steering and which cannot remained open. Here we show that quantum steering can be viewed as an inclusion problem in convex geometry. For the case of two spin-1/2 particles, this approach completely characterizes the set of states leading to EPR steering. In addition, we discuss the generalization to higher-dimensional systems as well as generalized measurements. Our results find applications in various protocols in quantum information processing, and moreover they are linked to quantum mechanical phenomena such as uncertainty relations and the question of which observables in quantum mechanics are jointly measurable.

DOI: 10.1103/PhysRevLett.122.240401 PMID: 31322372

114. Mol Inform. 2020 Jun 2. doi: 10.1002/minf.202000036. Online ahead of print.

Using the Semiempirical Quantum Mechanics in Improving the Molecular Docking: A Case Study with CDK2.

Bagheri S(1), Behnejad H(1), Firouzi R(2), Karimi-Jafari MH(3).

Author information: (1)Department of Physical Chemistry, School of Chemistry, College of Science, University of Tehran, Tehran, Iran. (2)Department of Physical Chemistry, Chemistry and Chemical Engineering Research Center of Iran, Tehran, Iran. (3)Department of Bioinformatics, Institute of Biochemistry and Biophysics, University of Tehran, Tehran, Iran.

In this study, we use some modified semiempirical quantum mechanics (SQM) methods for improving the molecular docking process. To this end, the three popular SQM Hamiltonians, PM6, PM6-D3H4X, and PM7 are employed for geometry optimization of some binding modes of ligands docked into the human cyclin-dependent kinase 2 (CDK2) by two widely used docking tools, AutoDock and AutoDock Vina. The results were analyzed with two different evaluation metrics: the symmetry-corrected heavy-atom RMSD and the fraction of recovered ligand-protein contacts. It is shown that the evaluation of the fraction of recovered contacts is more useful to measure the similarity between two structures when interacting with a protein. It was also found that AutoDock is more successful than AutoDock Vina in producing the correct ligand poses (RMSD≤2.0 Å) and ranking of the poses. It is also demonstrated that the ligand optimization at the SQM level improves the docking results and the SQM structures have a significantly better fit to the observed crystal structures. Finally, the SQM optimizations reduce the number of close contacts in the docking poses and successfully remove most of the clash or bad contacts between ligand and protein.

DOI: 10.1002/minf.202000036 PMID: 32485047

115. Science. 2010 Jul 23;329(5990):418-21. doi: 10.1126/science.1190545.

Ruling out multi-order interference in quantum mechanics.

Sinha U(1), Couteau C, Jennewein T, Laflamme R, Weihs G.

Author information: (1)Institute for Quantum Computing and Department of Physics and Astronomy, University of Waterloo, 200 University Avenue West, Waterloo, Ontario N2L 3G1, Canada. usinha@iqc.ca

Comment in Science. 2010 Jul 23;329(5990):396-7.

Quantum mechanics and gravitation are two pillars of modern physics. Despite their success in describing the physical world around us, they seem to be incompatible theories. There are suggestions that one of these theories must be generalized to achieve unification. For example, Born's rule--one of the axioms of quantum mechanics--could be violated. Born's rule predicts that quantum interference, as shown by a double-slit diffraction experiment, occurs from pairs of paths. A generalized version of quantum mechanics might allow multipath (i.e., higher-order) interference, thus leading to a deviation from the theory. We performed a three-slit experiment with photons and bounded the magnitude of three-path interference to less than 10(-2) of the expected two-path interference, thus ruling out third- and higher-order interference and providing a bound on the accuracy of Born's rule. Our experiment is consistent with the postulate both in semiclassical and quantum regimes.

DOI: 10.1126/science.1190545 PMID: 20651147

116. Phys Rev E. 2016 Jun;93(6):066103. doi: 10.1103/PhysRevE.93.066103. Epub 2016 Jun 29.

Comment on "Fractional quantum mechanics" and "Fractional Schrödinger equation".

Wei Y(1).

Author information: (1)Nanmengqian, Dafeng, Wuzhi, Jiaozuo, Henan, 454981, China.

In this Comment we point out some shortcomings in two papers [N. Laskin, Phys. Rev. E 62, 3135 (2000)10.1103/PhysRevE.62.3135; N. Laskin, Phys. Rev. E 66, 056108 (2002)10.1103/PhysRevE.66.056108]. We prove that the fractional uncertainty relation does not hold generally. The probability continuity equation in fractional quantum mechanics has a missing source term, which leads to particle teleportation, i.e., a particle can teleport from a place to another. Since the relativistic kinetic energy can be viewed as an approximate realization of the fractional kinetic energy, the particle teleportation should be an observable relativistic effect in quantum mechanics. With the help of this concept, superconductivity could be viewed as the teleportation of electrons from one side of a superconductor to another and superfluidity could be viewed as the teleportation of helium atoms from one end of a capillary tube to the other. We also point out how to teleport a particle to an arbitrary destination.

DOI: 10.1103/PhysRevE.93.066103 PMID: 27415397

117. J Chem Theory Comput. 2014 Sep 9;10(9):3784-90. doi: 10.1021/ct500512f.

Exact and Optimal Quantum Mechanics/Molecular Mechanics Boundaries.

Sun Q(1), Chan GK(1).

Author information: (1)Department of Chemistry, Princeton University , Princeton New Jersey 08544, United States.

Motivated by recent work in density matrix embedding theory, we define exact link orbitals that capture all quantum mechanical (QM) effects across arbitrary quantum mechanics/molecular mechanics (QM/MM) boundaries. Exact link orbitals are rigorously defined from the full QM solution, and their number is equal to the number of orbitals in the primary QM region. Truncating the exact set yields a smaller set of link orbitals optimal with respect to reproducing the primary region density matrix. We use the optimal link orbitals to obtain insight into the limits of QM/MM boundary treatments. We further analyze the popular general hybrid orbital (GHO) QM/MM boundary across a test suite of molecules. We find that GHOs are often good proxies for the most important optimal link orbital, although there is little detailed correlation between the detailed GHO composition and optimal link orbital valence weights. The optimal theory shows that anions and cations cannot be described by a single link orbital. However, expanding to include the second most important optimal link orbital in the boundary recovers an accurate description. The second optimal link orbital takes the chemically intuitive form of a donor or acceptor orbital for charge redistribution, suggesting that optimal link orbitals can be used as interpretative tools for electron transfer. We further find that two optimal link orbitals are also sufficient for boundaries that cut across double bonds. Finally, we suggest how to construct "approximately" optimal link orbitals for practical QM/MM calculations.

DOI: 10.1021/ct500512f PMID: 26588523

118. Chem Soc Rev. 2015 Apr 7;44(7):1763-76. doi: 10.1039/c4cs00348a. Epub 2015 Jan 22.

A multiscale quantum mechanics/electromagnetics method for device simulations.

Yam C(1), Meng L, Zhang Y, Chen G.

Author information: (1)Beijing Computational Science Research Center, Beijing 100084, China. yamcy@csrc.ac.cn.

Multiscale modeling has become a popular tool for research applying to different areas including materials science, microelectronics, biology, chemistry, etc. In this tutorial review, we describe a newly developed multiscale computational method, incorporating quantum mechanics into electronic device modeling with the electromagnetic environment included through classical electrodynamics. In the quantum mechanics/electromagnetics (QM/EM) method, the regions of the system where active electron scattering processes take place are treated quantum mechanically, while the surroundings are described by Maxwell's equations and a semiclassical drift-diffusion model. The QM model and the EM model are solved, respectively, in different regions of the system in a self-consistent manner. Potential distributions and current densities at the interface between QM and EM regions are employed as the boundary conditions for the quantum mechanical and electromagnetic simulations, respectively. The method is illustrated in the simulation of several realistic systems. In the case of junctionless field-effect transistors, transfer characteristics are obtained and a good agreement between experiments and simulations is achieved. Optical properties of a tandem photovoltaic cell are studied and the simulations demonstrate that multiple QM regions are coupled through the classical EM model. Finally, the study of a carbon nanotube-based molecular device shows the accuracy and efficiency of the QM/EM method.

DOI: 10.1039/c4cs00348a PMID: 25611987

119. Philos Trans A Math Phys Eng Sci. 2015 Aug 6;373(2047):20140236. doi: 10.1098/rsta.2014.0236.

Models on the boundary between classical and quantum mechanics.

Hooft G'(1).

Author information: (1)Institute for Theoretical Physics and Spinoza Institute, Utrecht University, PO Box 80.195, 3508 TD Utrecht, The Netherlands g.thooft@uu.nl.

Arguments that quantum mechanics cannot be explained in terms of any classical theory using only classical logic seem to be based on sound mathematical considerations: there cannot be physical laws that require 'conspiracy'. It may therefore be surprising that there are several explicit quantum systems where these considerations apparently do not apply. In this report, several such counterexamples are shown. These are quantum models that do have a classical origin. The most curious of these models is superstring theory. So now the question is asked: how can such a model feature 'conspiracy', and how bad is that? Is there conspiracy in the vacuum fluctuations? Arguments concerning Bell's theorem are further sharpened.

DOI: 10.1098/rsta.2014.0236 PMID: 26124246

120. Front Plant Sci. 2011 Apr 12;2:10. doi: 10.3389/fpls.2011.00010. eCollection 2011.

Epigenetics: Biology's Quantum Mechanics.

Jorgensen RA(1).

Author information: (1)Laboratorio (LANGEBIO) Nacional de Genómica para la Biodiversidad, Centro (CINVESTAV) de Investigación y Estudios Avanzados Irapuato, Guanajuato, México.

The perspective presented here is that modern genetics is at a similar stage of development as were early formulations of quantum mechanics theory in the 1920s and that in 2010 we are at the dawn of a new revolution in genetics that promises to enrich and deepen our understanding of the gene and the genome. The interrelationships and interdependence of two views of the gene - the molecular biological view and the epigenetic view - are explored, and it is argued that the classical molecular biological view is incomplete without incorporation of the epigenetic perspective and that in a sense the molecular biological view has been evolving to include the epigenetic view. Intriguingly, this evolution of the molecular view toward the broader and more inclusive epigenetic view of the gene has an intriguing, if not precise, parallel in the evolution of concepts of atomic physics from Newtonian mechanics to quantum mechanics that are interesting to consider.

DOI: 10.3389/fpls.2011.00010 PMCID: PMC3355681 PMID: 22639577

121. Methods Mol Biol. 2020;2114:257-268. doi: 10.1007/978-1-0716-0282-9_16.

Binding Free Energy Calculation Using Quantum Mechanics Aimed for Drug Lead Optimization.

Cavasotto CN(1)(2)(3)(4).

Author information: (1)Computational Drug Design and Biomedical Informatics Laboratory, Translational Medicine Research Institute (IIMT), CONICET-Universidad Austral, Derqui-Pilar, Buenos Aires, Argentina. CCavasotto@austral.edu.ar. (2)Austral Institute for Applied Artificial Intelligence, Universidad Austral, Derqui-Pilar, Buenos Aires, Argentina. CCavasotto@austral.edu.ar. (3)Facultad de Ciencias Biomédicas, Universidad Austral, Derqui-Pilar, Buenos Aires, Argentina. CCavasotto@austral.edu.ar. (4)Facultad de Ingeniería, Universidad Austral, Derqui-Pilar, Buenos Aires, Argentina. CCavasotto@austral.edu.ar.

The routine use of in silico tools is already established in drug lead design. Besides the use of molecular docking methods to screen large chemical libraries and thus prioritize compounds for purchase or synthesis, more accurate calculations of protein-ligand binding free energy has shown the potential to guide lead optimization, thus saving time and resources. Theoretical developments and advances in computing power have allowed quantum mechanical-based methods applied to calculations on biomacromolecules to be increasingly explored and used, with the purpose of providing a more accurate description of protein-ligand interactions and an enhanced level of accuracy in the calculation of binding affinities. It should be noted that the quantum mechanical formulation includes, in principle, all contributions to the energy, considering terms usually neglected in molecular mechanics force fields, such as electronic polarization, metal coordination, and covalent binding; moreover, quantum mechanical approaches are systematically improvable. By treating all elements and interactions on equal footing, and avoiding the need of system-dependent parameterizations, they provide a greater degree of transferability. In this review, we illustrate the increasing relevance of quantum mechanical methods for binding free energy calculation in the context of structure-based drug lead optimization, showing representative applications of the different approaches available.

DOI: 10.1007/978-1-0716-0282-9_16 PMID: 32016898

122. Prog Biophys Mol Biol. 2018 Dec;140:41-48. doi: 10.1016/j.pbiomolbio.2018.04.005. Epub 2018 Apr 13.

The Cosmologic continuum from physics to consciousness.

Torday JS(1), Miller WB Jr(2).

Author information: (1)Department of Pediatrics Harbor-UCLA Medical Center, USA. Electronic address: jtorday@ucla.edu. (2)Paradise Valley, AZ, USA. Electronic address: wbmiller1@cox.net.

Reduction of developmental biology to self-referential cell-cell communication offers a portal for understanding fundamental mechanisms of physiology as derived from physics through quantum mechanics. It is argued that self-referential organization is implicit to the Big Bang and its further expression is a recoil reaction to that Singularity. When such a frame is considered, in combination with experimental evidence for the importance of epigenetic inheritance, the unicellular state can be reappraised as the primary object of selection. This framework provides a significant shift in understanding the relationship between physics and biology, providing novel insights to the nature and origin of consciousness.

DOI: 10.1016/j.pbiomolbio.2018.04.005 PMID: 29709302 [Indexed for MEDLINE]

123. J Comput Chem. 2013 Apr 5;34(10):854-61. doi: 10.1002/jcc.23210. Epub 2012 Dec 28.

Calculation of wave-functions with frozen orbitals in mixed quantum mechanics/molecular mechanics methods. Part I. Application of the Huzinaga equation.

Ferenczy GG(1).

Author information: (1)MTA-SE Molecular Biophysics Research Group, Department of Biophysics and Radiation Biology, Semmelweis University, 1094 Budapest, Tűzoltóu. 37-47, Hungary. ferenczy.gyorgy@med.semmelweis-univ.hu

Mixed quantum mechanics/quantum mechanics (QM/QM) and quantum mechanics/molecular mechanics (QM/MM) methods make computations feasible for extended chemical systems by separating them into subsystems that are treated at different level of sophistication. In many applications, the subsystems are covalently bound and the use of frozen localized orbitals at the boundary is a possible way to separate the subsystems and to ensure a sensible description of the electronic structure near to the boundary. A complication in these methods is that orthogonality between optimized and frozen orbitals has to be warranted and this is usually achieved by an explicit orthogonalization of the basis set to the frozen orbitals. An alternative to this approach is proposed by calculating the wave-function from the Huzinaga equation that guaranties orthogonality to the frozen orbitals without basis set orthogonalization. The theoretical background and the practical aspects of the application of the Huzinaga equation in mixed methods are discussed. Forces have been derived to perform geometry optimization with wave-functions from the Huzinaga equation. Various properties have been calculated by applying the Huzinaga equation for the central QM subsystem, representing the environment by point charges and using frozen strictly localized orbitals to connect the subsystems. It is shown that a two to three bond separation of the chemical or physical event from the frozen bonds allows a very good reproduction (typically around 1 kcal/mol) of standard Hartree-Fock-Roothaan results. The proposed scheme provides an appropriate framework for mixed QM/QM and QM/MM methods.

DOI: 10.1002/jcc.23210 PMID: 23281055 [Indexed for MEDLINE]

124. J Chem Theory Comput. 2012 Apr 10;8(4):1351-9. doi: 10.1021/ct300114w. Epub 2012 Mar 27.

Photostability Mechanisms in Human γB-Crystallin: Role of the Tyrosine Corner Unveiled by Quantum Mechanics and Hybrid Quantum Mechanics/Molecular Mechanics Methodologies.

Marazzi M(1), Navizet I(2), Lindh R(3), Frutos LM(1).

Author information: (1)Departamento de Química Física, Universidad de Alcalá , E-28871 Alcalá de Henares (Madrid), Spain. (2)School of Chemistry, University of the Witwatersrand , ZA-2050 Johannesburg, South Africa. (3)Department of Chemistry, Ångström, The Theoretical Chemistry Programme, Uppsala University, SE-75120 Uppsala, Sweden.

The tyrosine corner is proposed as a featured element to enhance photostability in human γB-crystallin when exposed to UV irradiation. Different ultrafast processes were studied by multiconfigurational quantum chemistry coupled to molecular mechanics: photoinduced singlet-singlet energy, electron and proton transfer, as well as population and evolution of triplet states. The minimum energy paths indicate two possible UV photoinduced events: forward-backward proton-coupled electron transfer providing to the system a mechanism for ultrafast internal conversion, and energy transfer, leading to fluorescence or phosphorescence. The obtained results are in agreement with the available experimental data, being in line with the proposed photoinduced processes for the different tyrosine environments within γB-crystallin.

DOI: 10.1021/ct300114w PMID: 26596750

125. Curr Comput Aided Drug Des. 2012 Sep;8(3):249-54. doi: 10.2174/157340912801619102.

Quantum pharmacology for infectious diseases: a molecular connectivity approach.

Singh S(1).

Author information: (1)National Centre for Cell Science, NCCS Complex, Ganeshkhind, Pune University Campus, Pune 411007, India. shailza_iitd@yahoo.com

Infectious diseases are a major cause of global health, economic and social problems. Relationship between the infectious diseases and drugs designed to combat them can be understood by the Quantum Pharmacology approach. Quantum pharmacology which is an amalgamation of chemistry, quantum mechanics and computer modeling aims to understand the structure activity relationship of a drug. As compared to the classical MM, the hybrid QM/MM approach which takes into account the quantum mechanics along with the molecular mechanics facilitates the simulation of biological structures with greater accuracy and speed. This review highlights the importance of quantum mechanics for a better understanding of molecular systems and QSAR studies.

DOI: 10.2174/157340912801619102 PMID: 22738083 [Indexed for MEDLINE]

126. Rev Neurol. 2002 Jul 1-15;35(1):87-94.

[Quantum mechanics and brain: a critical review].

[Article in Spanish]

Pastor-Gómez J(1).

Author information: (1)Hospital Universitario de la Princesa, Madrid, España. jpastor@hlpr.insalud.es

Comment in Rev Neurol. 2003 Feb 15-28;36(4):400.

OBJECTIVE: Theories about consciousness are in an initial state of development. In the recent past, diverse theories have been proposed to explain the phenomenon of the consciousness using the Quantum Mechanics (QM) as a fundamental tool. Here, we criticize some of these theories in the light of the current knowledge in neuroscience. DEVELOPMENT: The QM theories of consciousness by John Eccles, Dana Zohar and Roger Penrose are discussed. For a better understanding of these theories, some physical principles of the quantum formalism are firstly introduced. We then expose these theories in the authors original formalism and discuss them from a neuroscientist point of view. DISCUSSION: As currently exposed, the three QM theories of consciousness suffer from important neuroscientist concerns. It is not necessary the use QM to explain different aspects of brain function such as consciousness, which would be better understood using tools from the neurosciences

PMID: 12389200 [Indexed for MEDLINE]

127. Future Med Chem. 2012 Jul;4(11):1479-94. doi: 10.4155/fmc.12.92.

Quantum kernel applications in medicinal chemistry.

Huang L(1), Massa L.

Author information: (1)Center for Computational Materials Science, Naval Research Laboratory, Washington, DC 20375-5341, USA. huang@nrl.navy.mil

Progress in the quantum mechanics of biological molecules is being driven by computational advances. The notion of quantum kernels can be introduced to simplify the formalism of quantum mechanics, making it especially suitable for parallel computation of very large biological molecules. The essential idea is to mathematically break large biological molecules into smaller kernels that are calculationally tractable, and then to represent the full molecule by a summation over the kernels. The accuracy of the kernel energy method (KEM) is shown by systematic application to a great variety of molecular types found in biology. These include peptides, proteins, DNA and RNA. Examples are given that explore the KEM across a variety of chemical models, and to the outer limits of energy accuracy and molecular size. KEM represents an advance in quantum biology applicable to problems in medicine and drug design.

DOI: 10.4155/fmc.12.92 PMID: 22857535 [Indexed for MEDLINE]

128. J Chem Phys. 2016 Jul 14;145(2):024703. doi: 10.1063/1.4956449.

Quantum mechanics capacitance molecular mechanics modeling of core-electron binding energies of methanol and methyl nitrite on Ag(111) surface.

Löytynoja T(1), Li X(2), Jänkälä K(1), Rinkevicius Z(2), Ågren H(2).

Author information: (1)Nano and Molecular Systems Research Unit, University of Oulu, P.O. Box 3000, FIN-90014 Oulu, Finland. (2)Division of Theoretical Chemistry and Biology, School of Biotechnology, Royal Institute of Technology, SE-106 91 Stockholm, Sweden.

We study a newly devised quantum mechanics capacitance molecular mechanics (QMCMM) method for the calculation of core-electron binding energies in the case of molecules adsorbed on metal surfaces. This yet untested methodology is applied to systems with monolayer of methanol/methyl nitrite on an Ag(111) surface at 100 K temperature. It was found out that the studied C, N, and O 1s core-hole energies converge very slowly as a function of the radius of the metallic cluster, which was ascribed to build up of positive charge on the edge of the Ag slab. Further analysis revealed that an extrapolation process can be used to obtain binding energies that deviated less than 0.5 eV against experiments, except in the case of methanol O 1s where the difference was as large as 1.8 eV. Additional QM-cluster calculations suggest that the latter error can be connected to the lack of charge transfer over the QM-CMM boundary. Thus, the results indicate that the QMCMM and QM-cluster methods can complement each other in a holistic picture of molecule-adsorbate core-ionization studies, where all types of intermolecular interactions are considered.

DOI: 10.1063/1.4956449 PMID: 27421423

129. J Chem Phys. 2006 Apr 21;124(15):154707. doi: 10.1063/1.2187485.

A QUICKSTEP-based quantum mechanics/molecular mechanics approach for silica.

Zipoli F(1), Laino T, Laio A, Bernasconi M, Parrinello M.

Author information: (1)Dipartimento di Scienza dei Materiali, Università di Milano-Bicocca, Via Cozzi 53, I-20125, Milano, Italy. federico.zipoli@mater.unimib.it

Quantum mechanics/molecular mechanics (QM/MM) approaches are currently used to describe several properties of silica-based systems, which are local in nature and require a quantum description of only a small number of atoms around the site of interest, e.g., local chemical reactivity or spectroscopic properties of point defects. We present a QM/MM scheme for silica suitable to be implemented in the general QM/MM framework recently developed for large scale molecular dynamics simulations, within the QUICKSTEP approach to the description of the quantum region. Our scheme has been validated by computing the structural and dynamical properties of an oxygen vacancy in alpha-quartz, a prototypical defect in silica. We have found that good convergence in the Si-Si bond length and formation energy is achieved by using a quantum cluster of only eight atoms in size. We check the suitability of the method for molecular dynamics and evaluate the Si-Si bond frequency from the velocity-velocity correlation function.

DOI: 10.1063/1.2187485 PMID: 16674251

130. Acta Hist Leopoldina. 2014;(63):187-200.

[Carl Friedrich von Weizsäcker and the interpretations of quantum theory].

[Article in German]

Stöckler M.

What are 'interpretations' of quantum theory? What are the differences between Carl Friedrich von Weizsäkcker's approach and contemporary views? The various interpretations of quantum mechanics give diverse answers to questions concerning the relation between measuring process and standard time development, the embedding of quantum objects in space ('wave-particle-dualism'), and the reference of state vectors. Does the wave function describe states in the real world or does it refer to our knowledge about nature? First, some relevant conceptions in Weizsäcker's book The Structure of Physics (Der Aufbau der Physik, 1985) are introduced. In a second step I point out why his approach is not any longer present in contemporary debates. One reason is that Weizsäcker is mainly affected by classical philosophy (Platon, Aristoteles, Kant). He could not esteem the philosophy of science that was developed in the spirit of logical empiricism. So he lost interest in disputes with Anglo-Saxon philosophy of quantum mechanics. Especially his interpretation of probability and his analysis of the collapse of the state function as change in knowledge differ from contemporary standard views. In recent years, however, epistemic interpretations of quantum mechanics are proposed that share some of Weizsäcker's intuitions.

PMID: 24974602 [Indexed for MEDLINE]

131. Philos Trans A Math Phys Eng Sci. 2016 May 28;374(2068):20150239. doi: 10.1098/rsta.2015.0239.

The future (and past) of quantum theory after the Higgs boson: a quantum-informational viewpoint.

Plotnitsky A(1).

Author information: (1)Theory and Cultural Studies Program, Purdue University, West Lafayette, IN 47907, USA plotnits@purdue.edu.

Taking as its point of departure the discovery of the Higgs boson, this article considers quantum theory, including quantum field theory, which predicted the Higgs boson, through the combined perspective of quantum information theory and the idea of technology, while also adopting anon-realistinterpretation, in 'the spirit of Copenhagen', of quantum theory and quantum phenomena themselves. The article argues that the 'events' in question in fundamental physics, such as the discovery of the Higgs boson (a particularly complex and dramatic, but not essentially different, case), are made possible by the joint workings of three technologies: experimental technology, mathematical technology and, more recently, digital computer technology. The article will consider the role of and the relationships among these technologies, focusing on experimental and mathematical technologies, in quantum mechanics (QM), quantum field theory (QFT) and finite-dimensional quantum theory, with which quantum information theory has been primarily concerned thus far. It will do so, in part, by reassessing the history of quantum theory, beginning with Heisenberg's discovery of QM, in quantum-informational and technological terms. This history, the article argues, is defined by the discoveries of increasingly complex configurations of observed phenomena and the emergence of the increasingly complex mathematical formalism accounting for these phenomena, culminating in the standard model of elementary-particle physics, defining the current state of QFT.

DOI: 10.1098/rsta.2015.0239 PMID: 27091170

132. Philos Trans A Math Phys Eng Sci. 2019 Nov 4;377(2157):20190089. doi: 10.1098/rsta.2019.0089. Epub 2019 Sep 16.

Spooky predictions at a distance: reality, complementarity and contextuality in quantum theory.

Plotnitsky A(1).

Author information: (1)Theory, Literature, and Cultural Studies Program, College of Liberal Arts, Purdue University, W. Lafayette, IN 47907, USA.

This article brings together reality, complementarity and contextuality in quantum theory. It clarifies Bohr's concept of complementarity by considering the non-realist epistemology and the corresponding interpretations of quantum mechanics, based in the concept of 'reality without realism'. Finally, as its main novel contribution, it establishes the connections between complementarity and contextuality. This article is part of the theme issue 'Contextuality and probability in quantum mechanics and beyond'.

DOI: 10.1098/rsta.2019.0089 PMID: 31522641

133. Phys Rev E Stat Nonlin Soft Matter Phys. 2005 Dec;72(6 Pt 2):066125. doi: 10.1103/PhysRevE.72.066125. Epub 2005 Dec 29.

Non-Hamiltonian commutators in quantum mechanics.

Sergi A(1).

Author information: (1)Dipartimento di Fisica, Sezione Fisica Teorica, Universitá degli Studi di Messina, Contrada Papardo Cassella Postale 50-98166 Messina, Italy. asergi@unime.it

The symplectic structure of quantum commutators is first unveiled and then exploited to describe generalized non-Hamiltonian brackets in quantum mechanics. It is easily recognized that quantum-classical systems are described by a particular realization of such a bracket. In light of previous work, this paper explains a unified approach to classical and quantum-classical non-Hamiltonian dynamics. In order to illustrate the use of non-Hamiltonian commutators, it is shown how to define thermodynamic constraints in quantum-classical systems. In particular, quantum-classical Nosé-Hoover equations of motion and the associated stationary density matrix are derived. The non-Hamiltonian commutators for both Nosé-Hoover chains and Nosé-Andersen (constant-pressure, constant-temperature) dynamics are also given. Perspectives of the formalism are discussed.

DOI: 10.1103/PhysRevE.72.066125 PMID: 16486028

134. Sci Rep. 2016 Jan 19;6:19364. doi: 10.1038/srep19364.

A Combination of Chemometrics and Quantum Mechanics Methods Applied to Analysis of Femtosecond Transient Absorption Spectrum of Ortho-Nitroaniline.

Yi J(1), Xiong Y(2), Cheng K(2), Li M(1), Chu G(3), Pu X(1), Xu T(2).

Author information: (1)College of Chemistry, Sichuan University, Chengdu 610064, People's Republic of China. (2)Institute of Chemical Material, China Academy of Engineering Physics (CAEP), Mianyang 621900, People's Republic of China. (3)Science and Technology on Plasma Physics Laboratory, Research Center of Laser Fusion, CAEP, Mianyang 621900, People's Republic of China.

A combination of the advanced chemometrics method with quantum mechanics calculation was for the first time applied to explore a facile yet efficient analysis strategy to thoroughly resolve femtosecond transient absorption spectroscopy of ortho-nitroaniline (ONA), served as a model compound of important nitroaromatics and explosives. The result revealed that the ONA molecule is primarily excited to S3 excited state from the ground state and then ultrafast relaxes to S2 state. The internal conversion from S2 to S1 occurs within 0.9 ps. One intermediate state S* was identified in the intersystem crossing (ISC) process, which is different from the specific upper triplet receiver state proposed in some other nitroaromatics systems. The S1 state decays to the S* one within 6.4 ps and then intersystem crossing to the lowest triplet state within 19.6 ps. T1 was estimated to have a lifetime up to 2 ns. The relatively long S* state and very long-lived T1 one should play a vital role as precursors to various nitroaromatic and explosive photoproducts.

DOI: 10.1038/srep19364 PMCID: PMC4726040 PMID: 26781083

135. Philos Trans A Math Phys Eng Sci. 2011 Dec 13;369(1956):4864-90. doi: 10.1098/rsta.2011.0179.

Uncertainty in quantum mechanics: faith or fantasy?

Penrose R(1).

Author information: (1)Mathematical Institute, 24-29 St Giles', Oxford OX1 3LB, UK. roger.penrose@maths.ox.ac.uk

The word 'uncertainty', in the context of quantum mechanics, usually evokes an impression of an essential unknowability of what might actually be going on at the quantum level of activity, as is made explicit in Heisenberg's uncertainty principle, and in the fact that the theory normally provides only probabilities for the results of quantum measurement. These issues limit our ultimate understanding of the behaviour of things, if we take quantum mechanics to represent an absolute truth. But they do not cause us to put that very 'truth' into question. This article addresses the issue of quantum 'uncertainty' from a different perspective, raising the question of whether this term might be applied to the theory itself, despite its unrefuted huge success over an enormously diverse range of observed phenomena. There are, indeed, seeming internal contradictions in the theory that lead us to infer that a total faith in it at all levels of scale leads us to almost fantastical implications.

DOI: 10.1098/rsta.2011.0179 PMID: 22042902

136. Ber Wiss. 2019 Dec;42(4):338-356. doi: 10.1002/bewi.201900007. Epub 2019 Nov 28.

Yoshikatsu Sugiura's Contribution to the Development of Quantum Physics in Japan.

Nakane M(1).

Author information: (1)Department of Law, Seijo University, Japan.

Previous research in the history of physics has led us to believe that Yoshio Nishina (1890-1951) virtually single-handedly imported quantum physics into Japan. However, there are first-hand accounts that Yoshikatsu Sugiura (1895-1960) also played an important role. Sugiura made his name in quantum chemistry with his contribution to the Heitler-London theory of the chemical bond. Yet, historians of physics have paid scant attention to him. This paper brings forward information on Sugiura from his letters, his scientific papers, and his own recollections until ca. 1930. By examining this material, the present paper studies Sugiura's accomplishments in Europe and his contributions to the development of quantum physics in Japan. We conclude that Sugiura was one of the most important physicists when it comes to the arrival of quantum physics in Japan. In addition, we assess why he has been under-appreciated in the history of physics in Japan. Our historical study on Sugiura suggests that, in addition to the position Nishina and his students rightfully occupy, there still are important unexplored aspects in the history of Japanese quantum physics.

DOI: 10.1002/bewi.201900007 PMID: 31777981

137. J Mol Model. 2016 Sep;22(9):218. doi: 10.1007/s00894-016-3083-0. Epub 2016 Aug 24.

A Monte Carlo-quantum mechanics study of a solvatochromic π* probe.

Domínguez M(1)(2), Rezende MC(3)(4).

Author information: (1)Facultad de Química y Biología, Universidad de Santiago de Chile, Av. Bernando O'Higgins 3363, Santiago, Chile. moises.dominguez@usach.cl. (2)Facultad de Química y Biología, Universidad de Santiago, Casilla 40, Correo 33, Santiago, Chile. moises.dominguez@usach.cl. (3)Facultad de Química y Biología, Universidad de Santiago de Chile, Av. Bernando O'Higgins 3363, Santiago, Chile. (4)Facultad de Química y Biología, Universidad de Santiago, Casilla 40, Correo 33, Santiago, Chile.

The solvation and the solvatochromic behavior of 5-(dimethylamino)-5'-nitro-2,2'-bithiophene 1, the basis of a π* scale of solvent polarities, was investigated theoretically in toluene, dichloromethane, methanol and formamide with a Monte Carlo and quantum mechanics (QM/MM) iterative approach. The calculated transition energies of the solvatochromic band of 1, obtained as averages of statistically uncorrelated configurations, including the solute and explicit solvent molecules of the first solvation layer, besides showing good agreement with the experimental transitions, reproduced very well the positive solvatochromism of this probe in various solvents.

DOI: 10.1007/s00894-016-3083-0 PMID: 27553303

138. Proteins. 2001 Sep 1;44(4):484-9. doi: 10.1002/prot.1114.

Quantum mechanics simulation of protein dynamics on long timescale.

Liu H(1), Elstner M, Kaxiras E, Frauenheim T, Hermans J, Yang W.

Author information: (1)Department of Chemistry, Duke University, Durham, North Carolina, USA.

Protein structure and dynamics are the keys to a wide range of problems in biology. In principle, both can be fully understood by using quantum mechanics as the ultimate tool to unveil the molecular interactions involved. Indeed, quantum mechanics of atoms and molecules have come to play a central role in chemistry and physics. In practice, however, direct application of quantum mechanics to protein systems has been prohibited by the large molecular size of proteins. As a consequence, there is no general quantum mechanical treatment that not only exceeds the accuracy of state-of-the-art empirical models for proteins but also maintains the efficiency needed for extensive sampling in the conformational space, a requirement mandated by the complexity of protein systems. Here we show that, given recent developments in methods, a general quantum mechanical-based treatment can be constructed. We report a molecular dynamics simulation of a protein, crambin, in solution for 350 ps in which we combine a semiempirical quantum-mechanical description of the entire protein with a description of the surrounding solvent, and solvent-protein interactions based on a molecular mechanics force field. Comparison with a recent very high-resolution crystal structure of crambin (Jelsch et al., Proc Natl Acad Sci USA 2000;102:2246-2251) shows that geometrical detail is better reproduced in this simulation than when several alternate molecular mechanics force fields are used to describe the entire system of protein and solvent, even though the structure is no less flexible. Individual atomic charges deviate in both directions from "canonical" values, and some charge transfer is found between the N and C-termini. The capability of simulating protein dynamics on and beyond the few hundred ps timescale with a demonstrably accurate quantum mechanical model will bring new opportunities to extend our understanding of a range of basic processes in biology such as molecular recognition and enzyme catalysis.

DOI: 10.1002/prot.1114 PMID: 11484226 [Indexed for MEDLINE]

139. Ann N Y Acad Sci. 2015 Dec;1361:18-35. doi: 10.1111/nyas.12860. Epub 2015 Sep 11.

The unification of physics: the quest for a theory of everything.

Paulson S(1), Gleiser M(2), Freese K(3)(4), Tegmark M(5).

Author information: (1)Wisconsin Public Radio, Madison, Wisconsin. (2)Dartmouth College, Hanover, New Hampshire. (3)NORDITA - Nordic Institute for Theoretical Physics, Stockholm, Sweden. (4)University of Michigan, Ann Arbor, Michigan. (5)Massachusetts Institute of Technology, Cambridge, Massachusetts.

The holy grail of physics has been to merge each of its fundamental branches into a unified "theory of everything" that would explain the functioning and existence of the universe. The last step toward this goal is to reconcile general relativity with the principles of quantum mechanics, a quest that has thus far eluded physicists. Will physics ever be able to develop an all-encompassing theory, or should we simply acknowledge that science will always have inherent limitations as to what can be known? Should new theories be validated solely on the basis of calculations that can never be empirically tested? Can we ever truly grasp the implications of modern physics when the basic laws of nature do not always operate according to our standard paradigms? These and other questions are discussed in this paper.

DOI: 10.1111/nyas.12860 PMID: 26359791 [Indexed for MEDLINE]

140. Phys Chem Chem Phys. 2010 May 21;12(19):5041-52. doi: 10.1039/b918608e. Epub 2010 Mar 2.

Application of high level wavefunction methods in quantum mechanics/molecular mechanics hybrid schemes.

Mata RA(1).

Author information: (1)Institut für Physikalische Chemie, Universität Göttingen, Tammannstrasse 6, D-37077 Gttingen, Germany.

In this Perspective, several developments in the field of quantum mechanics/molecular mechanics (QM/MM) approaches are reviewed. Emphasis is placed on the use of correlated wavefunction theory and new state of the art methods for the treatment of large quantum systems. Until recently, computational chemistry approaches to large/complex chemical problems have seldom been considered as tools for quantitative predictions. However, due to the tremendous development of computational resources and new quantum chemical methods, it is nowadays possible to describe the electronic structure of biomolecules at levels of theory which a decade ago were only possible for system sizes of up to 20 atoms. These advances are here outlined in the context of QM/MM. The article concludes with a short outlook on upcoming developments and possible bottlenecks for future applications.

DOI: 10.1039/b918608e PMID: 20445906

141. J Comput Chem. 2013 Mar 5;34(6):492-504. doi: 10.1002/jcc.23157. Epub 2012 Oct 29.

Block-adaptive quantum mechanics: an adaptive divide-and-conquer approach to interactive quantum chemistry.

Bosson M(1), Grudinin S, Redon S.

Author information: (1)NANO-D-INRIA Grenoble-Rhône-Alpes/CNRS Laboratoire Jean Kuntzmann, Rhone-Alpes 655, Avenue de l'Europe, Saint Ismier Cedex 38335, France. mael.bosson@inria.fr

We present a novel Block-Adaptive Quantum Mechanics (BAQM) approach to interactive quantum chemistry. Although quantum chemistry models are known to be computationally demanding, we achieve interactive rates by focusing computational resources on the most active parts of the system. BAQM is based on a divide-and-conquer technique and constrains some nucleus positions and some electronic degrees of freedom on the fly to simplify the simulation. As a result, each time step may be performed significantly faster, which in turn may accelerate attraction to the neighboring local minima. By applying our approach to the nonself-consistent Atom Superposition and Electron Delocalization Molecular Orbital theory, we demonstrate interactive rates and efficient virtual prototyping for systems containing more than a thousand of atoms on a standard desktop computer.

DOI: 10.1002/jcc.23157 PMID: 23108532 [Indexed for MEDLINE]

142. Phys Rev Lett. 2020 Jul 3;125(1):014101. doi: 10.1103/PhysRevLett.125.014101.

Early-Time Exponential Instabilities in Nonchaotic Quantum Systems.

Rozenbaum EB(1)(2), Bunimovich LA(3), Galitski V(1)(2).

Author information: (1)Joint Quantum Institute, University of Maryland, College Park, Maryland 20742, USA. (2)Condensed Matter Theory Center, Department of Physics, University of Maryland, College Park, Maryland 20742, USA. (3)School of Mathematics, Georgia Institute of Technology, Atlanta, Georgia 30332, USA.

The majority of classical dynamical systems are chaotic and exhibit the butterfly effect: a minute change in initial conditions has exponentially large effects later on. But this phenomenon is difficult to reconcile with quantum mechanics. One of the main goals in the field of quantum chaos is to establish a correspondence between the dynamics of classical chaotic systems and their quantum counterparts. In isolated systems in the absence of decoherence, there is such a correspondence in dynamics, but it usually persists only over a short time window, after which quantum interference washes out classical chaos. We demonstrate that quantum mechanics can also play the opposite role and generate exponential instabilities in classically nonchaotic systems within this early-time window. Our calculations employ the out-of-time-ordered correlator (OTOC)-a diagnostic that reduces to the Lyapunov exponent in the classical limit but is well defined for general quantum systems. We show that certain classically nonchaotic models, such as polygonal billiards, demonstrate a Lyapunov-like exponential growth of the OTOC at early times with Planck's-constant-dependent rates. This behavior is sharply contrasted with the slow early-time growth of the analog of the OTOC in the systems' classical counterparts. These results suggest that classical-to-quantum correspondence in dynamics is violated in the OTOC even before quantum interference develops.

DOI: 10.1103/PhysRevLett.125.014101 PMID: 32678633

143. Prog Biophys Mol Biol. 2018 Aug;136:37-39. doi: 10.1016/j.pbiomolbio.2018.02.002. Epub 2018 Feb 9.

Pleiotropy, the physiologic basis for biologic fields.

Torday JS(1).

Author information: (1)Department of Pediatrics, Harbor-UCLA Medical Center Torrance, CA 90502-2006, United States. Electronic address: jtorday@ucla.edu.

Biologic organisms act like fields. Hypothetically, pleiotropy results from the systematic re-purposing of genes over the course of the evolutionary history of the organism as pre-adaptations or exaptations. Mechanistically, pleiotropic genes are selected for during the process of evolution with reference to the First Principles of Physiology (FPP). Under stress conditions, pleiotropic genes will act as a functional network to cohesively maintain allostasis. There are strong homologies between Quantum Mechanics and the FPP. The homology between the Quantum states of the electron and cell may be due to the self-organizing principle that underlies both, hypothetically emanating from the Big Bang that formed the Universe some 13.8 billion years ago. The identification of the common origins and principles of physics and biology offers a cohesive explanation for origins and evolution of life.

DOI: 10.1016/j.pbiomolbio.2018.02.002 PMID: 29432781 [Indexed for MEDLINE]

144. J Chem Theory Comput. 2007 Mar;3(2):628-39. doi: 10.1021/ct600284f.

Automated Parametrization of Biomolecular Force Fields from Quantum Mechanics/Molecular Mechanics (QM/MM) Simulations through Force Matching.

Maurer P(1), Laio A(1), Hugosson HW(1), Colombo MC(1), Rothlisberger U(1).

Author information: (1)École Polytechnique Fédérale de Lausanne (EPFL), Institute of Chemical Sciences and Engineering, BCH-LCBC, CH-1015 Lausanne, Switzerland.

We introduce a novel procedure to parametrize biomolecular force fields. We perform finite-temperature quantum mechanics/molecular mechanics (QM/MM) molecular dynamics simulations, with the fragment or moiety that has to be parametrized being included in the QM region. By applying a force-matching algorithm, we derive a force field designed in order to reproduce the steric, electrostatic, and dynamic properties of the QM subsystem. The force field determined in this manner has an accuracy that is comparable to the one of the reference QM/MM calculation, but at a greatly reduced computational cost. This allows calculating quantities that would be prohibitive within a QM/MM approach, such as thermodynamic averages involving slow motions of a protein. The method is tested on three different systems in aqueous solution: dihydrogenphosphate, glycyl-alanine dipeptide, and a nitrosyl-dicarbonyl complex of technetium(I). Molecular dynamics simulations with the optimized force field show overall excellent performance in reproducing properties such as structures and dipole moments of the solutes as well as their solvation pattern.

DOI: 10.1021/ct600284f PMID: 26637041

145. Nat Commun. 2016 Oct 3;7:13022. doi: 10.1038/ncomms13022.

A universal test for gravitational decoherence.

Pfister C(1)(2), Kaniewski J(1)(2), Tomamichel M(2)(3), Mantri A(2), Schmucker R(2), McMahon N(4), Milburn G(4), Wehner S(1).

Author information: (1)QuTech, Delft University of Technology, Lorentzweg 1, Delft 2628 CJ, The Netherlands. (2)Centre for Quantum Technologies, 3 Science Drive 2, Singapore 117543, Singapore. (3)School of Physics, University of Sydney, Sydney, New South Wales 2006, Australia. (4)ARC Centre for Engineered Quantum Systems, School of Mathematics and Physics, The University of Queensland, St Lucia, Queensland 4072, Australia.

Quantum mechanics and the theory of gravity are presently not compatible. A particular question is whether gravity causes decoherence. Several models for gravitational decoherence have been proposed, not all of which can be described quantum mechanically. Since quantum mechanics may need to be modified, one may question the use of quantum mechanics as a calculational tool to draw conclusions from the data of experiments concerning gravity. Here we propose a general method to estimate gravitational decoherence in an experiment that allows us to draw conclusions in any physical theory where the no-signalling principle holds, even if quantum mechanics needs to be modified. As an example, we propose a concrete experiment using optomechanics. Our work raises the interesting question whether other properties of nature could similarly be established from experimental observations alone-that is, without already having a rather well-formed theory of nature to make sense of experimental data.

DOI: 10.1038/ncomms13022 PMCID: PMC5063961 PMID: 27694976

146. Ann N Y Acad Sci. 2005 Jun;1045:308-32. doi: 10.1196/annals.1350.026.

Chaos and quantum mechanics.

Habib S(1), Bhattacharya T, Greenbaum B, Jacobs K, Shizume K, Sundaram B.

Author information: (1)MS B285, Theoretical Division, The University of California, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA. habib@lanl.gov

The relationship between chaos and quantum mechanics has been somewhat uneasy--even stormy, in the minds of some people. However, much of the confusion may stem from inappropriate comparisons using formal analyses. In contrast, our starting point here is that a complete dynamical description requires a full understanding of the evolution of measured systems, necessary to explain actual experimental results. This is of course true, both classically and quantum mechanically. Because the evolution of the physical state is now conditioned on measurement results, the dynamics of such systems is intrinsically nonlinear even at the level of distribution functions. Due to this feature, the physically more complete treatment reveals the existence of dynamical regimes--such as chaos--that have no direct counterpart in the linear (unobserved) case. Moreover, this treatment allows for understanding how an effective classical behavior can result from the dynamics of an observed quantum system, both at the level of trajectories as well as distribution functions. Finally, we have the striking prediction that time-series from measured quantum systems can be chaotic far from the classical regime, with Lyapunov exponents differing from their classical values. These predictions can be tested in next-generation experiments.

DOI: 10.1196/annals.1350.026 PMID: 15980320

147. J Comput Aided Mol Des. 2017 Sep;31(9):789-800. doi: 10.1007/s10822-017-0042-5. Epub 2017 Jul 27.

Molden 2.0: quantum chemistry meets proteins.

Schaftenaar G(1), Vlieg E(2), Vriend G(3).

Author information: (1)CMBI, Radboudumc, Nijmegen, The Netherlands. Gijs.Schaftenaar@radboudumc.nl. (2)Institute for Molecules and Materials, Radboud University Nijmegen, Heyendaalseweg 135, 6525 AJ, Nijmegen, The Netherlands. (3)CMBI, Radboudumc, Nijmegen, The Netherlands.

Since the first distribution of Molden in 1995 and the publication of the first article about this software in 2000 work on Molden has continued relentlessly. A few of the many improved or fully novel features such as improved and broadened support for quantum chemistry calculations, preparation of ligands for use in drug design related softwares, and working with proteins for the purpose of ligand docking.

DOI: 10.1007/s10822-017-0042-5 PMCID: PMC5633641 PMID: 28752344 [Indexed for MEDLINE]

148. Ber Wiss. 2019 Dec;42(4):400-423. doi: 10.1002/bewi.201900008. Epub 2019 Dec 3.

Beyond Ideology: Epistemological Foundations of Vladimir Fock's approach to Quantum Theory.

Martinez JP(1).

Author information: (1)Postdoctoral Fellow, Universidade Federal da Bahia/CAPES, Brazil & Associate Researcher, Laboratoire SPHERE/CNRS, France.

Vladimir Fock was a Soviet theoretical physicist who, from the 1930s, worked to prove that modern physics was compatible with the Marxist philosophy of dialectical materialism. In 1957, he went to Copenhagen, and a dispute over the interpretation of quantum mechanics began with Niels Bohr. Fock later claimed that he had found points of convergence with his Danish colleague, most of them concerning issues of wording and recognition of the reality of the world independently of our mind. It led to a specific narrative among historians of physics on Fock and his interpretation of quantum mechanics: The Soviet physicist is often described as a member of the Copenhagen school that contributed to the rapprochement of the Soviet philosophy of physics with the ideas of complementarity in stripping away the positivism in its formulation. Our contribution aims to show that this ideological dimension was only one aspect of reality. Returning to the foundations of Fock's epistemology of physics, we argue that he relied on the principles of antireductionism and scientific realism to develop an interpretation of the theory that sought to overcome Bohr's approach and that the differences between the two men cannot be reduced to mere questions of formulation.

