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Journal articles on the topic 'Classical theories of gravity'

Author: Grafiati

Published: 9 March 2023

Last updated: 25 July 2025

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1

HA, YUAN K. "SEVERE CHALLENGES IN GRAVITY THEORIES." International Journal of Modern Physics: Conference Series 07 (January 2012): 219–26. http://dx.doi.org/10.1142/s2010194512004291.

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Gravity is specifically the attractive force between two masses separated at a distance. Is this force a derived or a fundamental interaction? We believe that all fundamental interactions are quantum in nature but a derived interaction may be classical. Severe challenges have appeared in many quantum theories of gravity. None of these theories has thus far attained its goal in quantizing gravity and some have met remarkable defeat. We are led to ponder whether gravitation is intrinsically classical and that there would exist a deeper and structurally different underlying theory which would giv

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2

Struyve, Ward. "Semi-classical approximations based on Bohmian mechanics." International Journal of Modern Physics A 35, no. 14 (2020): 2050070. http://dx.doi.org/10.1142/s0217751x20500700.

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Semi-classical theories are approximations to quantum theory that treat some degrees of freedom classically and others quantum mechanically. In the usual approach, the quantum degrees of freedom are described by a wave function which evolves according to some Schrödinger equation with a Hamiltonian that depends on the classical degrees of freedom. The classical degrees of freedom satisfy classical equations that depend on the expectation values of quantum operators. In this paper, we study an alternative approach based on Bohmian mechanics. In Bohmian mechanics the quantum system is not only d

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3

BERGSHOEFF, E., C. N. POPE, L. J. ROMANS, E. SEZGIN, and X. SHEN. "W∞ GRAVITY AND SUPER-W∞ GRAVITY." Modern Physics Letters A 05, no. 24 (1990): 1957–66. http://dx.doi.org/10.1142/s0217732390002237.

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4

Calcagni, Gianluca. "Multifractional theories: An updated review." Modern Physics Letters A 36, no. 14 (2021): 2140006. http://dx.doi.org/10.1142/s021773232140006x.

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The status of multifractional theories is reviewed using comparative tables. Theoretical foundations, classical matter and gravity dynamics, cosmology and experimental constraints are summarized and the application of the multifractional paradigm to quantum gravity is discussed. We also clarify the issue of unitarity in theories with integer-order derivatives.

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5

NOH, HYERIM, and JAI-CHAN HWANG. "COSMOLOGICAL PERTURBATIONS IN GENERALIZED GRAVITY THEORIES." Modern Physics Letters A 19, no. 13n16 (2004): 1203–6. http://dx.doi.org/10.1142/s0217732304014562.

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We present cosmological perturbation theory based on generalized gravity theories including string correction terms as well as a tachyonic complication. The classical evolution as well as the quantum generation processes in these variety of gravity theories are presented in unified forms. These apply both to the scalar- and tensor-type perturbations.

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6

Bahamonde, Sebastian, and Mir Faizal. "Is gravity actually the curvature of spacetime?" International Journal of Modern Physics D 28, no. 14 (2019): 1944021. http://dx.doi.org/10.1142/s0218271819440218.

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The Einstein equations, apart from being the classical field equations of General Relativity, are also the classical field equations of two other theories of gravity. As the experimental tests of General Relativity are done using the Einstein equations, we do not really know if gravity is the curvature of a torsionless spacetime or torsion of a curvatureless spacetime or if it occurs due to the nonmetricity of a curvatureless and torsionless spacetime. However, as the classical actions of all these theories differ from each other by the boundary terms, and the Casimir effect is a boundary effe

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7

Stelle, K. S. "Abdus Salam and quadratic curvature gravity: Classical solutions." International Journal of Modern Physics A 32, no. 09 (2017): 1741012. http://dx.doi.org/10.1142/s0217751x17410123.

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In 1978, Salam and Strathdee suggested on the basis of Froissart boundedness that curvature-squared terms should be included in the gravitational Lagrangian. Despite the presence of ghosts in such theories, the subject has remained a persistent topic in approaches to quantum gravity and cosmology. In this article, the space of spherically symmetric solutions to such theories is explored, highlighting horizonless solutions, wormholes and non-Schwarzschild black holes.

