Let Loop Quantum Gravity and Affine Quantum Gravity Examine Each Other
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Symmetry and Gravity
universe Article Making a Quantum Universe: Symmetry and Gravity Houri Ziaeepour 1,2 1 Institut UTINAM, CNRS UMR 6213, Observatoire de Besançon, Université de Franche Compté, 41 bis ave. de l’Observatoire, BP 1615, 25010 Besançon, France; [email protected] or [email protected] 2 Mullard Space Science Laboratory, University College London, Holmbury St. Mary, Dorking GU5 6NT, UK Received: 05 September 2020; Accepted: 17 October 2020; Published: 23 October 2020 Abstract: So far, none of attempts to quantize gravity has led to a satisfactory model that not only describe gravity in the realm of a quantum world, but also its relation to elementary particles and other fundamental forces. Here, we outline the preliminary results for a model of quantum universe, in which gravity is fundamentally and by construction quantic. The model is based on three well motivated assumptions with compelling observational and theoretical evidence: quantum mechanics is valid at all scales; quantum systems are described by their symmetries; universe has infinite independent degrees of freedom. The last assumption means that the Hilbert space of the Universe has SUpN Ñ 8q – area preserving Diff.pS2q symmetry, which is parameterized by two angular variables. We show that, in the absence of a background spacetime, this Universe is trivial and static. Nonetheless, quantum fluctuations break the symmetry and divide the Universe to subsystems. When a subsystem is singled out as reference—observer—and another as clock, two more continuous parameters arise, which can be interpreted as distance and time. We identify the classical spacetime with parameter space of the Hilbert space of the Universe. -
Why Is M-Theory the Leading Candidate for Theory of Everything?
Quanta Magazine Why Is M-Theory the Leading Candidate for Theory of Everything? The mother of all string theories passes a litmus test that, so far, no other candidate theory of quantum gravity has been able to match. By Natalie Wolchover It’s not easy being a “theory of everything.” A TOE has the very tough job of fitting gravity into the quantum laws of nature in such a way that, on large scales, gravity looks like curves in the fabric of space-time, as Albert Einstein described in his general theory of relativity. Somehow, space-time curvature emerges as the collective effect of quantized units of gravitational energy — particles known as gravitons. But naive attempts to calculate how gravitons interact result in nonsensical infinities, indicating the need for a deeper understanding of gravity. String theory (or, more technically, M-theory) is often described as the leading candidate for the theory of everything in our universe. But there’s no empirical evidence for it, or for any alternative ideas about how gravity might unify with the rest of the fundamental forces. Why, then, is string/M- theory given the edge over the others? [abstractions] The theory famously posits that gravitons, as well as electrons, photons and everything else, are not point-particles but rather imperceptibly tiny ribbons of energy, or “strings,” that vibrate in different ways. Interest in string theory soared in the mid-1980s, when physicists realized that it gave mathematically consistent descriptions of quantized gravity. But the five known versions of string theory were all “perturbative,” meaning they broke down in some regimes. -
Electron Shape and Structure: a New Vortex Theory
Journal of High Energy Physics, Gravitation and Cosmology, 2020, 6, 340-352 https://www.scirp.org/journal/jhepgc ISSN Online: 2380-4335 ISSN Print: 2380-4327 Electron Shape and Structure: A New Vortex Theory Nader Butto Petah Tikva, Israel How to cite this paper: Butto, N. (2020) Abstract Electron Shape and Structure: A New Vor- tex Theory. Journal of High Energy Phys- Along with all other quantum objects, an electron is partly a wave and partly ics, Gravitation and Cosmology, 6, 340-352. a particle. The corpuscular properties of a particle are demonstrated when it https://doi.org/10.4236/jhepgc.2020.63027 is shown to have a localized position in space along its trajectory at any given Received: May 19, 2020 moment. When an electron looks more like a particle it has