DOI: 10.1002/bewi.201900008 PMID: 31793002

149. J Phys Chem A. 2013 Apr 25;117(16):3442-8. doi: 10.1021/jp401067z. Epub 2013 Apr 15.

Multidimensional supersymmetric quantum mechanics: spurious states for the tensor sector two Hamiltonian.

Chou CC(1), Kouri DJ.

Author information: (1)Department of Chemistry, National Tsing Hua University, Hsinchu, 30013, Taiwan. ccchou@mx.nthu.edu.tw

We show that there exist spurious states for the sector two tensor Hamiltonian in multidimensional supersymmetric quantum mechanics. For one-dimensional supersymmetric quantum mechanics on an infinite domain, the sector one and two Hamiltonians have identical spectra with the exception of the ground state of the sector one. For tensorial multidimensional supersymmetric quantum mechanics, there exist normalizable spurious states for the sector two Hamiltonian with energy equal to the ground state energy of the sector one. These spurious states are annihilated by the adjoint charge operator, and hence, they do not correspond to physical states for the original Hamiltonian. The Hermitian property of the sector two Hamiltonian implies the orthogonality between spurious and physical states. In addition, we develop a method for construction of a specific form of the spurious states for any quantum system and also generate several spurious states for a two-dimensional anharmonic oscillator system and for the hydrogen atom.

DOI: 10.1021/jp401067z PMID: 23531015

150. Phys Rev E Stat Nonlin Soft Matter Phys. 2011 Feb;83(2 Pt 1):021121. doi: 10.1103/PhysRevE.83.021121. Epub 2011 Feb 28.

Similarity between quantum mechanics and thermodynamics: entropy, temperature, and Carnot cycle.

Abe S(1), Okuyama S.

Author information: (1)Department of Physical Engineering, Mie University, Mie 514-8507, Japan.

Comment in Phys Rev E Stat Nonlin Soft Matter Phys. 2015 May;91(5):056101. Phys Rev E Stat Nonlin Soft Matter Phys. 2015 May;91(5):056102.

The similarity between quantum mechanics and thermodynamics is discussed. It is found that if the Clausius equality is imposed on the Shannon entropy and the analog of the quantity of heat, then the value of the Shannon entropy comes to formally coincide with that of the von Neumann entropy of the canonical density matrix, and pure-state quantum mechanics apparently transmutes into quantum thermodynamics. The corresponding quantum Carnot cycle of a simple two-state model of a particle confined in a one-dimensional infinite potential well is studied, and its efficiency is shown to be identical to the classical one.

DOI: 10.1103/PhysRevE.83.021121 PMID: 21405832

151. Proc Natl Acad Sci U S A. 2014 Aug 5;111(31):11281-6. doi: 10.1073/pnas.1324238111. Epub 2014 Jul 11.

Quantum nonlocality does not exist.

Tipler FJ(1).

Author information: (1)Department of Mathematics, Tulane University, New Orleans, LA 70118 tipler@tulane.edu.

Quantum nonlocality is shown to be an artifact of the Copenhagen interpretation, in which each observed quantity has exactly one value at any instant. In reality, all physical systems obey quantum mechanics, which obeys no such rule. Locality is restored if observed and observer are both assumed to obey quantum mechanics, as in the many-worlds interpretation (MWI). Using the MWI, I show that the quantum side of Bell's inequality, generally believed nonlocal, is really due to a series of three measurements (not two as in the standard, oversimplified analysis), all three of which have only local effects. Thus, experiments confirming "nonlocality" are actually confirming the MWI. The mistaken interpretation of nonlocality experiments depends crucially on a question-begging version of the Born interpretation, which makes sense only in "collapse" versions of quantum theory, about the meaning of the modulus of the wave function, so I use the interpretation based on the MWI, namely that the wave function is a world density amplitude, not a probability amplitude. This view allows the Born interpretation to be derived directly from the Schrödinger equation, by applying the Schrödinger equation to both the observed and the observer.

DOI: 10.1073/pnas.1324238111 PMCID: PMC4128114 PMID: 25015084

Conflict of interest statement: The author declares no conflict of interest.

152. Proc Natl Acad Sci U S A. 1979 Oct;76(10):4768-72. doi: 10.1073/pnas.76.10.4768.

Lyapounov variable: Entropy and measurement in quantum mechanics.

Misra B(1), Prigogine I, Courbage M.

Author information: (1)Faculté des Sciences, Université Libre de Bruxelles, Brussels, Belgium.

We discuss the question of the dynamical meaning of the second law of thermodynamics in the framework of quantum mechanics. Previous discussion of the problem in the framework of classical dynamics has shown that the second law can be given a dynamical meaning in terms of the existence of so-called Lyapounov variables-i.e., dynamical variables varying monotonically in time without becoming contradictory. It has been found that such variables can exist in an extended framework of classical dynamics, provided that the dynamical motion is suitably unstable. In this paper we begin to extend these results to quantum mechanics. It is found that no dynamical variable with the characteristic properties of nonequilibrium entropy can be defined in the standard formulation of quantum mechanics. However, if the Hamiltonian has certain well-defined spectral properties, such variables can be defined but only as a nonfactorizable superoperator. Necessary nonfactorizability of such entropy operators M has the consequence that they cannot preserve the class of pure states. Physically, this means that the distinguishability between pure states and corresponding mixtures must be lost in the case of a quantal system for which the algebra of observables can be extended to include a new dynamical variable representing nonequilibrium entropy. We discuss how this result leads to a solution of the quantum measurement problem. It is also found that the question of existence of entropy of superoperators M is closely linked to the problem of defining an operator of time in quantum mechanics.

DOI: 10.1073/pnas.76.10.4768 PMCID: PMC413018 PMID: 16578757

153. Biosystems. 1999 Mar;49(3):229-37. doi: 10.1016/s0303-2647(98)00086-0.

Quantum mechanics in the present progressive mode and its significance in biological information processing.

Matsuno K(1), Paton RC.

Author information: (1)Department of BioEngineering, Nagaoka University of Technology, Japan.

Quantum mechanics practiced in the present progressive mode can incorporate into itself the propagation of a signal of a local character. It is possible to view that any movement in the present progressive mode is mutli-agential in the sense of internal interactions due to the absence of an external agency coordinating the global situation simultaneously. The idea of living memory is discussed as carrying the leftover from those actions completed and registered in the present perfect mode and surviving at any present moment. The occurrence of both the signal propagation of a local character and living memory is upheld upon exchange interaction of a quantum mechanical origin. Empirical evidence suggesting the likelihood of such an exchange interaction is found in the neurotransmitter-gated ion channels located on the plasma membrane of the muscle cell in the vicinity of secretory vesicles containing acetylcholine near the nerve terminal. Another case from the empirical evidence is seen in the actomyosin system demonstrating the unidirectional propagation of variations in the acceleration of the displacement of an actin filament sliding on myosin molecules in the presence of ATP molecules.

DOI: 10.1016/s0303-2647(98)00086-0 PMID: 10193761 [Indexed for MEDLINE]

154. Drug Des Devel Ther. 2017 Nov 8;11:3205. doi: 10.2147/DDDT.S155133. eCollection 2017.

Erratum: Quantum mechanics implementation in drug-design workflows: does it really help? [Corrigendum].

[No authors listed]

Erratum for Drug Des Devel Ther. 2017 Aug 31;11:2551-2564.

[This corrects the article on p. 2551 in vol. 11.].

DOI: 10.2147/DDDT.S155133 PMCID: PMC5685133 PMID: 29184390

155. Psychoanal Rev. 2013 Aug;100(4):543-58. doi: 10.1521/prev.2013.100.4.543.

Some thoughts about consciousness: from a quantum mechanics perspective.

Gargiulo GJ(1).

Author information: (1)JerryGargiulo@gmail.com

The article explores some of the basic findings of quantum physics and information theory and their possible usefulness in offering new vistas for understanding psychoanalysis and the patient-analyst interchange. Technical terms are explained and placed in context, and examples of applying quantum models to clinical experience are offered. Given the complexity of the findings of quantum mechanics and information theory, the article aims only to introduce some of the major concepts from these disciplines. Within this framework the article also briefly addresses the question of mind as well as the problematic of reducing the experience of consciousness to neurological brain functioning.

DOI: 10.1521/prev.2013.100.4.543 PMID: 23865992 [Indexed for MEDLINE]

156. J Chem Phys. 2016 Jun 21;144(23):234511. doi: 10.1063/1.4954064.

Solvent effects on the absorption spectrum and first hyperpolarizability of keto-enol tautomeric forms of anil derivatives: A Monte Carlo/quantum mechanics study.

Adriano Junior L(1), Fonseca TL(1), Castro MA(1).

Author information: (1)Instituto de Física, Universidade Federal de Goiás, CEP 74.690-900, Goiânia, GO, Brazil.

Theoretical results for the absorption spectrum and electric properties of the enol and keto tautomeric forms of anil derivatives in the gas-phase and in solution are presented. The electronic properties in chloroform, acetonitrile, methanol, and water were determined by carrying out sequential Monte Carlo simulations and quantum mechanics calculations based on the time dependent density functional theory and on the second-order Møller-Plesset perturbation theory method. The results illustrate the role played by electrostatic interactions in the electronic properties of anil derivatives in a liquid environment. There is a significant increase of the dipole moment in solution (20%-100%) relative to the gas-phase value. Solvent effects are mild for the absorption spectrum and linear polarizability but they can be particularly important for first hyperpolarizability. A large first hyperpolarizability contrast between the enol and keto forms is observed when absorption spectra present intense lowest-energy absorption bands. Dynamic results for the first hyperpolarizability are in qualitative agreement with the available experimental results.

DOI: 10.1063/1.4954064 PMID: 27334183

157. Methods Enzymol. 2016;577:251-86. doi: 10.1016/bs.mie.2016.05.046. Epub 2016 Jul 1.

Practical Aspects of Multiscale Classical and Quantum Simulations of Enzyme Reactions.

Dixit M(1), Das S(1), Mhashal AR(1), Eitan R(1), Major DT(2).

Author information: (1)Lise Meitner-Minerva Center of Computational Quantum Chemistry, Bar-Ilan University, Ramat Gan, Israel. (2)Lise Meitner-Minerva Center of Computational Quantum Chemistry, Bar-Ilan University, Ramat Gan, Israel. Electronic address: majort@biu.ac.il.

This chapter aims to present some basic multiscale approaches available for enzyme simulations, and to point out practical details and pitfalls that are not often discussed in the literature, but can greatly influence the outcome of any in silico enzyme study. We cover principle methodological steps of multiscale studies of general enzyme reactions. This includes choice of starting structures, boundary conditions, potential energy surfaces, reaction coordinates, simulation methods, as well as the choice of method for the treatment of nuclear quantum effects. Together, these and additional steps are crucial for the success of enzyme-modeling projects and should be considered prior to embarking on multiscale modeling.

DOI: 10.1016/bs.mie.2016.05.046 PMID: 27498641 [Indexed for MEDLINE]

158. Philos Trans A Math Phys Eng Sci. 2018 Jul 13;376(2123):20170312. doi: 10.1098/rsta.2017.0312.

'Space is blue and birds fly through it'.

Rovelli C(1).

Author information: (1)CPT, Aix-Marseille Université, Université de Toulon, CNRS, 13288 Marseille, France rovelli@cpt.univ-mrs.fr.

Quantum mechanics is not about 'quantum states': it is about values of physical variables. I give a short fresh presentation and update on the relational perspective on the theory, and a comment on its philosophical implications.This article is part of a discussion meeting issue 'Foundations of quantum mechanics and their impact on contemporary society'.

DOI: 10.1098/rsta.2017.0312 PMID: 29807892

159. Phys Chem Chem Phys. 2019 Oct 9;21(39):22160. doi: 10.1039/c9cp90238d.

Correction: Significance of hydrogen bonding networks in the proton-coupled electron transfer reactions of photosystem II from a quantum-mechanics perspective.

Chai J (1), Zheng Z , Pan H , Zhang S , Lakshmi KV , Sun YY .

Author information: (1)State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 201899, China. yysun@mail.sic.ac.cn.

Erratum for Phys Chem Chem Phys. 2019 Apr 24;21(17):8721-8728.

Correction for 'Significance of hydrogen bonding networks in the proton-coupled electron transfer reactions of photosystem II from a quantum-mechanics perspective' by Jun Chai et al., Phys. Chem. Chem. Phys., 2019, 21, 8721-8728.

DOI: 10.1039/c9cp90238d PMID: 31552964

160. J Phys Chem B. 2005 May 26;109(20):10474-83. doi: 10.1021/jp044185y.

Protein/ligand binding free energies calculated with quantum mechanics/molecular mechanics.

Gräter F(1), Schwarzl SM, Dejaegere A, Fischer S, Smith JC.

Author information: (1)IWR--Computational Biochemistry, University of Heidelberg, Im Neuenheimer Feld 368, 69120 Heidelberg, Germany.

The calculation of binding affinities for flexible ligands has hitherto required the availability of reliable molecular mechanics parameters for the ligands, a restriction that can in principle be lifted by using a mixed quantum mechanics/molecular mechanics (QM/MM) representation in which the ligand is treated quantum mechanically. The feasibility of this approach is evaluated here, combining QM/MM with the Poisson-Boltzmann/surface area model of continuum solvation and testing the method on a set of 47 benzamidine derivatives binding to trypsin. The experimental range of the absolute binding energy (DeltaG = -3.9 to -7.6 kcal/mol) is reproduced well, with a root-mean-square (RMS) error of 1.2 kcal/mol. When QM/MM is applied without reoptimization to the very different ligands of FK506 binding protein the RMS error is only 0.7 kcal/mol. The results show that QM/MM is a promising new avenue for automated docking and scoring of flexible ligands. Suggestions are made for further improvements in accuracy.

DOI: 10.1021/jp044185y PMID: 16852269 [Indexed for MEDLINE]

161. J Chem Phys. 2020 Jun 28;152(24):244119. doi: 10.1063/5.0006365.

Non-Hermitian quantum mechanics and exceptional points in molecular electronics.

Ernzerhof M(1), Giguère A(1), Mayou D(2).

Author information: (1)Département de Chimie, Université de Montréal, C.P. 6128 Succursale A, Montréal, Québec H3C 3J7, Canada. (2)Institut Néel, 25 Avenue des Martyrs, BP 166, 38042 Grenoble Cedex 9, France.

In non-Hermitian (NH) quantum mechanics, Hamiltonians are studied whose eigenvalues are not necessarily real since the condition of hermiticity is not imposed. Certain symmetries of NH operators can ensure that some or all of the eigenvalues are real and thus suitable for the description of physical systems whose energies are always real. While the mathematics of NH quantum mechanics is well developed, applications of the theory to real quantum systems are scarce, and no closed system is known whose Hamiltonian is NH. Here, we consider the elementary textbook example of a NH Hamiltonian matrix, and we show how it naturally emerges as a simplifying concept in the modeling of molecular electronic devices. We analyze the consequences of non-Hermiticity and exceptional points in the spectrum of NH operators for the molecular conductance and the spectral density of simple models for molecules on surfaces.

DOI: 10.1063/5.0006365 PMID: 32610942

162. J Chem Theory Comput. 2012 Apr 10;8(4):1190-9. doi: 10.1021/ct200859h. Epub 2012 Mar 14.

Dynamic Multiscale Quantum Mechanics/Electromagnetics Simulation Method.

Meng L(1), Yam C(1), Koo S(1), Chen Q(2), Wong N(2), Chen G(1).

Author information: (1)Department of Chemistry, The University of Hong Kong , Pokfulam Road, Hong Kong. (2)Department of Electrical and Electronic Engineering, The University of Hong Kong , Pokfulam Road, Hong Kong.

A newly developed hybrid quantum mechanics and electromagnetics (QM/EM) method [Yam et al. Phys. Chem. Chem. Phys.2011, 13, 14365] is generalized to simulate the real time dynamics. Instead of the electric and magnetic fields, the scalar and vector potentials are used to integrate Maxwell's equations in the time domain. The TDDFT-NEGF-EOM method [Zheng et al. Phys. Rev. B2007, 75, 195127] is employed to simulate the electronic dynamics in the quantum mechanical region. By allowing the penetration of a classical electromagnetic wave into the quantum mechanical region, the electromagnetic wave for the entire simulating region can be determined consistently by solving Maxwell's equations. The transient potential distributions and current density at the interface between quantum mechanical and classical regions are employed as the boundary conditions for the quantum mechanical and electromagnetic simulations, respectively. Charge distribution, current density, and potentials at different temporal steps and spatial scales are integrated seamlessly within a unified computational framework.

DOI: 10.1021/ct200859h PMID: 26596737

163. J Chem Phys. 2011 Dec 14;135(22):224111. doi: 10.1063/1.3666011.

Thermodynamic integration from classical to quantum mechanics.

Habershon S(1), Manolopoulos DE.

Author information: (1)Centre for Computational Chemistry, School of Chemistry, University of Bristol, Bristol BS8 1TS, United Kingdom. scott.habershon@bristol.ac.uk

We present a new method for calculating quantum mechanical corrections to classical free energies, based on thermodynamic integration from classical to quantum mechanics. In contrast to previous methods, our method is numerically stable even in the presence of strong quantum delocalization. We first illustrate the method and its relationship to a well-established method with an analysis of a one-dimensional harmonic oscillator. We then show that our method can be used to calculate the quantum mechanical contributions to the free energies of ice and water for a flexible water model, a problem for which the established method is unstable.

DOI: 10.1063/1.3666011 PMID: 22168684

164. J Chem Theory Comput. 2014 Aug 12;10(8):3354-68. doi: 10.1021/ct500211w.

Hybrid Quantum Mechanics/Molecular Mechanics Solvation Scheme for Computing Free Energies of Reactions at Metal-Water Interfaces.

Faheem M(1), Heyden A(1).

Author information: (1)Department of Chemical Engineering, University of South Carolina , 301 South Main Street, Columbia, South Carolina 29208, United States.

We report the development of a quantum mechanics/molecular mechanics free energy perturbation (QM/MM-FEP) method for modeling chemical reactions at metal-water interfaces. This novel solvation scheme combines planewave density function theory (DFT), periodic electrostatic embedded cluster method (PEECM) calculations using Gaussian-type orbitals, and classical molecular dynamics (MD) simulations to obtain a free energy description of a complex metal-water system. We derive a potential of mean force (PMF) of the reaction system within the QM/MM framework. A fixed-size, finite ensemble of MM conformations is used to permit precise evaluation of the PMF of QM coordinates and its gradient defined within this ensemble. Local conformations of adsorbed reaction moieties are optimized using sequential MD-sampling and QM-optimization steps. An approximate reaction coordinate is constructed using a number of interpolated states and the free energy difference between adjacent states is calculated using the QM/MM-FEP method. By avoiding on-the-fly QM calculations and by circumventing the challenges associated with statistical averaging during MD sampling, a computational speedup of multiple orders of magnitude is realized. The method is systematically validated against the results of ab initio QM calculations and demonstrated for C-C cleavage in double-dehydrogenated ethylene glycol on a Pt (111) model surface.

DOI: 10.1021/ct500211w PMID: 26588304

165. J Phys Chem A. 2011 Nov 17;115(45):12667-76. doi: 10.1021/jp203531x. Epub 2011 Jul 18.

Worlds apart in chemistry: a personal tribute to J. C. Slater.

Bader RF(1).

Author information: (1)Department of Chemistry, McMaster University, Hamilton, ON, Canada.

A reading of the book of Dirac's life entitled The Strangest Man is a most stirring experience, bringing one back to the beginnings of quantum mechanics where every attempt was made "to establish a basis for theoretical quantum mechanics founded exclusively on relationships between quantities which are in principle observable." The prime movers in this quest were Heisenberg and Dirac. One of Dirac's most important contributions in the passage from classical to quantum mechanics, a passage that consumed much of his early efforts, was unfortunately published in an obscure Russian journal where it remained largely unread until it was found by Feynman while a graduate student at Princeton. The paper posed the question, "what corresponds in the quantum theory to the Lagrangian method of classical mechanics?", a method that, as Dirac pointed out, is clearly superior in the simplicity of its structure to that of the classical Hamiltonian approach. Dirac's partial answer to this question provided the key to solving the problem of introducing the action integral into quantum mechanics that occupied Feynman's mind, leading to his formulation of the path integral technique. His contribution was followed two years later by Schwinger's independently derived statement of the quantum action principle, each contribution providing a complete formulation of quantum mechanics stated in terms of single principle. The present paper points out that the successful introduction of the action principle into quantum mechanics made possible by Dirac, enables one to proceed still further by extending Schwinger's quantum action principle to an open system, to an atom in a molecule. Thus the quantum theory of an atom in a molecule has its roots in the question posed by Dirac in 1933. The paper proposes a return to a greater use of the theorems of quantum mechanics in interpretive chemistry from that begun by Slater in 1933, a staunch advocate of theory following in the footsteps of observation.

DOI: 10.1021/jp203531x PMID: 21766823

166. J Phys Chem B. 2013 Dec 5;117(48):14960-6. doi: 10.1021/jp409568h. Epub 2013 Nov 21.

Quantum mechanics/molecular mechanics restrained electrostatic potential fitting.

Burger SK(1), Schofield J, Ayers PW.

Author information: (1)Department of Chemistry, University of Toronto , 80 St. George Street, Toronto, Ontario M5S 3H6, Canada.

We present a quantum mechanics/molecular mechanics (QM/MM) method to evaluate the partial charges of amino acid residues for use in MM potentials based on their protein environment. For each residue of interest, the nearby residues are included in the QM system while the rest of the protein is treated at the MM level of theory. After a short structural optimization, the partial charges of the central residue are fit to the electrostatic potential using the restrained electrostatic potential (RESP) method. The resulting charges and electrostatic potential account for the individual environment of the residue, although they lack the transferable nature of library partial charges. To evaluate the quality of the QM/MM RESP charges, thermodynamic integration is used to measure the pKa shift of the aspartic acid residues in three different proteins, turkey egg lysozyme, beta-cryptogein, and Thioredoxin. Compared to the AMBER ff99SB library values, the QM/MM RESP charges show better agreement between the calculated and experimental pK(a) values for almost all of the residues considered.

DOI: 10.1021/jp409568h PMID: 24176005 [Indexed for MEDLINE]

167. Phys Rev E Stat Nonlin Soft Matter Phys. 2011 Aug;84(2 Pt 2):026616. doi: 10.1103/PhysRevE.84.026616. Epub 2011 Aug 29.

Quantized Hamilton dynamics describes quantum discrete breathers in a simple way.

Igumenshchev K(1), Prezhdo O.

Author information: (1)Department of Chemistry, University of Rochester, Rochester, New York 14627, USA. kigumens@mail.rochester.edu

We study the localization of energy in a nonlinear coupled system, exhibiting so-called breather modes, using quantized Hamilton dynamics (QHD). Already at the lowest order, which is only twice as complex as classical mechanics, this simple semiclassical method incorporates quantum-mechanical effects. The transition between the localized and delocalized regimes is instantaneous in classical mechanics, while it is gradual due to tunneling in both quantum mechanics and QHD. In contrast to classical mechanics, which predicts an abrupt appearance of breathers, quantum mechanics and QHD show an alternation of localized and delocalized behavior in the transient region. QHD includes zero-point energy that is reflected in a shifted energy asymptote for the localized states, providing another improvement on the classical perspective. By detailed analysis of the distribution and transfer of energy within classical mechanics, QHD, and quantum dynamics, we conclude that QHD is an efficient approach that accounts for moderate quantum effects and can be used to identify quantum breathers in large nonlinear systems.

DOI: 10.1103/PhysRevE.84.026616 PMID: 21929137

168. Phys Rev Lett. 2019 Sep 13;123(11):110401. doi: 10.1103/PhysRevLett.123.110401.

Photon Bunching in a Rotating Reference Frame.

Restuccia S(1), Toroš M(2)(3), Gibson GM(1), Ulbricht H(2), Faccio D(1), Padgett MJ(1).

Author information: (1)School of Physics and Astronomy, University of Glasgow, Glasgow G12 8QQ, United Kingdom. (2)Department of Physics and Astronomy, University of Southampton, Southampton SO17 1BJ, United Kingdom. (3)Department of Physics and Astronomy, University College London, London WC1E 6BT, United Kingdom.

Although quantum physics is well understood in inertial reference frames (flat spacetime), a current challenge is the search for experimental evidence of nontrivial or unexpected behavior of quantum systems in noninertial frames. Here, we present a novel test of quantum mechanics in a noninertial reference frame: we consider Hong-Ou-Mandel (HOM) interference on a rotating platform and study the effect of uniform rotation on the distinguishability of the photons. Both theory and experiments show that the rotational motion induces a relative delay in the photon arrival times at the exit beam splitter and that this delay is observed as a shift in the position of the HOM dip. This experiment can be extended to a full general relativistic test of quantum physics using satellites in Earth's orbit and indicates a new route toward the use of photonic technologies for investigating quantum mechanics at the interface with relativity.

DOI: 10.1103/PhysRevLett.123.110401 PMID: 31573252

169. Sci Rep. 2018 Feb 14;8(1):2999. doi: 10.1038/s41598-018-21092-8.

Projective measurement onto arbitrary superposition of weak coherent state bases.

Izumi S(1)(2)(3), Takeoka M(4), Wakui K(4), Fujiwara M(4), Ema K(5), Sasaki M(4).

Author information: (1)National Institute of Information and Communications Technology, 4-2-1 Nukui-kita, Koganei, Tokyo, 184-8795, Japan. sizumi@fysik.dtu.dk. (2)Sophia University, 7-1 Kioicho, Chiyoda-ku, Tokyo, 102-8554, Japan. sizumi@fysik.dtu.dk. (3)Department of Physics, Technical University of Denmark, Building 309, 2800, Lyngby, Denmark. sizumi@fysik.dtu.dk. (4)National Institute of Information and Communications Technology, 4-2-1 Nukui-kita, Koganei, Tokyo, 184-8795, Japan. (5)Sophia University, 7-1 Kioicho, Chiyoda-ku, Tokyo, 102-8554, Japan.

One of the peculiar features in quantum mechanics is that a superposition of macroscopically distinct states can exist. In optical system, this is highlighted by a superposition of coherent states (SCS), i.e. a superposition of classical states. Recently this highly nontrivial quantum state and its variant have been demonstrated experimentally. Here we demonstrate the superposition of coherent states in quantum measurement which is also a key concept in quantum mechanics. More precisely, we propose and implement a projection measurement onto an arbitrary superposition of two weak coherent states in optical system. The measurement operators are reconstructed experimentally by a novel quantum detector tomography protocol. Our device is realized by combining the displacement operation and photon counting, well established technologies, and thus has implications in various optical quantum information processing applications.

DOI: 10.1038/s41598-018-21092-8 PMCID: PMC5813249 PMID: 29445101

Conflict of interest statement: The authors declare no competing interests.

170. Prog Biophys Mol Biol. 2017 Dec;131:242-250. doi: 10.1016/j.pbiomolbio.2017.09.003. Epub 2017 Sep 5.

Sheaf theoretic formulation for consciousness and qualia and relationship to the idealism of non-dual philosophies.

Kafatos MC(1), Kato GC(2).

Author information: (1)Fletcher Jones Endowed Professor of Computational Physics, Chapman University, Orange, CA 92866, United States. Electronic address: kafatos@chapman.edu. (2)Department of Mathematics, California Polytechnic State University, San Luis Obispo, CA 93407, United States. Electronic address: gkato@calpoly.edu.

Questions about the nature of reality, whether Consciousness is the fundamental reality in the universe, and what is Consciousness itself, have no answer in systems that assume an external reality independent of Consciousness. Ultimately, the ontological foundation of such systems is the absolute division of subject and object. We advocate instead what we consider to be an approach that is in agreement with the foundation of quantum reality, which is based on Rāmānuja's version of Vedanta philosophy and non-dual Kashmir Śaivism. Quantum mechanics opened the door to consciousness, but it cannot account for consciousness. However, the quantum measurement problem implies that we cannot remove subjective experience from the practice of science. It is then appropriate to seek mathematical formalisms for the workings of consciousness that don't rely on specific interpretations of quantum mechanics. Temporal topos provides such a framework. In the theory of temporal topos, which we outline here, the difference between a subject and an object involves the direction of a morphism in a category. We also note that in the dual category, the direction of the morphism is in the opposite direction compared with the original direction of the original category. The resulting formalism provides powerful ways to address consciousness and qualia, beyond attempts to account for consciousness through physical theories. We also discuss the implications of the mathematics presented here for the convergence of science and non-dualist philosophies, as an emerging science of Consciousness, that may bring out the underlying unity of physics, life and mind.

DOI: 10.1016/j.pbiomolbio.2017.09.003 PMID: 28887144 [Indexed for MEDLINE]

171. Philos Trans A Math Phys Eng Sci. 2016 Mar 13;374(2063):20150152. doi: 10.1098/rsta.2015.0152.

Pragmatic information in biology and physics.

Roederer JG(1).

Author information: (1)Geophysical Institute, University of Alaska Fairbanks, Fairbanks, AK 99775, USA jgroederer@alaska.edu.

I will show how an objective definition of the concept of information and the consideration of recent results about information processing in the human brain help clarify some fundamental aspects of physics and biology. Rather than attempting to define information ab initio, I introduce the concept of interaction between material bodies as a primary concept. Two distinct categories can be identified: (i) interactions which can always be reduced to a superposition of physical interactions (forces) between elementary constituents; and (ii) interactions between complex bodies which cannot be expressed as a superposition of interactions between parts, and in which patterns and forms (in space and/or time) play the determining role. Pragmatic information is then defined as the link between a given pattern and the ensuing pattern-specific change. I will show that pragmatic information is a biological concept; it plays no active role in the purely physical domain-it only does so when a living organism intervenes. The consequences for physics (including foundations of quantum mechanics) and biology (including brain function) will be discussed. This will include speculations about three fundamental transitions, from the quantum to the classical domain, from natural inanimate to living systems, and from subhuman to human brain information-processing operations, introduced here in their direct connection with the concept of pragmatic information.

DOI: 10.1098/rsta.2015.0152 PMID: 26857662 [Indexed for MEDLINE]

172. Biochem Soc Trans. 2016 Feb;44(1):51-60. doi: 10.1042/BST20150177.

The reaction mechanism of retaining glycosyltransferases.

Ardèvol A(1), Iglesias-Fernández J(1), Rojas-Cervellera V(1), Rovira C(2).

Author information: (1)Departament de Química Orgànica and Institut de Química Teòrica i Computacional (IQTCUB), Universitat de Barcelona, Martí i Franquès 1, 08028 Barcelona, Spain. (2)Departament de Química Orgànica and Institut de Química Teòrica i Computacional (IQTCUB), Universitat de Barcelona, Martí i Franquès 1, 08028 Barcelona, Spain Institució Catalana de Recerca i Estudis Avançats (ICREA), Passeig Lluís Companys, 23, 08018 Barcelona, Spain c.rovira@ub.edu.

The catalytic mechanism of retaining glycosyltransferases (ret-GTs) remains a controversial issue in glycobiology. By analogy to the well-established mechanism of retaining glycosidases, it was first suggested that ret-GTs follow a double-displacement mechanism. However, only family 6 GTs exhibit a putative nucleophile protein residue properly located in the active site to participate in catalysis, prompting some authors to suggest an unusual single-displacement mechanism [named as front-face or SNi (substitution nucleophilic internal)-like]. This mechanism has now received strong support, from both experiment and theory, for several GT families except family 6, for which a double-displacement reaction is predicted. In the last few years, we have uncovered the molecular mechanisms of several retaining GTs by means of quantum mechanics/molecular mechanics (QM/MM) metadynamics simulations, which we overview in the present work.

DOI: 10.1042/BST20150177 PMID: 26862188 [Indexed for MEDLINE]

173. Heliyon. 2019 Aug 6;5(8):e02224. doi: 10.1016/j.heliyon.2019.e02224. eCollection 2019 Aug.

Enhancing the energy spectrum of graphene quantum dot with external magnetic and Aharonov-Bohm flux fields.

Serrano Orozco FA(1), Avalos Ochoa JG(1), Rivas XC(1), Cuevas Figueroa JL(2), Carrada HMM(1).

Author information: (1)Instituto Politécnico Nacional, Escuela Superior de Ingeniería Mecanica y Eléctrica Unidad Culhuacan, CDMX 04430, Mexico. (2)Yachay Tech Univerity, School of Physical Sciences and Nanotechnology, 100115, Urcuqui, Ecuador.

In this paper, we have to apply the Dirac-Weyl equation to find the analytical energy eigenvalues of the graphene quantum dot interacting in the presence of AB-flux field and external magnetic field. We find that the energy eigenvalue of the graphene quantum dot decreases with both magnetic and AB-flux field but the effect of AB-flux field is more dominant. By ameliorating the intensity of the AB-flux field and keeping the magnetic field constant, the quantum-dot states entangled to produce Landau Levels. We show that besides using the graphene sheet and external magnetic field, the Aharonov-Bohm AB-flux field could as well be used to manipulate the carriers state energies in graphene.

DOI: 10.1016/j.heliyon.2019.e02224 PMCID: PMC6698883 PMID: 31440591

174. Phys Rev Lett. 2010 Apr 9;104(14):140401. doi: 10.1103/PhysRevLett.104.140401. Epub 2010 Apr 6.

Local quantum measurement and no-signaling imply quantum correlations.

Barnum H(1), Beigi S, Boixo S, Elliott MB, Wehner S.

Author information: (1)Perimeter Institute for Theoretical Physics, 31 Caroline Street N, Waterloo, Ontario, N2L 2Y5 Canada.

We show that, assuming that quantum mechanics holds locally, the finite speed of information is the principle that limits all possible correlations between distant parties to be quantum mechanical as well. Local quantum mechanics means that a Hilbert space is assigned to each party, and then all local positive-operator-valued measurements are (in principle) available; however, the joint system is not necessarily described by a Hilbert space. In particular, we do not assume the tensor product formalism between the joint systems. Our result shows that if any experiment would give nonlocal correlations beyond quantum mechanics, quantum theory would be invalidated even locally.

DOI: 10.1103/PhysRevLett.104.140401 PMID: 20481921

175. Comput Biol Med. 2010 Mar;40(3):359-62. doi: 10.1016/j.compbiomed.2010.01.007. Epub 2010 Feb 10.

The simulation of virus life cycle with quantum gates.

Shojaie F(1), Dehestani M.

Author information: (1)Department of Chemistry, Shahid Bahonar University of Kerman, Kerman, Iran. fahimeh_shojaie@yahoo.com

Quantum physics and molecular biology are two disciplines that have evolved relatively independently. However, recently a wealth of evidence has demonstrated the importance of quantum mechanics for biological systems and thus a new field of quantum biology is emerging. There are many claims that quantum mechanics plays a key role in the origin and/or operation of biological organisms. We consider the nucleonic acid of virus as a quantum system in this paper and discuss virus life cycle from the view-point of quantum and simulate it using quantum gates for the first time. The maximally entangled states show infected cell can change to entire cell, the virus can switch from the lysogenic to the lytic and the prophages can remain latent in the bacterial chromosome for many generations.

DOI: 10.1016/j.compbiomed.2010.01.007 PMID: 20149356 [Indexed for MEDLINE]

176. Nature. 2010 Jan 7;463(7277):68-71. doi: 10.1038/nature08688.

Quantum simulation of the Dirac equation.

Gerritsma R(1), Kirchmair G, Zähringer F, Solano E, Blatt R, Roos CF.

Author information: (1)Institut für Quantenoptik und Quanteninformation, Osterreichische Akademie der Wissenschaften, Otto-Hittmair-Platz 1, A-6020 Innsbruck, Austria.

The Dirac equation successfully merges quantum mechanics with special relativity. It provides a natural description of the electron spin, predicts the existence of antimatter and is able to reproduce accurately the spectrum of the hydrogen atom. The realm of the Dirac equation-relativistic quantum mechanics-is considered to be the natural transition to quantum field theory. However, the Dirac equation also predicts some peculiar effects, such as Klein's paradox and 'Zitterbewegung', an unexpected quivering motion of a free relativistic quantum particle. These and other predicted phenomena are key fundamental examples for understanding relativistic quantum effects, but are difficult to observe in real particles. In recent years, there has been increased interest in simulations of relativistic quantum effects using different physical set-ups, in which parameter tunability allows access to different physical regimes. Here we perform a proof-of-principle quantum simulation of the one-dimensional Dirac equation using a single trapped ion set to behave as a free relativistic quantum particle. We measure the particle position as a function of time and study Zitterbewegung for different initial superpositions of positive- and negative-energy spinor states, as well as the crossover from relativistic to non-relativistic dynamics. The high level of control of trapped-ion experimental parameters makes it possible to simulate textbook examples of relativistic quantum physics.

DOI: 10.1038/nature08688 PMID: 20054392

177. Nature. 2011 Jun 22;474(7352):490-3. doi: 10.1038/nature10119.

Experimental non-classicality of an indivisible quantum system.

Lapkiewicz R(1), Li P, Schaeff C, Langford NK, Ramelow S, Wieśniak M, Zeilinger A.

Author information: (1)Vienna Center for Quantum Science and Technology, Faculty of Physics, University of Vienna, Boltzmanngasse 5, Vienna A-1090, Austria.

Comment in Nature. 2011 Jun 23;474(7352):456-8.

In contrast to classical physics, quantum theory demands that not all properties can be simultaneously well defined; the Heisenberg uncertainty principle is a manifestation of this fact. Alternatives have been explored--notably theories relying on joint probability distributions or non-contextual hidden-variable models, in which the properties of a system are defined independently of their own measurement and any other measurements that are made. Various deep theoretical results imply that such theories are in conflict with quantum mechanics. Simpler cases demonstrating this conflict have been found and tested experimentally with pairs of quantum bits (qubits). Recently, an inequality satisfied by non-contextual hidden-variable models and violated by quantum mechanics for all states of two qubits was introduced and tested experimentally. A single three-state system (a qutrit) is the simplest system in which such a contradiction is possible; moreover, the contradiction cannot result from entanglement between subsystems, because such a three-state system is indivisible. Here we report an experiment with single photonic qutrits which provides evidence that no joint probability distribution describing the outcomes of all possible measurements--and, therefore, no non-contextual theory--can exist. Specifically, we observe a violation of the Bell-type inequality found by Klyachko, Can, Binicioğlu and Shumovsky. Our results illustrate a deep incompatibility between quantum mechanics and classical physics that cannot in any way result from entanglement.

DOI: 10.1038/nature10119 PMID: 21697945

178. Sci Rep. 2017 Mar 3;7:43365. doi: 10.1038/srep43365.

Recovering the quantum formalism from physically realist axioms.

Auffèves A(1), Grangier P(2).

Author information: (1)Institut Néel, BP 166, 25 rue des Martyrs, F38042 Grenoble Cedex 9, France. (2)Laboratoire Charles Fabry, IOGS, CNRS, Université Paris Saclay, F91127 Palaiseau, France.

We present a heuristic derivation of Born's rule and unitary transforms in Quantum Mechanics, from a simple set of axioms built upon a physical phenomenology of quantization. This approach naturally leads to the usual quantum formalism, within a new realistic conceptual framework that is discussed in details. Physically, the structure of Quantum Mechanics appears as a result of the interplay between the quantized number of "modalities" accessible to a quantum system, and the continuum of "contexts" that are required to define these modalities. Mathematically, the Hilbert space structure appears as a consequence of a specific "extra-contextuality" of modalities, closely related to the hypothesis of Gleason's theorem, and consistent with its conclusions.

DOI: 10.1038/srep43365 PMCID: PMC5335684 PMID: 28256539

Conflict of interest statement: The authors declare no competing financial interests.

179. Sci Adv. 2015 Oct 23;1(9):e1500838. doi: 10.1126/sciadv.1500838. eCollection 2015 Oct.

A quantum annealing architecture with all-to-all connectivity from local interactions.

Lechner W(1), Hauke P(1), Zoller P(1).

Author information: (1)Institute for Quantum Optics and Quantum Information, Austrian Academy of Sciences, 6020 Innsbruck, Austria. ; Institute for Theoretical Physics, University of Innsbruck, 6020 Innsbruck, Austria.

Quantum annealers are physical devices that aim at solving NP-complete optimization problems by exploiting quantum mechanics. The basic principle of quantum annealing is to encode the optimization problem in Ising interactions between quantum bits (qubits). A fundamental challenge in building a fully programmable quantum annealer is the competing requirements of full controllable all-to-all connectivity and the quasi-locality of the interactions between physical qubits. We present a scalable architecture with full connectivity, which can be implemented with local interactions only. The input of the optimization problem is encoded in local fields acting on an extended set of physical qubits. The output is-in the spirit of topological quantum memories-redundantly encoded in the physical qubits, resulting in an intrinsic fault tolerance. Our model can be understood as a lattice gauge theory, where long-range interactions are mediated by gauge constraints. The architecture can be realized on various platforms with local controllability, including superconducting qubits, NV-centers, quantum dots, and atomic systems.

DOI: 10.1126/sciadv.1500838 PMCID: PMC4646830 PMID: 26601316

180. Philos Trans A Math Phys Eng Sci. 2016 May 28;374(2068):20150242. doi: 10.1098/rsta.2015.0242.

1-1=Counterfactual: on the potency and significance of quantum non-events.

Elitzur AC(1), Cohen E(2).

Author information: (1)Iyar, The Israeli Institute for Advanced Research, Rehovot, Israel avshalom@iyar.org.il. (2)Iyar, The Israeli Institute for Advanced Research, Rehovot, Israel H.H. Wills Physics Laboratory, University of Bristol, Tyndall Avenue, Bristol BS8 1TL, UK.

We study the unique role played in quantum mechanics by non-events or 'counterfactuals'. Our earlier analysis of 'quantum oblivion' has revealed some subtle stages in the measurement process, which may end up in self-cancellation. To these findings, we now add two insights derived by two time-symmetric interpretations of quantum mechanics. (i) Like all quantum interactions, the non-event is formed by the conjunction of forward-plus-backward-evolving wave functions. (ii) Then, it is another feature of such dual evolutions, namely the involvement of negative masses and energies, that enables Nature to make some events 'unhappen' while leaving causal traces.

DOI: 10.1098/rsta.2015.0242 PMCID: PMC4843638 PMID: 27091159

181. Phys Rev Lett. 2016 Aug 26;117(9):099901. doi: 10.1103/PhysRevLett.117.099901. Epub 2016 Aug 22.

Erratum: Testing Nonassociative Quantum Mechanics [Phys. Rev. Lett. 115, 220402 (2015)].

Bojowald M, Brahma S, Büyükçam U.

Erratum for Phys Rev Lett. 2015 Nov 27;115(22):220402. Epub 2015 Nov 24.

This corrects the article DOI: 10.1103/PhysRevLett.115.220402.

DOI: 10.1103/PhysRevLett.117.099901 PMID: 27610892

182. Int J Clin Exp Hypn. 2020 Oct-Dec;68(4):433-450. doi: 10.1080/00207144.2020.1799380. Epub 2020 Aug 24.

From Quantum Physics to Quantum Hypnosis: A Quantum Mind Perspective.

De Benedittis G(1).

Author information: (1)Department of Neurosurgery, University of Milano , Italy.

A novel, heuristic model based upon chaotic complex systems theory and quantum mechanics is proposed to overcome the dichotomy between mind and body. The mind-body interface represents a chaotic system, ruled by the probability principle, as shown in quantum mechanics. Neuronal activity shows many patterns of chaotic behavior, and applications of chaotic patterns seem to be relevant for research regarding the mind-body relationship and the process of trance. A quantum consciousness theory has been proposed, largely controversial, since quantum physics applies to subatomic world and not to macrostructures, such as the brain. Quantum cognition is an emerging field that applies the formalism of quantum theory to model cognitive phenomena such as information processing by the human brain; it overcomes limits and shortcomings of cartesian dualism as well as quantum general theory. As hypnosis is a state of consciousness, it applies to hypnotic cognitive functioning rather than hypnotic structure.

DOI: 10.1080/00207144.2020.1799380 PMID: 32835610

183. Phys Rev E Stat Nonlin Soft Matter Phys. 2012 Jan;85(1 Pt 1):011110. doi: 10.1103/PhysRevE.85.011110. Epub 2012 Jan 5.

Entropy production and equilibration in Yang-Mills quantum mechanics.

Tsai HM(1), Müller B.

Author information: (1)Department of Physics, Duke University, Durham, North Carolina 27708, USA.

The Husimi distribution provides for a coarse-grained representation of the phase-space distribution of a quantum system, which may be used to track the growth of entropy of the system. We present a general and systematic method of solving the Husimi equation of motion for an isolated quantum system, and we construct a coarse-grained Hamiltonian whose expectation value is exactly conserved. As an application, we numerically solve the Husimi equation of motion for two-dimensional Yang-Mills quantum mechanics (the x-y model) and calculate the time evolution of the coarse-grained entropy of a highly excited state. We show that the coarse-grained entropy saturates to a value that coincides with the microcanonical entropy corresponding to the energy of the system.

DOI: 10.1103/PhysRevE.85.011110 PMID: 22400515 [Indexed for MEDLINE]

184. J Chem Phys. 2012 Jan 21;136(3):031102. doi: 10.1063/1.3680558.

Communication: quantum mechanics without wavefunctions.

Schiff J(1), Poirier B.

Author information: (1)Department of Mathematics, Bar-Ilan University, Ramat Gan 52900, Israel. schiff@math.biu.ac.il

We present a self-contained formulation of spin-free non-relativistic quantum mechanics that makes no use of wavefunctions or complex amplitudes of any kind. Quantum states are represented as ensembles of real-valued quantum trajectories, obtained by extremizing an action and satisfying energy conservation. The theory applies for arbitrary configuration spaces and system dimensionalities. Various beneficial ramifications-theoretical, computational, and interpretational-are discussed.

DOI: 10.1063/1.3680558 PMID: 22280737 [Indexed for MEDLINE]

185. Chemistry. 2019 Jun 4;25(31):7410-7415. doi: 10.1002/chem.201900460. Epub 2019 Mar 28.

Happy 150th Birthday to the Periodic Table.

Scerri ER(1).

Author information: (1)Department of Chemistry & Biochemistry, University of California Los Angeles, Los Angeles, CA, 90095, USA.

How many candles?! The year 2019 has been named as the International Year of the Periodic Table in accordance with Mendeleev's work from 1869. In line with other celebratory events and articles to be found this year in Chemistry-A European Journal, here, Eric R. Scerri provides an historical account of the development of the periodic table and some of the debates and considerations surrounding this fundamental elementary ensemble.

DOI: 10.1002/chem.201900460 PMID: 30920704

186. Prog Biophys Mol Biol. 2018 Dec;140:103-106. doi: 10.1016/j.pbiomolbio.2018.04.013. Epub 2018 May 2.

A diachronic evolutionary biologic perspective: Reconsidering the role of the eukaryotic unicell offers a 'Timeless' biology.

Torday JS(1).

Author information: (1)Department of Pediatrics, Harbor-UCLA, 1124 W.Carson Street, Torrance, CA 90502-2006, United States. Electronic address: jtorday@ucla.edu.

Biology has remained descriptive since its formalization by Linnaeus in the 18th Century. Dobzhansky has challenged us to think mechanistically by stating that 'Nothing in Biology makes sense except in the light of evolution', but NeoDarwinian evolution remains untestable or refutable. The physicist Bohm has encouraged us to recognize that our perception of 'reality' is mediated by our evolved, subjective senses, though there is a coherent Implicate Order just out of reach. Only recently has a novel understanding of physiologic evolution based on cell-cell communication for embryonic development and phylogeny offered the opportunity to mechanistically merge Quantum Mechanics with Evolutionary Biology.

DOI: 10.1016/j.pbiomolbio.2018.04.013 PMID: 29751939 [Indexed for MEDLINE]

187. Philos Trans A Math Phys Eng Sci. 2013 Mar 18;371(1989):20120057. doi: 10.1098/rsta.2012.0057. Print 2013 Apr 28.

PT-symmetric quantum electrodynamics and unitarity.

Milton KA(1), Abalo EK, Parashar P, Pourtolami N, Wagner J.