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8

KAZAKOV, KIRILL A. "CLASSICAL SCALE OF QUANTUM GRAVITY." International Journal of Modern Physics D 12, no. 09 (2003): 1715–19. http://dx.doi.org/10.1142/s0218271803004110.

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Characteristic length scale of the post-Newtonian corrections to the gravitational field of a body is given by its gravitational radius r g . The role of this scale in quantum domain is discussed in the context of the low-energy effective theory. The question of whether quantum gravity effects appear already at r g leads to the question of correspondence between classical and quantum theories, which in turn can be unambiguously resolved by considering the issue of general covariance. The O(ℏ0) loop contributions turn out to violate the principle of general covariance, thus revealing their esse

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9

AMELINO-CAMELIA, GIOVANNI. "DIMENSIONFUL DEFORMATIONS OF POINCARÉ SYMMETRIES FOR A QUANTUM GRAVITY WITHOUT IDEAL OBSERVERS." Modern Physics Letters A 13, no. 16 (1998): 1319–25. http://dx.doi.org/10.1142/s0217732398001376.

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Quantum mechanics is revisited as the appropriate theoretical framework for the description of the outcome of experiments that rely on the use of classical devices. In particular, it is emphasized that the limitations on the measurability of (pairs of conjugate) observables encoded in the formalism of quantum mechanics reproduce faithfully the "classical-device limit" of the corresponding limitations encountered in (real or gedanken) experimental setups. It is then argued that devices cannot behave classically in quantum gravity, and that this might raise serious problems for the search of a c

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10

CAVAGLIÀ, MARCO. "A NOTE ON WEYL TRANSFORMATIONS IN TWO-DIMENSIONAL DILATON GRAVITY." Modern Physics Letters A 15, no. 34 (2000): 2113–18. http://dx.doi.org/10.1142/s0217732300002437.

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11

Brandt, F. T., J. Frenkel, S. Martins-Filho, D. G. C. McKeon, and G. S. S. Sakoda. "Thermal gauge theories with Lagrange multiplier fields." Canadian Journal of Physics 100, no. 3 (2022): 139–44. http://dx.doi.org/10.1139/cjp-2021-0248.

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We study the Yang–Mills theory and quantum gravity at finite temperature, in the presence of Lagrange multiplier fields. These restrict the path integrals to field configurations, which obey the classical equations of motion. This has the effect of doubling the usual one-loop thermal contributions and of suppressing all radiative corrections at higher-loop order. Such theories are renormalizable at all temperatures. Some consequences of this result in quantum gravity are briefly examined.

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12

Padmanabhan, T. "Emergent gravity paradigm: Recent progress." Modern Physics Letters A 30, no. 03n04 (2015): 1540007. http://dx.doi.org/10.1142/s0217732315400076.

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Research during the last one decade or so suggests that the gravitational field equations in a large class of theories (including, but not limited to, general relativity) have the same status as the equations of, say, gas dynamics or elasticity. This paradigm provides a refreshingly different way of interpreting spacetime dynamics and highlights the fact that several features of classical gravitational theories have direct thermodynamic interpretation. I review the recent progress in this approach, achieved during the last few years.

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13

CIUFOLINI, IGNAZIO. "NEW CLASS OF METRIC THEORIES OF GRAVITY NOT DESCRIBED BY THE PARAMETRIZED POST-NEWTONIAN (PPN) FORMALISM." International Journal of Modern Physics A 06, no. 30 (1991): 5511–32. http://dx.doi.org/10.1142/s0217751x91002604.