no shape, “point Accepted: June 29, 2020 particle”, according to the Standard Model, meaning that it interacts as if it is Published: July 2, 2020 entirely located at a single point in space and does not spread out to fill a Copyright © 2020 by author(s) and three-dimensional volume. Therefore, in the sense of particle-like interac- Scientific Research Publishing Inc. tions, an electron has no shape. In this paper, a new theory is proposed in This work is licensed under the Creative which the electron has a structure and a shape. The central idea is that an Commons Attribution International electron is a frictionless vortex with conserved momentum made out of con- License (CC BY 4.0). http://creativecommons.org/licenses/by/4.0/ densed vacuum generated in the Big Bang from massless virtual photons that Open Access acquire mass when moving in the vortex at the speed of light. -
Deriving the Properties of Space Time Using the Non-Compressible
Deriving the properties of space time using the non-compressible solutions of the Navier-Stokes Equations Ryan McDuffee∗ (Dated: September 24, 2019) Recent observations of gravitational waves by the Laser Interferometer Gravitational-Wave Ob- servatory (LIGO) has confirmed one of the last outstanding predictions in general relativity and in the process opened up a new frontier in astronomy and astrophysics. Additionally the observation of gravitational waves has also given us the data needed to deduce the physical properties of space time. Bredberg et al have shown in their 2011 paper titled From Navier-Stokes to Einstein, that for every solution of the incompressible Navier-Stokes equation in p + 1 dimensions, there is a uniquely associated dual” solution of the vacuum Einstein equations in p + 2 dimensions. The author shows that the physical properties of space time can be deduced using the recent measurements from the Laser Interferometer Gravitational-Wave Observatory and solutions from the incompressible Navier-Stokes equation. I. INTRODUCTION to calculate a hypothetical viscosity of space time and thus deduce the structure. Albert Einstein first published his theory of general Before moving forward with the analysis, it must be relativity in 1915, a year later he would predict the exis- understood that the Viscosity of space time that the au- tence of gravitational waves [1]. He based this prediction thor is intending to calculate, is an analogues property on his observation that the linearized weak field equa- rather than a literal one. Meaning that rather then try- tions had wave solutions [2][3], these transverse waves ing to estimate the thickness of a fluid like space time, we would be comprised of spatial strain and travel at the intend to show that by calculating the viscosity term in speed of light and would be generated by the time varia- a Navier-Stokes like equation, it is possible to calculate tions of the mass quadrupole moment of the source. -
Jhep09(2019)100
Published for SISSA by Springer Received: July 29, 2019 Accepted: September 5, 2019 Published: September 12, 2019 A link that matters: towards phenomenological tests of unimodular asymptotic safety JHEP09(2019)100 Gustavo P. de Brito,a;b Astrid Eichhornc;b and Antonio D. Pereirad;b aCentro Brasileiro de Pesquisas F´ısicas (CBPF), Rua Dr Xavier Sigaud 150, Urca, Rio de Janeiro, RJ, Brazil, CEP 22290-180 bInstitute for Theoretical Physics, University of Heidelberg, Philosophenweg 16, 69120 Heidelberg, Germany cCP3-Origins, University of Southern Denmark, Campusvej 55, DK-5230 Odense M, Denmark dInstituto de F´ısica, Universidade Federal Fluminense, Campus da Praia Vermelha, Av. Litor^anea s/n, 24210-346, Niter´oi,RJ, Brazil E-mail: [email protected], [email protected], [email protected] Abstract: Constraining quantum gravity from observations is a challenge. We expand on the idea that the interplay of quantum gravity with matter could be key to meeting this challenge. Thus, we set out to confront different potential candidates for quantum gravity | unimodular asymptotic safety, Weyl-squared gravity and asymptotically safe gravity | with constraints arising from demanding an ultraviolet complete Standard Model. Specif- ically, we show that within approximations, demanding that quantum gravity solves the Landau-pole problems in Abelian gauge couplings and Yukawa couplings strongly con- strains the viable gravitational parameter space. In the case of Weyl-squared gravity with a dimensionless gravitational coupling, we also investigate whether the gravitational con- tribution to beta functions in the matter sector calculated from functional Renormalization Group techniques is universal, by studying the dependence on the regulator, metric field parameterization and choice of gauge. -