Author information: (1)Homer L. Dodge Department of Physics and Astronomy, University of Oklahoma, Norman, OK 73019-2061, USA. milton@nhn.ou.edu

More than 15 years ago, a new approach to quantum mechanics was suggested, in which Hermiticity of the Hamiltonian was to be replaced by invariance under a discrete symmetry, the product of parity and time-reversal symmetry, PT. It was shown that, if PT is unbroken, energies were, in fact, positive, and unitarity was satisfied. Since quantum mechanics is quantum field theory in one dimension--time--it was natural to extend this idea to higher-dimensional field theory, and in fact an apparently viable version of PT-invariant quantum electrodynamics (QED) was proposed. However, it has proved difficult to establish that the unitarity of the scattering matrix, for example, the Källén spectral representation for the photon propagator, can be maintained in this theory. This has led to questions of whether, in fact, even quantum mechanical systems are consistent with probability conservation when Green's functions are examined, since the latter have to possess physical requirements of analyticity. The status of PT QED will be reviewed in this paper, as well as the general issue of unitarity.

DOI: 10.1098/rsta.2012.0057 PMID: 23509383

188. Nature. 2004 Jun 17;429(6993):734-7. doi: 10.1038/nature02570.

Deterministic quantum teleportation with atoms.

Riebe M(1), Häffner H, Roos CF, Hänsel W, Benhelm J, Lancaster GP, Körber TW, Becher C, Schmidt-Kaler F, James DF, Blatt R.

Author information: (1)Institut für Experimentalphysik, Universität Innsbruck, Technikerstrasse 25, A-6020 Innsbruck, Austria.

Comment in Nature. 2004 Jun 17;429(6993):712-3.

Teleportation of a quantum state encompasses the complete transfer of information from one particle to another. The complete specification of the quantum state of a system generally requires an infinite amount of information, even for simple two-level systems (qubits). Moreover, the principles of quantum mechanics dictate that any measurement on a system immediately alters its state, while yielding at most one bit of information. The transfer of a state from one system to another (by performing measurements on the first and operations on the second) might therefore appear impossible. However, it has been shown that the entangling properties of quantum mechanics, in combination with classical communication, allow quantum-state teleportation to be performed. Teleportation using pairs of entangled photons has been demonstrated, but such techniques are probabilistic, requiring post-selection of measured photons. Here, we report deterministic quantum-state teleportation between a pair of trapped calcium ions. Following closely the original proposal, we create a highly entangled pair of ions and perform a complete Bell-state measurement involving one ion from this pair and a third source ion. State reconstruction conditioned on this measurement is then performed on the other half of the entangled pair. The measured fidelity is 75%, demonstrating unequivocally the quantum nature of the process.

DOI: 10.1038/nature02570 PMID: 15201903

189. Phys Rev Lett. 2010 Feb 12;104(6):061601. doi: 10.1103/PhysRevLett.104.061601. Epub 2010 Feb 12.

Complex correspondence principle.

Bender CM(1), Hook DW, Meisinger PN, Wang QH.

Author information: (1)Department of Physics, Washington University, St. Louis, Missouri 63130, USA.

Quantum mechanics and classical mechanics are distinctly different theories, but the correspondence principle states that quantum particles behave classically in the limit of high quantum number. In recent years much research has been done on extending both quantum and classical mechanics into the complex domain. These complex extensions continue to exhibit a correspondence, and this correspondence becomes more pronounced in the complex domain. The association between complex quantum mechanics and complex classical mechanics is subtle and demonstrating this relationship requires the use of asymptotics beyond all orders.

DOI: 10.1103/PhysRevLett.104.061601 PMID: 20366810

190. Biosystems. 2017 Feb;152:44-65. doi: 10.1016/j.biosystems.2016.12.003. Epub 2016 Dec 29.

Inverse Bayesian inference as a key of consciousness featuring a macroscopic quantum logical structure.

Gunji YP(1), Shinohara S(2), Haruna T(3), Basios V(4).

Author information: (1)Department of Intermedia Art and Science, School of Fundamental Science and Technology, Waseda University, Ohkubo 3-4-1, Shinjuku-ku, Tokyo 169-8555, Japan. Electronic address: yukio@waseda.jp. (2)Graduate School of Medicine, University of Tokyo, 7-3-1, Hongo, Bunkyo-ku, Tokyo 113-8655, Japan. (3)Department of Planetology, Faculty of Science, Kobe University, Rokkod-dai 1-1, Nada, Kobe 657-8501, Japan. (4)Department of Statistical Physics and Complex Systems, Université Libre de Bruxelles, Boulevard du Triomphe, B-1050 Brussels, Belgium.

To overcome the dualism between mind and matter and to implement consciousness in science, a physical entity has to be embedded with a measurement process. Although quantum mechanics have been regarded as a candidate for implementing consciousness, nature at its macroscopic level is inconsistent with quantum mechanics. We propose a measurement-oriented inference system comprising Bayesian and inverse Bayesian inferences. While Bayesian inference contracts probability space, the newly defined inverse one relaxes the space. These two inferences allow an agent to make a decision corresponding to an immediate change in their environment. They generate a particular pattern of joint probability for data and hypotheses, comprising multiple diagonal and noisy matrices. This is expressed as a nondistributive orthomodular lattice equivalent to quantum logic. We also show that an orthomodular lattice can reveal information generated by inverse syllogism as well as the solutions to the frame and symbol-grounding problems. Our model is the first to connect macroscopic cognitive processes with the mathematical structure of quantum mechanics with no additional assumptions.

DOI: 10.1016/j.biosystems.2016.12.003 PMID: 28041845 [Indexed for MEDLINE]

191. Phys Chem Chem Phys. 2014 Mar 7;16(9):3946-54. doi: 10.1039/c3cp53935k.

Insights into the phosphatase and the synthase activities of human bisphosphoglycerate mutase: a quantum mechanics/molecular mechanics simulation.

Chu WT(1), Zheng QC, Zhang HX.

Author information: (1)State Key Laboratory of Theoretical and Computational Chemistry, Institute of Theoretical Chemistry, Jilin University, Changchun 130023, China. zhengqc@jlu.edu.cn.

Bisphosphoglycerate mutase (BPGM) is a multi-activity enzyme. Its main function is to synthesize the 2,3-bisphosphoglycerate, the allosteric effector of hemoglobin. This enzyme can also catalyze the 2,3-bisphosphoglycerate to the 3-phosphoglycerate. In this study, the reaction mechanisms of both the phosphatase and the synthase activities of human bisphosphoglycerate mutase were theoretically calculated by using the quantum mechanics/molecular mechanics method based on the metadynamics and umbrella sampling simulations. The simulation results not only show the free energy curve of the phosphatase and the synthase reactions, but also reveal the important role of some residues in the active site. Additionally, the energy barriers of the two reactions indicate that the activity of the synthase in human bisphosphoglycerate mutase is much higher than that of the phosphatase. The estimated reaction barriers are consistent with the experimental data. Therefore, our work can give important information to understand the catalytic mechanism of the bisphosphoglycerate mutase family.

DOI: 10.1039/c3cp53935k PMID: 24441588 [Indexed for MEDLINE]

192. Nature. 2015 Apr 2;520(7545):66-8. doi: 10.1038/nature14331.

Atomic Hong-Ou-Mandel experiment.

Lopes R(1), Imanaliev A(1), Aspect A(1), Cheneau M(1), Boiron D(1), Westbrook CI(1).

Author information: (1)Laboratoire Charles Fabry, Institut d'Optique Graduate School - CNRS - Université Paris Sud, 2 avenue Augustin Fresnel, 91127 Palaiseau, France.

Comment in Nature. 2015 Apr 2;520(7545):36-7.

Two-particle interference is a fundamental feature of quantum mechanics, and is even less intuitive than wave-particle duality for a single particle. In this duality, classical concepts--wave or particle--are still referred to, and interference happens in ordinary space-time. On the other hand, two-particle interference takes place in a mathematical space that has no classical counterpart. Entanglement lies at the heart of this interference, as it does in the fundamental tests of quantum mechanics involving the violation of Bell's inequalities. The Hong, Ou and Mandel experiment is a conceptually simpler situation, in which the interference between two-photon amplitudes also leads to behaviour impossible to describe using a simple classical model. Here we report the realization of the Hong, Ou and Mandel experiment using atoms instead of photons. We create a source that emits pairs of atoms, and cause one atom of each pair to enter one of the two input channels of a beam-splitter, and the other atom to enter the other input channel. When the atoms are spatially overlapped so that the two inputs are indistinguishable, the atoms always emerge together in one of the output channels. This result opens the way to testing Bell's inequalities involving mechanical observables of massive particles, such as momentum, using methods inspired by quantum optics, and to testing theories of the quantum-to-classical transition. Our work also demonstrates a new way to benchmark non-classical atom sources that may be of interest for quantum information processing and quantum simulation.

DOI: 10.1038/nature14331 PMID: 25832404

193. J R Soc Interface. 2014 Jul 6;11(96):20140090. doi: 10.1098/rsif.2014.0090.

Unravelling novel synergies between organometallic and biological partners: a quantum mechanics/molecular mechanics study of an artificial metalloenzyme.

Ortega-Carrasco E(1), Lledós A(1), Maréchal JD(2).

Author information: (1)Departament de Química, Universitat Autònoma de Barcelona, Bellaterra 08193, Spain. (2)Departament de Química, Universitat Autònoma de Barcelona, Bellaterra 08193, Spain jeandidier.marechal@uab.cat.

In recent years, the design of artificial metalloenzymes obtained by the insertion of homogeneous catalysts into biological macromolecules has become a major field of research. These hybrids, and the corresponding X-ray structures of several of them, are offering opportunities to better understand the synergy between organometallic and biological subsystems. In this work, we investigate the resting state and activation process of a hybrid inspired by an oxidative haemoenzyme but presenting an unexpected reactivity and structural features. An extensive series of quantum mechanics/molecular mechanics calculations show that the resting state and the activation processes of the novel enzyme differ from naturally occurring haemoenzymes in terms of the electronic state of the metal, participation of the first coordination sphere of the metal and the dynamic process. This study presents novel insights into the sensitivity of the association between organometallic and biological partners and illustrates the molecular challenge that represents the design of efficient enzymes based on this strategy.

DOI: 10.1098/rsif.2014.0090 PMCID: PMC4032530 PMID: 24829279 [Indexed for MEDLINE]

194. Science. 2005 Feb 11;307(5711):875-9. doi: 10.1126/science.1107787.

Time and the quantum: erasing the past and impacting the future.

Aharonov Y(1), Zubairy MS.

Author information: (1)School of Physics and Astronomy, Tel Aviv University, Tel Aviv 69978, Israel.

The quantum eraser effect of Scully and Drühl dramatically underscores the difference between our classical conceptions of time and how quantum processes can unfold in time. Such eyebrow-raising features of time in quantum mechanics have been labeled "the fallacy of delayed choice and quantum eraser" on the one hand and described "as one of the most intriguing effects in quantum mechanics" on the other. In the present paper, we discuss how the availability or erasure of information generated in the past can affect how we interpret data in the present. The quantum eraser concept has been studied and extended in many different experiments and scenarios, for example, the entanglement quantum eraser, the kaon quantum eraser, and the use of quantum eraser entanglement to improve microscopic resolution.

DOI: 10.1126/science.1107787 PMID: 15705840

195. Front Chem. 2018 Apr 3;6:86. doi: 10.3389/fchem.2018.00086. eCollection 2018.

Steady-State Linear and Non-linear Optical Spectroscopy of Organic Chromophores and Bio-macromolecules.

Marazzi M(1)(2)(3), Gattuso H(1)(2), Monari A(1)(2), Assfeld X(1)(2).

Author information: (1)Laboratoire de Physique et Chimie Théoriques, Université de Lorraine-Nancy, UMR 7019, Vandoeuvre-lés-Nancy, France. (2)Laboratoire de Physique et Chimie Théoriques, Centre National de la Recherche Scientifique, UMR 7019, Vandoeuvre-lès-Nancy, France. (3)Departamento de Química, Centro de Investigacíon en Síntesis Química (CISQ), Universidad de La Rioja, Logroño, Spain.

Bio-macromolecules as DNA, lipid membranes and (poly)peptides are essential compounds at the core of biological systems. The development of techniques and methodologies for their characterization is therefore necessary and of utmost interest, even though difficulties can be experienced due to their intrinsic complex nature. Among these methods, spectroscopies, relying on optical properties are especially important to determine their macromolecular structures and behaviors, as well as the possible interactions and reactivity with external dyes-often drugs or pollutants-that can (photo)sensitize the bio-macromolecule leading to eventual chemical modifications, thus damages. In this review, we will focus on the theoretical simulation of electronic spectroscopies of bio-macromolecules, considering their secondary structure and including their interaction with different kind of (photo)sensitizers. Namely, absorption, emission and electronic circular dichroism (CD) spectra are calculated and compared with the available experimental data. Non-linear properties will be also taken into account by two-photon absorption, a highly promising technique (i) to enhance absorption in the red and infra-red windows and (ii) to enhance spatial resolution. Methodologically, the implications of using implicit and explicit solvent, coupled to quantum and thermal samplings of the phase space, will be addressed. Especially, hybrid quantum mechanics/molecular mechanics (QM/MM) methods are explored for a comparison with solely QM methods, in order to address the necessity to consider an accurate description of environmental effects on spectroscopic properties of biological systems.

DOI: 10.3389/fchem.2018.00086 PMCID: PMC5891624 PMID: 29666792

196. Heliyon. 2017 Nov 3;3(11):e00444. doi: 10.1016/j.heliyon.2017.e00444. eCollection 2017 Nov.

Demonstration of entanglement assisted invariance on IBM's quantum experience.

Deffner S(1).

Author information: (1)Department of Physics, University of Maryland Baltimore County, Baltimore, MD 21250, USA.

Quantum entanglement is among the most fundamental, yet from classical intuition also most surprising properties of the fully quantum nature of physical reality. We report several experiments performed on IBM's Quantum Experience demonstrating envariance - entanglement assisted invariance. Envariance is a recently discovered symmetry of composite quantum systems, which is at the foundational origin of physics and a quantum phenomenon of pure states. These very easily reproducible and freely accessible experiments on Quantum Experience provide simple tools to study the properties of envariance, and we illustrate this for several cases with "quantum universes" consisting of up to five qubits.

DOI: 10.1016/j.heliyon.2017.e00444 PMCID: PMC5683883 PMID: 29159322

197. Phys Rev Lett. 2017 Aug 4;119(5):050405. doi: 10.1103/PhysRevLett.119.050405. Epub 2017 Aug 4.

Determining Complementary Properties with Quantum Clones.

Thekkadath GS(1), Saaltink RY(1), Giner L(1), Lundeen JS(1).

Author information: (1)Department of Physics, Centre for Research in Photonics, University of Ottawa, 25 Templeton Street, Ottawa, Ontario K1N 6N5, Canada.

In a classical world, simultaneous measurements of complementary properties (e.g., position and momentum) give a system's state. In quantum mechanics, measurement-induced disturbance is largest for complementary properties and, hence, limits the precision with which such properties can be determined simultaneously. It is tempting to try to sidestep this disturbance by copying the system and measuring each complementary property on a separate copy. However, perfect copying is physically impossible in quantum mechanics. Here, we investigate using the closest quantum analog to this copying strategy, optimal cloning. The coherent portion of the generated clones' state corresponds to "twins" of the input system. Like perfect copies, both twins faithfully reproduce the properties of the input system. Unlike perfect copies, the twins are entangled. As such, a measurement on both twins is equivalent to a simultaneous measurement on the input system. For complementary observables, this joint measurement gives the system's state, just as in the classical case. We demonstrate this experimentally using polarized single photons.

DOI: 10.1103/PhysRevLett.119.050405 PMID: 28949711

198. Homeopathy. 2007 Jul;96(3):220-6. doi: 10.1016/j.homp.2007.05.005.

The nature of the active ingredient in ultramolecular dilutions.

Weingärtner O(1).

Author information: (1)Department of Basic Research, Dr. Reckeweg & Co. GmbH, Berliner Ring 32, D 64625 Bensheim, Germany. otto.weingaertner@reckeweg.de

This paper discusses the nature of the active ingredient of homeopathic ultramolecular dilutions in terms of quantitative physics. First, the problem of the nature of an active ingredient in ultramolecular dilutions is analysed leading to the recognition of the necessity of characterizing the active ingredient as a non-local quality. Second, non-locality in quantum mechanics, which is used as a paradigm, is formally presented. Third, a generalization of quantum mechanics is considered, focussing on the consequences of weakening of the axioms. The formal treatment leads to the possible extension of the validity of quantum theory to macroscopic or even non-physical systems under certain circumstances with a while maintaining non-local behaviour. With respect to the survival of entanglement in such non-quantum systems a strong relationship between homeopathy and non-local behaviour can be envisaged. I describe how several authors apply this relationship. In conclusion, the paper reviews how quantum mechanics is closely related to information theory but why weak quantum theory and homeopathy have not hitherto been related in the same way.

DOI: 10.1016/j.homp.2007.05.005 PMID: 17678820 [Indexed for MEDLINE]

199. Phys Rev E Stat Nonlin Soft Matter Phys. 2005 Oct;72(4 Pt 2):046219. doi: 10.1103/PhysRevE.72.046219. Epub 2005 Oct 27.

Irreversibility with quantum trajectories.

Wisniacki DA(1), Borondo F, Benito RM.

Author information: (1)Departamento de Química C-IX, Universidad Autónoma de Madrid, Cantoblanco, 28049-Madrid, Spain. wisniacki@df.uba.ar

Irreversibility is an important issue for many quantum processes. Loschmidt echoes, originally introduced as a way to gauge sensitivity to perturbations in quantum mechanics, have turned out to be a useful tool for its investigation. Following the philosophy supporting this idea, and using quantum trajectories as defined in the causal interpretation of quantum mechanics due to Bohm, we introduce in this paper a more informative alternative measure for irreversibility. The method is applied to the Bunimovich stadium billiard, a paradigmatic example of chaotic system, that constitutes an excellent model for mesoscopic devices.

DOI: 10.1103/PhysRevE.72.046219 PMID: 16383524

200. Ann N Y Acad Sci. 2019 Dec;1458(1):9-25. doi: 10.1111/nyas.14026. Epub 2019 Mar 22.

The mystery of our mathematical universe.

Paulson S(1), Gates SJ Jr(2), Wertheim M(3).

Author information: (1)Wisconsin Public Radio, Madison, Wisconsin. (2)Brown University, Providence, Rhode Island. (3)Institute for Figuring, Los Angeles, California.

Why is it that fundamental laws discovered through pure mathematics have been able to describe the behavior of our physical world with such precision? Given that the physical universe is composed of mathematical properties, some have posited that mathematics is the language of the universe, whose laws reveal what appears to be a hidden order in the natural world. Physicist S. James Gates, Jr. and science writer Margaret Wertheim explore the uncanny ability of mathematics to reveal the laws of nature.

DOI: 10.1111/nyas.14026 PMID: 30900261 [Indexed for MEDLINE]

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Items 1-200 of 200 (Display the 200 citations in PubMed)

1. Living Rev Relativ. 2019;22(1):1. doi: 10.1007/s41114-018-0017-4. Epub 2018 Dec 18.

Testing general relativity in cosmology.

Ishak M(1).

Author information: (1)Department of Physics, The University of Texas at Dallas, Richardson, TX 75080 USA.

We review recent developments and results in testing general relativity (GR) at cosmological scales. The subject has witnessed rapid growth during the last two decades with the aim of addressing the question of cosmic acceleration and the dark energy associated with it. However, with the advent of precision cosmology, it has also become a well-motivated endeavor by itself to test gravitational physics at cosmic scales. We overview cosmological probes of gravity, formalisms and parameterizations for testing deviations from GR at cosmological scales, selected modified gravity (MG) theories, gravitational screening mechanisms, and computer codes developed for these tests. We then provide summaries of recent cosmological constraints on MG parameters and selected MG models. We supplement these cosmological constraints with a summary of implications from the recent binary neutron star merger event. Next, we summarize some results on MG parameter forecasts with and without astrophysical systematics that will dominate the uncertainties. The review aims at providing an overall picture of the subject and an entry point to students and researchers interested in joining the field. It can also serve as a quick reference to recent results and constraints on testing gravity at cosmological scales.

DOI: 10.1007/s41114-018-0017-4 PMCID: PMC6299071 PMID: 30613193

2. Phys Rev Lett. 2019 Sep 20;123(12):121101. doi: 10.1103/PhysRevLett.123.121101.

Hierarchical Test of General Relativity with Gravitational Waves.

Isi M(1)(2), Chatziioannou K(1), Farr WM(1)(3).

Author information: (1)Center for Computational Astrophysics, Flatiron Institute, 162 5th Ave, New York, New York 10010, USA. (2)LIGO Laboratory and Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA. (3)Department of Physics and Astronomy, Stony Brook University, Stony Brook, New York 11794, USA.

We propose a hierarchical approach to testing general relativity with multiple gravitational wave detections. Unlike existing strategies, our method does not assume that parameters quantifying deviations from general relativity are either common or completely unrelated across all sources. We instead assume that these parameters follow some underlying distribution, which we parametrize and constrain. This can be then compared to the distribution expected from general relativity, i.e., no deviation in any of the events. We demonstrate that our method is robust to measurement uncertainties and can be applied to theories of gravity where the parameters beyond general relativity are related to each other, as generally expected. Our method contains the two extremes of common and unrelated parameters as limiting cases. We apply the hierarchical model to the population of 10 binary black hole systems so far detected by LIGO and Virgo. We do this for a parametrized test of gravitational wave generation, by modeling the population distribution of beyond-general-relativity parameters with a Gaussian distribution. We compute the mean and the variance of the population and show that both are consistent with general relativity for all parameters we consider. In the best case, we find that the population properties of the existing binary signals are consistent with general relativity at the ∼1% level. This hierarchical approach subsumes and extends existing methodologies and is more robust at revealing potential subtle deviations from general relativity with increasing number of detections.

DOI: 10.1103/PhysRevLett.123.121101 PMID: 31633980

3. Living Rev Relativ. 2018;21(1):7. doi: 10.1007/s41114-018-0016-5. Epub 2018 Aug 31.

Hamiltonian formulation of general relativity and post-Newtonian dynamics of compact binaries.

Schäfer G(1), Jaranowski P(2).

Author information: (1)1Friedrich-Schiller-Universität Jena, Jena, Germany. (2)2University of Białystok, Białystok, Poland.

Hamiltonian formalisms provide powerful tools for the computation of approximate analytic solutions of the Einstein field equations. The post-Newtonian computations of the explicit analytic dynamics and motion of compact binaries are discussed within the most often applied Arnowitt-Deser-Misner formalism. The obtention of autonomous Hamiltonians is achieved by the transition to Routhians. Order reduction of higher derivative Hamiltonians results in standard Hamiltonians. Tetrad representation of general relativity is introduced for the tackling of compact binaries with spinning components. Configurations are treated where the absolute values of the spin vectors can be considered constant. Compact objects are modeled by use of Dirac delta functions and their derivatives. Consistency is achieved through transition to d-dimensional space and application of dimensional regularization. At the fourth post-Newtonian level, tail contributions to the binding energy show up. The conservative spin-dependent dynamics finds explicit presentation in Hamiltonian form through next-to-next-to-leading-order spin-orbit and spin1-spin2 couplings and to leading-order in the cubic and quartic in spin interactions. The radiation reaction dynamics is presented explicitly through the third-and-half post-Newtonian order for spinless objects, and, for spinning bodies, to leading-order in the spin-orbit and spin1-spin2 couplings. The most important historical issues get pointed out.

DOI: 10.1007/s41114-018-0016-5 PMCID: PMC6133045 PMID: 30237750

4. Science. 2018 Jun 22;360(6395):1342-1346. doi: 10.1126/science.aao2469.

A precise extragalactic test of General Relativity.

Collett TE(1), Oldham LJ(2), Smith RJ(3), Auger MW(2), Westfall KB(4)(5), Bacon D(4), Nichol RC(4), Masters KL(4)(6), Koyama K(4), van den Bosch R(7).

Author information: (1)Institute of Cosmology and Gravitation, University of Portsmouth, Burnaby Road, Portsmouth PO1 3FX, UK. thomas.collett@port.ac.uk. (2)Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA, UK. (3)Centre for Extragalactic Astronomy, University of Durham, Durham DH1 3LE, UK. (4)Institute of Cosmology and Gravitation, University of Portsmouth, Burnaby Road, Portsmouth PO1 3FX, UK. (5)University of California Observatories-Lick Observatory, University of California-Santa Cruz, 1156 High Street, Santa Cruz, CA 95064, USA. (6)Department of Physics and Astronomy, Haverford College, 370 Lancaster Avenue, Haverford, PA 19041, USA. (7)Max Planck Institute for Astronomy, Königstuhl 17, 69117 Heidelberg, Germany.

Einstein's theory of gravity, General Relativity, has been precisely tested on Solar System scales, but the long-range nature of gravity is still poorly constrained. The nearby strong gravitational lens ESO 325-G004 provides a laboratory to probe the weak-field regime of gravity and measure the spatial curvature generated per unit mass, γ. By reconstructing the observed light profile of the lensed arcs and the observed spatially resolved stellar kinematics with a single self-consistent model, we conclude that γ = 0.97 ± 0.09 at 68% confidence. Our result is consistent with the prediction of 1 from General Relativity and provides a strong extragalactic constraint on the weak-field metric of gravity.

DOI: 10.1126/science.aao2469 PMID: 29930135

5. Rep Prog Phys. 2019 Jan;82(1):016904. doi: 10.1088/1361-6633/aae552. Epub 2018 Oct 1.

Self-force and radiation reaction in general relativity.

Barack L(1), Pound A.

Author information: (1)Mathematical Sciences, University of Southampton, Southampton SO17 1BJ, United Kingdom.

The detection of gravitational waves from binary black-hole mergers by the LIGO-Virgo Collaboration marks the dawn of an era when general-relativistic dynamics in its most extreme manifestation is directly accessible to observation. In the future, planned (space-based) observatories operating in the millihertz band will detect the intricate gravitational-wave signals from the inspiral of compact objects into massive black holes residing in galactic centers. Such inspiral events are extremely effective probes of black-hole geometries, offering unparalleled precision tests of general relativity in its most extreme regime. This prospect has in the past two decades motivated a programme to obtain an accurate theoretical model of the strong-field radiative dynamics in a two-body system with a small mass ratio. The problem naturally lends itself to a perturbative treatment based on a systematic expansion of the field equations in the small mass ratio. At leading order one has a pointlike particle moving in a geodesic orbit around the large black hole. At subsequent orders, interaction of the particle with its own gravitational perturbation gives rise to an effective 'self-force', which drives the radiative evolution of the orbit, and whose effects can be accounted for order by order in the mass ratio. This review surveys the theory of gravitational self-force in curved spacetime and its application to the astrophysical inspiral problem. We first lay the relevant formal foundation, describing the rigorous derivation of the equation of self-forced motion using matched asymptotic expansions and other ideas. We then review the progress that has been achieved in numerically calculating the self-force and its physical effects in astrophysically realistic inspiral scenarios. We highlight the way in which, nowadays, self-force calculations make a fruitful contact with other approaches to the two-body problem and help inform an accurate universal model of binary black hole inspirals, valid across all mass ratios. We conclude with a summary of the state of the art, open problems and prospects. Our review is aimed at non-specialist readers and is for the most part self-contained and non-technical; only elementary-level acquaintance with general relativity is assumed. Where useful, we draw on analogies with familiar concepts from Newtonian gravity or classical electrodynamics.

DOI: 10.1088/1361-6633/aae552 PMID: 30270849

6. Prog Biophys Mol Biol. 2018 Mar;133:27-29. doi: 10.1016/j.pbiomolbio.2017.10.004. Epub 2017 Oct 25.

A novel biological 'twin-father' temporal paradox of General Relativity in a Gödel universe - Where reproductive biology meets theoretical physics.

Ashrafian H(1).

Author information: (1)The Department of Surgery and Cancer, Imperial College London, 10th Floor, Queen Elizabeth the Queen Mother (QEQM) Building, Imperial College Healthcare NHS Trust at St Mary's Hospital, Praed Street, London, W2 1NY, United Kingdom. Electronic address: h.ashrafian@imperial.ac.uk.

Several temporal paradoxes exist in physics. These include General Relativity's grandfather and ontological paradoxes and Special Relativity's Langevin-Einstein twin-paradox. General relativity paradoxes can exist due to a Gödel universe that follows Gödel's closed timelike curves solution to Einstein's field equations. A novel biological temporal paradox of General Relativity is proposed based on reproductive biology's phenomenon of heteropaternal fecundation. Herein, dizygotic twins from two different fathers are the result of concomitant fertilization during one menstrual cycle. In this case an Oedipus-like individual exposed to a Gödel closed timelike curve would sire a child during his maternal fertilization cycle. As a consequence of heteropaternal superfecundation, he would father his own dizygotic twin and would therefore generate a new class of autofraternal superfecundation, and by doing so creating a 'twin-father' temporal paradox.

DOI: 10.1016/j.pbiomolbio.2017.10.004 PMID: 29079208 [Indexed for MEDLINE]

7. Living Rev Relativ. 2006;9(1):3. doi: 10.12942/lrr-2006-3. Epub 2006 Mar 27.

The Confrontation between General Relativity and Experiment.

Will CM(1).

Author information: (1)McDonnell Center for the Space Sciences Department of Physics, Washington University, St. Louis, MO 63130 USA.

The status of experimental tests of general relativity and of theoretical frameworks for analyzing them is reviewed. Einstein's equivalence principle (EEP) is well supported by experiments such as the Eötvös experiment, tests of special relativity, and the gravitational redshift experiment. Ongoing tests of EEP and of the inverse square law are searching for new interactions arising from unification or quantum gravity. Tests of general relativity at the post-Newtonian level have reached high precision, including the light deflection, the Shapiro time delay, the perihelion advance of Mercury, and the Nordtvedt effect in lunar motion. Gravitational wave damping has been detected in an amount that agrees with general relativity to better than half a percent using the Hulse-Taylor binary pulsar, and other binary pulsar systems have yielded other tests, especially of strong-field effects. When direct observation of gravitational radiation from astrophysical sources begins, new tests of general relativity will be possible.

DOI: 10.12942/lrr-2006-3 PMCID: PMC5256066 PMID: 28179873

8. Living Rev Relativ. 2001;4(1):4. doi: 10.12942/lrr-2001-4. Epub 2001 May 11.

The Confrontation between General Relativity and Experiment.

Will CM(1).

Author information: (1)McDonnell Center for the Space Sciences, Department of Physics, Washington University, 63130 St. Louis, MO USA.

The status of experimental tests of general relativity and of theoretical frameworks for analysing them are reviewed. Einstein's equivalence principle (EEP) is well supported by experiments such as the Eötvös experiment, tests of special relativity, and the gravitational redshift experiment. Future tests of EEP and of the inverse square law will search for new interactions arising from unification or quantum gravity. Tests of general relativity at the post-Newtonian level have reached high precision, including the light defl ection the Shapiro time delay, the perihelion advance of Mercury, and the Nordtvedt effect in lunar motion. Gravitational wave damping has been detected in an amount that agrees with general relativity to half a percent using the Hulse-Taylor binary pulsar, and new binary pulsar systems may yield further improvements. When direct observation of gravitational radiation from astrophysical sources begins, new tests of general relativity will be possible.

DOI: 10.12942/lrr-2001-4 PMCID: PMC5253802 PMID: 28163632

9. Science. 2015 Mar 6;347(6226):1103-8. doi: 10.1126/science.aaa4033.

A century of general relativity: astrophysics and cosmology.

Blandford RD(1).

Author information: (1)Kavli Institute for Particle Astrophysics and Cosmology, Stanford University, Stanford, CA, USA.

One hundred years after its birth, general relativity has become a highly successful physical theory in the sense that it has passed a large number of experimental and observational tests and finds extensive application to a wide variety of cosmic phenomena. It remains an active area of research as new tests are on the way, epitomized by the exciting prospect of detecting gravitational waves from merging black holes. General relativity is the essential foundation of the standard model of cosmology and underlies our description of the black holes and neutron stars that are ultimately responsible for the most powerful and dramatic cosmic sources. Its interface with physics on the smallest and largest scales will continue to provide fertile areas of investigation in its next century.

DOI: 10.1126/science.aaa4033 PMID: 25745165

10. Isis. 2015 Sep;106(3):598-620. doi: 10.1086/683425.

The Reinvention of General Relativity: A Historiographical Framework for Assessing One Hundred Years of Curved Space-time.

Blum A, Lalli R, Renn MJ.

The history of the theory of general relativity presents unique features. After its discovery, the theory was immediately confirmed and rapidly changed established notions of space and time. The further implications of general relativity, however, remained largely unexplored until the mid 1950s, when it came into focus as a physical theory and gradually returned to the mainstream of physics. This essay presents a historiographical framework for assessing the history of general relativity by taking into account in an integrated narrative intellectual developments, epistemological problems, and technological advances; the characteristics of post-World War II and Cold War science; and newly emerging institutional settings. It argues that such a framework can help us understand this renaissance of general relativity as a result of two main factors: the recognition of the untapped potential of general relativity and an explicit effort at community building, which allowed this formerly disparate and dispersed field to benefit from the postwar changes in the scientific landscape.

DOI: 10.1086/683425 PMID: 26685519 [Indexed for MEDLINE]

11. Rep Prog Phys. 2017 Oct;80(10):102901. doi: 10.1088/1361-6633/aa7bb1. Epub 2017 Aug 29.

Implications of a positive cosmological constant for general relativity.

Ashtekar A(1).

Author information: (1)Institute for Gravitation & the Cosmos, and Physics Department, Penn State, University Park, PA 16802, United States of America. CPT, Aix-Marseille Université, CNRS, F-13288 Marseille, France.

Most of the literature on general relativity over the last century assumes that the cosmological constant [Formula: see text] is zero. However, by now independent observations have led to a consensus that the dynamics of the universe is best described by Einstein's equations with a small but positive [Formula: see text]. Interestingly, this requires a drastic revision of conceptual frameworks commonly used in general relativity, no matter how small [Formula: see text] is. We first explain why, and then summarize the current status of generalizations of these frameworks to include a positive [Formula: see text], focusing on gravitational waves.

DOI: 10.1088/1361-6633/aa7bb1 PMID: 28849776

12. Phys Rev Lett. 2018 Oct 26;121(17):171601. doi: 10.1103/PhysRevLett.121.171601.

General Relativity from Scattering Amplitudes.

Bjerrum-Bohr NEJ(1), Damgaard PH(1), Festuccia G(2), Planté L(3), Vanhove P(4)(5).

Author information: (1)Niels Bohr International Academy and Discovery Center, The Niels Bohr Institute, Blegdamsvej 17, DK-2100 Copenhagen Ø, Denmark. (2)Department of Physics and Astronomy, Theoretical Physics, Ångströmlaboratoriet, Lägerhyddsvägen 1, Box 516 751 20 Uppsala, Sweden. (3)Ministère de l'économie et des finances, Direction générale des entreprises, 94200 Ivry-sur-Seine, France. (4)Institut de Physique Théorique, Université Paris-Saclay, CEA, CNRS, F-91191 Gif-sur-Yvette Cedex, France. (5)National Research University Higher School of Economics, 123592 Moscow, Russian Federation.

Weoutline the program to apply modern quantum field theory methods to calculate observables in classical general relativity through a truncation to classical terms of the multigraviton, two-body, on-shell scattering amplitudes between massive fields. Since only long-distance interactions corresponding to nonanalytic pieces need to be included, unitarity cuts provide substantial simplifications for both post-Newtonian and post-Minkowskian expansions. We illustrate this quantum field theoretic approach to classical general relativity by computing the interaction potentials to second order in the post-Newtonian expansion, as well as the scattering functions for two massive objects to second order in the post-Minkowskian expansion. We also derive an all-order exact result for gravitational light-by-light scattering.

DOI: 10.1103/PhysRevLett.121.171601 PMID: 30411923

13. Living Rev Relativ. 2014;17(1):4. doi: 10.12942/lrr-2014-4. Epub 2014 Jun 11.

The Confrontation between General Relativity and Experiment.

Will CM(1).

Author information: (1)Department of Physics, University of Florida, Gainesville, FL 32611 USA.

The status of experimental tests of general relativity and of theoretical frameworks for analyzing them is reviewed and updated. Einstein's equivalence principle (EEP) is well supported by experiments such as the Eötvös experiment, tests of local Lorentz invariance and clock experiments. Ongoing tests of EEP and of the inverse square law are searching for new interactions arising from unification or quantum gravity. Tests of general relativity at the post-Newtonian level have reached high precision, including the light deflection, the Shapiro time delay, the perihelion advance of Mercury, the Nordtvedt effect in lunar motion, and frame-dragging. Gravitational wave damping has been detected in an amount that agrees with general relativity to better than half a percent using the Hulse-Taylor binary pulsar, and a growing family of other binary pulsar systems is yielding new tests, especially of strong-field effects. Current and future tests of relativity will center on strong gravity and gravitational waves.

DOI: 10.12942/lrr-2014-4 PMCID: PMC5255900 PMID: 28179848

14. Phys Rev Lett. 2017 May 5;118(18):181301. doi: 10.1103/PhysRevLett.118.181301. Epub 2017 May 2.

New Probe of Departures from General Relativity Using Minkowski Functionals.

Fang W(1)(2), Li B(3), Zhao GB(4)(5).

Author information: (1)Department of Astronomy, University of Science and Technology of China, Hefei, Anhui 230026, People's Republic of China. (2)Key Laboratory for Research in Galaxies and Cosmology, Chinese Academy of Sciences, Hefei, Anhui 230026, People's Republic of China. (3)Institute for Computational Cosmology, Department of Physics, Durham University, Durham DH1 3LE, United Kingdom. (4)National Astronomy Observatories, Chinese Academy of Science, Beijing 100012, People's Republic of China. (5)Institute of Cosmology and Gravitation, University of Portsmouth, Portsmouth PO1 3FX, United Kingdom.

The morphological properties of the large scale structure of the Universe can be fully described by four Minkowski functionals (MFs), which provide important complementary information to other statistical observables such as the widely used 2-point statistics in configuration and Fourier spaces. In this work, for the first time, we present the differences in the morphology of the large scale structure caused by modifications to general relativity (to address the cosmic acceleration problem), by measuring the MFs from N-body simulations of modified gravity and general relativity. We find strong statistical power when using the MFs to constrain modified theories of gravity: with a galaxy survey that has survey volume ∼0.125(h^{-1} Gpc)^{3} and galaxy number density ∼1/(h^{-1} Mpc)^{3}, the two normal-branch Dvali-Gabadadze-Porrati models and the F5 f(R) model that we simulated can be discriminated from the ΛCDM model at a significance level ≳5σ with an individual MF measurement. Therefore, the MF of the large scale structure is potentially a powerful probe of gravity, and its application to real data deserves active exploration.

DOI: 10.1103/PhysRevLett.118.181301 PMID: 28524695

15. Phys Rev Lett. 2015 Aug 21;115(8):081301. doi: 10.1103/PhysRevLett.115.081301. Epub 2015 Aug 18.

New Area Law in General Relativity.

Bousso R(1), Engelhardt N(2).

Author information: (1)Department of Physics, University of California, Berkeley, California 94720, USA and Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA. (2)Department of Physics, University of California, Santa Barbara, California 93106, USA.

We report a new area law in general relativity. A future holographic screen is a hypersurface foliated by marginally trapped surfaces. We show that their area increases monotonically along the foliation. Future holographic screens can easily be found in collapsing stars and near a big crunch. Past holographic screens exist in any expanding universe and obey a similar theorem, yielding the first rigorous area law in big bang cosmology. Unlike event horizons, these objects can be identified at finite time and without reference to an asymptotic boundary. The Bousso bound is not used, but it naturally suggests a thermodynamic interpretation of our result.

DOI: 10.1103/PhysRevLett.115.081301 PMID: 26340179

16. Eur Phys J C Part Fields. 2018;78(11):880. doi: 10.1140/epjc/s10052-018-6303-1. Epub 2018 Oct 30.

Reply to "A comment on "A test of general relativity using the LARES and LAGEOS satellites and a GRACE Earth gravity model, by I. Ciufolini et al."".

Ciufolini I(1)(2), Pavlis EC(3), Ries J(4), Matzner R(5), Koenig R(6), Paolozzi A(7), Sindoni G(7), Gurzadyan V(8), Penrose R(9), Paris C(2).

Author information: (1)1Dip. Ingegneria dell'Innovazione, Università del Salento, Lecce, Italy. (2)2Centro Fermi-Museo Storico della Fisica e Centro Studi e Ricerche Enrico Fermi, Rome, Italy. (3)Joint Center for Earth Systems Technology (JCET), University of Maryland, Baltimore County, Maryland, USA. (4)4Center for Space Research, University of Texas at Austin, Austin, Texas, USA. (5)5Theory Group, University of Texas at Austin, Austin, Texas, USA. (6)6Helmholtz Centre Potsdam GFZ German Research Centre for Geosciences, Potsdam, Germany. (7)7Scuola di Ingegneria Aerospaziale, Sapienza Università di Roma, Rome, Italy. (8)Center for Cosmology and Astrophysics, Alikhanian National Laboratory, Yerevan, Armenia. (9)9Mathematical Institute, University of Oxford, Oxford, UK.

In 2016, we published "A test of general relativity using the LARES and LAGEOS satellites and a GRACE Earth's gravity model. Measurement of Earth's dragging of inertial frames [1]", a measurement of frame-dragging, a fundamental prediction of Einstein's theory of General Relativity, using the laser-ranged satellites LARES, LAGEOS and LAGEOS 2. The formal error, or precision, of our test was about 0.2% of frame-dragging, whereas the systematic error was estimated to be about 5%. In the 2017 paper "A comment on "A test of general relativity using the LARES and LAGEOS satellites and a GRACE Earth's gravity model by I. Ciufolini et al."" by L. Iorio [2] (called I2017 in the following), it was incorrectly claimed that, when comparing different Earth's gravity field models, the systematic error in our test due to the Earth's even zonal harmonics of degree 6, 8, 10 could be as large as 15%, 6% and 36%, respectively. Furthermore, I2017 contains other, also incorrect, claims about the number of necessary significant decimal digits of the coefficients used in our test (claimed to be nine), in order to eliminate the largest uncertainties in the even zonals of degree 2 and 4, and about the non-repeatability of our test. Here we analyze and rebut those claims in I2017.

DOI: 10.1140/epjc/s10052-018-6303-1 PMCID: PMC6394275 PMID: 30881204

17. Science. 2018 Jul 27;361(6400):366-371. doi: 10.1126/science.aat3363. Epub 2018 Jul 26.

Fundamentals of numerical relativity for gravitational wave sources.

Brügmann B(1).

Author information: (1)Theoretical Physics Institute, University of Jena, 07743 Jena, Germany. bernd.bruegmann@uni-jena.de.

Einstein's theory of general relativity affords an enormously successful description of gravity. The theory encodes the gravitational interaction in the metric, a tensor field on spacetime that satisfies partial differential equations known as the Einstein equations. This review introduces some of the fundamental concepts of numerical relativity-solving the Einstein equations on the computer-in simple terms. As a primary example, we consider the solution of the general relativistic two-body problem, which features prominently in the new field of gravitational wave astronomy.

DOI: 10.1126/science.aat3363 PMID: 30049876

18. Phys Rev Lett. 2017 May 26;118(21):211101. doi: 10.1103/PhysRevLett.118.211101. Epub 2017 May 25.

Testing General Relativity with Stellar Orbits around the Supermassive Black Hole in Our Galactic Center.

Hees A(1), Do T(1), Ghez AM(1), Martinez GD(1), Naoz S(1), Becklin EE(1), Boehle A(1), Chappell S(1), Chu D(1), Dehghanfar A(1), Kosmo K(1), Lu JR(2), Matthews K(3), Morris MR(1), Sakai S(1), Schödel R(4), Witzel G(1).

Author information: (1)Department of Physics and Astronomy, University of California, Los Angeles, California 90095, USA. (2)Astronomy Department, University of California, Berkeley, California 94720, USA. (3)Division of Physics, Mathematics, and Astronomy, California Institute of Technology, MC 301-17, Pasadena, California 91125, USA. (4)Instituto de Astrofísica de Andalucía (CSIC), Glorieta de la Astronomía S/N, 18008 Granada, Spain.

We demonstrate that short-period stars orbiting around the supermassive black hole in our Galactic center can successfully be used to probe the gravitational theory in a strong regime. We use 19 years of observations of the two best measured short-period stars orbiting our Galactic center to constrain a hypothetical fifth force that arises in various scenarios motivated by the development of a unification theory or in some models of dark matter and dark energy. No deviation from general relativity is reported and the fifth force strength is restricted to an upper 95% confidence limit of |α|<0.016 at a length scale of λ=150 astronomical units. We also derive a 95% confidence upper limit on a linear drift of the argument of periastron of the short-period star S0-2 of |ω[over ˙]_{S0-2}|<1.6×10^{-3} rad/yr, which can be used to constrain various gravitational and astrophysical theories. This analysis provides the first fully self-consistent test of the gravitational theory using orbital dynamic in a strong gravitational regime, that of a supermassive black hole. A sensitivity analysis for future measurements is also presented.

DOI: 10.1103/PhysRevLett.118.211101 PMID: 28598651

19. Rep Prog Phys. 2017 Feb;80(2):026001. doi: 10.1088/1361-6633/80/2/026001. Epub 2016 Dec 19.

Milestones of general relativity.

Pullin J(1).

Author information: (1)Department of Physics and Astronomy, Louisiana State University, Baton Rouge, LA 70803-4001, USA.

We present a summary for non-specialists of the special issue of the journal Classical and Quantum Gravity on 'Milestones of general relativity', commemorating the 100th anniversary of the theory.

DOI: 10.1088/1361-6633/80/2/026001 PMID: 27991442

20. Chaos Solitons Fractals. 2017 Oct;103:567-570. doi: 10.1016/j.chaos.2017.07.004. Epub 2017 Jul 20.

Extended Theory of Harmonic Maps Connects General Relativity to Chaos and Quantum Mechanism.

Ren G(1), Duan YS(2).

Author information: (1)The Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley CA 94720, USA. (2)The Department of Physics, Lanzhou University, Lanzhou, Gansu 730000, China.

General relativity and quantum mechanism are two separate rules of modern physics explaining how nature works. Both theories are accurate, but the direct connection between two theories was not yet clarified. Recently, researchers blur the line between classical and quantum physics by connecting chaos and entanglement equation. Here, we showed the Duan's extended HM theory, which has the solution of the general relativity, can also have the solutions of the classic chaos equations and even the solution of Schrödinger equation in quantum physics, suggesting the extended theory of harmonic maps may act as a universal theory of physics.

DOI: 10.1016/j.chaos.2017.07.004 PMCID: PMC6516492 PMID: 31097882

Conflict of interest statement: Competing financial interests The author(s) declare no competing financial interests.

21. Rep Prog Phys. 2017 Jan;80(1):016901. doi: 10.1088/0034-4885/80/1/016901. Epub 2016 Nov 7.

Numerical relativity beyond astrophysics.

Garfinkle D(1).

Author information: (1)Department of Physics, Oakland University, Rochester, MI 48309, USA. Michigan Center for Theoretical Physics, Randall Laboratory of Physics, University of Michigan, Ann Arbor, MI 48109-1120, USA.

Though the main applications of computer simulations in relativity are to astrophysical systems such as black holes and neutron stars, nonetheless there are important applications of numerical methods to the investigation of general relativity as a fundamental theory of the nature of space and time. This paper gives an overview of some of these applications. In particular we cover (i) investigations of the properties of spacetime singularities such as those that occur in the interior of black holes and in big bang cosmology. (ii) investigations of critical behavior at the threshold of black hole formation in gravitational collapse. (iii) investigations inspired by string theory, in particular analogs of black holes in more than 4 spacetime dimensions and gravitational collapse in spacetimes with a negative cosmological constant.

DOI: 10.1088/0034-4885/80/1/016901 PMID: 27819249

22. Living Rev Relativ. 2004;7(1):5. doi: 10.12942/lrr-2004-5. Epub 2004 Apr 8.

Quantum Gravity in Everyday Life: General Relativity as an Effective Field Theory.

Burgess CP(1).

Author information: (1)Physics Department, McGill University, 3600 University Street, Montréal, Québec Canada H3A 2T8.

This article is meant as a summary and introduction to the ideas of effective field theory as applied to gravitational systems, ideas which provide the theoretical foundations for the modern use of general relativity as a theory from which precise predictions are possible.