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After an introduction to theories of gravity alternative to general relativity, metric theories (Sec. 1) and the parametrized post-Newtonian (PPN) formalism (Sec. 2), we define a new class of metric theories of gravity (Sec. 3). It turns out that the post-Newtonian approximation of these new theories is not described by the PPN formalism (Sec. 4); in fact, in the limit of weak field and slow motions, the post-Newtonian expression of the metric tensor contains an, a priori, infinite set of new terms and correspondingly an, a priori, infinite set of new PPN parameters. As a consequence, the para

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NEUPANE, I. P. "BLACK HOLES, ENTROPY BOUND AND CAUSALITY VIOLATION." International Journal of Modern Physics A 24, no. 18n19 (2009): 3584–91. http://dx.doi.org/10.1142/s0217751x09047235.

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The gauge theory - gravity duality has provided us a way of studying QCD at high energies or short distances from straightforward calculations in classical general relativity. Among numerous results obtained so far, one of the most striking is the universality of the ratio of the shear viscosity to the entropy density. For all gauge theories with Einstein gravity dual this ratio has been found to be η/s = 1/4π. In this note, we consider higher curvature-corrected black hole solutions for which η/s can be smaller than 1/4π, thus violating the conjecture bound. Here we shall argue that the Gauss

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15

SCHALLER, PETER, and THOMAS STROBL. "POISSON STRUCTURE INDUCED (TOPOLOGICAL) FIELD THEORIES." Modern Physics Letters A 09, no. 33 (1994): 3129–36. http://dx.doi.org/10.1142/s0217732394002951.

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A class of two-dimensional field theories, based on (generically degenerate) Poisson structures and generalizing gravity-Yang–Mills systems, is presented. Locally, the solutions of the classical equations of motions are given. A general scheme for the quantization of the models in a Hamiltonian formulation is found. A BRS-formulation is outlined briefly.

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16

Giacchini, Breno, and Tibério Netto. "Regular Solutions in Higher-Derivative Gravity." Universe 4, no. 12 (2018): 140. http://dx.doi.org/10.3390/universe4120140.

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Local gravitational theories with more than four derivatives can have remarkable quantum properties. Namely, they can be super-renormalizable and may be unitary in the Lee-Wick sense, if the massive poles of the propagator are complex. It is important, therefore, to also explore the classical aspects of these theories. In this talk we present recent results in this direction. Specifically, we discuss the effect that that higher-order terms can have on the Newtonian potential and related singularities.

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17

Fabris, Júlio C., Marcelo H. Alvarenga, and Hermano Velten. "Using Cosmological Perturbation Theory to Distinguish between GR and Unimodular Gravity." Symmetry 15, no. 7 (2023): 1392. http://dx.doi.org/10.3390/sym15071392.

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Unimodular gravity is one of the oldest geometric gravity theories and alternatives to general relativity. Essentially, it is based on the Einstein–Hilbert Lagrangian with an additional constraint on the determinant of the metric. It can be explicitly shown that unimodular gravity can be recast as general relativity in the presence of a cosmological constant. This fact has led to many discussions on the equivalence of both theories at the classical and quantum levels. Here, we present an analysis focused on the classical scalar perturbations around a cosmological background. We focus on the un

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18

Radhakrishnan, Ramesh, Patrick Brown, Jacob Matulevich, Eric Davis, Delaram Mirfendereski, and Gerald Cleaver. "A Review of Stable, Traversable Wormholes in f(R) Gravity Theories." Symmetry 16, no. 8 (2024): 1007. http://dx.doi.org/10.3390/sym16081007.

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It has been proven that in standard Einstein gravity, exotic matter (i.e., matter violating the pointwise and averaged Weak and Null Energy Conditions) is required to stabilize traversable wormholes. Quantum field theory permits these violations due to the quantum coherent effects found in any quantum field. Even reasonable classical scalar fields violate the energy conditions. In the case of the Casimir effect and squeezed vacuum states, these violations have been experimentally proven. It is advantageous to investigate methods to minimize the use of exotic matter. One such area of interest i

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19

Azizi, Azizollah, and Soudabe Nasirimoghadam. "Behavior of light polarization in photon-scalar interaction." International Journal of Modern Physics A 32, no. 31 (2017): 1750177. http://dx.doi.org/10.1142/s0217751x17501779.