On the Axioms of Causal Set Theory
On the Axioms of Causal Set Theory Benjamin F. Dribus Louisiana State University [email protected] November 8, 2013 Abstract Causal set theory is a promising attempt to model fundamental spacetime structure in a discrete order-theoretic context via sets equipped with special binary relations, called causal sets. The el- ements of a causal set are taken to represent spacetime events, while its binary relation is taken to encode causal relations between pairs of events. Causal set theory was introduced in 1987 by Bombelli, Lee, Meyer, and Sorkin, motivated by results of Hawking and Malament relating the causal, conformal, and metric structures of relativistic spacetime, together with earlier work on discrete causal theory by Finkelstein, Myrheim, and 't Hooft. Sorkin has coined the phrase, \order plus number equals geometry," to summarize the causal set viewpoint regarding the roles of causal structure and discreteness in the emergence of spacetime geometry. This phrase represents a specific version of what I refer to as the causal metric hypothesis, which is the idea that the properties of the physical universe, and in particular, the metric properties of classical spacetime, arise from causal structure at the fundamental scale. Causal set theory may be expressed in terms of six axioms: the binary axiom, the measure axiom, countability, transitivity, interval finiteness, and irreflexivity. The first three axioms, which fix the physical interpretation of a causal set, and restrict its \size," appear in the literature either implic- itly, or as part of the preliminary definition of a causal set. The last three axioms, which encode the essential mathematical structure of a causal set, appear in the literature as the irreflexive formula- tion of causal set theory. -
Solution of the Logarithmic Schrödinger Equation with a Coulomb OPEN ACCESS Potential
Journal of Physics Communications PAPER • OPEN ACCESS Related content - Combined few-body and mean-field model Solution of the logarithmic Schrödinger equation for nuclei D Hove, E Garrido, P Sarriguren et al. with a Coulomb potential - Advanced multiconfiguration methods for complex atoms: Part I—Energies and wave functions To cite this article: T C Scott and J Shertzer 2018 J. Phys. Commun. 2 075014 Charlotte Froese Fischer, Michel Godefroid, Tomas Brage et al. - Schwartz interpolation for the Coulomb potential K M Dunseath, J-M Launay, M Terao- View the article online for updates and enhancements. Dunseath et al. This content was downloaded from IP address 131.169.95.169 on 12/04/2019 at 22:48 J. Phys. Commun. 2 (2018) 075014 https://doi.org/10.1088/2399-6528/aad302 PAPER Solution of the logarithmic Schrödinger equation with a Coulomb OPEN ACCESS potential RECEIVED 5 June 2018 T C Scott1,2 and J Shertzer3 REVISED 1 4 July 2018 Near Pte. Ltd, 15 Beach Road, 189677, Singapore 2 Institut für Physikalische Chemie, RWTH Aachen University, D-52056 Aachen, Germany ACCEPTED FOR PUBLICATION 3 Department of Physics, College of the Holy Cross, 1 College St, Worcester, MA 01610, United States of America 12 July 2018 PUBLISHED E-mail: [email protected] 24 July 2018 Keywords: logarithmic Schrödinger equation, Gaussons, finite element methods Original content from this work may be used under the terms of the Creative Abstract Commons Attribution 3.0 licence. The nonlinear logarithmic Schrödinger equation (log SE) appears in many branches of fundamental Any further distribution of physics, ranging from macroscopic superfluids to quantum gravity. -
Stochastic Hydrodynamic Analogy of Quantum Mechanics