DOI: 10.12942/lrr-2004-5 PMCID: PMC5253842 PMID: 28163641

23. Eur Phys J C Part Fields. 2018;78(10):866. doi: 10.1140/epjc/s10052-018-6356-1. Epub 2018 Oct 27.

Mapping nonlinear gravity into General Relativity with nonlinear electrodynamics.

Afonso VI(1), Olmo GJ(2)(3), Orazi E(4)(5), Rubiera-Garcia D(6).

Author information: (1)1Unidade Acadêmica de Física, Universidade Federal de Campina Grande, Campina Grande, PB 58429-900 Brazil. (2)2Departamento de Física Teórica and IFIC, Centro Mixto Universidad de Valencia - CSIC, Universidad de Valencia, Burjassot 46100 Valencia, Spain. (3)3Departamento de Física, Universidade Federal da Paraíba, 58051-900 João Pessoa, Paraíba Brazil. (4)4International Institute of Physics, Federal University of Rio Grande do Norte, Campus Universitário-Lagoa Nova, Natal, RN 59078-970 Brazil. (5)5Escola de Ciencia e Tecnologia, Universidade Federal do Rio Grande do Norte, Caixa, Postal 1524, Natal, 59078-970 Brazil. (6)6Instituto de Astrofísica e Ciências do Espaço, Faculdade de Ciências da Universidade de Lisboa, Edifício C8, Campo Grande, 1749-016 Lisbon Portugal.

We show that families of nonlinear gravity theories formulated in a metric-affine approach and coupled to a nonlinear theory of electrodynamics can be mapped into general relativity (GR) coupled to another nonlinear theory of electrodynamics. This allows to generate solutions of the former from those of the latter using purely algebraic transformations. This correspondence is explicitly illustrated with the Eddington-inspired Born-Infeld theory of gravity, for which we consider a family of nonlinear electrodynamics and show that, under the map, preserve their algebraic structure. For the particular case of Maxwell electrodynamics coupled to Born-Infeld gravity we find, via this correspondence, a Born-Infeld-type nonlinear electrodynamics on the GR side. Solving the spherically symmetric electrovacuum case for the latter, we show how the map provides directly the right solutions for the former. This procedure opens a new door to explore astrophysical and cosmological scenarios in nonlinear gravity theories by exploiting the full power of the analytical and numerical methods developed within the framework of GR.

DOI: 10.1140/epjc/s10052-018-6356-1 PMCID: PMC6244868 PMID: 30524194

24. Phys Rev Lett. 2018 Dec 21;121(25):251105. doi: 10.1103/PhysRevLett.121.251105.

Black Holes in an Effective Field Theory Extension of General Relativity.

Cardoso V(1)(2), Kimura M(1), Maselli A(1), Senatore L(3).

Author information: (1)CENTRA, Departamento de Física, Instituto Superior Técnico-IST, Universidade de Lisboa-UL, Avenida Rovisco Pais 1, 1049 Lisboa, Portugal. (2)CERN 1 Esplanade des Particules, Geneva 23, CH-1211, Switzerland. (3)SITP and KIPAC, Department of Physics and SLAC, Stanford University, Stanford, California 94305, USA.

Effective field theory methods suggest that some rather general extensions of general relativity include, or are mimicked by, certain higher-order curvature corrections, with coupling constants expected to be small but otherwise arbitrary. Thus, the tantalizing prospect to test the fundamental nature of gravity with gravitational-wave observations, in a systematic way, emerges naturally. Here, we build black hole solutions in such a framework and study their main properties. Once rotation is included, we find the first purely gravitational example of geometries without Z_{2} symmetry. Despite the higher-order operators of the theory, we show that linearized fluctuations of such geometries obey second-order differential equations. We find nonzero tidal Love numbers. We study and compute the quasinormal modes of such geometries. These results are of interest to gravitational-wave science but also potentially relevant for electromagnetic observations of the galactic center or x-ray binaries.

DOI: 10.1103/PhysRevLett.121.251105 PMID: 30608822

25. Living Rev Relativ. 2008;11(1):7. doi: 10.12942/lrr-2008-7. Epub 2008 Sep 19.

Numerical Hydrodynamics and Magnetohydrodynamics in General Relativity.

Font JA(1).

Author information: (1)Departamento de Astronomía y Astrofísica Edificio de Investigación "Jeroni Muñoz", Universidad de Valencia, Dr. Moliner 50, E-46100 Burjassot (Valencia), Spain.

This article presents a comprehensive overview of numerical hydrodynamics and magneto-hydrodynamics (MHD) in general relativity. Some significant additions have been incorporated with respect to the previous two versions of this review (2000, 2003), most notably the coverage of general-relativistic MHD, a field in which remarkable activity and progress has occurred in the last few years. Correspondingly, the discussion of astrophysical simulations in general-relativistic hydrodynamics is enlarged to account for recent relevant advances, while those dealing with general-relativistic MHD are amply covered in this review for the first time. The basic outline of this article is nevertheless similar to its earlier versions, save for the addition of MHD-related issues throughout. Hence, different formulations of both the hydrodynamics and MHD equations are presented, with special mention of conservative and hyperbolic formulations well adapted to advanced numerical methods. A large sample of numerical approaches for solving such hyperbolic systems of equations is discussed, paying particular attention to solution procedures based on schemes exploiting the characteristic structure of the equations through linearized Riemann solvers. As previously stated, a comprehensive summary of astrophysical simulations in strong gravitational fields is also presented. These are detailed in three basic sections, namely gravitational collapse, black-hole accretion, and neutron-star evolutions; despite the boundaries, these sections may (and in fact do) overlap throughout the discussion. The material contained in these sections highlights the numerical challenges of various representative simulations. It also follows, to some extent, the chronological development of the field, concerning advances in the formulation of the gravitational field, hydrodynamics and MHD equations and the numerical methodology designed to solve them. To keep the length of this article reasonable, an effort has been made to focus on multidimensional studies, directing the interested reader to earlier versions of the review for discussions on one-dimensional works. ELECTRONIC SUPPLEMENTARY MATERIAL: Supplementary material is available for this article at 10.12942/lrr-2008-7.

DOI: 10.12942/lrr-2008-7 PMCID: PMC5256108 PMID: 28179823

26. Heliyon. 2019 May 6;5(5):e01645. doi: 10.1016/j.heliyon.2019.e01645. eCollection 2019 May.

Bianchi type-V dark energy cosmological model in general relativity in the presence of massive scalar field.

Naidu RL(1), Aditya Y(2), Reddy DRK(3).

Author information: (1)Department Mathematics, GMR Institute of Technology, Rajam, 532 127, India. (2)Department of Mathematics, ANITS (A), Visakhapatnam, 531162, India. (3)Department of Applied Mathematics, Andhra University, Visakhapatnam, 530003, India.

In this paper, we discuss spatially homogeneous and anisotropic Bianchi type-V dark energy cosmological model in the presence of an attractive massive scalar field in general relativity. We have solved the field equations using (i) the shear scalar of the metric is proportional to the expansion scalar which results a relationship between metric potentials and (ii) a power law between the massive scalar field and the average scale factor. We have computed the cosmological parameters like dark energy density, equation of state parameter, skewness parameters, deceleration parameter and statefinder parameters of our dark energy model with massive strings and discussed their physical significance in the light of the recent scenario of accelerated expansion of the universe and cosmological observations.

DOI: 10.1016/j.heliyon.2019.e01645 PMCID: PMC6512874 PMID: 31192992

27. Living Rev Relativ. 2003;6(1):1. doi: 10.12942/lrr-2003-1. Epub 2003 Jan 28.

Relativity in the Global Positioning System.

Ashby N(1).

Author information: (1)Dept. of Physics, University of Colorado, Boulder, CO 80309-0390 USA.

The Global Positioning System (GPS) uses accurate, stable atomic clocks in satellites and on the ground to provide world-wide position and time determination. These clocks have gravitational and motional frequency shifts which are so large that, without carefully accounting for numerous relativistic effects, the system would not work. This paper discusses the conceptual basis, founded on special and general relativity, for navigation using GPS. Relativistic principles and effects which must be considered include the constancy of the speed of light, the equivalence principle, the Sagnac effect, time dilation, gravitational frequency shifts, and relativity of synchronization. Experimental tests of relativity obtained with a GPS receiver aboard the TOPEX/POSEIDON satellite will be discussed. Recently frequency jumps arising from satellite orbit adjustments have been identified as relativistic effects. These will be explained and some interesting applications of GPS will be discussed.

DOI: 10.12942/lrr-2003-1 PMCID: PMC5253894 PMID: 28163638

28. Living Rev Relativ. 2018;21(1):5. doi: 10.1007/s41114-018-0014-7. Epub 2018 Jul 5.

Geometrical inequalities bounding angular momentum and charges in General Relativity.

Dain S(1), Gabach-Clement ME(1).

Author information: (1)Facultad de Matemática, Astronomía y Física, Universidad Nacional de Córdoba, Instituto de Física Enrique Gaviola, Consejo Nacional de Investigaciones Científicas y Técnicas, Córdoba, Argentina.

Geometrical inequalities show how certain parameters of a physical system set restrictions on other parameters. For instance, a black hole of given mass can not rotate too fast, or an ordinary object of given size can not have too much electric charge. In this article, we are interested in bounds on the angular momentum and electromagnetic charges, in terms of total mass and size. We are mainly concerned with inequalities for black holes and ordinary objects. The former are the most studied systems in this context in General Relativity, and where most results have been found. Ordinary objects, on the other hand, present numerous challenges and many basic questions concerning geometrical estimates for them are still unanswered. We present the many results in these areas. We make emphasis in identifying the mathematical conditions that lead to such estimates, both for black holes and ordinary objects.

DOI: 10.1007/s41114-018-0014-7 PMCID: PMC6305357 PMID: 30613192

29. Eur Phys J C Part Fields. 2017;77(11):776. doi: 10.1140/epjc/s10052-017-5353-0. Epub 2017 Nov 18.

Palatini wormholes and energy conditions from the prism of general relativity.

Bejarano C(1)(2), Lobo FSN(3), Olmo GJ(2)(4), Rubiera-Garcia D(3).

Author information: (1)Instituto de Astronomía y Física del Espacio (IAFE, CONICET-UBA), Casilla de Correo 67, Sucursal 28, 1428 Buenos Aires, Argentina. (2)Departamento de Física Teórica and IFIC, Centro Mixto Universidad de Valencia-CSIC. Universidad de Valencia, Burjassot, 46100 Valencia, Spain. (3)Instituto de Astrofísica e Ciências do Espaço, Faculdade de Ciências da Universidade de Lisboa, Edifício C8, Campo Grande, 1749-016 Lisbon, Portugal. (4)Departamento de Física, Universidade Federal da Paraíba, 58051-900 João Pessoa Paraíba, Brazil.

Wormholes are hypothetical shortcuts in spacetime that in general relativity unavoidably violate all of the pointwise energy conditions. In this paper, we consider several wormhole spacetimes that, as opposed to the standard designer procedure frequently employed in the literature, arise directly from gravitational actions including additional terms resulting from contractions of the Ricci tensor with the metric, and which are formulated assuming independence between metric and connection (Palatini approach). We reinterpret such wormhole solutions under the prism of General Relativity and study the matter sources that thread them. We discuss the size of violation of the energy conditions in different cases and how this is related to the same spacetimes when viewed from the modified gravity side.

DOI: 10.1140/epjc/s10052-017-5353-0 PMCID: PMC5694534 PMID: 29200940

30. Rep Prog Phys. 2019 Jan;82(1):016902. doi: 10.1088/1361-6633/aadb16. Epub 2018 Aug 17.

Numerical relativity of compact binaries in the 21st century.

Duez MD(1), Zlochower Y.

Author information: (1)Department of Physics and Astronomy, Washington State University, Pullman, WA 99164, United States of America.

We review the dramatic progress in the simulations of compact objects and compact-object binaries that has taken place in the first two decades of the twenty-first century. This includes simulations of the inspirals and violent mergers of binaries containing black holes and neutron stars, as well as simulations of black-hole formation through failed supernovae and high-mass neutron star-neutron star mergers. Modeling such events requires numerical integration of the field equations of general relativity in three spatial dimensions, coupled, in the case of neutron-star containing binaries, with increasingly sophisticated treatment of fluids, electromagnetic fields, and neutrino radiation. However, it was not until 2005 that accurate long-term evolutions of binaries containing black holes were even possible (Pretorius 2005 Phys. Rev. Lett. 95 121101, Campanelli et al 2006 Phys. Rev. Lett. 96 111101, Baker et al 2006 Phys. Rev. Lett. 96 111102). Since then, there has been an explosion of new results and insights into the physics of strongly-gravitating system. Particular emphasis has been placed on understanding the gravitational wave and electromagnetic signatures from these extreme events. And with the recent dramatic discoveries of gravitational waves from merging black holes by the Laser Interferometric Gravitational Wave Observatory and Virgo, and the subsequent discovery of both electromagnetic and gravitational wave signals from a merging neutron star-neutron star binary, numerical relativity became an indispensable tool for the new field of multimessenger astronomy.

DOI: 10.1088/1361-6633/aadb16 PMID: 30117809

31. R Soc Open Sci. 2018 Apr 11;5(4):171109. doi: 10.1098/rsos.171109. eCollection 2018 Apr.

Generalized transformations and coordinates for static spherically symmetric general relativity.

Hill JM(1), O'Leary J(1)(2).

Author information: (1)School of Information Technology and Mathematical Sciences, University of South Australia, PO Box 2471, Adelaide, South Australia 5001, Australia. (2)SERC Limited, AITC2 Mount Stromlo Observatory, Canberra, Australian Capital Territory 2611, Australia.

We examine a static, spherically symmetric solution of the empty space field equations of general relativity with a non-orthogonal line element which gives rise to an opportunity that does not occur in the standard derivations of the Schwarzschild solution. In these derivations, convenient coordinate transformations and dynamical assumptions inevitably lead to the Schwarzschild solution. By relaxing these conditions, a new solution possibility arises and the resulting formalism embraces the Schwarzschild solution as a special case. The new solution avoids the coordinate singularity associated with the Schwarzschild solution and is achieved by obtaining a more suitable coordinate chart. The solution embodies two arbitrary constants, one of which can be identified as the Newtonian gravitational potential using the weak field limit. The additional arbitrary constant gives rise to a situation that allows for generalizations of the Eddington-Finkelstein transformation and the Kruskal-Szekeres coordinates.

DOI: 10.1098/rsos.171109 PMCID: PMC5936889 PMID: 29765624

Conflict of interest statement: We declare we have no competing interests.

32. Folia Morphol (Warsz). 2019;78(2):431-432. doi: 10.5603/FM.a2018.0086. Epub 2018 Sep 13.

Pancreatic theory of relativity..

Hać S(1).

Author information: (1)Department of General Endocrine and Transplant Surgery, Medical University of Gdansk, Poland. sthac@gumed.edu.pl.

Pancreatic duct and parenchyma has different benchmarks in nomenclature. The author discusses the proposition to unify the description system of procedures and surgeries within pancreas according to the direction of pancreatic juice natural flow.

DOI: 10.5603/FM.a2018.0086 PMID: 30211434 [Indexed for MEDLINE]

33. Living Rev Relativ. 2009;12(1):4. doi: 10.12942/lrr-2009-4. Epub 2009 Jun 19.

Quasi-Local Energy-Momentum and Angular Momentum in General Relativity.

Szabados LB(1).

Author information: (1)Wigner Research Centre for Physics of the Hungarian Academy of Sciences, P.O. Box 49, H-1525 Budapest 114, Hungary.

The present status of the quasi-local mass, energy-momentum and angular-momentum constructions in general relativity is reviewed. First, the general ideas, concepts, and strategies, as well as the necessary tools to construct and analyze the quasi-local quantities, are recalled. Then, the various specific constructions and their properties (both successes and deficiencies are discussed. Finally, some of the (actual and potential) applications of the quasi-local concepts and specific constructions are briefly mentioned.

DOI: 10.12942/lrr-2009-4 PMCID: PMC5256466 PMID: 28179826

34. Living Rev Relativ. 2013;16(1):7. doi: 10.12942/lrr-2013-7. Epub 2013 Sep 12.

Testing General Relativity with Low-Frequency, Space-Based Gravitational-Wave Detectors.

Gair JR(1), Vallisneri M(2), Larson SL(3), Baker JG(4).

Author information: (1)Institute of Astronomy, Madingley Road, Cambridge, CB3 0HA UK. (2)Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109 USA. (3)Center for Interdisclipinary Research and Exploration in Astrophysics, Department of Physics and Astronomy, Northwestern University, Evanston, IL 60208 USA. (4)Gravitational Astrophysics Lab, NASA Goddard Space Flight Center, 8800 Greenbelt Rd., Greenbelt, MD 20771 USA.

We review the tests of general relativity that will become possible with space-based gravitational-wave detectors operating in the ∼ 10-5 - 1 Hz low-frequency band. The fundamental aspects of gravitation that can be tested include the presence of additional gravitational fields other than the metric; the number and tensorial nature of gravitational-wave polarization states; the velocity of propagation of gravitational waves; the binding energy and gravitational-wave radiation of binaries, and therefore the time evolution of binary inspirals; the strength and shape of the waves emitted from binary mergers and ringdowns; the true nature of astrophysical black holes; and much more. The strength of this science alone calls for the swift implementation of a space-based detector; the remarkable richness of astrophysics, astronomy, and cosmology in the low-frequency gravitational-wave band make the case even stronger.

DOI: 10.12942/lrr-2013-7 PMCID: PMC5255528 PMID: 28163624

35. Eur Phys J C Part Fields. 2016;76(3):120. doi: 10.1140/epjc/s10052-016-3961-8. Epub 2016 Mar 4.

A test of general relativity using the LARES and LAGEOS satellites and a GRACE Earth gravity model: Measurement of Earth's dragging of inertial frames.

Ciufolini I(1)(2), Paolozzi A(2)(3), Pavlis EC(4), Koenig R(5), Ries J(6), Gurzadyan V(7), Matzner R(8), Penrose R(9), Sindoni G(10), Paris C(2)(3), Khachatryan H(7), Mirzoyan S(7).

Author information: (1)Dipartimento Ingegneria dell'Innovazione, Università del Salento, Lecce, Italy. (2)Museo della fisica e Centro studi e ricerche Enrico Fermi, Rome, Italy. (3)Scuola di Ingegneria Aerospaziale, Sapienza Università di Roma, Rome, Italy. (4)Joint Center for Earth Systems Technology (JCET), University of Maryland, Baltimore County, USA. (5)Helmholtz Centre Potsdam, GFZ German Research Centre for Geosciences, Potsdam, Germany. (6)Center for Space Research, University of Texas at Austin, Austin, USA. (7)Center for Cosmology and Astrophysics, Alikhanian National Laboratory and Yerevan State University, Yerevan, Armenia. (8)Theory Center, University of Texas at Austin, Austin, USA. (9)Mathematical Institute, University of Oxford, Oxford, UK. (10)DIAEE, Sapienza Università di Roma, Rome, Italy.

We present a test of general relativity, the measurement of the Earth's dragging of inertial frames. Our result is obtained using about 3.5 years of laser-ranged observations of the LARES, LAGEOS, and LAGEOS 2 laser-ranged satellites together with the Earth gravity field model GGM05S produced by the space geodesy mission GRACE. We measure [Formula: see text], where [Formula: see text] is the Earth's dragging of inertial frames normalized to its general relativity value, 0.002 is the 1-sigma formal error and 0.05 is our preliminary estimate of systematic error mainly due to the uncertainties in the Earth gravity model GGM05S. Our result is in agreement with the prediction of general relativity.

DOI: 10.1140/epjc/s10052-016-3961-8 PMCID: PMC4946852 PMID: 27471430

36. Living Rev Relativ. 2013;16(1):9. doi: 10.12942/lrr-2013-9. Epub 2013 Nov 6.

Gravitational-Wave Tests of General Relativity with Ground-Based Detectors and Pulsar-Timing Arrays.

Yunes N(1), Siemens X(2).

Author information: (1)Department of Physics, Montana State University, Bozeman, MO 59717 USA. (2)Center for Gravitation, Cosmology, and Astrophysics Department of Physics, University of Wisconsin-Milwaukee, P. O. Box 413, Milwaukee, WI 53201 USA.

This review is focused on tests of Einstein's theory of general relativity with gravitational waves that are detectable by ground-based interferometers and pulsar-timing experiments. Einstein's theory has been greatly constrained in the quasi-linear, quasi-stationary regime, where gravity is weak and velocities are small. Gravitational waves will allow us to probe a complimentary, yet previously unexplored regime: the non-linear and dynamical strong-field regime. Such a regime is, for example, applicable to compact binaries coalescing, where characteristic velocities can reach fifty percent the speed of light and gravitational fields are large and dynamical. This review begins with the theoretical basis and the predicted gravitational-wave observables of modified gravity theories. The review continues with a brief description of the detectors, including both gravitational-wave interferometers and pulsar-timing arrays, leading to a discussion of the data analysis formalism that is applicable for such tests. The review ends with a discussion of gravitational-wave tests for compact binary systems.

DOI: 10.12942/lrr-2013-9 PMCID: PMC5255575 PMID: 28179845

37. Living Rev Relativ. 2018;21(1):6. doi: 10.1007/s41114-018-0015-6. Epub 2018 Aug 20.

Computer algebra in gravity research.

MacCallum MAH(1).

Author information: (1)School of Mathematical Sciences, Queen Mary University of London, Mile End Road, London, E1 4NS UK.

The complicated nature of calculations in general relativity was one of the driving forces in the early development of computer algebra (CA). CA has become widely used in gravity research (GR) and its use can be expected to grow further. Here the general nature of computer algebra is discussed, along with some aspects of CA system design; features particular to GR's requirements are considered; information on packages for CA in GR is provided, both for those packages currently available and for their predecessors; and applications of CA in GR are outlined.

DOI: 10.1007/s41114-018-0015-6 PMCID: PMC6105178 PMID: 30174551

38. Phys Rev Lett. 2018 Sep 21;121(12):129902. doi: 10.1103/PhysRevLett.121.129902.

Erratum: Tests of General Relativity with GW150914 [Phys. Rev. Lett. 116, 221101 (2016)].

Abbott BP, Anonymous; LIGO Scientific and Virgo Collaboration 1, 2, 3.

Erratum for Phys Rev Lett. 2016 Jun 3;116(22):221101.

This corrects the article DOI: 10.1103/PhysRevLett.116.221101.

DOI: 10.1103/PhysRevLett.121.129902 PMID: 30296140

39. Nature. 2011 Sep 28;477(7366):567-9. doi: 10.1038/nature10445.

Gravitational redshift of galaxies in clusters as predicted by general relativity.

Wojtak R(1), Hansen SH, Hjorth J.

Author information: (1)Dark Cosmology Centre, Niels Bohr Institute, University of Copenhagen, Juliane Maries Vej 30, DK-2100 Copenhagen Ø, Denmark. wojtak@dark-cosmology.dk

Comment in Nature. 2011 Sep 29;477(7366):541-3.

The theoretical framework of cosmology is mainly defined by gravity, of which general relativity is the current model. Recent tests of general relativity within the Lambda Cold Dark Matter (ΛCDM) model have found a concordance between predictions and the observations of the growth rate and clustering of the cosmic web. General relativity has not hitherto been tested on cosmological scales independently of the assumptions of the ΛCDM model. Here we report an observation of the gravitational redshift of light coming from galaxies in clusters at the 99 per cent confidence level, based on archival data. Our measurement agrees with the predictions of general relativity and its modification created to explain cosmic acceleration without the need for dark energy (the f(R) theory), but is inconsistent with alternative models designed to avoid the presence of dark matter.

DOI: 10.1038/nature10445 PMID: 21956329

40. Living Rev Relativ. 2003;6(1):5. doi: 10.12942/lrr-2003-5. Epub 2003 Sep 9.

Testing General Relativity with Pulsar Timing.

Stairs IH(1).

Author information: (1)Dept. of Physics and Astronomy, University of British Columbia, 6224 Agricultural Road, Vancouver, B.C., V6T 1Z1 Canada.

Pulsars of very different types, including isolated objects and binaries (with short- and long-period orbits, and white-dwarf and neutron-star companions) provide the means to test both the predictions of general relativity and the viability of alternate theories of gravity. This article presents an overview of pulsars, then discusses the current status of and future prospects for tests of equivalence-principle violations and strong-field gravitational experiments.

DOI: 10.12942/lrr-2003-5 PMCID: PMC5253800 PMID: 28163640

41. Expert Rev Cardiovasc Ther. 2005 May;3(3):393-404. doi: 10.1586/14779072.3.3.393.

Adiposopathy, metabolic syndrome, quantum physics, general relativity, chaos and the Theory of Everything.

Bays H(1).

Author information: (1)L-MARC Research Center, 3288 Illinois Avenue, Louisville, KY 40213, USA. HBaysMD@aol.com

Excessive fat (adiposity) and dysfunctional fat (adiposopathy) constitute the most common worldwide epidemics of our time -- and perhaps of all time. Ongoing efforts to explain how the micro (adipocyte) and macro (body organ) biologic systems interact through function and dysfunction in promoting Type 2 diabetes mellitus, hypertension and dyslipidemia are not unlike the mechanistic and philosophical thinking processes involved in reconciling the micro (quantum physics) and macro (general relativity) theories in physics. Currently, the term metabolic syndrome refers to a constellation of consequences often associated with excess body fat and is an attempt to unify the associations known to exist between the four fundamental metabolic diseases of obesity, hyperglycemia (including Type 2 diabetes mellitus), hypertension and dyslipidemia. However, the association of adiposity with these metabolic disorders is not absolute and the metabolic syndrome does not describe underlying causality, nor does the metabolic syndrome necessarily reflect any reasonably related pathophysiologic process. Just as with quantum physics, general relativity and the four fundamental forces of the universe, the lack of an adequate unifying theory of micro causality and macro consequence is unsatisfying, and in medicine, impairs the development of agents that may globally improve both obesity and obesity-related metabolic disease. Emerging scientific and clinical evidence strongly supports the novel concept that it is not adiposity alone, but rather it is adiposopathy that is the underlying cause of most cases of Type 2 diabetes mellitus, hypertension and dyslipidemia. Adiposopathy is a plausible Theory of Everything for mankind's greatest metabolic epidemics.

DOI: 10.1586/14779072.3.3.393 PMID: 15889967 [Indexed for MEDLINE]

42. Living Rev Relativ. 2004;7(1):7. doi: 10.12942/lrr-2004-7. Epub 2004 Jun 21.

Brane-World Gravity.

Maartens R(1).

Author information: (1)Institute of Cosmology & Gravitation, Portsmouth University, Portsmouth, PO1 2EG UK.

The observable universe could be a 1 + 3-surface (the "brane") embedded in a 1 + 3 + d-dimensional spacetime (the "bulk"), with Standard Model particles and fields trapped on the brane while gravity is free to access the bulk. At least one of the d extra spatial dimensions could be very large relative to the Planck scale, which lowers the fundamental gravity scale, possibly even down to the electroweak (∼ TeV) level. This revolutionary picture arises in the framework of recent developments in M theory. The 1 + 10-dimensional M theory encompasses the known 1 + 9-dimensional superstring theories, and is widely considered to be a promising potential route to quantum gravity. General relativity cannot describe gravity at high enough energies and must be replaced by a quantum gravity theory, picking up significant corrections as the fundamental energy scale is approached. At low energies, gravity is localized at the brane and general relativity is recovered, but at high energies gravity "leaks" into the bulk, behaving in a truly higher-dimensional way. This introduces significant changes to gravitational dynamics and perturbations, with interesting and potentially testable implications for high-energy astrophysics, black holes, and cosmology. Brane-world models offer a phenomenological way to test some of the novel predictions and corrections to general relativity that are implied by M theory. This review discusses the geometry, dynamics and perturbations of simple brane-world models for cosmology and astrophysics, mainly focusing on warped 5-dimensional brane-worlds based on the Randall-Sundrum models.

DOI: 10.12942/lrr-2004-7 PMCID: PMC5255527 PMID: 28163642

43. Phys Rev Lett. 2016 Jan 22;116(3):031101. doi: 10.1103/PhysRevLett.116.031101. Epub 2016 Jan 19.

Testing General Relativity with the Shadow Size of Sgr A(*).

Johannsen T(1)(2), Broderick AE(1)(2), Plewa PM(3), Chatzopoulos S(3), Doeleman SS(4)(5), Eisenhauer F(3), Fish VL(4), Genzel R(3)(6), Gerhard O(3), Johnson MD(5).

Author information: (1)Perimeter Institute for Theoretical Physics, Waterloo, Ontario N2L 2Y5, Canada. (2)Department of Physics and Astronomy, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada. (3)Max-Planck-Institut für extraterrestrische Physik, 85741 Garching, Germany. (4)MIT Haystack Observatory, Westford, Massachusetts 01886, USA. (5)Harvard-Smithsonian Center for Astrophysics, Cambridge, Massachusetts 02138, USA. (6)Physics and Astronomy Departments, University of California, Berkeley, California 94720, USA.

In general relativity, the angular radius of the shadow of a black hole is primarily determined by its mass-to-distance ratio and depends only weakly on its spin and inclination. If general relativity is violated, however, the shadow size may also depend strongly on parametric deviations from the Kerr metric. Based on a reconstructed image of Sagittarius A^{*} (Sgr A^{*}) from a simulated one-day observing run of a seven-station Event Horizon Telescope (EHT) array, we employ a Markov chain Monte Carlo algorithm to demonstrate that such an observation can measure the angular radius of the shadow of Sgr A^{*} with an uncertainty of ∼1.5 μas (6%). We show that existing mass and distance measurements can be improved significantly when combined with upcoming EHT measurements of the shadow size and that tight constraints on potential deviations from the Kerr metric can be obtained.

DOI: 10.1103/PhysRevLett.116.031101 PMID: 26849580

44. Living Rev Relativ. 2014;17(1):7. doi: 10.12942/lrr-2014-7. Epub 2014 Aug 25.

Massive Gravity.

de Rham C(1).

Author information: (1)CERCA & Physics Department, Case Western Reserve University, 10900 Euclid Ave, Cleveland, OH 44106 USA.

We review recent progress in massive gravity. We start by showing how different theories of massive gravity emerge from a higher-dimensional theory of general relativity, leading to the Dvali-Gabadadze-Porrati model (DGP), cascading gravity, and ghost-free massive gravity. We then explore their theoretical and phenomenological consistency, proving the absence of Boulware-Deser ghosts and reviewing the Vainshtein mechanism and the cosmological solutions in these models. Finally, we present alternative and related models of massive gravity such as new massive gravity, Lorentz-violating massive gravity and non-local massive gravity.

DOI: 10.12942/lrr-2014-7 PMCID: PMC5256007 PMID: 28179850

45. Philos Trans A Math Phys Eng Sci. 2011 Dec 28;369(1957):4941-6. doi: 10.1098/rsta.2011.0366.

A new golden age: testing general relativity with cosmology.

Bean R(1), Ferreira PG, Taylor A.

Author information: (1)Department of Astronomy, Cornell University, Ithaca, NY 14853, USA.

Gravity drives the evolution of the Universe and is at the heart of its complexity. Einstein's field equations can be used to work out the detailed dynamics of space and time and to calculate the emergence of large-scale structure in the distribution of galaxies and radiation. Over the past few years, it has become clear that cosmological observations can be used not only to constrain different world models within the context of Einstein gravity but also to constrain the theory of gravity itself. In this article, we look at different aspects of this new field in which cosmology is used to test theories of gravity with a wide range of observations.

DOI: 10.1098/rsta.2011.0366 PMID: 22084284

46. Ann N Y Acad Sci. 2015 Dec;1361:18-35. doi: 10.1111/nyas.12860. Epub 2015 Sep 11.

The unification of physics: the quest for a theory of everything.

Paulson S(1), Gleiser M(2), Freese K(3)(4), Tegmark M(5).

DOI: 10.1111/nyas.12860 PMID: 26359791 [Indexed for MEDLINE]

47. Living Rev Relativ. 2016;19(1):2. doi: 10.1007/s41114-016-0001-9. Epub 2016 Oct 4.

Extraction of gravitational waves in numerical relativity.

Bishop NT(1), Rezzolla L(2).

Author information: (1)Department of Mathematics, Rhodes University, Grahamstown, 6140 South Africa. (2)Institute for Theoretical Physics, 60438 Frankfurt am Main, Germany ; Frankfurt Institute for Advanced Studies, 60438 Frankfurt am Main, Germany.

A numerical-relativity calculation yields in general a solution of the Einstein equations including also a radiative part, which is in practice computed in a region of finite extent. Since gravitational radiation is properly defined only at null infinity and in an appropriate coordinate system, the accurate estimation of the emitted gravitational waves represents an old and non-trivial problem in numerical relativity. A number of methods have been developed over the years to "extract" the radiative part of the solution from a numerical simulation and these include: quadrupole formulas, gauge-invariant metric perturbations, Weyl scalars, and characteristic extraction. We review and discuss each method, in terms of both its theoretical background as well as its implementation. Finally, we provide a brief comparison of the various methods in terms of their inherent advantages and disadvantages.

DOI: 10.1007/s41114-016-0001-9 PMCID: PMC5297365 PMID: 28190970

48. J Acoust Soc Am. 2019 Oct;146(4):2522. doi: 10.1121/1.5127756.

A model of speech production based on the acoustic relativity of the vocal tract.

Story BH(1), Bunton K(1).

Author information: (1)Speech, Language, and Hearing Sciences, University of Arizona, Tucson, Arizona 85721, USA.

A model is described in which the effects of articulatory movements to produce speech are generated by specifying relative acoustic events along a time axis. These events consist of directional changes of the vocal tract resonance frequencies that, when associated with a temporal event function, are transformed via acoustic sensitivity functions, into time-varying modulations of the vocal tract shape. Because the time course of the events may be considerably overlapped in time, coarticulatory effects are automatically generated. Production of sentence-level speech with the model is demonstrated with audio samples and vocal tract animations.

DOI: 10.1121/1.5127756 PMCID: PMC7064311 PMID: 31671993 [Indexed for MEDLINE]

49. Living Rev Relativ. 2010;13(1):5. doi: 10.12942/lrr-2010-5. Epub 2010 Sep 14.

Brane-World Gravity.

Maartens R(1), Koyama K(1).

Author information: (1)Institute of Cosmology & Gravitation, University of Portsmouth, Portsmouth, PO1 3FX UK.

The observable universe could be a 1+3-surface (the "brane") embedded in a 1+3+d-dimensional spacetime (the "bulk"), with Standard Model particles and fields trapped on the brane while gravity is free to access the bulk. At least one of the d extra spatial dimensions could be very large relative to the Planck scale, which lowers the fundamental gravity scale, possibly even down to the electroweak (∼ TeV) level. This revolutionary picture arises in the framework of recent developments in M theory. The 1+10-dimensional M theory encompasses the known 1+9-dimensional superstring theories, and is widely considered to be a promising potential route to quantum gravity. At low energies, gravity is localized at the brane and general relativity is recovered, but at high energies gravity "leaks" into the bulk, behaving in a truly higher-dimensional way. This introduces significant changes to gravitational dynamics and perturbations, with interesting and potentially testable implications for high-energy astrophysics, black holes, and cosmology. Brane-world models offer a phenomenological way to test some of the novel predictions and corrections to general relativity that are implied by M theory. This review analyzes the geometry, dynamics and perturbations of simple brane-world models for cosmology and astrophysics, mainly focusing on warped 5-dimensional brane-worlds based on the Randall-Sundrum models. We also cover the simplest brane-world models in which 4-dimensional gravity on the brane is modified at low energies - the 5-dimensional Dvali-Gabadadze-Porrati models. Then we discuss co-dimension two branes in 6-dimensional models.

DOI: 10.12942/lrr-2010-5 PMCID: PMC5479361 PMID: 28690420

50. Living Rev Relativ. 2000;3(1):2. doi: 10.12942/lrr-2000-2. Epub 2000 May 8.

Numerical Hydrodynamics in General Relativity.

Font JA(1).

Author information: (1)Max-Planck-Institut für Astrophysik, Karl-Schwarzschild-Str. 1, D-85740, Garching, Germany.

The current status of numerical solutions for the equations of ideal general relativistic hydrodynamics is reviewed. Different formulations of the equations are presented, with special mention of conservative and hyperbolic formulations well-adapted to advanced numerical methods. A representative sample of available numerical schemes is discussed and particular emphasis is paid to solution procedures based on schemes exploiting the characteristic structure of the equations through linearized Riemann solvers. A comprehensive summary of relevant astrophysical simulations in strong gravitational fields, including gravitational collapse, accretion onto black holes and evolution of neutron stars, is also presented. ELECTRONIC SUPPLEMENTARY MATERIAL: Supplementary material is available for this article at 10.12942/lrr-2000-2.

DOI: 10.12942/lrr-2000-2 PMCID: PMC5256036 PMID: 28179854

51. J Cosmet Dermatol. 2018 Oct;17(5):925-930. doi: 10.1111/jocd.12732. Epub 2018 Aug 6.

Introducing a novel model: The special theory of relativity for attractiveness to define a natural and pleasing outcome following cosmetic treatments.

Dayan S(1), Romero DH(2).

Author information: (1)University of Illinois, Department of Otolaryngology, Chicago, Illinois. (2)DeNova Research, Chicago, Illinois.

A meteoric expansion in esthetic medicine followed the introduction of nonsurgical cosmetic neuromodulators and fillers in the early 2000s, which has been recently declining. The initial inertia has likely been tempered by the cosmetically interested patient's fear of appearing unnatural. Defining a natural outcome is a mission essential to the advancement of esthetic medicine; however, achieving a natural result following cosmetic intervention is a misnomer and a logically flawed endeavor that cannot exist. The ever elusive "natural" that is loudly desired by the populous, and ardently pursued by both industry and physicians, can only be an interpreted deduction. To better define a natural outcome, a novel model based on the theory of relativity is suggested. Attractiveness consists of a 3-dimensional area defined by beauty, genuineness, and self-esteem. When all three variables are at a maximum, a desirable attractive appearance is achieved that can be interpreted as "natural." Similar to the time-space dilemma, attractiveness is relative, dynamic, and highly dependent on the position of the projector and the interpreter. The 3D cube of attractiveness is therefore contained within a 4th dimension that takes into account the perspective of the judger. It is hoped that by realizing a new theory of what defines a natural outcome, esthetic medicine will be prepared to meet the needs of future generations.

DOI: 10.1111/jocd.12732 PMID: 30084145 [Indexed for MEDLINE]

52. Behav Processes. 2017 Aug;141(Pt 1):85-91. doi: 10.1016/j.beproc.2017.04.018. Epub 2017 May 6.

On defining resurgence.

Lattal KA(1), Cançado CRX(2), Cook JE(2), Kincaid SL(2), Nighbor TD(2), Oliver AC(2).

Author information: (1)West Virginia University, United States. Electronic address: klattal@wvu.edu. (2)West Virginia University, United States.

A review of different investigators' definitions of resurgence revealed several common features: First, characteristics of the resurgent, or target, response, such as its transience; magnitude; time course within and across sessions; and relativity to a baseline response rate are not mentioned. Second, the target response is described as being established through its reinforcement in the first, or Training, phase of a resurgence procedure. Third, the target response must be eliminated as an alternative response is reinforced in the second, Alternative Reinforcement, phase of a resurgence procedure. Fourth, the alternative response must be extinguished during the Resurgence Test phase. Fifth, none of the definitions allude to any contribution of stimulus variables to resurgence. When reconsidered in light of contemporary research germane to these features, none of the reviewed definitions sufficiently reflect important variables in the generation and assessment of resurgence. The review concludes with a proposed working definition that takes into account contemporary research involving all of the aforementioned factors.

DOI: 10.1016/j.beproc.2017.04.018 PMID: 28487201 [Indexed for MEDLINE]

53. Phys Rev Lett. 2016 Jul 29;117(5):051102. doi: 10.1103/PhysRevLett.117.051102. Epub 2016 Jul 27.

Multiband Gravitational-Wave Astronomy: Parameter Estimation and Tests of General Relativity with Space- and Ground-Based Detectors.

Vitale S(1).

Author information: (1)LIGO, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.

With the discovery of the binary-black-hole (BBH) coalescence GW150914 the era of gravitational-wave (GW) astronomy has started. It has recently been shown that BBH with masses comparable to or higher than GW150914 would be visible in the Evolved Laser Interferometer Space Antenna (eLISA) band a few years before they finally merge in the band of ground-based detectors. This would allow for premerger electromagnetic alerts, dramatically increasing the chances of a joint detection, if BBHs are indeed luminous in the electromagnetic band. In this Letter we explore a quite different aspect of multiband GW astronomy, and verify if, and to what extent, measurement of masses and sky position with eLISA could improve parameter estimation and tests of general relativity with ground-based detectors. We generate a catalog of 200 BBHs and find that having prior information from eLISA can reduce the uncertainty in the measurement of source distance and primary black hole spin by up to factor of 2 in ground-based GW detectors. The component masses estimate from eLISA will not be refined by the ground based detectors, whereas joint analysis will yield precise characterization of the newly formed black hole and improve consistency tests of general relativity.

DOI: 10.1103/PhysRevLett.117.051102 PMID: 27517762

54. Nature. 2003 Sep 25;425(6956):374-6. doi: 10.1038/nature01997.

A test of general relativity using radio links with the Cassini spacecraft.

Bertotti B(1), Iess L, Tortora P.

Author information: (1)Dipartimento di Fisica Nucleare e Teorica, Università di Pavia, Via U. Bassi 6, I-27100, Pavia, Italy.

According to general relativity, photons are deflected and delayed by the curvature of space-time produced by any mass. The bending and delay are proportional to gamma + 1, where the parameter gamma is unity in general relativity but zero in the newtonian model of gravity. The quantity gamma - 1 measures the degree to which gravity is not a purely geometric effect and is affected by other fields; such fields may have strongly influenced the early Universe, but would have now weakened so as to produce tiny--but still detectable--effects. Several experiments have confirmed to an accuracy of approximately 0.1% the predictions for the deflection and delay of photons produced by the Sun. Here we report a measurement of the frequency shift of radio photons to and from the Cassini spacecraft as they passed near the Sun. Our result, gamma = 1 + (2.1 +/- 2.3) x 10(-5), agrees with the predictions of standard general relativity with a sensitivity that approaches the level at which, theoretically, deviations are expected in some cosmological models.

DOI: 10.1038/nature01997 PMID: 14508481

55. Eur Phys J C Part Fields. 2017;77(9):628. doi: 10.1140/epjc/s10052-017-5210-1. Epub 2017 Sep 20.

Nonlocal teleparallel cosmology.

Bahamonde S(1), Capozziello S(2)(3)(4), Faizal M(5)(6), Nunes RC(7).

Author information: (1)Department of Mathematics, University College London, Gower Street, London, WC1E 6BT UK. (2)Dipartimento di Fisica "E. Pancini", Universitá di Napoli "Federico II", Naples, Italy. (3)Gran Sasso Science Institute, Via F. Crispi 7, 67100 L'Aquila, Italy. (4)INFN Sez. di Napoli, Compl. Univ. di Monte S. Angelo, Edificio G, Via Cinthia, 80126 Naples, Italy. (5)Irving K. Barber School of Arts and Sciences, University of British Columbia - Okanagan, 3333 University Way, Kelowna, BC V1V 1V7 Canada. (6)Department of Physics and Astronomy, University of Lethbridge, Lethbridge, AB T1K 3M4 Canada. (7)Departamento de Física, Universidade Federal de Juiz de Fora, Juiz de Fora, MG 36036-330 Brazil.

Even though it is not possible to differentiate general relativity from teleparallel gravity using classical experiments, it could be possible to discriminate between them by quantum gravitational effects. These effects have motivated the introduction of nonlocal deformations of general relativity, and similar effects are also expected to occur in teleparallel gravity. Here, we study nonlocal deformations of teleparallel gravity along with its cosmological solutions. We observe that nonlocal teleparallel gravity (like nonlocal general relativity) is consistent with the present cosmological data obtained by SNe Ia + BAO + CC + [Formula: see text] observations. Along this track, future experiments probing nonlocal effects could be used to test whether general relativity or teleparallel gravity gives the most consistent picture of gravitational interaction.

DOI: 10.1140/epjc/s10052-017-5210-1 PMCID: PMC5606975 PMID: 28989322

56. Nature. 2019 Apr;568(7753):469-476. doi: 10.1038/s41586-019-1129-z. Epub 2019 Apr 24.

The new frontier of gravitational waves.

Miller MC(1)(2), Yunes N(3).

Author information: (1)Department of Astronomy, University of Maryland, College Park, MD, USA. miller@astro.umd.edu. (2)Joint Space-Science Institute, University of Maryland, College Park, MD, USA. miller@astro.umd.edu. (3)eXtreme Gravity Institute, Department of Physics, Montana State University, Bozeman, MT, USA. nicolas.yunes@montana.edu.

In 2015, almost a century after Einstein published the general theory of relativity, one of its most important predictions was verified by direct detection: the production of gravitational waves in spacetime by accelerating objects. Since then, gravitational-wave astronomy has enabled tests of the nature of gravity and the properties of black holes, and in 2017 electromagnetic observations of a double neutron star merger producing gravitational waves led to a focus on multi-messenger astronomy. Here we review the history and accomplishments of gravitational-wave astronomy and look towards the future.

DOI: 10.1038/s41586-019-1129-z PMID: 31019316

57. Nat Commun. 2019 Aug 21;10(1):3772. doi: 10.1038/s41467-019-11579-x.

Bell's theorem for temporal order.

Zych M(1), Costa F(2), Pikovski I(3)(4)(5), Brukner Č(6)(7).

Author information: (1)Centre for Engineered Quantum Systems, School of Mathematics and Physics, The University of Queensland, St. Lucia, QLD, 4072, Australia. m.zych@uq.edu.au. (2)Centre for Engineered Quantum Systems, School of Mathematics and Physics, The University of Queensland, St. Lucia, QLD, 4072, Australia. (3)ITAMP, Harvard-Smithsonian Center for Astrophysics, Cambridge, MA, 02138, USA. (4)Department of Physics, Harvard University, Cambridge, MA, 02138, USA. (5)Stevens Institute of Technology, Hoboken, NJ, 07030, USA. (6)Vienna Center for Quantum Science and Technology (VCQ), Faculty of Physics, University of Vienna, Boltzmanngasse 5, 1090, Vienna, Austria. (7)Institute for Quantum Optics and Quantum Information (IQOQI), Austrian Academy of Sciences, Boltzmanngasse 3, 1090, Vienna, Austria.

Time has a fundamentally different character in quantum mechanics and in general relativity. In quantum theory events unfold in a fixed order while in general relativity temporal order is influenced by the distribution of matter. When matter requires a quantum description, temporal order is expected to become non-classical-a scenario beyond the scope of current theories. Here we provide a direct description of such a scenario. We consider a thought experiment with a massive body in a spatial superposition and show how it leads to entanglement of temporal orders between time-like events. This entanglement enables accomplishing a task, violation of a Bell inequality, that is impossible under local classical temporal order; it means that temporal order cannot be described by any pre-defined local variables. A classical notion of a causal structure is therefore untenable in any framework compatible with the basic principles of quantum mechanics and classical general relativity.

DOI: 10.1038/s41467-019-11579-x PMCID: PMC6704104 PMID: 31434883

Conflict of interest statement: The authors declare no competing interests.

58. Phys Rev D. 2017 Jun 15;95(12):124057. doi: 10.1103/PhysRevD.95.124057. Epub 2017 Jun 30.

Gravitational wave content and stability of uniformly, rotating, triaxial neutron stars in general relativity.

Tsokaros A(1), Ruiz M(1), Paschalidis V(2), Shapiro SL(1)(3), Baiotti L(4), Uryū K(5).

Author information: (1)Department of Physics, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA. (2)Department of Physics, Princeton University, Princeton, New Jersey 08544, USA. (3)Department of Astronomy & NCSA, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA. (4)Graduate School of Science, Osaka University, 560-0043 Toyonaka, Japan. (5)Department of Physics, University of the Ryukyus, Senbaru, Nishihara, Okinawa 903-0213, Japan.

Targets for ground-based gravitational wave interferometers include continuous, quasiperiodic sources of gravitational radiation, such as isolated, spinning neutron stars. In this work, we perform evolution simulations of uniformly rotating, triaxially deformed stars, the compressible analogs in general relativity of incompressible, Newtonian Jacobi ellipsoids. We investigate their stability and gravitational wave emission. We employ five models, both normal and supramassive, and track their evolution with different grid setups and resolutions, as well as with two different evolution codes. We find that all models are dynamically stable and produce a strain that is approximately one-tenth the average value of a merging binary system. We track their secular evolution and find that all our stars evolve toward axisymmetry, maintaining their uniform rotation, rotational kinetic energy, and angular momentum profiles while losing their triaxiality.