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Quantum theories of gravity help us to improve our insight into the gravitational interactions. Motivated by the interesting effect of gravity on the photon trajectory, we treat a quantum recipe concluding a classical interaction of light and a massive object such as the sun. We use the linear quantum gravity to compute the classical potential of a photon interacting with a massive scalar. The leading terms have a traditional 1/r subordinate and demonstrate a polarization-dependent behavior. This result challenges the equivalence principle; attractive and/or repulsive interactions are admissib

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20

Anselmi, Damiano, and Milenko Halat. "Renormalizable acausal theories of classical gravity coupled with interacting quantum fields." Classical and Quantum Gravity 24, no. 8 (2007): 1927–54. http://dx.doi.org/10.1088/0264-9381/24/8/003.

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21

KOSLOWSKI, TIM A. "SHAPE DYNAMICS AND EFFECTIVE FIELD THEORY." International Journal of Modern Physics A 28, no. 13 (2013): 1330017. http://dx.doi.org/10.1142/s0217751x13300172.

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Shape dynamics is a gauge theory based on spatial diffeomorphism- and Weyl-invariance which is locally indistinguishable from classical general relativity. If taken seriously, it suggests that the space–time geometry picture that underlies general relativity can be replaced by a picture based on spatial conformal geometry. This classically well-understood trading of gauge symmetries opens new conceptual avenues in many approaches to quantum gravity. This paper focusses on the general implications for quantum gravity and effective field theory and considers the application of the shape dynamics

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22

Shankaranarayanan, S. "Strong gravity signatures in the polarization of gravitational waves." International Journal of Modern Physics D 28, no. 14 (2019): 1944020. http://dx.doi.org/10.1142/s0218271819440206.

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General Relativity is a hugely successful description of gravitation. However, both theory and observations suggest that General Relativity might have significant classical and quantum corrections in the Strong Gravity regime. Testing the strong field limit of gravity is one of the main objectives of the future gravitational wave detectors. One way to detect strong gravity is through the polarization of gravitational waves. For quasi-normal modes of black-holes in General Relativity, the two polarization states of gravitational waves have the same amplitude and frequency spectrum. Using the pr

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23

Alexander Milanich. "The mass of photons and gravity." World Journal of Advanced Research and Reviews 9, no. 3 (2021): 297–303. http://dx.doi.org/10.30574/wjarr.2021.9.3.0111.

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This article analyzes concepts of photons and results of old experiments with deflections of light by Sun’s gravity. It is possible to draw a conclusion that experimental results differ from theoretical predictions of both classical and General Relativity theories. In this article was proposed explanation based on alternative potential and the mass of photons.

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24

Alexander, Milanich. "The mass of photons and gravity." World Journal of Advanced Research and Reviews 09, no. 03 (2021): 297–303. https://doi.org/10.5281/zenodo.4661056.

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This article analyzes concepts of photons and results of old experiments with deflections of light by Sun’s gravity. It is possible to draw a conclusion that experimental results differ from theoretical predictions of both classical and General Relativity theories. In this article was proposed explanation based on alternative potential and the mass of photons. 

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25

KOEHLER, K., F. MANSOURI, CENALO VAZ, and L. WITTEN. "DE SITTER GRAVITY AND SUPERGRAVITY IN THREE DIMENSIONS AS CHERN-SIMONS THEORIES." Modern Physics Letters A 05, no. 12 (1990): 935–41. http://dx.doi.org/10.1142/s0217732390001037.

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We construct a de Sitter supergravity theory in 2 + 1 dimensions as the Chern-Simons gauge theory of the supergroup OSp (1|2; C). The resulting action is a consistent classical supergravity theory with a positive cosmological constant. As in other three dimensional Chern-Simons theories, diffeomorphisms are shown to be equivalent to gauge transformations of OSp (1|2; C) on shell. Consistency of the corresponding classical theory is briefly discussed.

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26

Capozziello, Salvatore, and Mariafelicia De Laurentis. "Noether symmetries in extended gravity quantum cosmology." International Journal of Geometric Methods in Modern Physics 11, no. 02 (2014): 1460004. http://dx.doi.org/10.1142/s0219887814600044.