The mass lowest limit of a black hole: the hydrodynamic approach to quantum gravity Piero Chiarelli National Council of Research of Italy, Area of Pisa, 56124 Pisa, Moruzzi 1, Italy Interdepartmental Center “E.Piaggio” University of Pisa Phone: +39-050-315-2359 Fax: +39-050-315-2166 Email: [email protected]. Abstract: In this work the quantum gravitational equations are derived by using the quantum hydrodynamic description. The outputs of the work show that the quantum dynamics of the mass distribution inside a black hole can hinder its formation if the mass is smaller than the Planck's one. The quantum-gravitational equations of motion show that the quantum potential generates a repulsive force that opposes itself to the gravitational collapse. The eigenstates in a central symmetric black hole realize themselves when the repulsive force of the quantum potential becomes equal to the gravitational one. The work shows that, in the case of maximum collapse, the mass of the black hole is concentrated inside a sphere whose radius is two times the Compton length of the black hole. The mass minimum is determined requiring that the gravitational radius is bigger than or at least equal to the radius of the state of maximum collapse. PACS: 04.60.-m Keywords: quantum gravity, minimum black hole mass, Planck's mass, quantum Kaluza Klein model 1. Introduction One of the unsolved problems of the theoretical physics is that of unifying the general relativity with the quantum mechanics. The former theory concerns the gravitation dynamics on large cosmological scale in a fully classical ambit, the latter one concerns, mainly, the atomic or sub-atomic quantum phenomena and the fundamental interactions [1-9]. -
Entropic Phase Maps in Discrete Quantum Gravity
entropy Article Entropic Phase Maps in Discrete Quantum Gravity Benjamin F. Dribus Department of Mathematics, William Carey University, 710 William Carey Parkway, Hattiesburg, MS 39401, USA; [email protected] or [email protected]; Tel.: +1-985-285-5821 Received: 26 May 2017; Accepted: 25 June 2017; Published: 30 June 2017 Abstract: Path summation offers a flexible general approach to quantum theory, including quantum gravity. In the latter setting, summation is performed over a space of evolutionary pathways in a history configuration space. Discrete causal histories called acyclic directed sets offer certain advantages over similar models appearing in the literature, such as causal sets. Path summation defined in terms of these histories enables derivation of discrete Schrödinger-type equations describing quantum spacetime dynamics for any suitable choice of algebraic quantities associated with each evolutionary pathway. These quantities, called phases, collectively define a phase map from the space of evolutionary pathways to a target object, such as the unit circle S1 ⊂ C, or an analogue such as S3 or S7. This paper explores the problem of identifying suitable phase maps for discrete quantum gravity, focusing on a class of S1-valued maps defined in terms of “structural increments” of histories, called terminal states. Invariants such as state automorphism groups determine multiplicities of states, and induce families of natural entropy functions. A phase map defined in terms of such a function is called an entropic phase map. The associated dynamical law may be viewed as an abstract combination of Schrödinger’s equation and the second law of thermodynamics. Keywords: quantum gravity; discrete spacetime; causal sets; path summation; entropic gravity 1. -
The Multiple Realizability of General Relativity in Quantum Gravity
The multiple realizability of general relativity in quantum gravity Rasmus Jaksland∗ Forthcoming in Synthese† Abstract Must a theory of quantum gravity have some truth to it if it can recover general rela- tivity in some limit of the theory? This paper answers this question in the negative by indicating that general relativity is multiply realizable in quantum gravity. The argu- ment is inspired by spacetime functionalism – multiple realizability being a central tenet of functionalism – and proceeds via three case studies: induced gravity, thermodynamic gravity, and entanglement gravity. In these, general relativity in the form of the Ein- stein field equations can be recovered from elements that are either manifestly multiply realizable or at least of the generic nature that is suggestive of functions. If general relativity, as argued here, can inherit this multiple realizability, then a theory of quantum gravity can recover general relativity while being completely wrong about the posited microstructure. As a consequence, the recovery of general relativity cannot serve