DOI: 10.1103/PhysRevD.95.124057 PMCID: PMC5988372 PMID: 29888340

59. J Phys Chem Lett. 2017 Sep 7;8(17):4017-4022. doi: 10.1021/acs.jpclett.7b02018. Epub 2017 Aug 15.

Tunneling Flight Time, Chemistry, and Special Relativity.

Petersen J(1), Pollak E(1).

Author information: (1)Chemical Physics Department, Weizmann Institute of Science , 76100 Rehovoth, Israel.

Attosecond ionization experiments have not resolved the question "What is the tunneling time?". Different definitions of tunneling time lead to different results. Second, a zero tunneling time for a material particle suggests that the nonrelativistic theory includes speeds greater than the speed of light. Chemical reactions, occurring via tunneling, should then not be considered in terms of a nonrelativistic quantum theory calling into question quantum dynamics computations on tunneling reactions. To answer these questions, we define a new experimentally measurable paradigm, the tunneling flight time, and show that it vanishes for scattering through an Eckart or a square barrier, irrespective of barrier length or height, generalizing the Hartman effect. We explain why this result does not lead to experimental measurement of speeds greater than the speed of light. We show that this tunneling is an incoherent process by comparing a classical Wigner theory with exact quantum mechanical computations.

DOI: 10.1021/acs.jpclett.7b02018 PMID: 28792772

60. Qual Life Res. 2018 Jun;27(6):1493-1500. doi: 10.1007/s11136-018-1811-x. Epub 2018 Feb 12.

The 'new normal': relativity of quality of life judgments in individuals with bipolar disorder-a qualitative study.

Morton E(1), Michalak E(2), Hole R(3), Buzwell S(1), Murray G(4)(5).

Author information: (1)Faculty of Health, Arts and Design Swinburne University, Melbourne, Australia. (2)Division of Mood Disorders, Department of Psychiatry, University of British Columbia, Vancouver, BC, Canada. (3)School of Social Work, University of British Columbia Okanagan, Kelowna, BC, Canada. (4)Faculty of Health, Arts and Design Swinburne University, Melbourne, Australia. gwm@swin.edu.au. (5)Department of Psychological Sciences, Swinburne University of Technology, PO Box 218, John Street, Hawthorn, VIC, 3122, Australia. gwm@swin.edu.au.

PURPOSE: Quality of life (QoL) is increasingly a target of interventions for bipolar disorders (BD). While the subjective experience of consumers is often elevated as central to the construct of QoL in BD, limited investigation in this area means subjective QoL remains poorly understood. The present qualitative study seeks to address this by investigating how people with BD appraise the quality of their lives in the context of a QoL self-management intervention. METHODS: Semi-structured interviews were conducted with 43 individuals who had participated in a self-management intervention for improving QoL in BD. Individuals were questioned about experiences of the intervention and perceptions of their QoL. Thematic analysis was used to explore participants' appraisal of their QoL. RESULTS: An overarching theme concerned the intrinsic relativity of subjective QoL: individuals located QoL as relative to self, others and possible futures. Incorporating illness-related reference points for QoL ('given my circumstances…') was associated with perceptions of improved QoL. Deliberately modifying reference points for QoL was perceived as self-compassionate. CONCLUSION: The present study generates novel hypotheses about how individuals with BD make sense of their QoL. Data suggest that individuals located their QoL relative to a variety of reference points, use of which was flexible. In accord with gap theories of QoL, individuals experienced acceptance of illness impacts as improving subjective sense of QoL. Rather than 'settling for' a lower standard of QoL, individuals experienced these changes as adaptive and positive. Findings are discussed in relation to the measurement and amelioration of QoL in BD.

DOI: 10.1007/s11136-018-1811-x PMID: 29435800 [Indexed for MEDLINE]

61. eNeuro. 2016 Nov 1;3(5):ENEURO.0022-16.2016. doi: 10.1523/ENEURO.0022-16.2016. eCollection 2016 Sep-Oct.

Striatal Activity and Reward Relativity: Neural Signals Encoding Dynamic Outcome Valuation.

Webber ES(1), Mankin DE(1), Cromwell HC(1).

Author information: (1)Department of Psychology, Bowling Green State University, Bowling Green, Ohio 43403; J.P. Scott Center for Neuroscience, Mind & Behavior, Bowling Green State University, Bowling Green, Ohio 43403.

The striatum is a key brain region involved in reward processing. Striatal activity has been linked to encoding reward magnitude and integrating diverse reward outcome information. Recent work has supported the involvement of striatum in the valuation of outcomes. The present work extends this idea by examining striatal activity during dynamic shifts in value that include different levels and directions of magnitude disparity. A novel task was used to produce diverse relative reward effects on a chain of instrumental action. Rats (Rattus norvegicus) were trained to respond to cues associated with specific outcomes varying by food pellet magnitude. Animals were exposed to single-outcome sessions followed by mixed-outcome sessions, and neural activity was compared among identical outcome trials from the different behavioral contexts. Results recording striatal activity show that neural responses to different task elements reflect incentive contrast as well as other relative effects that involve generalization between outcomes or possible influences of outcome variety. The activity that was most prevalent was linked to food consumption and post-food consumption periods. Relative encoding was sensitive to magnitude disparity. A within-session analysis showed strong contrast effects that were dependent upon the outcome received in the immediately preceding trial. Significantly higher numbers of responses were found in ventral striatum linked to relative outcome effects. Our results support the idea that relative value can incorporate diverse relationships, including comparisons from specific individual outcomes to general behavioral contexts. The striatum contains these diverse relative processes, possibly enabling both a higher information yield concerning value shifts and a greater behavioral flexibility.

DOI: 10.1523/ENEURO.0022-16.2016 PMCID: PMC5089537 PMID: 27822506 [Indexed for MEDLINE]

62. Living Rev Relativ. 2009;12(1):1. doi: 10.12942/lrr-2009-1. Epub 2009 Jan 9.

Spectral Methods for Numerical Relativity.

Grandclément P(1), Novak J(1).

Author information: (1)Laboratoire Univers et Théories, UMR 8102 du C.N.R.S., Observatoire de Paris, F-92195 Meudon Cedex, France.

Equations arising in general relativity are usually too complicated to be solved analytically and one must rely on numerical methods to solve sets of coupled partial differential equations. Among the possible choices, this paper focuses on a class called spectral methods in which, typically, the various functions are expanded in sets of orthogonal polynomials or functions. First, a theoretical introduction of spectral expansion is given with a particular emphasis on the fast convergence of the spectral approximation. We then present different approaches to solving partial differential equations, first limiting ourselves to the one-dimensional case, with one or more domains. Generalization to more dimensions is then discussed. In particular, the case of time evolutions is carefully studied and the stability of such evolutions investigated. We then present results obtained by various groups in the field of general relativity by means of spectral methods. Work, which does not involve explicit time-evolutions, is discussed, going from rapidly-rotating strange stars to the computation of black-hole-binary initial data. Finally, the evolution of various systems of astrophysical interest are presented, from supernovae core collapse to black-hole-binary mergers.

DOI: 10.12942/lrr-2009-1 PMCID: PMC5253976 PMID: 28163610

63. Prog Biophys Mol Biol. 2015 Dec;119(3):257-69. doi: 10.1016/j.pbiomolbio.2015.06.008. Epub 2015 Jul 2.

Why natural science needs phenomenological philosophy.

Rosen SM(1).

Author information: (1)The College of Staten Island of the City University of New York, United States. Electronic address: stevenrosen@shaw.ca.

Through an exploration of theoretical physics, this paper suggests the need for regrounding natural science in phenomenological philosophy. To begin, the philosophical roots of the prevailing scientific paradigm are traced to the thinking of Plato, Descartes, and Newton. The crisis in modern science is then investigated, tracking developments in physics, science's premier discipline. Einsteinian special relativity is interpreted as a response to the threat of discontinuity implied by the Michelson-Morley experiment, a challenge to classical objectivism that Einstein sought to counteract. We see that Einstein's efforts to banish discontinuity ultimately fall into the "black hole" predicted in his general theory of relativity. The unavoidable discontinuity that haunts Einstein's theory is also central to quantum mechanics. Here too the attempt has been made to manage discontinuity, only to have this strategy thwarted in the end by the intractable problem of quantum gravity. The irrepressible discontinuity manifested in the phenomena of modern physics proves to be linked to a merging of subject and object that flies in the face of Cartesian philosophy. To accommodate these radically non-classical phenomena, a new philosophical foundation is called for: phenomenology. Phenomenological philosophy is elaborated through Merleau-Ponty's concept of depth and is then brought into focus for use in theoretical physics via qualitative work with topology and hypercomplex numbers. In the final part of this paper, a detailed summary is offered of the specific application of topological phenomenology to quantum gravity that was systematically articulated in The Self-Evolving Cosmos (Rosen, 2008a).

DOI: 10.1016/j.pbiomolbio.2015.06.008 PMID: 26143599 [Indexed for MEDLINE]

64. Science. 2006 Oct 6;314(5796):97-102. doi: 10.1126/science.1132305. Epub 2006 Sep 14.

Tests of general relativity from timing the double pulsar.

Kramer M(1), Stairs IH, Manchester RN, McLaughlin MA, Lyne AG, Ferdman RD, Burgay M, Lorimer DR, Possenti A, D'Amico N, Sarkissian JM, Hobbs GB, Reynolds JE, Freire PC, Camilo F.

Author information: (1)University of Manchester, Jodrell Bank Observatory, Macclesfield SK11 9DL, UK. mkramer@jb.man.ac.uk

The double pulsar system PSR J0737-3039A/B is unique in that both neutron stars are detectable as radio pulsars. They are also known to have much higher mean orbital velocities and accelerations than those of other binary pulsars. The system is therefore a good candidate for testing Einstein's theory of general relativity and alternative theories of gravity in the strong-field regime. We report on precision timing observations taken over the 2.5 years since its discovery and present four independent strong-field tests of general relativity. These tests use the theory-independent mass ratio of the two stars. By measuring relativistic corrections to the Keplerian description of the orbital motion, we find that the "post-Keplerian" parameter s agrees with the value predicted by general relativity within an uncertainty of 0.05%, the most precise test yet obtained. We also show that the transverse velocity of the system's center of mass is extremely small. Combined with the system's location near the Sun, this result suggests that future tests of gravitational theories with the double pulsar will supersede the best current solar system tests. It also implies that the second-born pulsar may not have formed through the core collapse of a helium star, as is usually assumed.

DOI: 10.1126/science.1132305 PMID: 16973838

65. Eur Phys J C Part Fields. 2018;78(10):818. doi: 10.1140/epjc/s10052-018-6285-z. Epub 2018 Oct 10.

Tidal Love numbers of neutron stars in f(R) gravity.

Yazadjiev SS(1)(2)(3), Doneva DD(2)(4), Kokkotas KD(2).

Author information: (1)1Department of Theoretical Physics, Faculty of Physics, Sofia University, 1164 Sofia, Bulgaria. (2)2Theoretical Astrophysics, Eberhard-Karls University of Tübingen, 72076 Tübingen, Germany. (3)3Institute of Mathematics and Informatics, Bulgarian Academy of Sciences, Acad. G. Bonchev St. 8, 1113 Sofia, Bulgaria. (4)4INRNE - Bulgarian Academy of Sciences, 1784 Sofia, Bulgaria.

The recent detection of gravitational waves from a neutron star merger was a significant step towards constraining the nuclear matter equation of state by using the tidal Love numbers (TLNs) of the merging neutron stars. Measuring or constraining the neutron star TLNs allows us in principle to exclude or constraint many equations of state. This approach, however, has the drawback that many modified theories of gravity could produce deviations from General Relativity similar to the deviations coming from the uncertainties in the equation of state. The first and the most natural step in resolving the mentioned problem is to quantify the effects on the TLNs from the modifications of General Relativity. With this motivation in mind, in the present paper we calculate the TLNs of (non-rotating) neutron stars in R2 -gravity. More precisely, by solving numerically the perturbation equations, we calculate explicitly the polar and the axial l = 2 TLNs for three characteristic realistic equations of state and compare the results to General Relativity. Our results show that while the polar TLNs are slightly influenced by the R2 modification of General Relativity, the axial TLNs can be several times larger (in terms of the absolute value) compared to the general relativistic case.

DOI: 10.1140/epjc/s10052-018-6285-z PMCID: PMC6244867 PMID: 30524193

66. Phys Rev E. 2020 May;101(5-1):052105. doi: 10.1103/PhysRevE.101.052105.

Caloric curves of classical self-gravitating systems in general relativity.

Alberti G(1), Chavanis PH(2).

Author information: (1)Laboratoire de Physique Théorique, Université de Toulouse, CNRS, UPS, France and Living Systems Research, Roseggerstraße 27/2, A-9020 Klagenfurt am Wörthersee, Austria. (2)Laboratoire de Physique Théorique, Université de Toulouse, CNRS, UPS, France.

We determine the caloric curves of classical self-gravitating systems at statistical equilibrium in general relativity. In the classical limit, the caloric curves of a self-gravitating gas depend on a unique parameter ν=GNm/Rc^{2}, called the compactness parameter, where N is the particle number and R the system's size. Typically, the caloric curves have the form of a double spiral. The "cold spiral," corresponding to weakly relativistic configurations, is a generalization of the caloric curve of nonrelativistic classical self-gravitating systems. The "hot spiral," corresponding to strongly relativistic configurations, is similar (but not identical) to the caloric curve of the ultrarelativistic self-gravitating black-body radiation. We introduce two types of normalization of energy and temperature to obtain asymptotic caloric curves describing, respectively, the cold and the hot spirals in the limit ν→0. As the number of particles increases, the cold and the hot spirals approach each other, merge at ν_{S}^{'}=0.128, form a loop above ν_{S}=0.1415, reduce to a point at ν_{max}=0.1764, and finally disappear. Therefore, the double spiral shrinks when the compactness parameter ν increases, implying that general relativistic effects render the system more unstable. We discuss the nature of the gravitational collapse at low and high energies with respect to a dynamical (fast) or a thermodynamical (slow) instability. We also provide an historical account of the developments of the statistical mechanics of classical self-gravitating systems in Newtonian gravity and general relativity.

DOI: 10.1103/PhysRevE.101.052105 PMID: 32575217

67. Proc Natl Acad Sci U S A. 2017 Mar 21;114(12):E2303-E2309. doi: 10.1073/pnas.1616427114. Epub 2017 Mar 7.

Entanglement of quantum clocks through gravity.

Castro Ruiz E(1)(2), Giacomini F(3)(2), Brukner Č(3)(2).

Author information: (1)Vienna Center for Quantum Science and Technology, Faculty of Physics, University of Vienna, A-1090 Vienna, Austria; esteban.castro.ruiz@univie.ac.at. (2)Institute for Quantum Optics and Quantum Information, Austrian Academy of Sciences, A-1090 Vienna, Austria. (3)Vienna Center for Quantum Science and Technology, Faculty of Physics, University of Vienna, A-1090 Vienna, Austria.

In general relativity, the picture of space-time assigns an ideal clock to each world line. Being ideal, gravitational effects due to these clocks are ignored and the flow of time according to one clock is not affected by the presence of clocks along nearby world lines. However, if time is defined operationally, as a pointer position of a physical clock that obeys the principles of general relativity and quantum mechanics, such a picture is, at most, a convenient fiction. Specifically, we show that the general relativistic mass-energy equivalence implies gravitational interaction between the clocks, whereas the quantum mechanical superposition of energy eigenstates leads to a nonfixed metric background. Based only on the assumption that both principles hold in this situation, we show that the clocks necessarily get entangled through time dilation effect, which eventually leads to a loss of coherence of a single clock. Hence, the time as measured by a single clock is not well defined. However, the general relativistic notion of time is recovered in the classical limit of clocks.

DOI: 10.1073/pnas.1616427114 PMCID: PMC5373405 PMID: 28270623

Conflict of interest statement: The authors declare no conflict of interest.

68. Nature. 2001 Jul 12;412(6843):158-60. doi: 10.1038/35084015.

A test of general relativity from the three-dimensional orbital geometry of a binary pulsar.

van Straten W(1), Bailes M, Britton M, Kulkarni SR, Anderson SB, Manchester RN, Sarkissian J.

Author information: (1)Centre for Astrophysics and Supercomputing, Swinburne University of Technology, PO Box 218, Hawthorn, Victoria 3122, Australia. wvanstra@mania.physics.swin.edu.au

Binary pulsars provide an excellent system for testing general relativity because of their intrinsic rotational stability and the precision with which radio observations can be used to determine their orbital dynamics. Measurements of the rate of orbital decay of two pulsars have been shown to be consistent with the emission of gravitational waves as predicted by general relativity, but independent verification was not possible. Such verification can in principle be obtained by determining the orbital inclination in a binary pulsar system using only classical geometrical constraints. This would permit a measurement of the expected retardation of the pulse signal arising from the general relativistic curvature of space-time in the vicinity of the companion object (the 'Shapiro delay'). Here we report high-precision radio observations of the binary millisecond pulsar PSR J0437-4715, which establish the three-dimensional structure of its orbit. We see the Shapiro delay predicted by general relativity, and we determine the mass of the neutron star and its white dwarf companion. The determination of such masses is necessary in order to understand the origin and evolution of neutron stars.

DOI: 10.1038/35084015 PMID: 11449265

69. Nature. 2010 Mar 11;464(7286):256-8. doi: 10.1038/nature08857.

Confirmation of general relativity on large scales from weak lensing and galaxy velocities.

Reyes R(1), Mandelbaum R, Seljak U, Baldauf T, Gunn JE, Lombriser L, Smith RE.

Author information: (1)Princeton University Observatory, Peyton Hall, Princeton, New Jersey 08544, USA. rreyes@astro.princeton.edu

Comment in Nature. 2010 Mar 11;464(7286):172-3.

Although general relativity underlies modern cosmology, its applicability on cosmological length scales has yet to be stringently tested. Such a test has recently been proposed, using a quantity, E(G), that combines measures of large-scale gravitational lensing, galaxy clustering and structure growth rate. The combination is insensitive to 'galaxy bias' (the difference between the clustering of visible galaxies and invisible dark matter) and is thus robust to the uncertainty in this parameter. Modified theories of gravity generally predict values of E(G) different from the general relativistic prediction because, in these theories, the 'gravitational slip' (the difference between the two potentials that describe perturbations in the gravitational metric) is non-zero, which leads to changes in the growth of structure and the strength of the gravitational lensing effect. Here we report that E(G) = 0.39 +/- 0.06 on length scales of tens of megaparsecs, in agreement with the general relativistic prediction of E(G) approximately 0.4. The measured value excludes a model within the tensor-vector-scalar gravity theory, which modifies both Newtonian and Einstein gravity. However, the relatively large uncertainty still permits models within f(R) theory, which is an extension of general relativity. A fivefold decrease in uncertainty is needed to rule out these models.

DOI: 10.1038/nature08857 PMID: 20220843

70. Phys Rev Lett. 2019 Feb 15;122(6):061106. doi: 10.1103/PhysRevLett.122.061106.

Action Principle for Newtonian Gravity.

Hansen D(1), Hartong J(2), Obers NA(3).

Author information: (1)Institut für Theoretische Physik, Eidgenössische Technische Hochschule Zürich Wolfgang-Pauli-Strasse 27, 8093 Zürich, Switzerland. (2)School of Mathematics and Maxwell Institute for Mathematical Sciences, University of Edinburgh, Peter Guthrie Tait Road, Edinburgh EH9 3FD, United Kingdom. (3)The Niels Bohr Institute, Copenhagen University, Blegdamsvej 17, DK-2100 Copenhagen Ø, Denmark.

We derive an action whose equations of motion contain the Poisson equation of Newtonian gravity. The construction requires a new notion of Newton-Cartan geometry based on an underlying symmetry algebra that differs from the usual Bargmann algebra. This geometry naturally arises in a covariant 1/c expansion of general relativity, with c being the speed of light. By truncating this expansion at subleading order, we obtain the field content and transformation rules of the fields that appear in the action of Newtonian gravity. The equations of motion generalize Newtonian gravity by allowing for the effect of gravitational time dilation due to strong gravitational fields.

DOI: 10.1103/PhysRevLett.122.061106 PMID: 30822041

71. Interface Focus. 2017 Oct 6;7(5):20160159. doi: 10.1098/rsfs.2016.0159. Epub 2017 Aug 18.

Evolution viewed from physics, physiology and medicine.

Noble D(1).

Author information: (1)Department of Physiology, Anatomy and Genetics, University of Oxford, Parks Road, Oxford OX1 3PT, UK.

Stochasticity is harnessed by organisms to generate functionality. Randomness does not, therefore, necessarily imply lack of function or 'blind chance' at higher levels. In this respect, biology must resemble physics in generating order from disorder. This fact is contrary to Schrödinger's idea of biology generating phenotypic order from molecular-level order, which inspired the central dogma of molecular biology. The order originates at higher levels, which constrain the components at lower levels. We now know that this includes the genome, which is controlled by patterns of transcription factors and various epigenetic and reorganization mechanisms. These processes can occur in response to environmental stress, so that the genome becomes 'a highly sensitive organ of the cell' (McClintock). Organisms have evolved to be able to cope with many variations at the molecular level. Organisms also make use of physical processes in evolution and development when it is possible to arrive at functional development without the necessity to store all information in DNA sequences. This view of development and evolution differs radically from that of neo-Darwinism with its emphasis on blind chance as the origin of variation. Blind chance is necessary, but the origin of functional variation is not at the molecular level. These observations derive from and reinforce the principle of biological relativity, which holds that there is no privileged level of causation. They also have important implications for medical science.

DOI: 10.1098/rsfs.2016.0159 PMCID: PMC5566812 PMID: 28839924

Conflict of interest statement: I declare I have no competing interests.

72. Living Rev Relativ. 2005;8(1):2. doi: 10.12942/lrr-2005-2. Epub 2005 Mar 18.

The Einstein-Vlasov System/Kinetic Theory.

Andréasson H(1).

Author information: (1)Department of Mathematics, Chalmers University of Technology, S-412 96 Göteborg, Sweden.

The main purpose of this article is to provide a guide to theorems on global properties of solutions to the Einstein-Vlasov system. This system couples Einstein's equations to a kinetic matter model. Kinetic theory has been an important field of research during several decades in which the main focus has been on nonrelativistic and special relativistic physics, i.e. to model the dynamics of neutral gases, plasmas, and Newtonian self-gravitating systems. In 1990, Rendall and Rein initiated a mathematical study of the Einstein-Vlasov system. Since then many theorems on global properties of solutions to this system have been established. The Vlasov equation describes matter phenomenologically, and it should be stressed that most of the theorems presented in this article are not presently known for other such matter models (i.e. fluid models). This paper gives introductions to kinetic theory in non-curved spacetimes and then the Einstein-Vlasov system is introduced. We believe that a good understanding of kinetic theory in non-curved spacetimes is fundamental to good comprehension of kinetic theory in general relativity.

DOI: 10.12942/lrr-2005-2 PMCID: PMC5253932 PMID: 28163646

73. Living Rev Relativ. 2017;20(1):6. doi: 10.1007/s41114-017-0009-9. Epub 2017 Nov 22.

Black holes, hidden symmetries, and complete integrability.

Frolov VP(1), Krtouš P(2), Kubizňák D(3).

Author information: (1)Department of Physics, Theoretical Physics Institute, University of Alberta, Edmonton, AB T6G 2G7 Canada. (2)Institute of Theoretical Physics, Faculty of Mathematics and Physics, Charles University, V Holešovičkách 2, Prague, Czech Republic. (3)Perimeter Institute, 31 Caroline St. N, Waterloo, ON N2L 2Y5 Canada.

The study of higher-dimensional black holes is a subject which has recently attracted vast interest. Perhaps one of the most surprising discoveries is a realization that the properties of higher-dimensional black holes with the spherical horizon topology and described by the Kerr-NUT-(A)dS metrics are very similar to the properties of the well known four-dimensional Kerr metric. This remarkable result stems from the existence of a single object called the principal tensor. In our review we discuss explicit and hidden symmetries of higher-dimensional Kerr-NUT-(A)dS black hole spacetimes. We start with discussion of the Killing and Killing-Yano objects representing explicit and hidden symmetries. We demonstrate that the principal tensor can be used as a "seed object" which generates all these symmetries. It determines the form of the geometry, as well as guarantees its remarkable properties, such as special algebraic type of the spacetime, complete integrability of geodesic motion, and separability of the Hamilton-Jacobi, Klein-Gordon, and Dirac equations. The review also contains a discussion of different applications of the developed formalism and its possible generalizations.

DOI: 10.1007/s41114-017-0009-9 PMCID: PMC5700430 PMID: 29213211

74. IEEE Trans Vis Comput Graph. 2006 Jul-Aug;12(4):522-34. doi: 10.1109/TVCG.2006.69.

Explanatory and illustrative visualization of special and general relativity.

Weiskopf D(1), Borchers M, Ertl T, Falk M, Fechtig O, Frank R, Grave F, King A, Kraus U, Müller T, Nollert HP, Rica Mendez I, Ruder H, Schafhitzel T, Schär S, Zahn C, Zatloukal M.

Author information: (1)Graphics, Visualization, and Usability Lab, School of Computing Science, Simon Fraser University, Burnaby, Canada. weiskopf@cs.sfu.ca

This paper describes methods for explanatory and illustrative visualizations used to communicate aspects of Einstein's theories of special and general relativity, their geometric structure, and of the related fields of cosmology and astrophysics. Our illustrations target a general audience of laypersons interested in relativity. We discuss visualization strategies, motivated by physics education and the didactics of mathematics, and describe what kind of visualization methods have proven to be useful for different types of media, such as still images in popular science magazines, film contributions to TV shows, oral presentations, or interactive museum installations. Our primary approach is to adopt an egocentric point of view: The recipients of a visualization participate in a visually enriched thought experiment that allows them to experience or explore a relativistic scenario. In addition, we often combine egocentric visualizations with more abstract illustrations based on an outside view in order to provide several presentations of the same phenomenon. Although our visualization tools often build upon existing methods and implementations, the underlying techniques have been improved by several novel technical contributions like image-based special relativistic rendering on GPUs, special relativistic 4D ray tracing for accelerating scene objects, an extension of general relativistic ray tracing to manifolds described by multiple charts, GPU-based interactive visualization of gravitational light deflection, as well as planetary terrain rendering. The usefulness and effectiveness of our visualizations are demonstrated by reporting on experiences with, and feedback from, recipients of visualizations and collaborators.

DOI: 10.1109/TVCG.2006.69 PMID: 16805261 [Indexed for MEDLINE]

75. Rep Prog Phys. 2019 Aug;82(8):086901. doi: 10.1088/1361-6633/ab2429. Epub 2019 May 23.

Horndeski theory and beyond: a review.

Kobayashi T(1).

Author information: (1)Department of Physics, Rikkyo University, Toshima, Tokyo 171-8501, Japan.

This article is intended to review the recent developments in the Horndeski theory and its generalization, which provide us with a systematic understanding of scalar-tensor theories of gravity as well as a powerful tool to explore astrophysics and cosmology beyond general relativity. This review covers the generalized Galileons, (the rediscovery of) the Horndeski theory, cosmological perturbations in the Horndeski theory, cosmology with a violation of the null energy condition, degenerate higher-order scalar-tensor theories and their status after GW170817, the Vainshtein screening mechanism in the Horndeski theory and beyond, and hairy black hole solutions.

DOI: 10.1088/1361-6633/ab2429 PMID: 31121569

76. Phys Rev Lett. 2008 Mar 7;100(9):091101. doi: 10.1103/PhysRevLett.100.091101. Epub 2008 Mar 3.

Kerr black holes are not unique to general relativity.

Psaltis D(1), Perrodin D, Dienes KR, Mocioiu I.

Author information: (1)Department of Physics, University of Arizona, Tucson, AZ 85721, USA.

Erratum in Phys Rev Lett. 2008 Mar 21;100(11):119902.

Considerable attention has recently focused on gravity theories obtained by extending general relativity with additional scalar, vector, or tensor degrees of freedom. In this Letter, we show that the black-hole solutions of these theories are essentially indistinguishable from those of general relativity. Thus, we conclude that a potential observational verification of the Kerr metric around an astrophysical black hole cannot, in and of itself, be used to distinguish between these theories. On the other hand, it remains true that detection of deviations from the Kerr metric will signify the need for a major change in our understanding of gravitational physics.

DOI: 10.1103/PhysRevLett.100.091101 PMID: 18352688

77. Rep Prog Phys. 2019 Jan;82(1):016905. doi: 10.1088/1361-6633/aab906. Epub 2018 Mar 23.

Squeezed vacuum states of light for gravitational wave detectors.

Barsotti L(1), Harms J, Schnabel R.

Author information: (1)LIGO, Massachusetts Institute of Technology, Cambridge, MA 02139, United States of America.

A century after Einstein's formulation of general relativity, the detectors of the Laser Interferometer Gravitational-wave Observatory (LIGO) made the first direct detection of gravitational waves. This historic achievement was the culmination of a world-wide effort and decades of instrument research. While sufficient for this monumental discovery, the current generation of gravitational-wave detectors represent the least sensitive devices necessary for the task; improved detectors will be required to fully exploit this new window on the Universe. In this paper, we review the application of squeezed vacuum states of light to gravitational-wave detectors as a way to reduce quantum noise, which currently limits their performance in much of the detection band.

DOI: 10.1088/1361-6633/aab906 PMID: 29569572

78. Acta Psychol (Amst). 2019 Mar;194:77-86. doi: 10.1016/j.actpsy.2019.02.003. Epub 2019 Feb 22.

Time dilation and acceleration in depression.

Kent L(1), Van Doorn G(2), Klein B(3).

Author information: (1)School of Health Sciences and Psychology, Federation University Australia, Australia. Electronic address: lachkent@yahoo.com.au. (2)School of Health Sciences and Psychology, Federation University Australia, Australia. (3)Biopsychosocial & eHealth Research & Innovation Hub & DVC-R Portfolio, Federation University Australia, Australia.

BACKGROUND: A recent meta-analysis left open a significant question regarding altered time perception in depression: Why do depressed people overproduce short durations and under-produce longer durations if their present experience is that time flows slowly? Experience and judgement of time do not seem to accord with one another. ANALYSIS: By excluding two of the six studies on methodological grounds from a previous meta-analysis of medium-length interval productions, and re-analysing the remaining four studies, the present paper finds that subjective time accelerates from initial dilation within present experience (approximately 1 s duration) to subsequent acceleration within working memory (approximately 30 s duration) when depressed. PROPOSALS: It is proposed that depressive time dilation and acceleration refer to the default mode and central executive networks, respectively. The acceleration effect is suggested to occur due to mood congruency between long intervals, boredom, and depression. This mood congruency leads to the automatic recall of intrusive, negative, and non-specific autobiographical long-term memories used to judge intervals from previous experience. Acceleration in working memory then occurs according to the contextual change model of duration estimation. LIMITATIONS: The meta-analysis is limited to four studies only, but provides a potential link between time experience and judgement within the same explanatory model. CONCLUSIONS: Similarities between psychological time dilation/acceleration and physical time dilation/acceleration are discussed.

DOI: 10.1016/j.actpsy.2019.02.003 PMID: 30798221 [Indexed for MEDLINE]

79. Nature. 1977 May 12;267(5607):128-30. doi: 10.1038/267128a0.

Cosmological tests of general relativity.

Hut P(1).

Author information: (1)The Astronomical Institute, Utrecht, The Netherlands.

General relativity theory could be tested on a cosmological scale by measuring the Hubble constant and the deceleration parameter, if, in addition, everything could be known about the matter filling the universe. If, on the other hand, nothing could be presupposed about the matter content of the universe, general relativity could not be tested by measuring any number of time derivatives of the scale factor. But upon making the assumption of a universe filled with a non-interacting mixture of non-relativistic matter and radiation we can in principle test general relativity by measuring the first five derivatives of the scale factor. In the following, some general relations are presented using this assumption.

DOI: 10.1038/267128a0 PMID: 16073411

80. Living Rev Relativ. 2010;13(1):3. doi: 10.12942/lrr-2010-3. Epub 2010 Jun 23.

f(R) Theories.

De Felice A(1), Tsujikawa S(1).

Author information: (1)Department of Physics, Faculty of Science, Tokyo University of Science, 1-3, Kagurazaka, Shinjuku-ku, Tokyo, 162-8601 Japan.

Over the past decade, f(R) theories have been extensively studied as one of the simplest modifications to General Relativity. In this article we review various applications of f(R) theories to cosmology and gravity - such as inflation, dark energy, local gravity constraints, cosmological perturbations, and spherically symmetric solutions in weak and strong gravitational backgrounds. We present a number of ways to distinguish those theories from General Relativity observationally and experimentally. We also discuss the extension to other modified gravity theories such as Brans-Dicke theory and Gauss-Bonnet gravity, and address models that can satisfy both cosmological and local gravity constraints.

DOI: 10.12942/lrr-2010-3 PMCID: PMC5255939 PMID: 28179828

81. Philos Trans A Math Phys Eng Sci. 2011 Dec 28;369(1957):5042-57. doi: 10.1098/rsta.2011.0293.

Testing general relativity: from local to cosmological scales.

Uzan JP(1).

Author information: (1)Institut d'Astrophysique de Paris, UMR-7095 du CNRS, Université Pierre et Marie Curie, 98 bis bd Arago, 75014 Paris, France. uzan@iap.fr

I summarize various tests of general relativity on astrophysical scales, based on the large-scale structure of the universe but also on other systems, in particular the constants of physics. I emphasize the importance of hypotheses on the geometric structures of our universe while performing such tests and discuss their complementarity as well as their possible extensions.

DOI: 10.1098/rsta.2011.0293 PMID: 22084292

82. Phys Rev Lett. 2017 Sep 15;119(11):111101. doi: 10.1103/PhysRevLett.119.111101. Epub 2017 Sep 12.

Gravitational Wave Oscillations in Bigravity.

Max K(1), Platscher M(2), Smirnov J(3).

Author information: (1)Scuola Normale Superiore and INFN Pisa, Piazza dei Cavalieri, 7-56126 Pisa, Italy. (2)Max-Planck-Institut für Kernphysik, Saupfercheckweg 1, 69117 Heidelberg, Germany. (3)INFN divisione di Firenze, Dipartimento di Fisica, Università di Firenze, Via Sansone 1, 50019 Sesto Fiorentino, Florence, Italy.

We derive consistent equations for gravitational wave oscillations in bigravity. In this framework a second dynamical tensor field is introduced in addition to general relativity and coupled such that one massless and one massive linear combination arise. Only one of the two tensors is the physical metric coupling to matter, and thus the basis in which gravitational waves propagate is different from the basis where the wave is produced and detected. Therefore, one should expect-in analogy to neutrino oscillations-to observe an oscillatory behavior. We show for the first time how this behavior arises explicitly, discuss phenomenological implications, and present new limits on the graviton parameter space in bigravity.

DOI: 10.1103/PhysRevLett.119.111101 PMID: 28949201

83. Philos Trans A Math Phys Eng Sci. 2015 Aug 28;373(2049):20140354. doi: 10.1098/rsta.2014.0354.

On cosmology in the laboratory.

Leonhardt U(1).

Author information: (1)Weizmann Institute of Science, Rehovot 76100, Israel ulf.leonhardt@weizmann.ac.il.

In transformation optics, ideas from general relativity have been put to practical use for engineering problems. This article asks the question how this debt can be repaid. In discussing a series of recent laboratory experiments, it shows how insights from wave phenomena shed light on the quantum physics of the event horizon.

DOI: 10.1098/rsta.2014.0354 PMCID: PMC4528832 PMID: 26217062

84. Living Rev Relativ. 2008;11(1):10. doi: 10.12942/lrr-2008-10. Epub 2008 Dec 12.

Physics of Neutron Star Crusts.

Chamel N(1), Haensel P(2).

Author information: (1)Institut d'Astronomie et d'Astrophysique, Université Libre de Bruxelles, CP226, Boulevard du Triomphe, B-1050 Brussels, Belgium. (2)Nicolaus Copernicus Astronomical Center, Polish Academy of Sciences, Bartycka 18, 00-716 Warszawa, Poland.

The physics of neutron star crusts is vast, involving many different research fields, from nuclear and condensed matter physics to general relativity. This review summarizes the progress, which has been achieved over the last few years, in modeling neutron star crusts, both at the microscopic and macroscopic levels. The confrontation of these theoretical models with observations is also briefly discussed.

DOI: 10.12942/lrr-2008-10 PMCID: PMC5255077 PMID: 28163609

85. Phys Rev Lett. 2009 Jan 16;102(2):021101. doi: 10.1103/PhysRevLett.102.021101. Epub 2009 Jan 15.

Quasilocal mass in general relativity.

Wang MT(1), Yau ST.

Author information: (1)Columbia University, Department of Mathematics, 2990 Broadway, New York, New York 10027, USA.

There have been many attempts to define the notion of quasilocal mass for a spacelike two surface in spacetime by the Hamilton-Jacobi analysis. The essential difficulty in this approach is to identify the right choice of the background configuration to be subtracted from the physical Hamiltonian. Quasilocal mass should be non-negative for surfaces in general spacetime and zero for surfaces in flat spacetime. In this Letter, we propose a new definition of gauge-independent quasilocal mass and prove that it has the desired properties.

DOI: 10.1103/PhysRevLett.102.021101 PMID: 19257261

86. Philos Trans A Math Phys Eng Sci. 2015 Aug 6;373(2047):20140242. doi: 10.1098/rsta.2014.0242.

Geometry of mass.

Dietrich DD(1).

Author information: (1)Arnold Sommerfeld Center for Theoretical Physics, Ludwig-Maximilians-Universität München, 80333 München, Germany Institut für Theoretische Physik, Goethe-Universität, 60438 Frankfurt am Main, Germany dietrich@th.physik.uni-frankfurt.de.

We study the effect of mass on geometric descriptions of gauge field theories. In an approach in which the massless theory resembles general relativity, the introduction of the mass entails non-zero torsion and the generalization to Einstein-Cartan-Sciama-Kibble theories. The relationships to pure torsion formulations (teleparallel gravity) and to higher gauge theories are also discussed.

DOI: 10.1098/rsta.2014.0242 PMID: 26124248

87. Cogn Sci. 2019 Jan;43(1). doi: 10.1111/cogs.12708.

Keeping the Result in Sight and Mind: General Cognitive Principles and Language-Specific Influences in the Perception and Memory of Resultative Events.

Sakarias M(1), Flecken M(1)(2).

Author information: (1)Neurobiology of Language Department, Max Planck Institute for Psycholinguistics. (2)Donders Institute for Brain, Cognition and Behavior, Radboud University Nijmegen.

We study how people attend to and memorize endings of events that differ in the degree to which objects in them are affected by an action: Resultative events show objects that undergo a visually salient change in state during the course of the event (peeling a potato), and non-resultative events involve objects that undergo no, or only partial state change (stirring in a pan). We investigate general cognitive principles, and potential language-specific influences, in verbal and nonverbal event encoding and memory, across two experiments with Dutch and Estonian participants. Estonian marks a viewer's perspective on an event's result obligatorily via grammatical case on direct object nouns: Objects undergoing a partial/full change in state in an event are marked with partitive/accusative case, respectively. Therefore, we hypothesized increased saliency of object states and event results in Estonian speakers, as compared to speakers of Dutch. Findings show (a) a general cognitive principle of attending carefully to endings of resultative events, implying cognitive saliency of object states in event processing; (b) a language-specific boost on attention and memory of event results under verbal task demands in Estonian speakers. Results are discussed in relation to theories of event cognition, linguistic relativity, and thinking for speaking.

DOI: 10.1111/cogs.12708 PMID: 30648801 [Indexed for MEDLINE]

88. Nature. 2018 Jul;559(7712):73-76. doi: 10.1038/s41586-018-0265-1. Epub 2018 Jul 4.

Universality of free fall from the orbital motion of a pulsar in a stellar triple system.

Archibald AM(1)(2), Gusinskaia NV(3), Hessels JWT(3)(4), Deller AT(5)(6), Kaplan DL(7), Lorimer DR(8)(9), Lynch RS(9)(10), Ransom SM(11), Stairs IH(12).

Author information: (1)Anton Pannekoek Institute for Astronomy, University of Amsterdam, Amsterdam, The Netherlands. archibald@astron.nl. (2)Netherlands Institute for Radio Astronomy (ASTRON), Dwingeloo, The Netherlands. archibald@astron.nl. (3)Anton Pannekoek Institute for Astronomy, University of Amsterdam, Amsterdam, The Netherlands. (4)Netherlands Institute for Radio Astronomy (ASTRON), Dwingeloo, The Netherlands. (5)Centre for Astrophysics and Supercomputing, Swinburne University of Technology, Hawthorn, Victoria, Australia. (6)The Australian Research Council Centre of Excellence for Gravitational Wave Discovery (OzGrav), Hawthorn, Victoria, Australia. (7)Department of Physics, University of Wisconsin-Milwaukee, Milwaukee, WI, USA. (8)Department of Physics and Astronomy, West Virginia University, Morgantown, WV, USA. (9)Center for Gravitational Waves and Cosmology, Morgantown, WV, USA. (10)Green Bank Observatory, Green Bank, WV, USA. (11)National Radio Astronomy Observatory, Charlottesville, VA, USA. (12)Department of Physics and Astronomy, University of British Columbia, Vancouver, British Columbia, Canada.

Comment in Nature. 2018 Jul;559(7712):40-41.

Einstein's theory of gravity-the general theory of relativity1-is based on the universality of free fall, which specifies that all objects accelerate identically in an external gravitational field. In contrast to almost all alternative theories of gravity2, the strong equivalence principle of general relativity requires universality of free fall to apply even to bodies with strong self-gravity. Direct tests of this principle using Solar System bodies3,4 are limited by the weak self-gravity of the bodies, and tests using pulsar-white-dwarf binaries5,6 have been limited by the weak gravitational pull of the Milky Way. PSR J0337+1715 is a hierarchical system of three stars (a stellar triple system) in which a binary consisting of a millisecond radio pulsar and a white dwarf in a 1.6-day orbit is itself in a 327-day orbit with another white dwarf. This system permits a test that compares how the gravitational pull of the outer white dwarf affects the pulsar, which has strong self-gravity, and the inner white dwarf. Here we report that the accelerations of the pulsar and its nearby white-dwarf companion differ fractionally by no more than 2.6 × 10-6. For a rough comparison, our limit on the strong-field Nordtvedt parameter, which measures violation of the universality of free fall, is a factor of ten smaller than that obtained from (weak-field) Solar System tests3,4 and a factor of almost a thousand smaller than that obtained from other strong-field tests5,6.

DOI: 10.1038/s41586-018-0265-1 PMID: 29973733

89. Phys Rev Lett. 2011 Jun 24;106(25):251103. doi: 10.1103/PhysRevLett.106.251103. Epub 2011 Jun 24.

Pure connection action principle for general relativity.

Krasnov K(1).

Author information: (1)School of Mathematical Sciences, University of Nottingham, Nottingham NG7 2RD, United Kingdom.

It has already been known for two decades that general relativity can be reformulated as a certain gauge theory, so that the only dynamical field is an SO(3) connection and the spacetime metric appears as a derived object. However, no simple action principle realizing these ideas has been available. A new elegant action principle for such a "pure connection" formulation of GR is described.

DOI: 10.1103/PhysRevLett.106.251103 PMID: 21770626

90. Science. 2018 Sep 14;361(6407):1101-1104. doi: 10.1126/science.aat9042.

Quantum entanglement of the spin and orbital angular momentum of photons using metamaterials.

Stav T(1), Faerman A(2), Maguid E(2), Oren D(1), Kleiner V(2), Hasman E(3), Segev M(4).

Author information: (1)Physics Department and Solid State Institute, Technion, Haifa 32000, Israel. (2)Micro and Nanooptics Laboratory, Faculty of Mechanical Engineering, and Russell Berrie Nanotechnology Institute, Technion, Haifa 32000, Israel. (3)Micro and Nanooptics Laboratory, Faculty of Mechanical Engineering, and Russell Berrie Nanotechnology Institute, Technion, Haifa 32000, Israel. mehasman@technion.ac.il msegev@technion.ac.il. (4)Physics Department and Solid State Institute, Technion, Haifa 32000, Israel. mehasman@technion.ac.il msegev@technion.ac.il.

Metamaterials constructed from deep subwavelength building blocks have been used to demonstrate phenomena ranging from negative refractive index and ε-near-zero to cloaking, emulations of general relativity, and superresolution imaging. More recently, metamaterials have been suggested as a new platform for quantum optics. We present the use of a dielectric metasurface to generate entanglement between the spin and orbital angular momentum of photons. We demonstrate the generation of the four Bell states on a single photon by using the geometric phase that arises from the photonic spin-orbit interaction and subsequently show nonlocal correlations between two photons that interacted with the metasurface. Our results show that metamaterials are suitable for the generation and manipulation of entangled photon states, introducing the area of quantum optics metamaterials.

DOI: 10.1126/science.aat9042 PMID: 30213909

91. Sci Rep. 2019 Nov 4;9(1):15881. doi: 10.1038/s41598-019-52183-9.

Satellite Laser-Ranging as a Probe of Fundamental Physics.

Ciufolini I(1), Matzner R(2), Paolozzi A(3), Pavlis EC(4), Sindoni G(3), Ries J(5), Gurzadyan V(6), Koenig R(7).

Author information: (1)Dip. Ingegneria dell'Innovazione, Università del Salento, Lecce, and Centro Fermi, Rome, Italy. (2)Theory Center, University of Texas at Austin, Austin, USA. richard.matzner@sbcglobal.net. (3)Scuola di Ingegneria Aerospaziale, Sapienza Università di Roma, Roma, Italy. (4)Joint Center for Earth Systems Technology (JCET), University of Maryland, Baltimore County, USA. (5)Center for Space Research, University of Texas at Austin, Austin, USA. (6)Center for Cosmology and Astrophysics, Alikhanian National Laboratory and Yerevan State University, Yerevan, Armenia. (7)Helmholtz Centre Potsdam German Research Centre for Geosciences - GFZ, Potsdam, Germany.

Satellite laser-ranging is successfully used in space geodesy, geodynamics and Earth sciences; and to test fundamental physics and specific features of General Relativity. We present a confirmation to approximately one part in a billion of the fundamental weak equivalence principle ("uniqueness of free fall") in the Earth's gravitational field, obtained with three laser-ranged satellites, at previously untested range and with previously untested materials. The weak equivalence principle is at the foundation of General Relativity and of most gravitational theories.

DOI: 10.1038/s41598-019-52183-9 PMCID: PMC6828690 PMID: 31685911

Conflict of interest statement: The authors declare no competing interests.

92. Phys Rev Lett. 2009 Dec 11;103(24):241301. doi: 10.1103/PhysRevLett.103.241301. Epub 2009 Dec 8.

Cosmological tests of general relativity with future tomographic surveys.

Zhao GB(1), Pogosian L, Silvestri A, Zylberberg J.

Author information: (1)Department of Physics, Simon Fraser University, Burnaby, British Columbia, V5A 1S6, Canada.

Future weak lensing surveys will map the evolution of matter perturbations and gravitational potentials, yielding a new test of general relativity on cosmic scales. They will probe the relations between matter overdensities, local curvature, and the Newtonian potential. These relations can be modified in alternative gravity theories or by the effects of massive neutrinos or exotic dark energy fluids. We introduce two functions of time and scale which account for any such modifications in the linear regime. We use a principal component analysis to find the eigenmodes of these functions that cosmological data will constrain. The number of constrained modes gives a model-independent forecast of how many parameters describing deviations from general relativity could be constrained, along with w(z). The modes' scale and time dependence tell us which theoretical models will be better tested.

DOI: 10.1103/PhysRevLett.103.241301 PMID: 20366194

93. Rep Prog Phys. 2018 Mar;81(3):036001. doi: 10.1088/1361-6633/aaa4ab.

Higher-order theories of gravity: diagnosis, extraction and reformulation via non-metric extra degrees of freedom-a review.

Belenchia A(1), Letizia M, Liberati S, Di Casola E.

Author information: (1)Institute for Quantum Optics and Quantum Information (IQOQI), Boltzmanngasse 3 1090 Vienna, Austria.