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We summarize the use of Noether symmetries in Minisuperspace Quantum Cosmology. In particular, we consider minisuperspace models, showing that the existence of conserved quantities gives selection rules that allow to recover classical behaviors in cosmic evolution according to the so-called Hartle criterion. Such a criterion selects correlated regions in the configuration space of dynamical variables whose meaning is related to the emergence of classical observable universes. Some minisuperspace models are worked out starting from Extended Gravity, in particular coming from scalar-tensor, f(R)

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27

Shrimali, Vinay. "Advancements and Theoretical Approaches in Gravity Manipulation Technologies: Bridging Science and Speculation." INTERANTIONAL JOURNAL OF SCIENTIFIC RESEARCH IN ENGINEERING AND MANAGEMENT 09, no. 03 (2025): 1–9. https://doi.org/10.55041/ijsrem42556.

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This paper delves into the current state of gravity manipulation technologies, examining both theoretical frameworks and experimental advancements. It reviews classical and modern physics theories related to gravity, explores emerging technologies with potential for manipulating gravitational forces, and evaluates speculative concepts such as anti-gravity devices and gravitomagnetic effects. The goal is to assess the feasibility of these technologies and their potential applications in transportation, energy, and space exploration.

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28

Galley, Thomas D., Flaminia Giacomini, and John H. Selby. "Any consistent coupling between classical gravity and quantum matter is fundamentally irreversible." Quantum 7 (October 16, 2023): 1142. http://dx.doi.org/10.22331/q-2023-10-16-1142.

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When gravity is sourced by a quantum system, there is tension between its role as the mediator of a fundamental interaction, which is expected to acquire nonclassical features, and its role in determining the properties of spacetime, which is inherently classical. Fundamentally, this tension should result in breaking one of the fundamental principles of quantum theory or general relativity, but it is usually hard to assess which one without resorting to a specific model. Here, we answer this question in a theory-independent way using General Probabilistic Theories (GPTs). We consider the inter

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29

Ichinose, Shoichi. "New Algorithm for Tensor Calculation in Field Theories." International Journal of Modern Physics C 09, no. 02 (1998): 243–64. http://dx.doi.org/10.1142/s0129183198000182.

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Tensor calculation of suffix-contraction is carried out by a C-program. Tensors are represented graphically, and the algorithm makes use of the topology of the graphs. Classical and quantum gravity, in the weak-field perturbative approach, is a special interest. Examples of the leading order calculation of some general invariants such as RμνλσRμνλσ are given. Application to Weyl anomaly calculation is also discussed.

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30

Bernardo, Heliudson, Benjamin Bose, Guilherme Franzmann, et al. "Modified Gravity Approaches to the Cosmological Constant Problem." Universe 9, no. 2 (2023): 63. http://dx.doi.org/10.3390/universe9020063.

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The cosmological constant and its phenomenology remain among the greatest puzzles in theoretical physics. We review how modifications of Einstein’s general relativity could alleviate the different problems associated with it that result from the interplay of classical gravity and quantum field theory. We introduce a modern and concise language to describe the problems associated with its phenomenology, and inspect no-go theorems and their loopholes to motivate the approaches discussed here. Constrained gravity approaches exploit minimal departures from general relativity; massive gravity intro

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31

Anastopoulos, Charis, and Bei-Lok Hu. "Gravity, Quantum Fields and Quantum Information: Problems with Classical Channel and Stochastic Theories." Entropy 24, no. 4 (2022): 490. http://dx.doi.org/10.3390/e24040490.

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In recent years an increasing number of papers have attempted to mimic or supplant quantum field theory in discussions of issues related to gravity by the tools and through the perspective of quantum information theory, often in the context of alternative quantum theories. In this article, we point out three common problems in such treatments. First, we show that the notion of interactions mediated by an information channel is not, in general, equivalent to the treatment of interactions by quantum field theory. When used to describe gravity, this notion may lead to inconsistencies with general

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32

UNNIKRISHNAN, C. S., and G. T. GILLIES. "BEND IT LIKE EINSTEIN: GRAVITATIONAL DEFLECTION OF CLASSICAL, QUANTUM AND EXOTIC LIGHT." International Journal of Modern Physics D 18, no. 14 (2009): 2159–66. http://dx.doi.org/10.1142/s0218271809016089.