as the ultimate arbiter that decides which theory of quantum gravity that is worthy of pursuit, even though it is of course not irrelevant either qua quantum gravity. Thus, the recovery of general relativity in string theory, for instance, does not guarantee that the stringy account of the world is on the right track; despite sentiments to the contrary among string theorists. Keywords quantum gravity, general relativity, spacetime functionalism, entanglement, emergent gravity, multiple realizability, string theory ∗Department of Philosophy and Religious Studies, NTNU – Norwegian University of Science and Technology, Trondheim, Norway. Email: [email protected] †This is a post-peer-review, pre-copyedit version of an article published in Synthese. -
Redalyc.Big Extra Dimensions Make a Too Small
Brazilian Journal of Physics ISSN: 0103-9733 [email protected] Sociedade Brasileira de Física Brasil Sorkin, Rafael D. Big extra dimensions make A too Small Brazilian Journal of Physics, vol. 35, núm. 2A, june, 2005, pp. 280-283 Sociedade Brasileira de Física Sâo Paulo, Brasil Available in: http://www.redalyc.org/articulo.oa?id=46435212 How to cite Complete issue Scientific Information System More information about this article Network of Scientific Journals from Latin America, the Caribbean, Spain and Portugal Journal's homepage in redalyc.org Non-profit academic project, developed under the open access initiative 280 Brazilian Journal of Physics, vol. 35, no. 2A, June, 2005 Big Extra Dimensions Make L too Small Rafael D. Sorkin Perimeter Institute, 31 Caroline Street North, Waterloo ON, N2L 2Y5 Canada and Department of Physics, Syracuse University, Syracuse, NY 13244-1130, U.S.A. Received on 23 February, 2005 I argue that the true quantum gravity scale cannot be much larger than the Planck length, because if it were then the quantum gravity-induced fluctuations in L would be insufficient to produce the observed cosmic “dark energy”. If one accepts this argument, it rules out scenarios of the “large extra dimensions” type. I also point out that the relation between the lower and higher dimensional gravitational constants in a Kaluza-Klein theory is precisely what is needed in order that a black hole’s entropy admit a consistent higher dimensional interpretation in terms of an underlying spatio-temporal discreteness. Probably few people anticipate that laboratory experiments in L far too small to be compatible with its observed value. -
Resolving Cosmological Singularity Problem in Logarithmic Superfluid Theory of Physical Vacuum
XXI International Meeting of Physical Interpretations of Relativity Theory IOP Publishing Journal of Physics: Conference Series 1557 (2020) 012038 doi:10.1088/1742-6596/1557/1/012038 Resolving cosmological singularity problem in logarithmic superfluid theory of physical vacuum K G Zloshchastiev Institute of Systems Science, Durban University of Technology, Durban, South Africa E-mail: [email protected] Abstract. A paradigm of the physical vacuum as a non-trivial quantum object, such as superfluid, opens an entirely new prospective upon origins and interpretations of Lorentz symmetry and spacetime, black holes, cosmological evolution and singularities. Using the logarithmic superfluid model, one can formulate a post-relativistic theory of superfluid vacuum, which is not only essentially quantum but also successfully recovers special and general relativity in the \phononic" (low-momenta) limit. Thus, it represents spacetime as an induced observer- dependent phenomenon. We focus on the cosmological aspects of the logarithmic superfluid vacuum theory and show how can the related singularity problem be resolved in this approach. 1. Introduction It is a general consensus now that the physical vacuum, or a non-removable background, is a nontrivial object whose properties' studies are of utmost importance, because it affects the most fundamental notions our physics is based upon, such as space, time, matter, field, and fundamental symmetries. An internal structure of physical vacuum is still a subject of debates based on different views and approaches, which generally agree on the main paradigm, but differ in details; some introduction can be found in monographs by Volovik and Huang [1, 2]. It is probably Dirac who can be regarded as a forerunner of the superfluid vacuum theory (SVT).