Modifications of Einstein's theory of gravitation have been extensively considered in the past years, in connection to both cosmology and quantum gravity. Higher-curvature and higher-derivative gravity theories constitute the main examples of such modifications. These theories exhibit, in general, more degrees of freedom than those found in standard general relativity; counting, identifying, and retrieving the description/representation of such dynamical variables is currently an open problem, and a decidedly nontrivial one. In this work we review, via both formal arguments and custom-made examples, the most relevant methods to unveil the gravitational degrees of freedom of a given model, discussing the merits, subtleties and pitfalls of the various approaches.

DOI: 10.1088/1361-6633/aaa4ab PMID: 29293086

94. Phys Rev Lett. 2012 May 11;108(19):191101. doi: 10.1103/PhysRevLett.108.191101. Epub 2012 May 8.

Generating matter inhomogeneities in general relativity.

Coley AA(1), Lim WC.

Author information: (1)Department of Mathematics & Statistics, Dalhousie University, Halifax, Nova Scotia, Canada B3H 3J5. aac@mathstat.dal.ca

In this Letter we discuss a natural general relativistic mechanism that causes inhomogeneities and hence generates matter perturbations in the early Universe. We concentrate on spikes, both incomplete spikes and recurring spikes, that naturally occur in the initial oscillatory regime of general cosmological models. In particular, we explicitly show that spikes occurring in a class of G2 models lead to inhomogeneities that, due to gravitational instability, leave small residual imprints on matter in the form of matter perturbations. The residual matter overdensities from recurring spikes are not local but form on surfaces. We discuss the potential physical consequences of the residual matter imprints and their possible effect on the subsequent formation of large-scale structure.

DOI: 10.1103/PhysRevLett.108.191101 PMID: 23003021

95. Living Rev Relativ. 2004;7(1):1. doi: 10.12942/lrr-2004-1. Epub 2004 Feb 2.

Conformal Infinity.

Frauendiener J(1).

Author information: (1)Institut für Theoretische Astrophysik, Universität Tübingen, Auf der Morgenstelle 10, D-72076 Tübingen, Germany.

The notion of conformal infinity has a long history within the research in Einstein's theory of gravity. Today, "conformal infinity" is related to almost all other branches of research in general relativity, from quantisation procedures to abstract mathematical issues to numerical applications. This review article attempts to show how this concept gradually and inevitably evolved from physical issues, namely the need to understand gravitational radiation and isolated systems within the theory of gravitation, and how it lends itself very naturally to the solution of radiation problems in numerical relativity. The fundamental concept of null-infinity is introduced. Friedrich's regular conformal field equations are presented and various initial value problems for them are discussed. Finally, it is shown that the conformal field equations provide a very powerful method within numerical relativity to study global problems such as gravitational wave propagation and detection.

DOI: 10.12942/lrr-2004-1 PMCID: PMC5256109 PMID: 28179863

96. Phys Rev Lett. 2009 Nov 13;103(20):201102. doi: 10.1103/PhysRevLett.103.201102. Epub 2009 Nov 12.

Recovering general relativity from massive gravity.

Babichev E(1), Deffayet C, Ziour R.

Author information: (1)AstroParticule and Cosmologie, UMR 7164-CNRS, Université Denis Diderot-Paris 7, CEA, Observatoire de Paris, 10 rue Alice Domon et Léonie Duquet, F-75205 Paris Cedex 13, France.

We obtain static, spherically symmetric, and asymptotically flat numerical solutions of massive gravity with a source. Those solutions show, for the first time explicitly, a recovery of the Schwarzschild solution of general relativity via the so-called Vainshtein mechanism.

DOI: 10.1103/PhysRevLett.103.201102 PMID: 20365973

97. Proc Math Phys Eng Sci. 2015 May 8;471(2177):20140834. doi: 10.1098/rspa.2014.0834.

No regularity singularities exist at points of general relativistic shock wave interaction between shocks from different characteristic families.

Reintjes M(1), Temple B(2).

Author information: (1)IMPA-Instituto Nacional de Matemática Pura e Aplicada , Rio de Janeiro, Brazil. (2)Department of Mathematics , University of California , Davis, CA 95616, USA.

We give a constructive proof that coordinate transformations exist which raise the regularity of the gravitational metric tensor from C0,1 to C1,1 in a neighbourhood of points of shock wave collision in general relativity. The proof applies to collisions between shock waves coming from different characteristic families, in spherically symmetric spacetimes. Our result here implies that spacetime is locally inertial and corrects an error in our earlier Proc. R. Soc. A publication, which led us to the false conclusion that such coordinate transformations, which smooth the metric to C1,1, cannot exist. Thus, our result implies that regularity singularities (a type of mild singularity introduced in our Proc. R. Soc. A paper) do not exist at points of interacting shock waves from different families in spherically symmetric spacetimes. Our result generalizes Israel's celebrated 1966 paper to the case of such shock wave interactions but our proof strategy differs fundamentally from that used by Israel and is an extension of the strategy outlined in our original Proc. R. Soc. A publication. Whether regularity singularities exist in more complicated shock wave solutions of the Einstein-Euler equations remains open.

DOI: 10.1098/rspa.2014.0834 PMCID: PMC4984983 PMID: 27547092

98. J Genet. 2019 Jun;98(2):39.

Evolutionary dynamics models in biometrical genetics supports QTL × environment interactions.

Fattahi F(1), Fakheri BA.

Author information: (1)Faculty of Agriculture, Department of Plant Breeding and Biotechnology, University of Zabol, Sistan and Baluchestan 98615538, Iran. frs_fth@yahoo.com.

The process of development of quantitative trait locus (QTL) involves interactions between many factors, both environmental and genetic, in which many genes interact often in no additive pathways together and with environment. Integration of the mathematical, statistical and biological aspects of these subjects has made important and interesting results. In this review, mathematical methods offered to study the QTL × environment interactions. The topic is circumscribed, going from basic selection equations to models of evolution of QTLs. Discrete and continuous time mathematical models and subsequently, QTL modelling were introduced with and without environmental interactions. The mathematical models derived here showed that the gradients of mean fitness which have revealed in studies by many researchers had a basic role in mathematical genetics, evolutionary aspects of biometrical genetics and QTL analysis. QTL × environment interactions were studied mathematically including fitness components too. It was revealed that QTL × environment interactions in fitness could generate a balancing selection. Also, QTL analysis could be used to calculate the geometry of the phenotype landscape. In this paper, models applied in biometrical genetics corresponds to QTL analysis and matched with results from other researchers. The originality of this synthesis is the evolutionary modelling of QTL × environment interactions which can be used to investigate the extinction or stability of a population. Also to emphasize that although some scientific subjects like Brownian motion, quantum mechanics, general relativity, differential geometry, and evolutionarybiometrical genetics were apparently different subjects, but the mathematical models were the backbone of these branches of science. This implies that such matters in nature have probably common and elegant basis. The perspective of the subject of this paper in future will be a new and interesting branch of interdisciplinary science.

PMID: 31204724 [Indexed for MEDLINE]

99. Phys Rev Lett. 2003 Jan 17;90(2):021301. doi: 10.1103/PhysRevLett.90.021301. Epub 2003 Jan 15.

Canonical quantization of general relativity in discrete space-times.

Gambini R(1), Pullin J.

Author information: (1)Instituto de Física, Facultad de Ciencias, Universidad de la República, Iguá 4225, CP 11400 Montevideo, Uruguay.

It has long been recognized that lattice gauge theory formulations, when applied to general relativity, conflict with the invariance of the theory under diffeomorphisms. We analyze discrete lattice general relativity and develop a canonical formalism that allows one to treat constrained theories in Lorentzian signature space-times. The presence of the lattice introduces a "dynamical gauge" fixing that makes the quantization of the theories conceptually clear, albeit computationally involved. The problem of a consistent algebra of constraints is automatically solved in our approach. The approach works successfully in other field theories as well, including topological theories. A simple cosmological application exhibits quantum elimination of the singularity at the big bang.

DOI: 10.1103/PhysRevLett.90.021301 PMID: 12570532

100. Nature. 2018 Dec;564(7734):87-90. doi: 10.1038/s41586-018-0738-2. Epub 2018 Nov 28.

Atomic clock performance enabling geodesy below the centimetre level.

McGrew WF(1)(2), Zhang X(1)(3), Fasano RJ(1)(2), Schäffer SA(1)(4), Beloy K(1), Nicolodi D(1)(2), Brown RC(1)(5), Hinkley N(1)(2)(6), Milani G(1)(7)(8), Schioppo M(1)(9), Yoon TH(1)(10), Ludlow AD(11)(12).

Author information: (1)National Institute of Standards and Technology, Boulder, CO, USA. (2)Department of Physics, University of Colorado, Boulder, CO, USA. (3)State Key Laboratory of Advanced Optical Communication Systems and Networks, Institute of Quantum Electronics, School of Electronics Engineering and Computer Science, Peking University, Beijing, China. (4)Niels Bohr Institute, University of Copenhagen, Copenhagen, Denmark. (5)Georgia Tech Research Institute, Atlanta, GA, USA. (6)Stable Laser Systems, Boulder, CO, USA. (7)Istituto Nazionale di Ricerca Metrologica, Torino, Italy. (8)Politecnico di Torino, Torino, Italy. (9)National Physical Laboratory (NPL), Teddington, UK. (10)Department of Physics, Korea University, Seoul, South Korea. (11)National Institute of Standards and Technology, Boulder, CO, USA. andrew.ludlow@nist.gov. (12)Department of Physics, University of Colorado, Boulder, CO, USA. andrew.ludlow@nist.gov.

The passage of time is tracked by counting oscillations of a frequency reference, such as Earth's revolutions or swings of a pendulum. By referencing atomic transitions, frequency (and thus time) can be measured more precisely than any other physical quantity, with the current generation of optical atomic clocks reporting fractional performance below the 10-17 level1-5. However, the theory of relativity prescribes that the passage of time is not absolute, but is affected by an observer's reference frame. Consequently, clock measurements exhibit sensitivity to relative velocity, acceleration and gravity potential. Here we demonstrate local optical clock measurements that surpass the current ability to account for the gravitational distortion of space-time across the surface of Earth. In two independent ytterbium optical lattice clocks, we demonstrate unprecedented values of three fundamental benchmarks of clock performance. In units of the clock frequency, we report systematic uncertainty of 1.4 × 10-18, measurement instability of 3.2 × 10-19 and reproducibility characterized by ten blinded frequency comparisons, yielding a frequency difference of [-7 ± (5)stat ± (8)sys] × 10-19, where 'stat' and 'sys' indicate statistical and systematic uncertainty, respectively. Although sensitivity to differences in gravity potential could degrade the performance of the clocks as terrestrial standards of time, this same sensitivity can be used as a very sensitive probe of geopotential5-9. Near the surface of Earth, clock comparisons at the 1 × 10-18 level provide a resolution of one centimetre along the direction of gravity, so the performance of these clocks should enable geodesy beyond the state-of-the-art level. These optical clocks could further be used to explore geophysical phenomena10, detect gravitational waves11, test general relativity12 and search for dark matter13-17.

DOI: 10.1038/s41586-018-0738-2 PMID: 30487601

101. Phys Rev Lett. 2007 Mar 16;98(11):111102. doi: 10.1103/PhysRevLett.98.111102. Epub 2007 Mar 15.

Testing general relativity with atom interferometry.

Dimopoulos S(1), Graham PW, Hogan JM, Kasevich MA.

Author information: (1)Department of Physics, Stanford University, Stanford, California 94305, USA.

The unprecedented precision of atom interferometry will soon lead to laboratory tests of general relativity to levels that will rival or exceed those reached by astrophysical observations. We propose such an experiment that will initially test the equivalence principle to 1 part in 10(15) (300 times better than the current limit), and 1 part in 10(17) in the future. It will also probe general relativistic effects - such as the nonlinear three-graviton coupling, the gravity of an atom's kinetic energy, and the falling of light - to several decimals. In contrast with astrophysical observations, laboratory tests can isolate these effects via their different functional dependence on experimental variables.

DOI: 10.1103/PhysRevLett.98.111102 PMID: 17501039

102. Nature. 2018 Apr;556(7700):223-226. doi: 10.1038/s41586-018-0019-0. Epub 2018 Apr 11.

Experimentally generated randomness certified by the impossibility of superluminal signals.

Bierhorst P(1)(2), Knill E(3)(4), Glancy S(3), Zhang Y(3)(5), Mink A(6)(7), Jordan S(6), Rommal A(8), Liu YK(6), Christensen B(9), Nam SW(3), Stevens MJ(3), Shalm LK(3)(10).

Author information: (1)National Institute of Standards and Technology, Boulder, CO, USA. peter.bierhorst@nist.gov. (2)Department of Physics, University of Colorado, Boulder, CO, USA. peter.bierhorst@nist.gov. (3)National Institute of Standards and Technology, Boulder, CO, USA. (4)Center for Theory of Quantum Matter, University of Colorado, Boulder, CO, USA. (5)NTT Basic Research Laboratories and NTT Research Center for Theoretical Quantum Physics, NTT Corporation, Atsugi, Japan. (6)National Institute of Standards and Technology, Gaithersburg, MD, USA. (7)Theiss Research, La Jolla, CA, USA. (8)Muhlenberg College, Allentown, PA, USA. (9)Department of Physics, University of Wisconsin, Madison, WI, USA. (10)Department of Physics, University of Colorado, Boulder, CO, USA.

Comment in Nature. 2018 Apr;556(7700):176-177.

From dice to modern electronic circuits, there have been many attempts to build better devices to generate random numbers. Randomness is fundamental to security and cryptographic systems and to safeguarding privacy. A key challenge with random-number generators is that it is hard to ensure that their outputs are unpredictable1-3. For a random-number generator based on a physical process, such as a noisy classical system or an elementary quantum measurement, a detailed model that describes the underlying physics is necessary to assert unpredictability. Imperfections in the model compromise the integrity of the device. However, it is possible to exploit the phenomenon of quantum non-locality with a loophole-free Bell test to build a random-number generator that can produce output that is unpredictable to any adversary that is limited only by general physical principles, such as special relativity1-11. With recent technological developments, it is now possible to carry out such a loophole-free Bell test12-14,22. Here we present certified randomness obtained from a photonic Bell experiment and extract 1,024 random bits that are uniformly distributed to within 10-12. These random bits could not have been predicted according to any physical theory that prohibits faster-than-light (superluminal) signalling and that allows independent measurement choices. To certify and quantify the randomness, we describe a protocol that is optimized for devices that are characterized by a low per-trial violation of Bell inequalities. Future random-number generators based on loophole-free Bell tests may have a role in increasing the security and trust of our cryptographic systems and infrastructure.

DOI: 10.1038/s41586-018-0019-0 PMID: 29643486

103. Rep Prog Phys. 2017 Dec;80(12):126901. doi: 10.1088/1361-6633/aa7e14.

Black holes in loop quantum gravity.

Perez A(1).

Author information: (1)Centre de Physique Théorique, Aix Marseille Universit, Universit de Toulon, CNRS, UMR 7332, 13288 Marseille, France.

This is a review of results on black hole physics in the context of loop quantum gravity. The key feature underlying these results is the discreteness of geometric quantities at the Planck scale predicted by this approach to quantum gravity. Quantum discreteness follows directly from the canonical quantization prescription when applied to the action of general relativity that is suitable for the coupling of gravity with gauge fields, and especially with fermions. Planckian discreteness and causal considerations provide the basic structure for the understanding of the thermal properties of black holes close to equilibrium. Discreteness also provides a fresh new look at more (at the moment) speculative issues, such as those concerning the fate of information in black hole evaporation. The hypothesis of discreteness leads, also, to interesting phenomenology with possible observational consequences. The theory of loop quantum gravity is a developing program; this review reports its achievements and open questions in a pedagogical manner, with an emphasis on quantum aspects of black hole physics.

DOI: 10.1088/1361-6633/aa7e14 PMID: 28696338

104. Phys Rev Lett. 2019 Jul 26;123(4):041102. doi: 10.1103/PhysRevLett.123.041102.

Black-Hole Remnants from Black-Hole-Neutron-Star Mergers.

Zappa F(1), Bernuzzi S(1), Pannarale F(2)(3), Mapelli M(4)(5)(6)(7), Giacobbo N(4)(5)(6).

Author information: (1)Theoretisch-Physikalisches Institut, Friedrich-Schiller-Universität Jena, 07743 Jena, Germany. (2)Dipartimento di Fisica, Università di Roma "Sapienza", Piazzale A. Moro 5, I-00185 Roma, Italy. (3)INFN Sezione di Roma, Piazzale A. Moro 5, I-00185 Roma, Italy. (4)Physics and Astronomy Department Galileo Galilei, University of Padova, Vicolo dell'Osservatorio 3, I-35122 Padova, Italy. (5)INAF-Osservatorio Astronomico di Padova, Vicolo dell'Osservatorio 5, I-35122 Padova, Italy. (6)INFN-Padova, Via Marzolo 8, I-35131 Padova, Italy. (7)Institut für Astro- und Teilchenphysik, Universität Innsbruck, Technikerstrasse 25/8, A-6020 Innsbruck, Austria.

Observations of gravitational waves and their electromagnetic counterparts may soon uncover the existence of coalescing compact binary systems formed by a stellar-mass black hole and a neutron star. These mergers result in a remnant black hole, possibly surrounded by an accretion disk. The mass and spin of the remnant black hole depend on the properties of the coalescing binary. We construct a map from the binary components to the remnant black hole using a sample of numerical-relativity simulations of different mass ratios q, (anti)aligned dimensionless spins of the black hole a_{BH}, and several neutron star equations of state. Given the binary total mass, the mass and spin of the remnant black hole can therefore be determined from the three parameters (q,a_{BH},Λ), where Λ is the tidal deformability of the neutron star. Our models also incorporate the binary black hole and test-mass limit cases and we discuss a simple extension for generic black-hole spins. We combine the remnant characterization with recent population synthesis simulations for various metallicities of the progenitor stars that generated the binary system. We predict that black-hole-neutron-star mergers produce a population of remnant black holes with masses distributed around 7 M_{⊙} and 9 M_{⊙}. For isotropic spin distributions, nonmassive accretion disks are favored: no bright electromagnetic counterparts are expected in such mergers.

DOI: 10.1103/PhysRevLett.123.041102 PMID: 31491270

105. Living Rev Relativ. 2005;8(1):12. doi: 10.12942/lrr-2005-12. Epub 2005 Dec 16.

Analogue Gravity.

Barceló C(1), Liberati S(2), Visser M(3).

Author information: (1)Instituto de Astrofísica de Andalucía (CSIC), Camino Bajo de Huetor 50, 18008 Granada, Spain. (2)International School for Advanced Studies and INFN, Via Beirut 2-4, 34014 Trieste, Italy. (3)School of Mathematics, Statistics, and Computer Science, Victoria University of Wellington, PO Box 600, Wellington, New Zealand.

Analogue models of (and for) gravity have a long and distinguished history dating back to the earliest years of general relativity. In this review article we will discuss the history, aims, results, and future prospects for the various analogue models. We start the discussion by presenting a particularly simple example of an analogue model, before exploring the rich history and complex tapestry of models discussed in the literature. The last decade in particular has seen a remarkable and sustained development of analogue gravity ideas, leading to some hundreds of published articles, a workshop, two books, and this review article. Future prospects for the analogue gravity programme also look promising, both on the experimental front (where technology is rapidly advancing) and on the theoretical front (where variants of analogue models can be used as a springboard for radical attacks on the problem of quantum gravity).

DOI: 10.12942/lrr-2005-12 PMCID: PMC5255570 PMID: 28179871

106. Gegenbaurs Morphol Jahrb. 1987;133(2):227-47.

[Bioenergetics].

[Article in German]

Fischer G.

As introduced previously, the information field can serve as a base for inferences in terms of dynamics but also of relativity, with the latter being discussed regarding the possibility of transformation between information and energy (and mass as well). An energy equivalent of information is obtained: b, a new constant of nature, patterned after the mechanical equivalent of heat. Some approaches to the calculation of b are considered. Proceeding from the laws of transformation, a more general rule of information conservation is obtained, which may also be written as an equation of matter. The transformations can be presented also by geometrical means. In the m-W-I model space, all biological processes seem to be functions of time. By letting time be x4 = ict with a view to the spatial coordinates of the model space, the Minkowski space is shown to apply to biology too, where it seems to have implications similar to those it has in physics. In 2 tables, a systematic listing of origins and results of biodynamics and bioenergetics (biorelativity) is given.

PMID: 3305140 [Indexed for MEDLINE]

107. Chirality. 2015 Jun;27(6):375-81. doi: 10.1002/chir.22439. Epub 2015 Apr 28.

Chirality and gravitational parity violation.

Bargueño P(1).

Author information: (1)Departamento de Física, Universidad de los Andes, Apartado Aéreo, Bogotá, Distrito Capital, Colombia.

In this review, parity-violating gravitational potentials are presented as possible sources of both true and false chirality. In particular, whereas phenomenological long-range spin-dependent gravitational potentials contain both truly and falsely chiral terms, it is shown that there are models that extend general relativity including also coupling of fermionic degrees of freedom to gravity in the presence of torsion, which give place to short-range truly chiral interactions similar to that usually considered in molecular physics. Physical mechanisms which give place to gravitational parity violation together with the expected size of the effects and their experimental constraints are discussed. Finally, the possible role of parity-violating gravity in the origin of homochirality and a road map for future research works in quantum chemistry is presented.

DOI: 10.1002/chir.22439 PMID: 25919812 [Indexed for MEDLINE]

108. Living Rev Relativ. 2014;17(1):2. doi: 10.12942/lrr-2014-2. Epub 2014 Feb 13.

Gravitational Radiation from Post-Newtonian Sources and Inspiralling Compact Binaries.

Blanchet L(1).

Author information: (1)Institut d'Astrophysique de Paris, 98bis Boulevard Arago, 75014 Paris, France.

To be observed and analyzed by the network of gravitational wave detectors on ground (LIGO, VIRGO, etc.) and by the future detectors in space (eLISA, etc.), inspiralling compact binaries - binary star systems composed of neutron stars and/or black holes in their late stage of evolution - require high-accuracy templates predicted by general relativity theory. The gravitational waves emitted by these very relativistic systems can be accurately modelled using a high-order post-Newtonian gravitational wave generation formalism. In this article, we present the current state of the art on post-Newtonian methods as applied to the dynamics and gravitational radiation of general matter sources (including the radiation reaction back onto the source) and inspiralling compact binaries. We describe the post-Newtonian equations of motion of compact binaries and the associated Lagrangian and Hamiltonian formalisms, paying attention to the self-field regularizations at work in the calculations. Several notions of innermost circular orbits are discussed. We estimate the accuracy of the post-Newtonian approximation and make a comparison with numerical computations of the gravitational self-force for compact binaries in the small mass ratio limit. The gravitational waveform and energy flux are obtained to high post-Newtonian order and the binary's orbital phase evolution is deduced from an energy balance argument. Some landmark results are given in the case of eccentric compact binaries - moving on quasi-elliptical orbits with non-negligible eccentricity. The spins of the two black holes play an important role in the definition of the gravitational wave templates. We investigate their imprint on the equations of motion and gravitational wave phasing up to high post-Newtonian order (restricting to spin-orbit effects which are linear in spins), and analyze the post-Newtonian spin precession equations as well as the induced precession of the orbital plane.

DOI: 10.12942/lrr-2014-2 PMCID: PMC5256563 PMID: 28179846

109. Phys Rev Lett. 2019 Oct 18;123(16):161101. doi: 10.1103/PhysRevLett.123.161101.

Learning about Black Hole Binaries from their Ringdown Spectra.

Hughes SA(1), Apte A(1), Khanna G(2), Lim H(1).

Author information: (1)Department of Physics and MIT Kavli Institute, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA. (2)Department of Physics, University of Massachusetts, Dartmouth, Massachusetts 02747, USA.

The coalescence of two black holes generates gravitational waves that carry detailed information about the properties of those black holes and their binary configuration. The final coalescence cycles are in the form of a ringdown: a superposition of quasinormal modes of the merged remnant black hole. Each mode has an oscillation frequency and decay time that in general relativity is determined by the remnant's mass and spin. Measuring the frequency and decay time of multiple modes makes it possible to measure the remnant's mass and spin, and to test the waves against the predictions of gravity theories. In this Letter, we show that the relative amplitudes of these modes encode information about a binary's geometry. Focusing on the large mass-ratio limit, which provides a simple-to-use tool for effectively exploring parameter space, we demonstrate how a binary's geometry is encoded in the relative amplitudes of these modes, and how to parametrize the modes in this limit. Although more work is needed to assess how well this carries over to less extreme mass ratios, our results indicate that measuring multiple ringdown modes from coalescence may aid in measuring important source properties, such as the misalignment of its members' spins and orbit.

DOI: 10.1103/PhysRevLett.123.161101 PMID: 31702329

110. Living Rev Relativ. 2004;7(1):10. doi: 10.12942/lrr-2004-10. Epub 2004 Dec 15.

Isolated and Dynamical Horizons and Their Applications.

Ashtekar A(1), Krishnan B(2).

Author information: (1)Institute for Gravitational Physics and Geometry, Pennsylvania State University, University Park, PA 16801 USA ; Kavli Institute of Theoretical Physics, University of California, Santa Barbara, CA 93106-4030 USA ; Max-Planck-Institut für Gravitationsphysik, Albert-Einstein-Institut, Am Mühlenberg 1, 14476 Golm, Germany ; Erwin-Schrödinger-Institut, Boltzmanngasse 9, 1090 Vienna, Austria. (2)Max-Planck-Institut für Gravitationsphysik, Albert-Einstein-Institut, Am Mühlenberg 1, 14476 Golm, Germany ; Erwin-Schrödinger-Institut, Boltzmanngasse 9, 1090 Vienna, Austria.

Over the past three decades, black holes have played an important role in quantum gravity, mathematical physics, numerical relativity and gravitational wave phenomenology. However, conceptual settings and mathematical models used to discuss them have varied considerably from one area to another. Over the last five years a new, quasi-local framework was introduced to analyze diverse facets of black holes in a unified manner. In this framework, evolving black holes are modelled by dynamical horizons and black holes in equilibrium by isolated horizons. We review basic properties of these horizons and summarize applications to mathematical physics, numerical relativity, and quantum gravity. This paradigm has led to significant generalizations of several results in black hole physics. Specifically, it has introduced a more physical setting for black hole thermodynamics and for black hole entropy calculations in quantum gravity, suggested a phenomenological model for hairy black holes, provided novel techniques to extract physics from numerical simulations, and led to new laws governing the dynamics of black holes in exact general relativity.

DOI: 10.12942/lrr-2004-10 PMCID: PMC5253930 PMID: 28163644

111. Phys Rev Lett. 2004 Aug 20;93(8):081103. doi: 10.1103/PhysRevLett.93.081103. Epub 2004 Aug 20.

Proposed new test of spin effects in general relativity.

O'Connell RF(1).

Author information: (1)Department of Physics and Astronomy, Louisiana State University, Baton Rouge, LA70803-4001, USA. rfoc@phys.lsu.edu

The recent discovery of a double-pulsar PSR J0737-3039A/B provides an opportunity of unequivocally observing, for the first time, spin effects in general relativity. Existing efforts involve detection of the precession of the spinning body itself. However, for a close binary system, spin effects on the orbit may also be discernible. Not only do they add to the advance of the periastron (by an amount which is small compared to the conventional contribution) but they also give rise to a precession of the orbit about the spin direction. The measurement of such an effect would also give information on the moment of inertia of pulsars.

DOI: 10.1103/PhysRevLett.93.081103 PMID: 15447169

112. Phys Rev Lett. 2007 May 18;98(20):201102. doi: 10.1103/PhysRevLett.98.201102. Epub 2007 May 17.

Choreographic solution to the general-relativistic three-body problem.

Imai T(1), Chiba T, Asada H.

Author information: (1)Faculty of Science and Technology, Hirosaki University, Hirosaki 036-8561, Japan.

We reexamine the three-body problem in the framework of general relativity. The Newtonian N-body problem admits choreographic solutions, where a solution is called choreographic if every massive particle moves periodically in a single closed orbit. One is a stable figure-eight orbit for a three-body system, which was found first by Moore (1993) and rediscovered with its existence proof by Chenciner and Montgomery (2000). In general relativity, however, the periastron shift prohibits a binary system from orbiting in a single closed curve. Therefore, it is unclear whether general-relativistic effects admit choreography such as the figure eight. We examine general-relativistic corrections to initial conditions so that an orbit for a three-body system can be choreographic and a figure eight. This illustration suggests that the general-relativistic N-body problem also may admit a certain class of choreographic solutions.

DOI: 10.1103/PhysRevLett.98.201102 PMID: 17677685

113. Proc Natl Acad Sci U S A. 2017 Mar 21;114(12):3017-3025. doi: 10.1073/pnas.1612908114. Epub 2017 Mar 10.

LIGO and the opening of a unique observational window on the universe.

Kalogera V(1), Lazzarini A(2).

Author information: (1)Center for Interdisciplinary Exploration & Research in Astrophysics and Department of Physics & Astronomy, Northwestern University, Evanston, IL 60208-3112. (2)Laser Interferometer Gravitational-Wave Observatory Laboratory, California Institute of Technology, Pasadena, CA 91125-0001 lazz@ligo.caltech.edu.

A unique window on the universe opened on September 14, 2015, with direct detection of gravitational waves by the Advanced Laser Interferometer Gravitational-Wave Observatory (LIGO) detectors. This event culminated a half-century effort around the globe to develop terrestrial detectors of adequate sensitivity to achieve this goal. It also happened appropriately only a few months before the centennial of Einstein's final paper introducing the general theory of relativity. This detection provided the surprising discovery of a coalescing pair of "heavy" black holes (more massive than [Formula: see text] M[Formula: see text]) leading to the formation of a spinning [Formula: see text]62 solar mass black hole. One more binary black-hole detection and a significant candidate event demonstrated that a population of such merging binaries is formed in nature with a broad mass spectrum. This unique observational sample has already provided concrete measurements on the coalescence rates and has allowed us to test the theory of general relativity in the strong-field regime. As this nascent field of gravitational-wave astrophysics is emerging we are looking forward to the detection of binary mergers involving neutron stars and their electromagnetic counterparts, as well as continuous-wave sources, supernovae, a stochastic confusion background of compact-object mergers, known sources detected in unexpected ways, and completely unknown sources.

DOI: 10.1073/pnas.1612908114 PMCID: PMC5373410 PMID: 28283663

Conflict of interest statement: The authors declare no conflict of interest.

114. Nature. 2004 Oct 21;431(7011):958-60. doi: 10.1038/nature03007.

A confirmation of the general relativistic prediction of the Lense-Thirring effect.

Ciufolini I(1), Pavlis EC.

Author information: (1)Dipartimento di Ingegneria dell'Innovazione, Università di Lecce and INFN Sezione di Lecce, Via Monteroni, 73100 Lecce, Italy. ignazio.ciufolini@unile.it

Comment in Nature. 2004 Oct 21;431(7011):918-9.

An important early prediction of Einstein's general relativity was the advance of the perihelion of Mercury's orbit, whose measurement provided one of the classical tests of Einstein's theory. The advance of the orbital point-of-closest-approach also applies to a binary pulsar system and to an Earth-orbiting satellite. General relativity also predicts that the rotation of a body like Earth will drag the local inertial frames of reference around it, which will affect the orbit of a satellite. This Lense-Thirring effect has hitherto not been detected with high accuracy, but its detection with an error of about 1 per cent is the main goal of Gravity Probe B--an ongoing space mission using orbiting gyroscopes. Here we report a measurement of the Lense-Thirring effect on two Earth satellites: it is 99 +/- 5 per cent of the value predicted by general relativity; the uncertainty of this measurement includes all known random and systematic errors, but we allow for a total +/- 10 per cent uncertainty to include underestimated and unknown sources of error.

DOI: 10.1038/nature03007 PMID: 15496915

115. J Am Psychoanal Assoc. 1989;37(4):1071-96. doi: 10.1177/000306518903700410.

Ego analysis and the relativity of defense: technical implications of the structural theory.

Apfelbaum B(1), Gill MM.

Author information: (1)Department of Psychiatry, University of Illinois Medical Center, Chicago 60612.

We suggest that it is recognition of the relativity of defense, of the fact that the same content can be either defense or wish, rather than recognition of unconscious defense, that distinguishes the structural from the topographic theory. The structural theory did not simply add to the topographic theory the recognition that defense can be unconscious; it represents a radical shift in the concept of defense and of the relation between defense and wish. Accordingly, ego analysis, as the technical approach generated by the structural theory, is not complementary or preliminary to id analysis, the technical approach generated by the topographic theory. We attempt to demonstrate that the two theories represent antagonistic paradigms, both theoretically and technically. We suggest that "defense before drive," the structural formula for interpretation, made ego syntonicity a crucial determinant in formulating interpretations, and assumed the relativity of defense. Accordingly, the structural revision made possible an equidistant position between defense and wish, reducing reliance on suggestion and establishing interpretive neutrality, which we distinguish from behavioral neutrality.

DOI: 10.1177/000306518903700410 PMID: 2698897 [Indexed for MEDLINE]

116. Proc Math Phys Eng Sci. 2017 Dec;473(2208):20170596. doi: 10.1098/rspa.2017.0596. Epub 2017 Dec 6.

The complex and quaternionic quantum bit from relativity of simultaneity on an interferometer.

Garner AJP(1)(2), Müller MP(3)(4)(5)(6), Dahlsten OCO(2)(7)(8).

Author information: (1)Centre for Quantum Technologies, National University of Singapore, 3 Science Drive 2, 117543 Singapore. (2)Atomic and Laser Physics, Clarendon Laboratory, University of Oxford, Parks Road, Oxford OX1 3PU, UK. (3)Institute for Quantum Optics and Quantum Information, Austrian Academy of Sciences, Boltzmanngasse 3, 1090 Vienna, Austria. (4)Perimeter Institute for Theoretical Physics, Waterloo, Ontario, Canada N2L 2Y5. (5)Department of Applied Mathematics, University of Western Ontario, London, Ontario, Canada N6A 5BY. (6)Department of Philosophy, University of Western Ontario, London, Ontario, Canada N6A 5BY. (7)Physics Department, Southern University of Science and Technology, Xueyuan Boulevard, Nanshan District, Shenzhen, China. (8)London Institute for Mathematical Sciences, 35a South Street, Mayfair, London W1K 2XF, UK.

The patterns of fringes produced by an interferometer have long been important testbeds for our best contemporary theories of physics. Historically, interference has been used to contrast quantum mechanics with classical physics, but recently experiments have been performed that test quantum theory against even more exotic alternatives. A physically motivated family of theories are those where the state space of a two-level system is given by a sphere of arbitrary dimension. This includes classical bits, and real, complex and quaternionic quantum theory. In this paper, we consider relativity of simultaneity (i.e. that observers may disagree about the order of events at different locations) as applied to a two-armed interferometer, and show that this forbids most interference phenomena more complicated than those of complex quantum theory. If interference must depend on some relational property of the setting (such as path difference), then relativity of simultaneity will limit state spaces to standard complex quantum theory, or a subspace thereof. If this relational assumption is relaxed, we find one additional theory compatible with relativity of simultaneity: quaternionic quantum theory. Our results have consequences for current laboratory interference experiments: they have to be designed carefully to avoid rendering beyond-quantum effects invisible by relativity of simultaneity.

DOI: 10.1098/rspa.2017.0596 PMCID: PMC5746585 PMID: 29290735

Conflict of interest statement: We have no competing interests.

117. Living Rev Relativ. 2012;15(1):8. doi: 10.12942/lrr-2012-8. Epub 2012 Jul 4.

Binary Neutron Star Mergers.

Faber JA(1), Rasio FA(2).

Author information: (1)Center for Computational Relativity and Gravitation and School of Mathematical Sciences, Rochester Institute of Technology, 85 Lomb Memorial Drive, Rochester, NY 14623 USA. (2)Center for Interdisciplinary Exploration and Research in Astrophysics, and Department of Physics & Astronomy, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208 USA.

We review the current status of studies of the coalescence of binary neutron star systems. We begin with a discussion of the formation channels of merging binaries and we discuss the most recent theoretical predictions for merger rates. Next, we turn to the quasi-equilibrium formalisms that are used to study binaries prior to the merger phase and to generate initial data for fully dynamical simulations. The quasi-equilibrium approximation has played a key role in developing our understanding of the physics of binary coalescence and, in particular, of the orbital instability processes that can drive binaries to merger at the end of their lifetimes. We then turn to the numerical techniques used in dynamical simulations, including relativistic formalisms, (magneto-)hydrodynamics, gravitational-wave extraction techniques, and nuclear microphysics treatments. This is followed by a summary of the simulations performed across the field to date, including the most recent results from both fully relativistic and microphysically detailed simulations. Finally, we discuss the likely directions for the field as we transition from the first to the second generation of gravitational-wave interferometers and while supercomputers reach the petascale frontier.

DOI: 10.12942/lrr-2012-8 PMCID: PMC5255524 PMID: 28163622

118. Isis. 2004 Dec;95(4):640-8. doi: 10.1086/430654.

The relativity revolution from the perspective of historical epistemology.

Renn J(1).

Author information: (1)Max Planck Institute for the History of Science, Wilhelmstr. 44, 10117 Berlin, Germany.

This essay analyzes Einstein's relativity revolution as part of a long-term development of knowledge in which the knowledge system of classical physics was reorganized in a process of reflection, described here as a "Copernican process." This process led in 1905 to the introduction of fundamentally new concepts of space, time, matter, and radiation. On the basis of an extensive historical reconstruction, the heuristics of Einstein's creation of the general theory of relativity, completing the relativity revolution, is interpreted as a further transformation of the knowledge of classical physics, starting from conceiving gravitation as a borderline problem between field theory and mechanics. The essay thus provides an answer to the puzzle of how Einstein was able to create a theory capable of accounting for a wide range of phenomena that were discovered only much later.

DOI: 10.1086/430654 PMID: 16011299 [Indexed for MEDLINE]

119. Living Rev Relativ. 2015;18(1):1. doi: 10.1007/lrr-2015-1. Epub 2015 Sep 21.

Exploring New Physics Frontiers Through Numerical Relativity.

Cardoso V(1), Gualtieri L(2), Herdeiro C(3), Sperhake U(4).

Author information: (1)CENTRA, Departamento de Física, Instituto Superior Técnico, Universidade de Lisboa, Avenida Rovisco Pais 1, 1049 Lisboa, Portugal ; Perimeter Institute for Theoretical Physics, Waterloo, Ontario N2L 2Y5 Canada. (2)Dipartimento di Fisica, Università di Roma "La Sapienza" & Sezione INFN Roma1, P.A. Moro 5, 00185 Roma, Italy. (3)Departamento de Física da Universidade de Aveiro and CIDMA, Campus de Santiago, 3810-183 Aveiro, Portugal. (4)DAMTP, Centre for Mathematical Sciences, University of Cambridge, Wilberforce Road, Cambridge, CB3 0WA UK.

The demand to obtain answers to highly complex problems within strong-field gravity has been met with significant progress in the numerical solution of Einstein's equations - along with some spectacular results - in various setups. We review techniques for solving Einstein's equations in generic spacetimes, focusing on fully nonlinear evolutions but also on how to benchmark those results with perturbative approaches. The results address problems in high-energy physics, holography, mathematical physics, fundamental physics, astrophysics and cosmology.

DOI: 10.1007/lrr-2015-1 PMCID: PMC5255938 PMID: 28179851

120. Phys Rev Lett. 2004 Nov 19;93(21):211101. doi: 10.1103/PhysRevLett.93.211101. Epub 2004 Nov 15.

Minimum length from quantum mechanics and classical general relativity.

Calmet X(1), Graesser M, Hsu SD.

Author information: (1)California Institute of Technology, Pasadena, California 91125, USA. calmet@theory.caltech.edu

We derive fundamental limits on measurements of position, arising from quantum mechanics and classical general relativity. First, we show that any primitive probe or target used in an experiment must be larger than the Planck length lP. This suggests a Planck-size minimum ball of uncertainty in any measurement. Next, we study interferometers (such as LIGO) whose precision is much finer than the size of any individual components and hence are not obviously limited by the minimum ball. Nevertheless, we deduce a fundamental limit on their accuracy of order lP. Our results imply a device independent limit on possible position measurements.

DOI: 10.1103/PhysRevLett.93.211101 PMID: 15600988

121. Phys Rev Lett. 2019 Dec 6;123(23):231103. doi: 10.1103/PhysRevLett.123.231103.

Dynamically Stable Ergostars Exist: General Relativistic Models and Simulations.

Tsokaros A(1), Ruiz M(1), Sun L(1), Shapiro SL(1)(2), Uryū K(3).

Author information: (1)Department of Physics, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA. (2)Department of Astronomy & NCSA, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA. (3)Department of Physics, University of the Ryukyus, Senbaru, Nishihara, Okinawa 903-0213, Japan.

We construct the first dynamically stable ergostars (equilibrium neutron stars that contain an ergoregion) for a compressible, causal equation of state. We demonstrate their stability by evolving both strict and perturbed equilibrium configurations in full general relativity for over a hundred dynamical timescales (≳30 rotational periods) and observing their stationary behavior. This stability is in contrast to earlier models which prove radially unstable to collapse. Our solutions are highly differentially rotating hypermassive neutron stars with a corresponding spherical compaction of C=0.3. Such ergostars can provide new insights into the geometry of spacetimes around highly compact, rotating objects and on the equation of state at supranuclear densities. Ergostars may form as remnants of extreme binary neutron star mergers and possibly provide another mechanism for powering short gamma-ray bursts.

DOI: 10.1103/PhysRevLett.123.231103 PMID: 31868499

122. Rep Prog Phys. 2017 Feb;80(2):026901. doi: 10.1088/1361-6633/80/2/026901. Epub 2016 Dec 23.

The initial value problem as it relates to numerical relativity.

Tichy W(1).

Author information: (1)Department of Physics, Florida Atlantic University, Boca Raton, FL 33431, USA.

Spacetime is foliated by spatial hypersurfaces in the 3+1 split of general relativity. The initial value problem then consists of specifying initial data for all fields on one such a spatial hypersurface, such that the subsequent evolution forward in time is fully determined. On each hypersurface the 3-metric and extrinsic curvature describe the geometry. Together with matter fields such as fluid velocity, energy density and rest mass density, the 3-metric and extrinsic curvature then constitute the initial data. There is a lot of freedom in choosing such initial data. This freedom corresponds to the physical state of the system at the initial time. At the same time the initial data have to satisfy the Hamiltonian and momentum constraint equations of general relativity and can thus not be chosen completely freely. We discuss the conformal transverse traceless and conformal thin sandwich decompositions that are commonly used in the construction of constraint satisfying initial data. These decompositions allow us to specify certain free data that describe the physical nature of the system. The remaining metric fields are then determined by solving elliptic equations derived from the constraint equations. We describe initial data for single black holes and single neutron stars, and how we can use conformal decompositions to construct initial data for binaries made up of black holes or neutron stars. Orbiting binaries will emit gravitational radiation and thus lose energy. Since the emitted radiation tends to circularize the orbits over time, one can thus expect that the objects in a typical binary move on almost circular orbits with slowly shrinking radii. This leads us to the concept of quasi-equilibrium, which essentially assumes that time derivatives are negligible in corotating coordinates for binaries on almost circular orbits. We review how quasi-equilibrium assumptions can be used to make physically well motivated approximations that simplify the elliptic equations we have to solve.

DOI: 10.1088/1361-6633/80/2/026901 PMID: 28008887

123. Opt Express. 2018 Jul 9;26(14):17820-17829. doi: 10.1364/OE.26.017820.

Wave dynamics on toroidal surface.

Wang D, Liu C, Liu H, Han J, Zhang S.

Wave dynamics on curved surfaces has attracted growing attention due to its close resemblance to the warped space time governed by general relativity. It also opens up opportunities for designing functional optical devices such as geodesic lenses. In this work we study the wave dynamics on the surface of a torus, a shape of considerable interest due to its nontrivial topology. Governed by the conservation of angular momentum, light propagates on the torus in two different types of modes: one is able to twist around and sweep through the whole surface of the torus; the other is confined within a certain angular range along the torus latitude direction. The confined mode exhibits an interesting self focusing or imaging behavior, which, similar to a geometric lens, shows no dependence of wavelength and thus suffers no chromatic aberration. By changing the geometric parameters of the torus, both the focusing point and the focusing distance can be controlled. Our work provides a new approach to manipulation of light propagation on a curved surface under the conservation of angular momentum.

DOI: 10.1364/OE.26.017820 PMID: 30114067

124. Science. 1990 Nov 9;250(4982):770-6. doi: 10.1126/science.250.4982.770.

General relativity at 75: how right was einstein?

Will CM.

The status of experimental tests of general relativity is reviewed on the occasion of its 75th anniversary. Einstein's equivalence principle is well supported by experiments such as the Eötvös experiment, tests of special relativity, and the gravitational redshift experiment. Tests of general relativity have reached high precision, including the light deflection and the perihelion advance of Mercury, proposed by Einstein 75 years ago, and new tests such as the Shapiro time delay and the Nordtvedt effect in lunar motion. Gravitational wave damping has been detected to an accuracy of 1 percent on the basis of measurements of the binary pulsar. The status of the "fifth force" is discussed, along with the frontiers of experimental relativity, including proposals for testing relativistic gravity with advanced technology and spacecraft.

DOI: 10.1126/science.250.4982.770 PMID: 17759970

125. Phys Rev Lett. 2019 Nov 8;123(19):191101. doi: 10.1103/PhysRevLett.123.191101.

Fundamental Physics Implications for Higher-Curvature Theories from Binary Black Hole Signals in the LIGO-Virgo Catalog GWTC-1.

Nair R(1), Perkins S(1)(2), Silva HO(1)(2), Yunes N(1)(2).

Author information: (1)eXtreme Gravity Institute, Department of Physics, Montana State University, Bozeman, Montana 59717, USA. (2)Department of Physics, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA.

Erratum in Phys Rev Lett. 2020 Apr 24;124(16):169904.

Gravitational-wave astronomy offers not only new vistas into the realm of astrophysics, but it also opens an avenue for probing, for the first time, general relativity in its strong-field, nonlinear, and dynamical regime, where the theory's predictions manifest themselves in their full glory. We present a study of whether the gravitational-wave events detected so far by the LIGO-Virgo scientific collaborations can be used to probe higher-curvature corrections to general relativity. In particular, we focus on two examples: Einstein-dilaton-Gauss-Bonnet and dynamical Chern-Simons gravity. We find that the two events with a low-mass m≈7 M_{⊙} BH (GW151226 and GW170608) place stringent constraints on Einstein-dilaton-Gauss-Bonnet gravity, α_{EDGB}^{1/2}≲5.6 km, whereas dynamical Chern-Simons gravity remains unconstrained by the gravitational-wave observations analyzed.

DOI: 10.1103/PhysRevLett.123.191101 PMID: 31765188

126. Phys Rev Lett. 2019 Sep 13;123(11):110401. doi: 10.1103/PhysRevLett.123.110401.

Photon Bunching in a Rotating Reference Frame.

Restuccia S(1), Toroš M(2)(3), Gibson GM(1), Ulbricht H(2), Faccio D(1), Padgett MJ(1).

DOI: 10.1103/PhysRevLett.123.110401 PMID: 31573252

127. Living Rev Relativ. 2007;10(1):3. doi: 10.12942/lrr-2007-3. Epub 2007 Jun 1.

Event and Apparent Horizon Finders for 3 + 1 Numerical Relativity.

Thornburg J(1)(2).

Author information: (1)School of Mathematics, University of Southampton, Highfield, Southampton SO17 1BJ UK. (2)Albert Einstein Institute, Max Planck Institute for Gravitational Physics, Am Mühlenberg 1, 14476 Potsdam, Germany.

Event and apparent horizons are key diagnostics for the presence and properties of black holes. In this article I review numerical algorithms and codes for finding event and apparent horizons in numerically-computed spacetimes, focusing on calculations done using the 3 + 1 ADM formalism. The event horizon of an asymptotically-flat spacetime is the boundary between those events from which a future-pointing null geodesic can reach future null infinity and those events from which no such geodesic exists. The event horizon is a (continuous) null surface in spacetime. The event horizon is defined nonlocally in time: it is a global property of the entire spacetime and must be found in a separate post-processing phase after all (or at least the nonstationary part) of spacetime has been numerically computed. There are three basic algorithms for finding event horizons, based on integrating null geodesics forwards in time, integrating null geodesics backwards in time, and integrating null surfaces backwards in time. The last of these is generally the most efficient and accurate. In contrast to an event horizon, an apparent horizon is defined locally in time in a spacelike slice and depends only on data in that slice, so it can be (and usually is) found during the numerical computation of a spacetime. A marginally outer trapped surface (MOTS) in a slice is a smooth closed 2-surface whose future-pointing outgoing null geodesics have zero expansion Θ. An apparent horizon is then defined as a MOTS not contained in any other MOTS. The MOTS condition is a nonlinear elliptic partial differential equation (PDE) for the surface shape, containing the ADM 3-metric, its spatial derivatives, and the extrinsic curvature as coefficients. Most "apparent horizon" finders actually find MOTSs. There are a large number of apparent horizon finding algorithms, with differing trade-offs between speed, robustness, accuracy, and ease of programming. In axisymmetry, shooting algorithms work well and are fairly easy to program. In slices with no continuous symmetries, spectral integral-iteration algorithms and elliptic-PDE algorithms are fast and accurate, but require good initial guesses to converge. In many cases, Schnetter's "pretracking" algorithm can greatly improve an elliptic-PDE algorithm's robustness. Flow algorithms are generally quite slow but can be very robust in their convergence. Minimization methods are slow and relatively inaccurate in the context of a finite differencing simulation, but in a spectral code they can be relatively faster and more robust.

DOI: 10.12942/lrr-2007-3 PMCID: PMC5660890 PMID: 29142498

128. Living Rev Relativ. 2000;3(1):4. doi: 10.12942/lrr-2000-4. Epub 2000 Aug 23.

Conformal Infinity.

Frauendiener J(1).

Author information: (1)Institut für Theoretische Astrophysik, Universität Tübingen, Auf der Morgenstelle 10, D-72076, Tübingen Germany.

The notion of conformal infinity has a long history within the research in Einstein's theory of gravity. Today, "conformal infinity" is related with almost all other branches of research in general relativity, from quantisation procedures to abstract mathematical issues to numerical applications. This review article attempts to show how this concept gradually and inevitably evolved out of physical issues, namely the need to understand gravitational radiation and isolated systems within the theory of gravitation and how it lends itself very naturally to solve radiation problems in numerical relativity. The fundamental concept of null-infinity is introduced. Friedrich's regular conformal field equations are presented and various initial value problems for them are discussed. Finally, it is shown that the conformal field equations provide a very powerful method within numerical relativity to study global problems such as gravitational wave propagation and detection.

DOI: 10.12942/lrr-2000-4 PMCID: PMC5253926 PMID: 28163630

129. Phys Rev Lett. 2008 Feb 29;100(8):081102. doi: 10.1103/PhysRevLett.100.081102. Epub 2008 Feb 27.

Deformations of the constraint algebra of Ashtekar's Hamiltonian formulation of general relativity.

Krasnov K(1).

Author information: (1)School of Mathematical Sciences, University of Nottingham, Nottingham, NG7 2RD, United Kingdom.

We show that the constraint algebra of Ashtekar's Hamiltonian formulation of general relativity can be nontrivially deformed by allowing the cosmological constant to become an arbitrary function of the (Weyl) curvature. Our result implies that there is not one but infinitely many (parametrized by an arbitrary function) four-dimensional generally covariant local gravity theories propagating 2 degrees of freedom.

DOI: 10.1103/PhysRevLett.100.081102 PMID: 18352613

130. Nature. 2008 Apr 17;452(7189):851-3. doi: 10.1038/nature06896.

A massive binary black-hole system in OJ 287 and a test of general relativity.

Valtonen MJ(1), Lehto HJ, Nilsson K, Heidt J, Takalo LO, Sillanpää A, Villforth C, Kidger M, Poyner G, Pursimo T, Zola S, Wu JH, Zhou X, Sadakane K, Drozdz M, Koziel D, Marchev D, Ogloza W, Porowski C, Siwak M, Stachowski G, Winiarski M, Hentunen VP, Nissinen M, Liakos A, Dogru S.

Author information: (1)Department of Physics and Tuorla Observatory, University of Turku, Vaisäläntie 20, FI-21500 Piikkiö, Finland. mvaltonen2001@yahoo.com

Tests of Einstein's general theory of relativity have mostly been carried out in weak gravitational fields where the space-time curvature effects are first-order deviations from Newton's theory. Binary pulsars provide a means of probing the strong gravitational field around a neutron star, but strong-field effects may be best tested in systems containing black holes. Here we report such a test in a close binary system of two candidate black holes in the quasar OJ 287. This quasar shows quasi-periodic optical outbursts at 12-year intervals, with two outburst peaks per interval. The latest outburst occurred in September 2007, within a day of the time predicted by the binary black-hole model and general relativity. The observations confirm the binary nature of the system and also provide evidence for the loss of orbital energy in agreement (within 10 per cent) with the emission of gravitational waves from the system. In the absence of gravitational wave emission the outburst would have happened 20 days later.

DOI: 10.1038/nature06896 PMID: 18421348

131. Nature. 2019 Jul;571(7766):528-531. doi: 10.1038/s41586-019-1403-0. Epub 2019 Jul 24.

General relativistic orbital decay in a seven-minute-orbital-period eclipsing binary system.

Burdge KB(1), Coughlin MW(2), Fuller J(2), Kupfer T(3), Bellm EC(4), Bildsten L(3)(5), Graham MJ(2), Kaplan DL(6), Roestel JV(2), Dekany RG(7), Duev DA(2), Feeney M(7), Giomi M(8), Helou G(9), Kaye S(7), Laher RR(9), Mahabal AA(2), Masci FJ(9), Riddle R(7), Shupe DL(9), Soumagnac MT(10), Smith RM(7), Szkody P(4), Walters R(7), Kulkarni SR(2), Prince TA(2).

Author information: (1)Division of Physics, Mathematics and Astronomy, California Institute of Technology, Pasadena, CA, USA. kburdge@caltech.edu. (2)Division of Physics, Mathematics and Astronomy, California Institute of Technology, Pasadena, CA, USA. (3)Kavli Institute for Theoretical Physics, University of California Santa Barbara, Santa Barbara, CA, USA. (4)Department of Astronomy, University of Washington, Seattle, WA, USA. (5)Department of Physics, University of California Santa Barbara, Santa Barbara, CA, USA. (6)Department of Physics, University of Wisconsin-Milwaukee, Milwaukee, WI, USA. (7)Caltech Optical Observatories, California Institute of Technology, Pasadena, CA, USA. (8)Humboldt-Universität zu Berlin, Berlin, Germany. (9)IPAC, California Institute of Technology, Pasadena, CA, USA. (10)Benoziyo Center for Astrophysics, Weizmann Institute of Science, Rehovot, Israel.

General relativity1 predicts that short-orbital-period binaries emit considerable amounts of gravitational radiation. The upcoming Laser Interferometer Space Antenna2 (LISA) is expected to detect tens of thousands of such systems3 but few have been identified4, of which only one5 is eclipsing-the double-white-dwarf binary SDSS J065133.338+284423.37, which has an orbital period of 12.75 minutes. Here we report the discovery of an eclipsing double-white-dwarf binary system, ZTF J153932.16+502738.8, with an orbital period of 6.91 minutes. This system has an orbit so compact that the entire binary could fit within the diameter of the planet Saturn. The system exhibits a deep eclipse, and a double-lined spectroscopic nature. We see rapid orbital decay, consistent with that expected from general relativity. ZTF J153932.16+502738.8 is a strong source of gravitational radiation close to the peak of LISA's sensitivity, and we expect it to be detected within the first week of LISA observations, once LISA launches in approximately 2034.

DOI: 10.1038/s41586-019-1403-0 PMID: 31341301

132. Ann N Y Acad Sci. 2014 Oct;1326:18-25. doi: 10.1111/nyas.12542. Epub 2014 Sep 25.

The birth of spacetime atoms as the passage of time.

Dowker F(1).

Author information: (1)Blackett Laboratory, Imperial College, London, United Kingdom.

In the following discussion I suggest that the reason there is no consensus on whether the passage of time is physical is that our current best theory of spacetime, general relativity, lacks such a concept. This means that the sense-experience of passage, appealed to by those who claim it is physical, cannot be properly expressed: it is not even a fact. I draw attention to work in the literature on a model of a growing, granular spacetime--arising within a proposed theory of quantum spacetime called causal set theory--that does contain the concept of passage as the coming into being or birth of atoms of spacetime. I present an example from the history of science of a sense-experience that cannot be understood within one theory but is revealed to be an important fact within a better successor theory.

DOI: 10.1111/nyas.12542 PMID: 25257658 [Indexed for MEDLINE]

133. Am J Psychiatry. 1979 Jan;136(1):38-43. doi: 10.1176/ajp.136.1.38.

Einstein's creative thinking and the general theory of relativity: a documented report.

Rothenberg A.

A document written by Albert Einstein has recently come to light in which the eminent scientist described the actual sequence of his thoughts leading to the development of the general theory of relativity. The key creative thought was an instance of a type of creative cognition the author has previously designated "Janusian thinking," Janusian thinking consists of actively conceiving two or more opposite or antithetical concepts, ideas, or images simultaneously. This form of high-level secondary process cognition has been found to operate widely in art, science, and other fields.

DOI: 10.1176/ajp.136.1.38 PMID: 365000 [Indexed for MEDLINE]

134. Phys Rev Lett. 2019 Oct 25;123(17):171102. doi: 10.1103/PhysRevLett.123.171102.

Interior of a Binary Black Hole Merger.

Pook-Kolb D(1)(2), Birnholtz O(3), Krishnan B(1)(2), Schnetter E(4)(5)(6).

Author information: (1)Max-Planck-Institut für Gravitationsphysik (Albert Einstein Institute), Callinstrasse 38, 30167 Hannover, Germany. (2)Leibniz Universität Hannover, 30167 Hannover, Germany. (3)Center for Computational Relativity and Gravitation, Rochester Institute of Technology, 170 Lomb Memorial Drive, Rochester, New York 14623, USA. (4)Perimeter Institute for Theoretical Physics, Waterloo, Ontario N2L 2Y5, Canada. (5)Physics & Astronomy Department, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada. (6)Center for Computation & Technology, Louisiana State University, Baton Rouge, Louisiana 70803, USA.

We find strong numerical evidence for a new phenomenon in a binary black hole spacetime, namely, the merger of marginally outer trapped surfaces (MOTSs). By simulating the head-on collision of two nonspinning unequal mass black holes, we observe that the MOTS associated with the final black hole merges with the two initially disjoint surfaces corresponding to the two initial black holes. This yields a connected sequence of MOTSs interpolating between the initial and final state all the way through the nonlinear binary black hole merger process. In addition, we show the existence of a MOTS with self-intersections formed immediately after the merger. This scenario now allows us to track physical quantities (such as mass, angular momentum, higher multipoles, and fluxes) across the merger, which can be potentially compared with the gravitational wave signal in the wave zone, and with observations by gravitational wave detectors. This also suggests a possibility of proving the Penrose inequality mathematically for generic astrophysical binary back hole configurations.

DOI: 10.1103/PhysRevLett.123.171102 PMID: 31702254

135. Phys Rev Lett. 2016 Jun 24;116(25):251601. doi: 10.1103/PhysRevLett.116.251601. Epub 2016 Jun 21.

Three-Dimensional Extended Bargmann Supergravity.

Bergshoeff E(1), Rosseel J(2).

Author information: (1)Van Swinderen Institute for Particle Physics and Gravity, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands. (2)Albert Einstein Center for Fundamental Physics, University of Bern, Sidlerstrasse 5, 3012 Bern, Switzerland.

We show that three-dimensional general relativity, augmented with two vector fields, allows for a nonrelativistic limit, different from the standard limit leading to Newtonian gravity, that results in a well-defined action which is of the Chern-Simons type. We show that this three-dimensional "extended Bargmann gravity," after coupling to matter, leads to equations of motion allowing a wider class of background geometries than the ones that one encounters in Newtonian gravity. We give the supersymmetric generalization of these results and point out an important application in the context of calculating partition functions of nonrelativistic field theories using localization techniques.

DOI: 10.1103/PhysRevLett.116.251601 PMID: 27391712

136. Phys Rev Lett. 2011 Jun 3;106(22):221101. doi: 10.1103/PhysRevLett.106.221101. Epub 2011 May 31.

Gravity Probe B: final results of a space experiment to test general relativity.

Everitt CW(1), DeBra DB, Parkinson BW, Turneaure JP, Conklin JW, Heifetz MI, Keiser GM, Silbergleit AS, Holmes T, Kolodziejczak J, Al-Meshari M, Mester JC, Muhlfelder B, Solomonik VG, Stahl K, Worden PW Jr, Bencze W, Buchman S, Clarke B, Al-Jadaan A, Al-Jibreen H, Li J, Lipa JA, Lockhart JM, Al-Suwaidan B, Taber M, Wang S.

Author information: (1)HEPL, Stanford University, Stanford, California 94305-4085, USA. francis1@stanford.edu

Gravity Probe B, launched 20 April 2004, is a space experiment testing two fundamental predictions of Einstein's theory of general relativity (GR), the geodetic and frame-dragging effects, by means of cryogenic gyroscopes in Earth orbit. Data collection started 28 August 2004 and ended 14 August 2005. Analysis of the data from all four gyroscopes results in a geodetic drift rate of -6601.8±18.3 mas/yr and a frame-dragging drift rate of -37.2±7.2 mas/yr, to be compared with the GR predictions of -6606.1 mas/yr and -39.2 mas/yr, respectively ("mas" is milliarcsecond; 1 mas=4.848×10(-9) rad).

DOI: 10.1103/PhysRevLett.106.221101 PMID: 21702590

137. Eur Phys J C Part Fields. 2017;77(5):335. doi: 10.1140/epjc/s10052-017-4879-5. Epub 2017 May 20.

Black holes in multi-fractional and Lorentz-violating models.

Calcagni G(1), Rodríguez Fernández D(2), Ronco M(3)(4).

Author information: (1)Instituto de Estructura de la Materia, CSIC, Serrano 121, 28006 Madrid, Spain. (2)Department of Physics, Universidad de Oviedo, Avda. Calvo Sotelo 18, 33007 Oviedo, Spain. (3)Dipartimento di Fisica, Università di Roma "La Sapienza", P.le A. Moro 2, 00185 Rome, Italy. (4)INFN, Sez. Roma1, P.le A. Moro 2, 00185 Rome, Italy.

We study static and radially symmetric black holes in the multi-fractional theories of gravity with q-derivatives and with weighted derivatives, frameworks where the spacetime dimension varies with the probed scale and geometry is characterized by at least one fundamental length [Formula: see text]. In the q-derivatives scenario, one finds a tiny shift of the event horizon. Schwarzschild black holes can present an additional ring singularity, not present in general relativity, whose radius is proportional to [Formula: see text]. In the multi-fractional theory with weighted derivatives, there is no such deformation, but non-trivial geometric features generate a cosmological-constant term, leading to a de Sitter-Schwarzschild black hole. For both scenarios, we compute the Hawking temperature and comment on the resulting black-hole thermodynamics. In the case with q-derivatives, black holes can be hotter than usual and possess an additional ring singularity, while in the case with weighted derivatives they have a de Sitter hair of purely geometric origin, which may lead to a solution of the cosmological constant problem similar to that in unimodular gravity. Finally, we compare our findings with other Lorentz-violating models.

DOI: 10.1140/epjc/s10052-017-4879-5 PMCID: PMC5438828 PMID: 28596703

138. Rep Prog Phys. 2015 Nov;78(11):116901. doi: 10.1088/0034-4885/78/11/116901. Epub 2015 Oct 16.

Magnetars: the physics behind observations. A review.

Turolla R(1), Zane S, Watts AL.

Author information: (1)Department of Physics and Astronomy, University of Padova, via Marzolo 8, 35131 Padova, Italy. Mullard Space Science Laboratory, University College London, Holbury St. Mary, Surrey, RH5 6NT, UK.

Magnetars are the strongest magnets in the present universe and the combination of extreme magnetic field, gravity and density makes them unique laboratories to probe current physical theories (from quantum electrodynamics to general relativity) in the strong field limit. Magnetars are observed as peculiar, burst-active x-ray pulsars, the anomalous x-ray pulsars (AXPs) and the soft gamma repeaters (SGRs); the latter emitted also three 'giant flares', extremely powerful events during which luminosities can reach up to 10(47) erg s(-1) for about one second. The last five years have witnessed an explosion in magnetar research which has led, among other things, to the discovery of transient, or 'outbursting', and 'low-field' magnetars. Substantial progress has been made also on the theoretical side. Quite detailed models for explaining the magnetars' persistent x-ray emission, the properties of the bursts, the flux evolution in transient sources have been developed and confronted with observations. New insight on neutron star asteroseismology has been gained through improved models of magnetar oscillations. The long-debated issue of magnetic field decay in neutron stars has been addressed, and its importance recognized in relation to the evolution of magnetars and to the links among magnetars and other families of isolated neutron stars. The aim of this paper is to present a comprehensive overview in which the observational results are discussed in the light of the most up-to-date theoretical models and their implications. This addresses not only the particular case of magnetar sources, but the more fundamental issue of how physics in strong magnetic fields can be constrained by the observations of these unique sources.

DOI: 10.1088/0034-4885/78/11/116901 PMID: 26473534

139. Front Psychol. 2015 Oct 31;6:1631. doi: 10.3389/fpsyg.2015.01631. eCollection 2015.

Language may indeed influence thought.

Zlatev J(1), Blomberg J(2).

Author information: (1)Centre for Languages and Literature, Lund University Lund, Sweden. (2)Centre for Languages and Literature/Department of Philosophy, Lund University Lund, Sweden ; Institut für Sprache und Kommunikation, Technische Universität Berlin Berlin, Germany.

We discuss four interconnected issues that we believe have hindered investigations into how language may affect thinking. These have had a tendency to reappear in the debate concerning linguistic relativity over the past decades, despite numerous empirical findings. The first is the claim that it is impossible to disentangle language from thought, making the question concerning "influence" pointless. The second is the argument that it is impossible to disentangle language from culture in general, and from social interaction in particular, so it is impossible to attribute any differences in the thought patterns of the members of different cultures to language per se. The third issue is the objection that methodological and empirical problems defeat all but the most trivial version of the thesis of linguistic influence: that language gives new factual information. The fourth is the assumption that since language can potentially influence thought from "not at all" to "completely," the possible forms of linguistic influence can be placed on a cline, and competing theories can be seen as debating the actual position on this cline. We analyze these claims and show that the first three do not constitute in-principle objections against the validity of the project of investigating linguistic influence on thought, and that the last one is not the best way to frame the empirical challenges at hand. While we do not argue for any specific theory or mechanism for linguistic influence on thought, our discussion and the reviewed literature show that such influence is clearly possible, and hence in need of further investigations.

DOI: 10.3389/fpsyg.2015.01631 PMCID: PMC4628110 PMID: 26582997

140. Philos Trans A Math Phys Eng Sci. 2011 Dec 28;369(1957):5058-67. doi: 10.1098/rsta.2011.0370.

Redshift-space distortions.

Percival WJ(1), Samushia L, Ross AJ, Shapiro C, Raccanelli A.

Author information: (1)Institute of Cosmology and Gravitation, University of Portsmouth, Dennis Sciama Building, Portsmouth PO1 3FX, UK. will.percival@port.ac.uk

Comparing measurements of redshift-space distortions (RSDs) with geometrical observations of the expansion of the Universe offers tremendous potential for testing general relativity on very large scales. The basic linear theory of RSDs in the distant-observer limit has been known for 25 years and the effect has been conclusively observed in numerous galaxy surveys. The next generation of galaxy survey will observe many millions of galaxies over volumes of many tens of Gpc(3). They will provide RSD measurements of such exquisite precision that we will have to carefully analyse and correct for many systematic deviations from this simple picture in order to fully exploit the statistical precision obtained. We review RSD theory and show how ubiquitous RSDs actually are, and then consider a number of potential systematic effects, shamelessly highlighting recent work in which we have been involved. This review ends by looking ahead to the future surveys that will make the next generation of RSD measurements.

DOI: 10.1098/rsta.2011.0370 PMID: 22084293

141. Phys Rev Lett. 2006 Jan 27;96(3):031101. doi: 10.1103/PhysRevLett.96.031101. Epub 2006 Jan 25.

Collapse of magnetized hypermassive neutron stars in general relativity.

Duez MD(1), Liu YT, Shapiro SL, Shibata M, Stephens BC.

Author information: (1)Department of Physics, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA.

Hypermassive neutron stars (HMNSs)--equilibrium configurations supported against collapse by rapid differential rotation--are possible transient remnants of binary neutron-star mergers. Using newly developed codes for magnetohydrodynamic simulations in dynamical spacetimes, we are able to track the evolution of a magnetized HMNS in full general relativity for the first time. We find that secular angular momentum transport due to magnetic braking and the magnetorotational instability results in the collapse of an HMNS to a rotating black hole, accompanied by a gravitational wave burst. The nascent black hole is surrounded by a hot, massive torus undergoing quasistationary accretion and a collimated magnetic field. This scenario suggests that HMNS collapse is a possible candidate for the central engine of short gamma-ray bursts.

DOI: 10.1103/PhysRevLett.96.031101 PMID: 16486677

142. Phys Rev Lett. 2001 Apr 2;86(14):2942-5. doi: 10.1103/PhysRevLett.86.2942.

Deflection of spacecraft trajectories as a new test of general relativity.

Longuski JM(1), Fischbach E, Scheeres DJ.

Author information: (1)School of Aeronautics and Astronautics, Purdue University, West Lafayette, Indiana 47907-1282, USA.

We derive a simple formula which gives the general relativistic deflection of a spacecraft, idealized as a point mass, for all values of the asymptotic speed V(infinity) (0< or =V(infinity)< or =1). Using this formula we suggest a new test of general relativity (GR) which can be carried out during a proposed interstellar mission that involves a close pass of the Sun. We show that, with foreseeable improvements in spacecraft tracking sensitivity, the deflection of a spacecraft's trajectory in the gravitational field of the Sun could provide a new test of GR.

DOI: 10.1103/PhysRevLett.86.2942 PMID: 11290078 [Indexed for MEDLINE]

143. Phys Rev Lett. 2014 Mar 28;112(12):121101. doi: 10.1103/PhysRevLett.112.121101. Epub 2014 Mar 26.

Effectively universal behavior of rotating neutron stars in general relativity makes them even simpler than their Newtonian counterparts.

Pappas G(1), Apostolatos TA(2).

Author information: (1)SISSA, Via Bonomea 265, 34136 Trieste, Italy. (2)Section of Astrophysics, Astronomy, and Mechanics, Department of Physics, University of Athens, Panepistimiopolis Zografos GR15783, Athens, Greece.

Recently, it was shown that slowly rotating neutron stars exhibit an interesting correlation between their moment of inertia I, their quadrupole moment Q, and their tidal deformation Love number λ (the I-Love-Q relations), independently of the equation of state of the compact object. In the present Letter a similar, more general, universality is shown to hold true for all rotating neutron stars within general relativity; the first four multipole moments of the neutron star are related in a way independent of the nuclear matter equation of state we assume. By exploiting this relation, we can describe quite accurately the geometry around a neutron star with fewer parameters, even if we don't know precisely the equation of state. Furthermore, this universal behavior displayed by neutron stars could promote them to a more promising class of candidates (next to black holes) for testing theories of gravity.

DOI: 10.1103/PhysRevLett.112.121101 PMID: 24724643

144. Hist Philos Life Sci. 2005;27(3-4):465-78.

Causation and space-time.

Lam V(1).

Author information: (1)University of Lausanne, Department of Philosophy & Centre Romand for Logic, History & Philosophy of Science 1015 Lausanne, Switzerland.

This paper considers the physical accounts of causation in terms of conserved quantities in the light of the theory of general relativity. As it is rather well-known among physicists, there are several difficulties with the notions of conservation and localization of the (gravitational) energy-momentum within general relativity. We first begin to review the so-called conserved quantity theory of causation mainly due to Dowe and Salmon, then we discuss some consequences of these difficulties for this physical account of causation. We argue that these difficulties are due to the fundamental nature of the space-time structure as described by GR, which the conserved quantity theory of causation does not account for.

PMID: 16898213 [Indexed for MEDLINE]

145. Philos Trans A Math Phys Eng Sci. 2008 May 28;366(1871):1867-74. doi: 10.1098/rsta.2007.2193.

Gauge formulation of general relativity using conformal and spin symmetries.

Wang CH(1).

Author information: (1)Department of Physics, University of Aberdeen, King's College, Aberdeen, UK.

The gauge symmetry inherent in Maxwell's electromagnetics has a profound impact on modern physics. Following the successful quantization of electromagnetics and other higher order gauge field theories, the gauge principle has been applied in various forms to quantize gravity. A notable development in this direction is loop quantum gravity based on the spin-gauge treatment. This paper considers a further incorporation of the conformal gauge symmetry in canonical general relativity. This is a new conformal decomposition in that it is applied to simplify recently formulated parameter-free construction of spin-gauge variables for gravity. The resulting framework preserves many main features of the existing canonical framework for loop quantum gravity regarding the spin network representation and Thiemann's regularization. However, the Barbero-Immirzi parameter is converted into the conformal factor as a canonical variable. It behaves like a scalar field but is somehow non-dynamical since the Hamiltonian constraint does not depend on its momentum. The essential steps of the mathematical derivation of this parameter-free framework for the spin-gauge variables of gravity are spelled out. The implications for the loop quantum gravity programme are briefly discussed.

DOI: 10.1098/rsta.2007.2193 PMID: 18218597

146. Phys Rev Lett. 2017 Mar 10;118(10):101301. doi: 10.1103/PhysRevLett.118.101301. Epub 2017 Mar 10.

Cosmic Tsunamis in Modified Gravity: Disruption of Screening Mechanisms from Scalar Waves.

Hagala R(1), Llinares C(2), Mota DF(1).

Author information: (1)Institute of Theoretical Astrophysics, University of Oslo, PO Box 1029 Blindern, 0315 Oslo, Norway. (2)Institute for Computational Cosmology, Department of Physics, Durham University, Durham DH1 3LE, United Kingdom.

Extending general relativity by adding extra degrees of freedom is a popular approach for explaining the accelerated expansion of the Universe and to build high energy completions of the theory of gravity. The presence of such new degrees of freedom is, however, tightly constrained from several observations and experiments that aim to test general relativity in a wide range of scales. The viability of a given modified theory of gravity, therefore, strongly depends on the existence of a screening mechanism that suppresses the extra degrees of freedom. We perform simulations, and find that waves propagating in the new degrees of freedom can significantly impact the efficiency of some screening mechanisms, thereby threatening the viability of these modified gravity theories. Specifically, we show that the waves produced in the symmetron model can increase the amplitude of the fifth force and the parametrized post Newtonian parameters by several orders of magnitude.

DOI: 10.1103/PhysRevLett.118.101301 PMID: 28339227

147. Philos Trans A Math Phys Eng Sci. 2011 Dec 28;369(1957):4998-5002. doi: 10.1098/rsta.2011.0284.

A gravitational puzzle.

Caldwell RR(1).

Author information: (1)Department of Physics and Astronomy, Dartmouth College, Hanover, NH 03755, USA. robert.r.caldwell@dartmouth.edu

The challenge to understand the physical origin of the cosmic acceleration is framed as a problem of gravitation. Specifically, does the relationship between stress-energy and space-time curvature differ on large scales from the predictions of general relativity. In this article, we describe efforts to model and test a generalized relationship between the matter and the metric using cosmological observations. Late-time tracers of large-scale structure, including the cosmic microwave background, weak gravitational lensing, and clustering are shown to provide good tests of the proposed solution. Current data are very close to proving a critical test, leaving only a small window in parameter space in the case that the generalized relationship is scale free above galactic scales.

DOI: 10.1098/rsta.2011.0284 PMID: 22084289

148. Philos Trans A Math Phys Eng Sci. 2011 Dec 28;369(1957):4962-75. doi: 10.1098/rsta.2011.0291.

Modifications of gravity.

Skordis C(1).

Author information: (1)School of Physics and Astronomy, University of Nottingham, Nottingham NG8 2RD, UK. skordis@nottingham.ac.uk

General relativity (GR) is a phenomenologically successful theory that rests on firm foundations, but has not been tested on cosmological scales. The deep mystery of dark energy (and possibly even the requirement of cold dark matter (CDM)) has increased the need for testing modifications to GR, as the inference of such otherwise undetected fluids depends crucially on the theory of gravity. Here, I discuss a general scheme for constructing consistent and covariant modifications to the Einstein equations. This framework is such that there is a clear connection between the modification and the underlying field content that produces it. I argue that this is mandatory for distinguishing modifications of gravity from conventional fluids. I give a non-trivial example, a simple metric-based modification of the fluctuation equations for which the background is exact ΛCDM, but differs from it in the perturbations. I show how this can be generalized and solved in terms of two arbitrary functions. Finally, I discuss future prospects and directions of research.

DOI: 10.1098/rsta.2011.0291 PMID: 22084286

149. Eur Phys J C Part Fields. 2016;76(10):578. doi: 10.1140/epjc/s10052-016-4419-8. Epub 2016 Oct 25.

Modified teleparallel theories of gravity: Gauss-Bonnet and trace extensions.

Bahamonde S(1), Böhmer CG(1).

Author information: (1)Department of Mathematics, University College London, Gower Street, London, WC1E 6BT UK.

We investigate modified theories of gravity in the context of teleparallel geometries with possible Gauss-Bonnet contributions. The possible coupling of gravity with the trace of the energy-momentum tensor is also taken into account. This is motivated by the various different theories formulated in the teleparallel approach and the metric approach without discussing the exact relationship between them. Our formulation clarifies the connections between different well-known theories. For instance, we are able to formulate the correct teleparallel equivalent of Gauss-Bonnet modified general relativity, amongst other results. Finally, we are able to identify modified gravity models which have not been studied in the past. These appear naturally within our setup and would make a interesting starting point for further studies.

DOI: 10.1140/epjc/s10052-016-4419-8 PMCID: PMC5080365 PMID: 27829817

150. Eur Phys J C Part Fields. 2017;77(9):605. doi: 10.1140/epjc/s10052-017-5183-0. Epub 2017 Sep 14.

Local conformal symmetry in non-Riemannian geometry and the origin of physical scales.

de Cesare M(1), Moffat JW(2), Sakellariadou M(1)(2).

Author information: (1)1Theoretical Particle Physics and Cosmology Group, Department of Physics, King's College London, Strand, London, WC2R 2LS UK. (2)2Perimeter Institute for Theoretical Physics, Waterloo, ON N2L 2Y5 Canada.

We introduce an extension of the Standard Model and General Relativity built upon the principle of local conformal invariance, which represents a generalization of a previous work by Bars, Steinhardt and Turok. This is naturally realized by adopting as a geometric framework a particular class of non-Riemannian geometries, first studied by Weyl. The gravitational sector is enriched by a scalar and a vector field. The latter has a geometric origin and represents the novel feature of our approach. We argue that physical scales could emerge from a theory with no dimensionful parameters, as a result of the spontaneous breakdown of conformal and electroweak symmetries. We study the dynamics of matter fields in this modified gravity theory and show that test particles follow geodesics of the Levi-Civita connection, thus resolving an old criticism raised by Einstein against Weyl's original proposal.

DOI: 10.1140/epjc/s10052-017-5183-0 PMCID: PMC6959388 PMID: 32009847

151. Science. 2015 Mar 6;347(6226):1100-2. doi: 10.1126/science.aaa0980.

The dark side of cosmology: dark matter and dark energy.

Spergel DN(1).

Author information: (1)Princeton University, Princeton, NJ 08544, USA. dns@astro.princeton.edu.

A simple model with only six parameters (the age of the universe, the density of atoms, the density of matter, the amplitude of the initial fluctuations, the scale dependence of this amplitude, and the epoch of first star formation) fits all of our cosmological data . Although simple, this standard model is strange. The model implies that most of the matter in our Galaxy is in the form of "dark matter," a new type of particle not yet detected in the laboratory, and most of the energy in the universe is in the form of "dark energy," energy associated with empty space. Both dark matter and dark energy require extensions to our current understanding of particle physics or point toward a breakdown of general relativity on cosmological scales.

DOI: 10.1126/science.aaa0980 PMID: 25745164

152. Phys Rev Lett. 2004 Aug 20;93(8):081101. doi: 10.1103/PhysRevLett.93.081101. Epub 2004 Aug 18.

Gluing initial data sets for general relativity.

Chruściel PT(1), Isenberg J, Pollack D.

Author information: (1)Départemént de Mathématiques, Faculté des Sciences, Université de Tours, Parc de Grandmont, F37200 Tours, France.

We establish an optimal gluing construction for general relativistic initial data sets. The construction is optimal in two distinct ways. First, it applies to generic initial data sets and the required (generically satisfied) hypotheses are geometrically and physically natural. Second, the construction is completely local in the sense that the initial data is left unaltered on the complement of arbitrarily small neighborhoods of the points about which the gluing takes place. Using this construction we establish the existence of cosmological, maximal globally hyperbolic, vacuum space-times with no constant mean curvature spacelike Cauchy surfaces.

DOI: 10.1103/PhysRevLett.93.081101 PMID: 15447167

153. Rev Sci Instrum. 2017 Sep;88(9):094501. doi: 10.1063/1.4986226.

Astronomical time-of-flight photon speedometer.

Miller JB(1), Miller TE(2), Hoffert MJ(3), Dingle LA(3), Harwell R(3), Hayes E(3).

Author information: (1)Chemistry Department-MS5413, Western Michigan University, Kalamazoo, Michigan 49008, USA. (2)BlueRad, 108 Titleist Drive, Bluefield, Virginia 24605, USA. (3)Tierra Astronomical Institute, 2364 S. Annadel, Rowland Heights, California 91748, USA.

A dual-band, fiber-optic, photon time-of-flight instrument was developed. Its design was optimized for measuring the velocity of visible photons emanating from relatively dim astronomical sources (apparent magnitude m>12), such as distant galaxies and quasars. We report the first direct photon group velocity measurements for extragalactic objects. The photon group velocity is found to be 3.00±0.03×108 ms-1 and is invariant, within experimental error, over the range of redshifts measured (0≤z≤1.33). This measurement provides additional validation of general relativity and is consistent with the Friedmann-Lemaître-Robertson-Walker and hyperbolic anti-de Sitter metrics but not with the elliptical de Sitter metric.

DOI: 10.1063/1.4986226 PMID: 28964243

154. Proc Natl Acad Sci U S A. 1992 Aug 1;89(15):6703-5. doi: 10.1073/pnas.89.15.6703.

Note on the form of the metric for an isolated vortex in general relativity.

Pekeris CL(1), Frankowski K.

Author information: (1)Department of Applied Mathematics, Weizmann Institute of Science, Rehovot, Israel.

Calling a metric semidiagonal if it has a single off-diagonal element g t, we show that the stationary interior solution for a cylindrically symmetrical perfect fluid possessing an angular momentum cannot have a semidiagonal metric, unless the motion of the fluid particles is purely rotational around the axis of symmetry. A discussion is given of the relativistic spherical vortex in flat space, with a view of seeking a solution for such an isolated vortex in which gravitation is not neglected.

DOI: 10.1073/pnas.89.15.6703 PMCID: PMC49571 PMID: 11607309

155. Appl Opt. 2018 Jul 10;57(20):5844-5851. doi: 10.1364/AO.57.005844.

Analysis of 90 day operation of the GINGERINO gyroscope.

Belfi J, Beverini N, Carelli G, Di Virgilio A, Giacomelli U, Maccioni E, Simonelli A, Stefani F, Terreni G.

Gyroscopes IN GEneral Relativity (GINGER) is a proposed experiment with the aim of measuring in a ground laboratory the gravitoelectric and gravitomagnetic effects foreseen by general relativity through an array of ring laser gyroscopes. GINGERINO is a square ring-laser prototype that has been built to investigate the level of noise inside the Gran Sasso underground laboratory. GINGERINO has shown the advantage of the underground location. Now it provides suitable data for geophysics and seismology. Since May 2017, it has continuously acquired data. The analysis of the first 90 days shows that the duty cycle is higher than 95%, and the quantum shot noise limit is of the order of 10-10(rad/s)/Hz. It is located in a seismically active area, and it recorded part of the central Italy earthquakes. Its high sensitivity in the frequency band of fraction of hertz makes it suitable for seismology studies. The main purpose of the present analysis is to investigate the long-term response of the apparatus. Simple and fast routines to suppress the disturbances coming from the laser have been developed. The Allan deviation of the raw data reaches some 10-6 after about 106 s of integration time, while the processed data show an improvement of 1 order of magnitude. Disturbances at the daily time scale are present in the processed data, and the expected signal induced by polar motion and solid Earth tides is covered by those disturbances.

DOI: 10.1364/AO.57.005844 PMID: 30118056

156. Cogn Emot. 2019 Jun;33(4):848-854. doi: 10.1080/02699931.2018.1483322. Epub 2018 Jun 6.

No grammatical gender effect on affective ratings: evidence from Italian and German languages.

Montefinese M(1), Ambrosini E(2)(3), Roivainen E(4).

Author information: (1)a Department of Experimental Psychology , University College London , London , UK. (2)b Department of Neuroscience , University of Padua , Padua , Italy. (3)c Department of General Psychology , University of Padua , Padua , Italy. (4)d Oulu University Hospital , Oulu , Finland.

In this study, we tested the linguistic relativity hypothesis by studying the effect of grammatical gender (feminine vs. masculine) on affective judgments of conceptual representation in Italian and German. In particular, we examined the within- and cross-language grammatical gender effect and its interaction with participants' demographic characteristics (such as, the raters' age and sex) on semantic differential scales (affective ratings of valence, arousal and dominance) in Italian and German speakers. We selected the stimuli and the relative affective measures from Italian and German adaptations of the ANEW (Affective Norms for English Words). Bayesian and frequentist analyses yielded evidence for the absence of within- and cross-languages effects of grammatical gender and sex- and age-dependent interactions. These results suggest that grammatical gender does not affect judgments of affective features of semantic representation in Italian and German speakers, since an overt coding of word grammar is not required. Although further research is recommended to refine the impact of the grammatical gender on properties of semantic representation, these results have implications for any strong view of the linguistic relativity hypothesis.

DOI: 10.1080/02699931.2018.1483322 PMID: 29873624 [Indexed for MEDLINE]

157. Phys Rev Lett. 2012 Nov 30;109(22):221102. doi: 10.1103/PhysRevLett.109.221102. Epub 2012 Nov 27.

Binary black-hole mergers in magnetized disks: simulations in full general relativity.

Farris BD(1), Gold R, Paschalidis V, Etienne ZB, Shapiro SL.

Author information: (1)Department of Physics, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA. bfarris2@illinois.edu

We present results from the first fully general relativistic, magnetohydrodynamic (MHD) simulations of an equal-mass black-hole binary (BHBH) in a magnetized, circumbinary accretion disk. We simulate both the pre- and postdecoupling phases of a BHBH-disk system and both "cooling" and "no-cooling" gas flows. Prior to decoupling, the competition between the binary tidal torques and the effective viscous torques due to MHD turbulence depletes the disk interior to the binary orbit. However, it also induces a two-stream accretion flow and mildly relativistic polar outflows from the BHs. Following decoupling, but before gas fills the low-density "hollow" surrounding the remnant, the accretion rate is reduced, while there is a prompt electromagnetic luminosity enhancement following merger due to shock heating and accretion onto the spinning BH remnant. This investigation, though preliminary, previews more detailed general relativistic, MHD simulations we plan to perform in anticipation of future, simultaneous detections of gravitational and electromagnetic radiation from a merging BHBH-disk system.

DOI: 10.1103/PhysRevLett.109.221102 PMID: 23368111

158. Iperception. 2019 Sep 12;10(5):2041669519872226. doi: 10.1177/2041669519872226. eCollection 2019 Sep-Oct.

Variation of Saturation Across Hue Affects Unique and Typical Hue Choices.

Witzel C(1).

Author information: (1)Justus-Liebig-Universität, Gießen, Germany.

Most studies on colour categorisation and many studies on unique hues have used samples of maximally saturated Munsell chips that vary in saturation across hue. Here we show that observers' choices of category prototypes and unique hues depend on the variation of Munsell chroma across hue. Both unique hue and prototype choices were shifted towards the more saturated hues in the respective stimulus set. This effect of saturation may explain cross-cultural regularities in colour categorisation. More generally, these findings highlight the importance of controlling saturation when measuring colour categories and unique hues.

DOI: 10.1177/2041669519872226 PMCID: PMC6743204 PMID: 31548872

159. Phys Rev Lett. 2018 Dec 7;121(23):231101. doi: 10.1103/PhysRevLett.121.231101.

Gravitational Redshift Test Using Eccentric Galileo Satellites.

Delva P(1), Puchades N(1)(2), Schönemann E(3), Dilssner F(3), Courde C(4), Bertone S(5), Gonzalez F(6), Hees A(1), Le Poncin-Lafitte C(1), Meynadier F(1), Prieto-Cerdeira R(6), Sohet B(1), Ventura-Traveset J(7), Wolf P(1).

Author information: (1)SYRTE, Observatoire de Paris, Université PSL, CNRS, Sorbonne Université, LNE, 61 avenue de l'Observatoire 75014 Paris, France. (2)Departamento de Astronomia y Astrofisica, Edificio de Investigación Jerónimo Muñoz, C/ Dr. Moliner, 50, 46100 Burjassot (Valencia), Spain. (3)European Space Operations Center, ESA/ESOC, 64293 Darmstadt, Germany. (4)UMR Geoazur, Université de Nice, Observatoire de la Côte d'Azur, 250 rue A. Einstein, F-06560 Valbonne, France. (5)Astronomical Institute, University of Bern, Sidlerstrasse 5 CH-3012 Bern, Switzerland. (6)European Space and Technology Centre, ESA/ESTEC, 2200 AG Noordwijk, Netherlands. (7)European Space and Astronomy Center, ESA/ESAC, 28692 Villanueva de la Cañada, Spain.

We report on a new test of the gravitational redshift and thus of local position invariance, an integral part of the Einstein equivalence principle, which is the foundation of general relativity and all metric theories of gravitation. We use data spanning 1008 days from two satellites of Galileo, Europe's global satellite navigation system, which were launched in 2014, but accidentally delivered on elliptic rather than circular orbits. The resulting modulation of the gravitational redshift of the onboard atomic clocks allows the redshift determination with high accuracy. Additionally, specific laser ranging campaigns to the two satellites have enabled a good estimation of systematic effects related to orbit uncertainties. Together with a careful conservative modeling and control of other systematic effects we measure the fractional deviation of the gravitational redshift from the prediction by general relativity to be (0.19±2.48)×10^{-5} at 1 sigma, improving the best previous test by a factor 5.6. To our knowledge, this represents the first reported improvement on one of the longest standing results in experimental gravitation, the Gravity Probe A hydrogen maser rocket experiment back in 1976.

DOI: 10.1103/PhysRevLett.121.231101 PMID: 30576203

160. Phys Rev Lett. 2017 Dec 22;119(25):251306. doi: 10.1103/PhysRevLett.119.251306. Epub 2017 Dec 22.

Gravitational Mechanisms to Self-Tune the Cosmological Constant: Obstructions and Ways Forward.

Niedermann F(1), Padilla A(1).

Author information: (1)School of Physics and Astronomy, University of Nottingham, Nottingham NG7 2RD, United Kingdom.

Gravitational models of self-tuning are those in which vacuum energy has no observable effect on spacetime curvature, even though it is a priori unsuppressed below the cutoff. We complement Weinberg's no-go theorem by studying field-theoretic completions of self-adjustment allowing for broken translations as well as other generalizations, and identify new obstructions. Our analysis uses a very general Källén-Lehmann spectral representation of the exchange amplitude for conserved sources of energy-momentum and exploits unitarity and Lorentz invariance to show that a transition from self-tuning of long wavelength sources to near general relativity (GR) on shorter scales is generically not possible. We search for novel ways around our obstructions and highlight two interesting possibilities. The first is an example of a unitary field configuration on anti-de Sitter space with the desired transition from self-tuning to GR. A second example is motivated by vacuum energy sequestering.

DOI: 10.1103/PhysRevLett.119.251306 PMID: 29303323

161. Ber Wiss. 2019 Dec;42(4):357-374. doi: 10.1002/bewi.201900011. Epub 2019 Dec 2.

Quantum Cultures during the Prehistory of Quantum Gravity: Léon Rosenfeld's Early Contributions to Quantum Gravity.

Peruzzi G(1), Rocci A(1).

Author information: (1)Department of Physics and Astronomy 'G. Galilei,', University of Padova, Italy.

In this paper we consider the prehistory of quantum gravity (1916-1930) from two perspectives. First, we investigate how this research field constituted itself and we propose for the first time a red thread to trace its evolution in this earliest period. Second, we focus on a case study: the earliest work of Léon Rosenfeld. In 1927 he tried to merge wave mechanics with general relativity in the context of a five-dimensional universe. We describe how Oskar Klein, Louis de Broglie, and Théophile De Donder influenced Rosenfeld's work and analyze how and why Rosenfeld attempted to reconcile Einstein's theory with quantum phenomena. We argue that Rosenfeld investigated for the first time the corrections to a classical space-time metric generated by a quantum source. As far as we know, Rosenfeld's approach has been largely ignored until today: he himself considered it "an accident." After having reconsidered its connection with de Broglie's ideas and Rosenfeld's interpretation of the wave function in 1927, we argue that Rosenfeld's work can be interpreted as a first attempt to introduce the pilot-wave theory in the context of quantum gravity and we infer that this was one of the reasons that ruled it out.

DOI: 10.1002/bewi.201900011 PMID: 31789468

162. Phys Rev Lett. 2001 Mar 5;86(10):1931-4. doi: 10.1103/PhysRevLett.86.1931.

Radiation reaction and the self-force for a point mass in general relativity.

Detweiler S(1).

Author information: (1)Department of Physics, P.O. Box 118440, University of Florida, Gainesville, Florida 32611-8440, USA.

A point particle of mass mu moving on a geodesic creates a perturbation h(mu), of the spacetime metric g(0), that diverges at the particle. Simple expressions are given for the singular mu/r part of h(mu) and its quadrupole distortion caused by the spacetime. Subtracting these from h(mu) leaves a remainder h(R) that is C1. The self-force on the particle from its own gravitational field corrects the world line at O(mu) to be a geodesic of g(0)+h(R). For the case that the particle is a small nonrotating black hole, an approximate solution to the Einstein equations is given with error of O(mu(2)) as mu-->0.

DOI: 10.1103/PhysRevLett.86.1931 PMID: 11289823

163. Phys Rev Lett. 2007 Jun 29;98(26):261101. doi: 10.1103/PhysRevLett.98.261101. Epub 2007 Jun 29.

3D collapse of rotating stellar iron cores in general relativity including deleptonization and a nuclear equation of state.

Ott CD(1), Dimmelmeier H, Marek A, Janka HT, Hawke I, Zink B, Schnetter E.

Author information: (1)Max-Planck-Institut für Gravitationsphysik, Albert-Einstein-Institut, Am Mühlenberg 1, D-14476 Potsdam, Germany.

We present 2D and 3D simulations of the collapse of rotating stellar iron cores in general relativity employing a nuclear equation of state and an approximate treatment of deleptonization. We compare fully general relativistic and conformally flat evolutions and find that the latter treatment is sufficiently accurate for the core-collapse supernova problem. We focus on gravitational wave (GW) emission from rotating collapse, bounce, and early postbounce phases. Our results indicate that the GW signature of these phases is much more generic than previously estimated. We also track the growth of a nonaxisymmetric instability in one model, leading to strong narrow-band GW emission.

DOI: 10.1103/PhysRevLett.98.261101 PMID: 17678077

164. Sci Total Environ. 2019 Feb 25;653:1262-1271. doi: 10.1016/j.scitotenv.2018.10.433. Epub 2018 Nov 5.

Generating hourly local weather data with high spatially resolution and the applications in bioclimatic performance.

Lin FY(1), Huang KT(2), Lin TP(1), Hwang RL(3).

Author information: (1)Department of Architecture, National Cheng Kung University, Taiwan. (2)Department of Bioenvironmental Systems Engineering, National Taiwan University, Taiwan. (3)Department of Industrial Technology Education, National Kaohsiung Normal University, Taiwan. Electronic address: rueylung@nknu.edu.tw.

As urbanization expands and diversifies, weather data produced by a single weather station in a suburb are no longer adequate to represent and reflect microclimatic changes of a city. This study selected 34 automatic weather stations in Tainan City, Taiwan, to conduct temperature and humidity measurements over a period of one year. Based on those observed weather data and urban environment parameters obtained from a geographic information system, as well as morphing approach, this study constructed a method of generating hourly local weather data for urban areas while accounting for urban heat island (UHI) effect in summer. Meanwhile, we discussed the relativities of the urban form and its structure against the variations of local hourly temperature and relative humidity under six buffer scenarios. Error analysis results revealed that minimal prediction errors can be obtained using the buffer scenario involving a 1000 × 1000 m2 four-layer buffer with inner and outer layers and upwind and downwind areas. Finally, using the hourly weather data produced for Tainan City, we calculated the long-term cumulative UHI intensity (UHII) and urban bioclimatic indexes (i.e., thermal stress, use of natural ventilation, and cooling degree day) and investigated how urban form and structure are related to UHII, thermal stress, use of natural ventilation, and cooling degree day. The results can inform urban policy making.

DOI: 10.1016/j.scitotenv.2018.10.433 PMID: 30759566

165. Proc Math Phys Eng Sci. 2017 Nov;473(2207):20160887. doi: 10.1098/rspa.2016.0887. Epub 2017 Nov 22.

An instability of the standard model of cosmology creates the anomalous acceleration without dark energy.

Smoller J(1), Temple B(2), Vogler Z(2).

Author information: (1)Department of Mathematics, University of Michigan, Ann Arbor, MI 48109, USA. (2)Department of Mathematics, University of California, Davis, CA 95616, USA.

We identify the condition for smoothness at the centre of spherically symmetric solutions of Einstein's original equations without the cosmological constant or dark energy. We use this to derive a universal phase portrait which describes general, smooth, spherically symmetric solutions near the centre of symmetry when the pressure p=0. In this phase portrait, the critical k=0 Friedmann space-time appears as a saddle rest point which is unstable to spherical perturbations. This raises the question as to whether the Friedmann space-time is observable by redshift versus luminosity measurements looking outwards from any point. The unstable manifold of the saddle rest point corresponding to Friedmann describes the evolution of local uniformly expanding space-times whose accelerations closely mimic the effects of dark energy. A unique simple wave perturbation from the radiation epoch is shown to trigger the instability, match the accelerations of dark energy up to second order and distinguish the theory from dark energy at third order. In this sense, anomalous accelerations are not only consistent with Einstein's original theory of general relativity, but are a prediction of it without the cosmological constant or dark energy.

DOI: 10.1098/rspa.2016.0887 PMCID: PMC5719618 PMID: 29225487

Conflict of interest statement: We have no competing interests.

166. Phys Rev Lett. 2016 Nov 18;117(21):211102. doi: 10.1103/PhysRevLett.117.211102. Epub 2016 Nov 16.

Radiative Screening of Fifth Forces.

Burrage C(1), Copeland EJ(1), Millington P(1).

Author information: (1)School of Physics and Astronomy, University of Nottingham, Nottingham NG7 2RD, United Kingdom.

We describe a symmetron model in which the screening of fifth forces arises at the one-loop level through the Coleman-Weinberg mechanism of spontaneous symmetry breaking. We show that such a theory can avoid current constraints on the existence of fifth forces but still has the potential to give rise to observable deviations from general relativity, which could be seen in cold atom experiments.

DOI: 10.1103/PhysRevLett.117.211102 PMID: 27911565

167. Eur Phys J C Part Fields. 2018;78(6):474. doi: 10.1140/epjc/s10052-018-5967-x. Epub 2018 Jun 9.

Gravitational waves in modified teleparallel theories of gravity.

Abedi H(1), Capozziello S(2)(3)(4)(5).

Author information: (1)1Department of Physics, University of Tehran, North Kargar Ave, Tehran, Iran. (2)2Dipartimento di Fisica, Università di Napoli "Federico II", Via Cinthia, 80126 Naples, Italy. (3)3Istituto Nazionale di Fisica Nucleare (INFN), Sez. di Napoli, Via Cinthia, Naples, Italy. (4)4Gran Sasso Science Institute, Via F. Crispi 7, 67100 L'Aquila, Italy. (5)5Tomsk State Pedagogical University, Ul. Kievskaya, 60, Tomsk, 634061 Russia.

Teleparallel theory of gravity and its modifications have been studied extensively in literature. However, gravitational waves has not been studied enough in the framework of teleparallelism. In the present study, we discuss gravitational waves in general theories of teleparallel gravity containing the torsion scalar T, the boundary term B and a scalar field ϕ . The goal is to classify possible new polarizations generalizing results presented in Bamba et al. (Phys Lett B 727:194-198, arXiv:1309.2698, 2013). We show that, if the boundary term is minimally coupled to the torsion scalar and the scalar field, gravitational waves have the same polarization modes of General Relativity.

DOI: 10.1140/epjc/s10052-018-5967-x PMCID: PMC5994224 PMID: 29937692

168. Phys Rev Lett. 2012 Jul 13;109(2):021101. doi: 10.1103/PhysRevLett.109.021101. Epub 2012 Jul 10.

New insights on the matter-gravity coupling paradigm.

Delsate T(1), Steinhoff J.

Author information: (1)CENTRA, Instituto Superior Técnico, Avenida Rovisco Pais 1, 1049-001 Lisbon, Portugal, EU.

The coupling between matter and gravity in general relativity is given by a proportionality relation between the stress tensor and the geometry. This is an oriented assumption driven by the fact that both the stress tensor and the Einstein tensor are divergenceless. However, general relativity is in essence a nonlinear theory, so there is no obvious reason why the coupling to matter should be linear. On another hand, modified theories of gravity usually affect the vacuum dynamics, yet keep the coupling to matter linear. In this Letter, we address the implications of consistent nonlinear gravity-matter coupling. The Eddington-inspired Born-Infeld theory recently introduced by Bañados and Ferreira provides an enlightening realization of such coupling modifications. We find that this theory coupled to a perfect fluid reduces to general relativity coupled to a nonlinearly modified perfect fluid, leading to an ambiguity between modified coupling and modified equation of state. We discuss observational consequences of this degeneracy and argue that such a completion of general relativity is viable from both an experimental and theoretical point of view through energy conditions, consistency, and singularity-avoidance perspectives. We use these results to discuss the impact of changing the coupling paradigm.

DOI: 10.1103/PhysRevLett.109.021101 PMID: 23030149

169. Phys Rev Lett. 2014 Dec 31;113(26):261103. doi: 10.1103/PhysRevLett.113.261103. Epub 2014 Dec 31.

Taming the nonlinearity of the Einstein equation.

Harte AI(1).

Author information: (1)Max-Planck-Institut für Gravitationsphysik, Albert-Einstein-Institut Am Mühlenberg 1, 14476 Golm, Germany.

Many of the technical complications associated with the general theory of relativity ultimately stem from the nonlinearity of Einstein's equation. It is shown here that an appropriate choice of dynamical variables may be used to eliminate all such nonlinearities beyond a particular order: Both Landau-Lifshitz and tetrad formulations of Einstein's equation are obtained that involve only finite products of the unknowns and their derivatives. Considerable additional simplifications arise in physically interesting cases where metrics become approximately Kerr or, e.g., plane waves, suggesting that the variables described here can be used to efficiently reformulate perturbation theory in a variety of contexts. In all cases, these variables are shown to have simple geometrical interpretations that directly relate the local causal structure associated with the metric of interest to the causal structure associated with a prescribed background. A new method to search for exact solutions is outlined as well.

DOI: 10.1103/PhysRevLett.113.261103 PMID: 25615299

170. Phys Rev Lett. 2018 Dec 21;121(25):251101. doi: 10.1103/PhysRevLett.121.251101.

From Scattering Amplitudes to Classical Potentials in the Post-Minkowskian Expansion.

Cheung C(1), Rothstein IZ(2), Solon MP(1).

Author information: (1)Walter Burke Institute for Theoretical Physics, California Institute of Technology, Pasadena, California 91125, USA. (2)Department of Physics, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, USA.

We combine tools from effective field theory and generalized unitarity to construct a map between on-shell scattering amplitudes and the classical potential for interacting spinless particles. For general relativity, we obtain analytic expressions for the classical potential of a binary black hole system at second order in the gravitational constant and all orders in velocity. Our results exactly match all known results up to fourth post-Newtonian order, and offer a simple check of future higher order calculations. By design, these methods should extend to higher orders in perturbation theory.

DOI: 10.1103/PhysRevLett.121.251101 PMID: 30608807

171. Phys Rev Lett. 2002 May 6;88(18):181301. doi: 10.1103/PhysRevLett.88.181301. Epub 2002 Apr 22.

Conservation laws for collisions of branes and shells in general relativity.

Langlois D(1), Maeda K, Wands D.

Author information: (1)Institut d'Astrophysique de Paris (CNRS), 98 bis Boulevard Arago, 75014 Paris, France.

We consider the collision of self-gravitating n-branes in a (n+2)-dimensional spacetime. We show that there is a geometrical constraint which can be expressed as a simple sum rule for angles characterizing Lorentz boosts between branes and the intervening spacetime regions. This constraint can then be reinterpreted as either energy or momentum conservation at the collision.

DOI: 10.1103/PhysRevLett.88.181301 PMID: 12005673

172. Living Rev Relativ. 2007;10(1):5. doi: 10.12942/lrr-2007-5. Epub 2007 Dec 11.

Critical Phenomena in Gravitational Collapse.

Gundlach C(1), Martín-García JM(2)(3).

Author information: (1)School of Mathematics, University of Southampton, Southampton, SO17 1BJ UK. (2)Institut d'Astrophysique de Paris CNRS & Université Pierre et Marie Curie, 98 bis boulevard Arago, 75014 Paris, France. (3)Laboratoire Univers et Théories CNRS & Université Paris Diderot, 5 place Jules Janssen, 92190 Meudon, France.

As first discovered by Choptuik, the black hole threshold in the space of initial data for general relativity shows both surprising structure and surprising simplicity. Universality, power-law scaling of the black hole mass, and scale echoing have given rise to the term "critical phenomena". They are explained by the existence of exact solutions which are attractors within the black hole threshold, that is, attractors of codimension one in phase space, and which are typically self-similar. Critical phenomena give a natural route from smooth initial data to arbitrarily large curvatures visible from infinity, and are therefore likely to be relevant for cosmic censorship, quantum gravity, astrophysics, and our general understanding of the dynamics of general relativity.

DOI: 10.12942/lrr-2007-5 PMCID: PMC5256106 PMID: 28179820

173. J Comput Chem. 2018 Jun 30;39(17):1051-1058. doi: 10.1002/jcc.25135. Epub 2018 Jan 9.

The general setting for the zero-flux condition: The lagrangian and zero-flux conditions that give the heisenberg equation of motion.

Anderson JSM(1)(2)(3), Ayers PW(1).

Author information: (1)Department of Chemistry & Chemical Biology, McMaster University, Hamilton, Ontario, Canada. (2)iTHES Research Group, RIKEN, 2-1, Hirosawa, Wako-shi, Saitama, 351-0198, Japan. (3)Department of Chemical System Engineering, School of Engineering, University of Tokyo, 7-3-1, Hongo, Bunkyo-ku, Tokyo, 113-8656, Japan.

Generalizing our recent work on relativistic generalizations of the quantum theory of atoms in molecules, we present the general setting under which the principle of stationary action for a region leads to open quantum subsystems. The approach presented here is general and works for any Hamiltonian, and when a reasonable Lagrangian is selected, it often leads to the integral of the Laplacian of the electron density on the region vanishing as a necessary condition for the zero-flux surface. Alternatively, with this method, one can design a Lagrangian that leads to a surface of interest (though this Lagrangian may not be, and indeed probably will not be, "reasonable"). For any reasonable Lagrangian for the electronic wave function and any two-component method (related by integration by parts to the Hamiltonian) considered, the Bader definition of an atom is recaptured. © 2018 Wiley Periodicals, Inc.

DOI: 10.1002/jcc.25135 PMID: 29315672

174. Living Rev Relativ. 2001;4(1):3. doi: 10.12942/lrr-2001-3. Epub 2001 Mar 20.

Characteristic Evolution and Matching.

Winicour J(1).

Author information: (1)Max-Planck-Institut für Gravitationsphysik, Albert-Einstein-Institut, 14476 Golm, Germany.

I review the development of numerical evolution codes for general relativity based upon the characteristic initial value problem. Progress is traced from the early stage of 1D feasibility studies to current 3D codes that simulate binary black holes. A prime application of characteristic evolution is Cauchy-characteristic matching, which is also reviewed.

DOI: 10.12942/lrr-2001-3 PMCID: PMC5253873 PMID: 28163631

175. Philos Trans A Math Phys Eng Sci. 2020 May;378(2170):20190175. doi: 10.1098/rsta.2019.0175. Epub 2020 Mar 30.

A new continuum model for general relativistic viscous heat-conducting media.

Romenski E(1)(2), Peshkov I(3), Dumbser M(3), Fambri F(4).

Author information: (1)Sobolev Institute of Mathematics, 4 Acad. Koptyug Avenue, Novosibirsk 630090, Russia. (2)Novosibirsk State University, 1 Pirogova st., Novosibirsk 630090, Russia. (3)Laboratory of Applied Mathematics, University of Trento, Via Mesiano 77, Trento 38123, Italy. (4)Max-Planck Institute for Plasma Physics, Boltzmannstr. 2, Garching 85748, Germany.

The lack of formulation of macroscopic equations for irreversible dynamics of viscous heat-conducting media compatible with the causality principle of Einstein's special relativity and the Euler-Lagrange structure of general relativity is a long-lasting problem. In this paper, we propose a possible solution to this problem in the framework of SHTC equations. The approach does not rely on postulates of equilibrium irreversible thermodynamics but treats irreversible processes from the non-equilibrium point of view. Thus, each transfer process is characterized by a characteristic velocity of perturbation propagation in the non-equilibrium state, as well as by an intrinsic time/length scale of the dissipative dynamics. The resulting system of governing equations is formulated as a first-order system of hyperbolic equations with relaxation-type irreversible terms. Via a formal asymptotic analysis, we demonstrate that classical transport coefficients such as viscosity, heat conductivity, etc., are recovered in leading terms of our theory as effective transport coefficients. Some numerical examples are presented in order to demonstrate the viability of the approach. This article is part of the theme issue 'Fundamental aspects of nonequilibrium thermodynamics'.

DOI: 10.1098/rsta.2019.0175 PMCID: PMC7134950 PMID: 32223401

Conflict of interest statement: The authors declare that they have no competing interests.

176. Ann N Y Acad Sci. 2014 Oct;1326:42-59. doi: 10.1111/nyas.12510. Epub 2014 Sep 29.

Problem of time: facets and Machian strategy.

Anderson E(1).

Author information: (1)Centre for Theoretical Cosmology, DAMTP, University of Cambridge, Cambridge, United Kingdom.

The problem of time is that "time" in each of ordinary quantum theory and general relativity are mutually incompatible notions. This causes difficulties in trying to put these two theories together to form a theory of quantum gravity. The problem of time has eight facets in canonical approaches. I clarify that all but one of these facets already occur at the classical level, and reconceptualize and re-name some of these facets as follows. The frozen formalism problem becomes temporal relationalism, the thin sandwich problem becomes configurational relationalism, via the notion of best matching. The problem of observables becomes the problem of beables, and the functional evolution problem becomes the constraint closure problem. I also outline how each of the global and multiple-choice problems of time have their own plurality of facets. This article additionally contains a local resolution to the problem of time at the conceptual level and which is actually realizable for the relational triangle and minisuperspace models. This resolution is, moreover, Machian, and has three levels: classical, semiclassical, and a combined semiclassical-histories-timeless records scheme. I end by delineating the current frontiers of this program toward resolution of the problem of time in the cases of full general relativity and of slightly inhomogeneous cosmology.

DOI: 10.1111/nyas.12510 PMID: 25266113 [Indexed for MEDLINE]

177. Phys Rev Lett. 2018 May 18;120(20):201104. doi: 10.1103/PhysRevLett.120.201104.

New Class of Quasinormal Modes of Neutron Stars in Scalar-Tensor Gravity.

Mendes RFP(1), Ortiz N(2).

Author information: (1)Instituto de Física, Universidade Federal Fluminense, Av. Gal. Milton Tavares de Souza s/n, Gragoatá, 24210-346 Niterói, Rio de Janeiro, Brazil. (2)Perimeter Institute for Theoretical Physics, 31 Caroline Street North, Waterloo, Ontario N2L 2Y5, Canada.

Detection of the characteristic spectrum of pulsating neutron stars can be a powerful tool not only to probe the nuclear equation of state but also to test modifications to general relativity. However, the shift in the oscillation spectrum induced by modified theories of gravity is often small and degenerate with our ignorance of the equation of state. In this Letter, we show that the coupling to additional degrees of freedom present in modified theories of gravity can give rise to new families of modes, with no counterpart in general relativity, which could be sufficiently well resolved in frequency space to allow for clear detection. We present a realization of this idea by performing a thorough study of radial oscillations of neutron stars in massless scalar-tensor theories of gravity. We anticipate astrophysical scenarios where the presence of this class of quasinormal modes could be probed with electromagnetic and gravitational wave measurements.

DOI: 10.1103/PhysRevLett.120.201104 PMID: 29864365

178. Phys Rev Lett. 2018 Aug 17;121(7):071102. doi: 10.1103/PhysRevLett.121.071102.

Testing Gravitational Memory Generation with Compact Binary Mergers.

Yang H(1)(2), Martynov D(3)(4).

Author information: (1)Perimeter Institute for Theoretical Physics, Waterloo, Ontario N2L2Y5, Canada. (2)University of Guelph, Guelph, Ontario N2L3G1, Canada. (3)LIGO, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA. (4)School of Physics and Astronomy and Institute of Gravitational Wave Astronomy, University of Birmingham, Edgbaston, Birmingham B15 2TT, United Kingdom.

Gravitational memory is an important prediction of General Relativity, which is intimately related to asymptotic symmetries at null infinity and the so-called soft graviton theorem. For a given transient astronomical event, the angular distribution of energy and angular momentum fluxes uniquely determine the displacement and spin memory effect in the sky. We investigate the possibility of using the binary black hole merger events detected by Advanced LIGO/Virgo to test the relation between the source's energy emission and the gravitational memory measured on Earth, as predicted by General Relativity. We find that while it is difficult for Advanced LIGO/Virgo one-year detection of a third-generation detector network will easily rule out the hypothesis assuming isotropic memory distribution. In addition, we construct a phenomenological model for memory waveforms of binary neutron star mergers and use it to address the detectability of memory from these events in the third-generation detector era. We find that measuring gravitational memory from neutron star mergers is a possible way to distinguish between different neutron star equations of state.

DOI: 10.1103/PhysRevLett.121.071102 PMID: 30169084

179. Phys Rev Lett. 2000 Dec 18;85(25):5272-5. doi: 10.1103/PhysRevLett.85.5272.

Making classical and quantum canonical general relativity computable through a power series expansion in the inverse cosmological constant.

Gambini R(1), Pullin J.

Author information: (1)Instituto de Física, Facultad de Ciencias, Iguá 4225, esq. Mataojo, Montevideo, Uruguay.

We consider general relativity with a cosmological constant as a perturbative expansion around a completely solvable diffeomorphism invariant field theory. This theory is the lambda --> infinity limit of general relativity. This allows an explicit perturbative computational setup in which the quantum states of the theory and the classical observables can be explicitly computed. An unexpected relationship arises at a quantum level between the discrete spectrum of the volume operator and the allowed values of the cosmological constant.

DOI: 10.1103/PhysRevLett.85.5272 PMID: 11135974

180. Science. 2004 Apr 23;304(5670):547-52. doi: 10.1126/science.1096986.

Pulsars in binary systems: probing binary stellar evolution and general relativity.

Stairs IH(1).

Author information: (1)Department of Physics and Astronomy, University of British Columbia, 6224 Agricultural Road, Vancouver, BC V6T 1Z1, Canada. stairs@astro.ubc.ca

Radio pulsars in binary orbits often have short millisecond spin periods as a result of mass transfer from their companion stars. They therefore act as very precise, stable, moving clocks that allow us to investigate a large set of otherwise inaccessible astrophysical problems. The orbital parameters derived from high-precision binary pulsar timing provide constraints on binary evolution, characteristics of the binary pulsar population, and the masses of neutron stars with different mass-transfer histories. These binary systems also test gravitational theories, setting strong limits on deviations from general relativity. Surveys for new pulsars yield new binary systems that increase our understanding of all these fields and may open up whole new areas of physics, as most spectacularly evidenced by the recent discovery of an extremely relativistic double-pulsar system.

DOI: 10.1126/science.1096986 PMID: 15105492

181. Macromol Rapid Commun. 2016 May;37(9):769-74. doi: 10.1002/marc.201600057. Epub 2016 Mar 29.

Polyphosphazene Based Star-Branched and Dendritic Molecular Brushes.

Henke H(1), Posch S(2), Brüggemann O(1), Teasdale I(1).

Author information: (1)Institute of Polymer Chemistry, Johannes Kepler University Linz, Altenberger Straße 69, ,4040, Linz, Austria. (2)Department of Applied Experimental Biophysics, Institute of Biophysics, Johannes Kepler University Linz, Gruberstraße 40, ,4020, Linz, Austria.

A new synthetic procedure is described for the preparation of poly(organo)phosphazenes with star-branched and star dendritic molecular brush type structures, thus describing the first time it has been possible to prepare controlled, highly branched architectures for this type of polymer. Furthermore, as a result of the extremely high-arm density generated by the phosphazene repeat unit, the second-generation structures represent quite unique architectures for any type of polymer. Using two relativity straight forward iterative syntheses it is possible to prepare globular highly branched polymers with up to 30 000 functional end groups, while keeping relatively narrow polydispersities (1.2-1.6). Phosphine mediated polymerization of chlorophosphoranimine is first used to prepare three-arm star polymers. Subsequent substitution with diphenylphosphine moieties gives poly(organo)phosphazenes to function as multifunctional macroinitiators for the growth of a second generation of polyphosphazene arms. Macrosubstitution with Jeffamine oligomers gives a series of large, water soluble branched macromolecules with high-arm density and hydrodynamic diameters between 10 and 70 nm.

DOI: 10.1002/marc.201600057 PMCID: PMC4907350 PMID: 27027404 [Indexed for MEDLINE]

182. Nat Commun. 2011 Oct 18;2:505. doi: 10.1038/ncomms1498.

Quantum interferometric visibility as a witness of general relativistic proper time.

Zych M(1), Costa F, Pikovski I, Brukner Č.

Author information: (1)Faculty of Physics, University of Vienna, Boltzmanngasse 5, 1090 Vienna, Austria. magdalena.zych@univie.ac.at

Current attempts to probe general relativistic effects in quantum mechanics focus on precision measurements of phase shifts in matter-wave interferometry. Yet, phase shifts can always be explained as arising because of an Aharonov-Bohm effect, where a particle in a flat space-time is subject to an effective potential. Here we propose a quantum effect that cannot be explained without the general relativistic notion of proper time. We consider interference of a 'clock'-a particle with evolving internal degrees of freedom-that will not only display a phase shift, but also reduce the visibility of the interference pattern. According to general relativity, proper time flows at different rates in different regions of space-time. Therefore, because of quantum complementarity, the visibility will drop to the extent to which the path information becomes available from reading out the proper time from the 'clock'. Such a gravitationally induced decoherence would provide the first test of the genuine general relativistic notion of proper time in quantum mechanics.

DOI: 10.1038/ncomms1498 PMCID: PMC3221301 PMID: 22009037

183. Ann PDE. 2019;5(1):2. doi: 10.1007/s40818-018-0058-8. Epub 2019 Jan 8.

Boundedness and Decay for the Teukolsky Equation on Kerr Spacetimes I: The Case |a| ≪ M.

Dafermos M(1)(2), Holzegel G(3), Rodnianski I(2).

Author information: (1)1Department of Pure Mathematics and Mathematical Statistics, University of Cambridge, Wilberforce Road, Cambridge, CB3 0WA UK. (2)2Department of Mathematics, Princeton University, Fine Hall, Washington Road, Princeton, NJ 08544 USA. (3)3Department of Mathematics, Imperial College London, South Kensington Campus, London, SW7 2AZ UK.

We prove boundedness and polynomial decay statements for solutions of the spin ± 2 Teukolsky equation on a Kerr exterior background with parameters satisfying |a| ≪ M . The bounds are obtained by introducing generalisations of the higher order quantities P and P_ used in our previous work on the linear stability of Schwarzschild. The existence of these quantities in the Schwarzschild case is related to the transformation theory of Chandrasekhar. In a followup paper, we shall extend this result to the general sub-extremal range of parameters |a| < M . As in the Schwarzschild case, these bounds provide the first step in proving the full linear stability of the Kerr metric to gravitational perturbations.

DOI: 10.1007/s40818-018-0058-8 PMCID: PMC6499082 PMID: 31119213

184. Eur Phys J C Part Fields. 2018;78(7):586. doi: 10.1140/epjc/s10052-018-6064-x. Epub 2018 Jul 20.

Static and slowly rotating neutron stars in scalar-tensor theory with self-interacting massive scalar field.

Staykov KV(1), Popchev D(1), Doneva DD(2)(3), Yazadjiev SS(1)(4).

Author information: (1)1Department of Theoretical Physics, Faculty of Physics, Sofia University, 1164 Sofia, Bulgaria. (2)2Theoretical Astrophysics, Eberhard Karls University of Tübingen, 72076 Tübingen, Germany. (3)3INRNE, Bulgarian Academy of Sciences, 1784 Sofia, Bulgaria. (4)4Institute of Mathematics and Informatics, Bulgarian Academy of Sciences, Acad. G. Bonchev Street 8, 1113 Sofia, Bulgaria.

Binary pulsar observations and gravitational wave detections seriously constrained scalar-tensor theories with massless scalar field allowing only small deviations from general relativity. If we consider a nonzero mass of the scalar field, though, significant deviations from general relativity are allowed for values of the parameters that are in agreement with the observations. In the present paper we extend this idea and we study scalar-tensor theory with massive field with self-interaction term in the potential. The additional term suppresses the scalar field in the neutron star models in addition to the effect of the mass of the scalar field but still, large deviations from pure GR can be observed for values of the parameters that are in agreement with the observations.

DOI: 10.1140/epjc/s10052-018-6064-x PMCID: PMC6061109 PMID: 30100815

185. Phys Rev E. 2017 Jul;96(1-1):012211. doi: 10.1103/PhysRevE.96.012211. Epub 2017 Jul 14.

Properties and relative measure for quantifying quantum synchronization.

Li W(1), Zhang W(2), Li C(1), Song H(1).

Author information: (1)School of Physics, Dalian University of Technology, Dalian 116024, China. (2)Beijing Computational Science Research Center, Beijing 100193, China.

Although quantum synchronization phenomena and corresponding measures have been widely discussed recently, it is still an open question how to characterize directly the influence of nonlocal correlation, which is the key distinction for identifying classical and quantum synchronizations. In this paper, we present basic postulates for quantifying quantum synchronization based on the related theory in Mari's work [Phys. Rev. Lett. 111, 103605 (2013)PRLTAO0031-900710.1103/PhysRevLett.111.103605], and we give a general formula of a quantum synchronization measure with clear physical interpretations. By introducing Pearson's parameter, we show that the obvious characteristics of our measure are the relativity and monotonicity. As an example, the measure is applied to describe synchronization among quantum optomechanical systems under a Markovian bath. We also show the potential by quantifying generalized synchronization and discrete variable synchronization with this measure.

DOI: 10.1103/PhysRevE.96.012211 PMID: 29347171

186. Philos Trans R Soc Lond B Biol Sci. 2010 Jan 12;365(1537):133-45. doi: 10.1098/rstb.2009.0154.

Evolution: like any other science it is predictable.

Morris SC(1).

Author information: (1)Department of Earth Sciences, University of Cambridge, Cambridge, UK. sc113@esc.cam.ac.uk

Evolutionary biology rejoices in the diversity of life, but this comes at a cost: other than working in the common framework of neo-Darwinian evolution, specialists in, for example, diatoms and mammals have little to say to each other. Accordingly, their research tends to track the particularities and peculiarities of a given group and seldom enquires whether there are any wider or deeper sets of explanations. Here, I present evidence in support of the heterodox idea that evolution might look to a general theory that does more than serve as a tautology ('evolution explains evolution'). Specifically, I argue that far from its myriad of products being fortuitous and accidental, evolution is remarkably predictable. Thus, I urge a move away from the continuing obsession with Darwinian mechanisms, which are entirely uncontroversial. Rather, I emphasize why we should seek explanations for ubiquitous evolutionary convergence, as well as the emergence of complex integrated systems. At present, evolutionary theory seems to be akin to nineteenth-century physics, blissfully unaware of the imminent arrival of quantum mechanics and general relativity. Physics had its Newton, biology its Darwin: evolutionary biology now awaits its Einstein.

DOI: 10.1098/rstb.2009.0154 PMCID: PMC2842699 PMID: 20008391 [Indexed for MEDLINE]

187. Phys Rev Lett. 2018 Sep 28;121(13):131104. doi: 10.1103/PhysRevLett.121.131104.

Massive Boson Superradiant Instability of Black Holes: Nonlinear Growth, Saturation, and Gravitational Radiation.

East WE(1).

Author information: (1)Perimeter Institute for Theoretical Physics, Waterloo, Ontario N2L 2Y5, Canada.

We study the superradiant instability of a massive boson around a spinning black hole in full general relativity without assuming spatial symmetries. We focus on the case of a rapidly spinning black hole in the presence of a vector boson with a Compton wavelength comparable to the black hole radius, which is the regime where relativistic effects are maximized. We follow the growth of the boson cloud through superradiance into the nonlinear regime as it spins down the black hole, reaches a maximum energy, and begins to dissipate through the emission of gravitational waves. We find that the superradiant instability can efficiently convert a significant fraction of a black hole's rotational energy into gravitational radiation.

DOI: 10.1103/PhysRevLett.121.131104 PMID: 30312089

188. Phys Rev Lett. 2002 Dec 30;89(27):271101. doi: 10.1103/PhysRevLett.89.271101. Epub 2002 Dec 19.

A radiation scalar for numerical relativity.

Beetle C(1), Burko LM.

Author information: (1)Department of Physics, University of Utah, Salt Lake City, UT 84112, USA.

This Letter describes a scalar curvature invariant for general relativity with a certain, distinctive feature. While many such invariants exist, this one vanishes in regions of space-time which can be said unambiguously to contain no gravitational radiation. In more general regions which incontrovertibly support nontrivial radiation fields, it can be used to extract local, coordinate-independent information partially characterizing that radiation. While a clear, physical interpretation is possible only in such radiation zones, a simple algorithm can be given to extend the definition smoothly to generic regions of space-time.

DOI: 10.1103/PhysRevLett.89.271101 PMID: 12513189

189. Phys Rev Lett. 2018 Mar 30;120(13):131101. doi: 10.1103/PhysRevLett.120.131101.

Fate of Large-Scale Structure in Modified Gravity After GW170817 and GRB170817A.

Amendola L(1), Kunz M(2), Saltas ID(3), Sawicki I(3).

Author information: (1)InstiQuai Ernest Ansermettut für Theoretische Physik, Ruprecht-Karls-Universität Heidelberg, Philosophenweg 16, 69120 Heidelberg, Germany. (2)Départment de Physique Théorique and Center for Astroparticle Physics, Université de Genève, Quai Ernest Ansermet 24, CH-1211 Genéve 4, Switzerland. (3)CEICO, Institute of Physics of the Czech Academy of Sciences, Na Slovance 2, 182 21 Praha 8, Czechia.

The coincident detection of gravitational waves (GW) and a gamma-ray burst from a merger of neutron stars has placed an extremely stringent bound on the speed of GWs. We showed previously that the presence of gravitational slip (η) in cosmology is intimately tied to modifications of GW propagation. This new constraint implies that the only remaining viable source of gravitational slip is a conformal coupling to gravity in scalar-tensor theories, while viable vector-tensor theories cannot now generate gravitational slip at all. We discuss structure formation in the remaining viable models, demonstrating that (i) the dark-matter growth rate must now be at least as fast as in general relativity (GR), with the possible exception of that beyond the Horndeski model, and (ii) if there is any scale dependence at all in the slip parameter, it is such that it takes the GR value at large scales. We show a consistency relation that must be violated if gravity is modified.

DOI: 10.1103/PhysRevLett.120.131101 PMID: 29694183

190. Phys Rev Lett. 2019 Jan 11;122(1):011101. doi: 10.1103/PhysRevLett.122.011101.

High-Accuracy Mass, Spin, and Recoil Predictions of Generic Black-Hole Merger Remnants.

Varma V(1), Gerosa D(1), Stein LC(1)(2), Hébert F(1), Zhang H(1)(3).

Author information: (1)TAPIR 350-17, California Institute of Technology, 1200 E California Boulevard, Pasadena, California 91125, USA. (2)Department of Physics and Astronomy, The University of Mississippi, University, Mississippi 38677, USA. (3)Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA.

We present accurate fits for the remnant properties of generically precessing binary black holes, trained on large banks of numerical-relativity simulations. We use Gaussian process regression to interpolate the remnant mass, spin, and recoil velocity in the seven-dimensional parameter space of precessing black-hole binaries with mass ratios q≤2, and spin magnitudes χ_{1}, χ_{2}≤0.8. For precessing systems, our errors in estimating the remnant mass, spin magnitude, and kick magnitude are lower than those of existing fitting formulae by at least an order of magnitude (improvement is also reported in the extrapolated region at high mass ratios and spins). In addition, we also model the remnant spin and kick directions. Being trained directly on precessing simulations, our fits are free from ambiguities regarding the initial frequency at which precessing quantities are defined. We also construct a model for remnant properties of aligned-spin systems with mass ratios q≤8, and spin magnitudes χ_{1}, χ_{2}≤0.8. As a byproduct, we also provide error estimates for all fitted quantities, which can be consistently incorporated into current and future gravitational-wave parameter-estimation analyses. Our model(s) are made publicly available through a fast and easy-to-use Python module called surfinBH.

DOI: 10.1103/PhysRevLett.122.011101 PMID: 31012642

191. Opt Express. 2018 Dec 10;26(25):33263-33277. doi: 10.1364/OE.26.033263.

Generalization of Wolf effect of light on arbitrary two-dimensional surface of revolution.

Xu C, Abbas A, Wang LG.

Investigation of physics on two-dimensional curved surface has significant meaning in study of general relativity, inasmuch as its realizability in experimental analogy and verification of faint gravitational effects in laboratory. Several phenomena about dynamics of particles and electromagnetic waves have been explored on curved surfaces. Here we consider Wolf effect, a phenomenon of spectral shift due to the fluctuating nature of light fields, on an arbitrary surface of revolution (SOR). The general expression of the propagation of partially coherent beams propagating on arbitrary SOR is derived and the corresponding evolution of light spectrum is also obtained. We investigate the extra influence of surface topology on spectral shift by defining two quantities, effective propagation distance and effective transverse distance, and compare them with longitudinal and transverse proper lengths. Spectral shift is accelerated when the defined effective quantities are greater than real proper lengths, and vice versa. We also employ some typical SORs, cylindrical surfaces, conical surfaces, SORs generated by power function and periodic peanut-shell shapes, as examples to provide concrete analyses. This work generalizes the research of Wolf effect to arbitrary SORs, and provides a universal method for analyzing properties of propagation compared with that in flat space for any SOR whose topology is known.

DOI: 10.1364/OE.26.033263 PMID: 30645482

192. Interface Focus. 2012 Feb 6;2(1):55-64. doi: 10.1098/rsfs.2011.0067. Epub 2011 Nov 9.

A theory of biological relativity: no privileged level of causation.

Noble D(1).

Author information: (1)Department of Physiology , Anatomy and Genetics , University of Oxford, Parks Road, Oxford OX1 3PT , UK.

Must higher level biological processes always be derivable from lower level data and mechanisms, as assumed by the idea that an organism is completely defined by its genome? Or are higher level properties necessarily also causes of lower level behaviour, involving actions and interactions both ways? This article uses modelling of the heart, and its experimental basis, to show that downward causation is necessary and that this form of causation can be represented as the influences of initial and boundary conditions on the solutions of the differential equations used to represent the lower level processes. These insights are then generalized. A priori, there is no privileged level of causation. The relations between this form of 'biological relativity' and forms of relativity in physics are discussed. Biological relativity can be seen as an extension of the relativity principle by avoiding the assumption that there is a privileged scale at which biological functions are determined.

DOI: 10.1098/rsfs.2011.0067 PMCID: PMC3262309 PMID: 23386960

193. Front Psychol. 2019 Dec 3;10:2706. doi: 10.3389/fpsyg.2019.02706. eCollection 2019.

Cognitive Representation of Spontaneous Motion in a Second Language: An Exploration of Chinese Learners of English.

Ji Y(1).

Author information: (1)School of Arts and Humanities, Shenzhen University, Shenzhen, China.

This study tests whether Chinese learners of English can reconstruct their cognitive pattern in the direction of the target system when judging the similarity between spontaneous motion screens in a match-to-sample task. English main verbs encode Manner of motion only, while Chinese verb compounds express Manner and Path simultaneously. Chinese monolinguals are thus predicted to develop a motion cognition pattern highlighting both Manner and Path salience whereas English monolinguals are more likely to be Manner-oriented. Our research findings are twofold. First, when assessed by the explicit measure of selection strategies (i.e., either Manner-match or Path-match), both monolingual and L2 learners show a general preference for the Path-match. However, when gauged by the implicit measure of processing speed (i.e., reaction time), Chinese monolinguals reacted significantly quicker than their English counterparts, particularly in making Path-matched judgments. Further, the L2 English learners across proficiencies responded significantly more slowly than their monolingual counterparts even at an advanced stage of acquisition, suggesting that the process of conceptual reconstructing, as demonstrated in our experiment, can be cognitively demanding and needs a longer period of time to complete. These findings are generally consistent with a weak version of the linguistic relativity hypothesis.

DOI: 10.3389/fpsyg.2019.02706 PMCID: PMC6902645 PMID: 31849795

194. Phys Rev Lett. 2018 Jun 1;120(22):221101. doi: 10.1103/PhysRevLett.120.221101.

Convective Excitation of Inertial Modes in Binary Neutron Star Mergers.

De Pietri R(1)(2), Feo A(2)(3), Font JA(4)(5), Löffler F(6)(7), Maione F(1)(2), Pasquali M(1)(2), Stergioulas N(8).

Author information: (1)Parma University, Parco Area delle Scienze 7/A, I-43124 Parma (PR), Italy. (2)INFN gruppo collegato di Parma, Parco Area delle Scienze 7/A, I-43124 Parma (PR), Italy. (3)Department of Chemistry, Life Sciences and Environmental Sustainability, Parma University, Parco Area delle Scienze, 157/A, I-43124 Parma (PR), Italy. (4)Departamento de Astronomía y Astrofísica, Universitat de València, Dr. Moliner 50, 46100 Burjassot (València), Spain. (5)Observatori Astronòmic, Universitat de València, C/ Catedrático José Beltrán 2, 46980 Paterna (València), Spain. (6)Heinz-Nixdorf Chair for Distributed Information Systems, Friedrich Schiller University Jena, 07743 Jena, Germany. (7)Center for Computation and Technology, Louisiana State University, Baton Rouge, Louisiana 70803, USA. (8)Department of Physics, Aristotle University of Thessaloniki, Thessaloniki 54124, Greece.

We present the first very long-term simulations (extending up to ∼140 ms after merger) of binary neutron star mergers with piecewise polytropic equations of state and in full general relativity. Our simulations reveal that, at a time of 30-50 ms after merger, parts of the star become convectively unstable, which triggers the excitation of inertial modes. The excited inertial modes are sustained up to several tens of milliseconds and are potentially observable by the planned third-generation gravitational-wave detectors at frequencies of a few kilohertz. Since inertial modes depend on the rotation rate of the star and they are triggered by a convective instability in the postmerger remnant, their detection in gravitational waves will provide a unique opportunity to probe the rotational and thermal state of the merger remnant. In addition, our findings have implications for the long-term evolution and stability of binary neutron star remnants.

DOI: 10.1103/PhysRevLett.120.221101 PMID: 29906154

195. Philos Trans A Math Phys Eng Sci. 2020 Aug 7;378(2177):20190232. doi: 10.1098/rsta.2019.0232. Epub 2020 Jul 20.

Optical analogues of black-hole horizons.

Rosenberg Y(1).

Author information: (1)Department of Physics of Complex Systems, Weizmann Institute of Science, Rehovot 7610001, Israel.

Hawking radiation is unlikely to be measured from a real black hole, but can be tested in laboratory analogues. It was predicted as a consequence of quantum mechanics and general relativity, but turned out to be more universal. A refractive index perturbation produces an optical analogue of the black-hole horizon and Hawking radiation that is made of light. We discuss the central and recent experiments of the optical analogue, using hands-on physics. We stress the roles of classical fields, negative frequencies, 'regular optics' and dispersion. Opportunities and challenges ahead are briefly mentioned. This article is part of a discussion meeting issue 'The next generation of analogue gravity experiments'.

DOI: 10.1098/rsta.2019.0232 PMCID: PMC7422881 PMID: 32684128

Conflict of interest statement: I declare I have no competing interests.

196. Phys Rev Lett. 2018 Jun 8;120(23):231101. doi: 10.1103/PhysRevLett.120.231101.

First Predictions of the Angular Power Spectrum of the Astrophysical Gravitational Wave Background.

Cusin G(1), Dvorkin I(2), Pitrou C(3), Uzan JP(3).

Author information: (1)Astrophysics Department, University of Oxford, DWB, Keble Road, Oxford OX1 3RH, United Kingdom. (2)Max Planck Institute for Gravitational Physics (Albert Einstein Institute), Am Mühlenberg 1, Potsdam-Golm 14476, Germany. (3)Institut d'Astrophysique de Paris, CNRS UMR 7095, Sorbonne Université, Institut Lagrange de Paris, 98 bis, Bd Arago, 75014 Paris, France.

We present the first predictions for the angular power spectrum of the astrophysical gravitational wave background constituted of the radiation emitted by all resolved and unresolved astrophysical sources. Its shape and amplitude depend on both the astrophysical properties on galactic scales and on cosmological properties. We show that the angular power spectrum behaves as C_{ℓ}∝1/ℓ on large scales and that relative fluctuations of the signal are of order 30% at 100 Hz. We also present the correlations of the astrophysical gravitational wave background with weak lensing and galaxy distribution. These numerical results pave the way to the study of a new observable at the crossroad between general relativity, astrophysics, and cosmology.

DOI: 10.1103/PhysRevLett.120.231101 PMID: 29932710

197. Phys Rev Lett. 2006 Jul 14;97(2):021601. doi: 10.1103/PhysRevLett.97.021601. Epub 2006 Jul 11.

Very special relativity.

Cohen AG(1), Glashow SL.

Author information: (1)Physics Department, Boston University, Massachusetts 02215, USA. cohen@bu.edu

By very special relativity (VSR) we mean descriptions of nature whose space-time symmetries are certain proper subgroups of the Poincaré group. These subgroups contain space-time translations together with at least a two-parameter subgroup of the Lorentz group isomorphic to that generated by K(x) + J(y) and K(y)- J(x). We find that VSR implies special relativity (SR) in the context of local quantum field theory or of conservation. Absent both of these added hypotheses, VSR provides a simulacrum of SR for which most of the consequences of Lorentz invariance remain wholly or essentially intact, and for which many sensitive searches for departures from Lorentz invariance must fail. Several feasible experiments are discussed for which Lorentz-violating effects in VSR may be detectable.

DOI: 10.1103/PhysRevLett.97.021601 PMID: 16907430

198. Living Rev Relativ. 2014;17(1):1. doi: 10.12942/lrr-2014-1. Epub 2014 Feb 6.

The Hole Argument and Some Physical and Philosophical Implications.

Stachel J(1).

Author information: (1)Center for Einstein Studies, Boston University, 745 Commonwealth Avenue, Boston, MA 02215 USA.

This is a historical-critical study of the hole argument, concentrating on the interface between historical, philosophical and physical issues. Although it includes a review of its history, its primary aim is a discussion of the contemporary implications of the hole argument for physical theories based on dynamical, background-independent space-time structures. The historical review includes Einstein's formulations of the hole argument, Kretschmann's critique, as well as Hilbert's reformulation and Darmois' formulation of the general-relativistic Cauchy problem. The 1970s saw a revival of interest in the hole argument, growing out of attempts to answer the question: Why did three years elapse between Einstein's adoption of the metric tensor to represent the gravitational field and his adoption of the Einstein field equations? The main part presents some modern mathematical versions of the hole argument, including both coordinate-dependent and coordinate-independent definitions of covariance and general covariance; and the fiber bundle formulation of both natural and gauge natural theories. By abstraction from continuity and differentiability, these formulations can be extended from differentiable manifolds to any set; and the concepts of permutability and general permutability applied to theories based on relations between the elements of a set, such as elementary particle theories. We are closing with an overview of current discussions of philosophical and physical implications of the hole argument.

DOI: 10.12942/lrr-2014-1 PMCID: PMC5253803 PMID: 28163626

199. Phys Rev Lett. 2018 Jun 15;120(24):243901. doi: 10.1103/PhysRevLett.120.243901.

Controlling Surface Plasmons Through Covariant Transformation of the Spin-Dependent Geometric Phase Between Curved Metamaterials.

Zhong F(1), Li J(2)(3), Liu H(1), Zhu S(1).

Author information: (1)National Laboratory of Solid State Microstructures & School of Physics, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China. (2)School of Physics and Astronomy, University of Birmingham, Birmingham B15 2TT, United Kingdom. (3)Department of Physics, The Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, China.

General relativity uses curved space-time to describe accelerating frames. The movement of particles in different curved space-times can be regarded as equivalent physical processes based on the covariant transformation between different frames. In this Letter, we use one-dimensional curved metamaterials to mimic accelerating particles in curved space-times. The different curved shapes of structures are used to mimic different accelerating frames. The different geometric phases along the structure are used to mimic different movements in the frame. Using the covariant principle of general relativity, we can obtain equivalent nanostructures based on space-time transformations, such as the Lorentz transformation and conformal transformation. In this way, many covariant structures can be found that produce the same surface plasmon fields when excited by spin photons. A new kind of accelerating beam, the Rindler beam, is obtained based on the Rindler metric in gravity. Very large effective indices can be obtained in such systems based on geometric-phase gradient. This general covariant design method can be extended to many other optical media.

DOI: 10.1103/PhysRevLett.120.243901 PMID: 29956963

200. Leadersh Health Serv (Bradf Engl). 2019 Jun 28;32(3):364-386. doi: 10.1108/LHS-01-2018-0004. Epub 2018 Jun 5.

Millennial managers: exploring the next generation of talent.

Gerard N(1).

Author information: (1)Health Care Administration, College of Health and Human Services, California State University Long Beach , Long Beach, California, USA.

PURPOSE: While considerable scholarly attention has been given to "millennials" (those born between 1981 and 1997), little is known of this generation's ability to influence healthcare organizations and managerial roles in particular. This paper aims to clarify why millennials enter the healthcare management field and how their motivations correlate with preferences for working in various healthcare sectors and with various patient populations. DESIGN/METHODOLOGY/APPROACH: Survey data were collected from 107 millennials pursuing bachelor degrees in healthcare management by using a modified version of the multidimensional work motivation scale. Further data were collected on millennials' preferences for working in various healthcare sectors and with various patient populations. Correlational analyses were conducted to examine the relationship between types of motivation and workplace preferences. Cross-cultural differences were also examined within this generational set. FINDINGS: Results indicate a significant positive relationship between intrinsic motivation and preferences for working on the payer side of the industry and within finance and IT functions. Findings also reveal a significant positive relationship between prosocial motivation and preferences for working with more vulnerable patient populations. Variance in work motivation among cultural sub-sets of millennials suggests different upbringings, or alternatively, cultural relativity of the motivational constructs themselves. RESEARCH LIMITATIONS/IMPLICATIONS: Despite offering key insights into the next generation of healthcare managers, this study is limited by a sample of millennials from one large, metropolitan university in the USA and thus may not represent the views of all millennials. PRACTICAL IMPLICATIONS: To select, retain and develop the next generation of healthcare managers, it is incumbent upon organizations to better understanding millennials' motivations and preferences. ORIGINALITY/VALUE: This study is the first of its kind to illuminate the motivations and preferences that underpin a key and growing segment of the healthcare workforce. Millennials, now the largest and most diverse generation on the planet, are poised to change the landscape of health care.

DOI: 10.1108/LHS-01-2018-0004 PMID: 31298086 [Indexed for MEDLINE]