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Gravitational bending of light is a spectacular prediction of Einstein's general relativity, tested and observed in numerous situations. We examine the fine structure of gravitational bending in new light to obtain insights pertaining to some deep links between gravity and quantum mechanics. The new results include quantum-theoretical interpretation of part of the light bending, making a good case for gravity encompassing wave–particle duality, perhaps a new insight for quantum gravity itself. We reiterate the mutual compatibility of the equivalence principle and quantum dynamics in a simple p

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33

GAITAN DEVERAS, ROLANDO. "ON UNITARITY OF A LINEARIZED YANG–MILLS FORMULATION FOR MASSLESS AND MASSIVE GRAVITY WITH PROPAGATING TORSION." International Journal of Modern Physics A 25, no. 26 (2010): 4911–32. http://dx.doi.org/10.1142/s0217751x10050561.

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A perturbative regime based on contortion as a dynamical variable and metric as a (classical) fixed background, is performed in the context of a pure Yang–Mills formulation for gravity in a (2+1)-dimensional space–time. In the massless case, we show that the theory contains three degrees of freedom and only one is a nonunitary mode. Next, we introduce quadratical terms dependent on torsion, which preserve parity and general covariance. The linearized version reproduces an analogue Hilbert–Einstein–Fierz–Pauli unitary massive theory plus three massless modes, two of them represents nonunitary o

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34

OBUKHOV, YURI N. "POINCARÉ GAUGE GRAVITY: SELECTED TOPICS." International Journal of Geometric Methods in Modern Physics 03, no. 01 (2006): 95–137. http://dx.doi.org/10.1142/s021988780600103x.

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In the gauge theory of gravity based on the Poincaré group (the semidirect product of the Lorentz group and the spacetime translations) the mass (energy–momentum) and the spin are treated on an equal footing as the sources of the gravitational field. The corresponding spacetime manifold carries the Riemann–Cartan geometric structure with the nontrivial curvature and torsion. We describe some aspects of the classical Poincaré gauge theory of gravity. Namely, the Lagrange–Noether formalism is presented in full generality, and the family of quadratic (in the curvature and the torsion) models is a

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35

Ashtekar, Abhay. "Exploring Quantum Geometry Created by Quantum Matter." Physics 4, no. 4 (2022): 1384–402. http://dx.doi.org/10.3390/physics4040089.

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Exactly soluble models can serve as excellent tools to explore conceptual issues in non-perturbative quantum gravity. In perturbative approaches, it is only the two radiative modes of the linearized gravitational field that are quantized. The goal of this investigation is to probe the ‘Coulombic’ aspects of quantum geometry that are governed entirely by matter sources. Since there are no gravitational waves in three dimensions, 3-dimensional (3-d) gravity coupled to matter provides an ideal arena for this task. The analysis presented here reveals novel aspects of quantum gravity that bring out

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Alfaro, Jorge, та Pablo González. "δ Gravity: Dark Sector, Post-Newtonian Limit and Schwarzschild Solution". Universe 5, № 5 (2019): 96. http://dx.doi.org/10.3390/universe5050096.

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We present a new kind of model, which we call δ Theories, where standard theories are modified including new fields, motivated by an additional symmetry ( δ symmetry). In previous works, we proved that δ Theories just live at one loop, so the model in a quantum level can be interesting. In the gravitational case, we have δ Gravity, based on two symmetric tensors, g μ ν and g ˜ μ ν , where quantum corrections can be controlled. In this paper, a review of the classical limit of δ Gravity in a Cosmological level will be developed, where we explain the accelerated expansion of the universe without

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Monteiro, Ricardo, Donal O'Connell, and Chris D. White. "Gravity as a double copy of gauge theory: from amplitudes to black holes." International Journal of Modern Physics D 24, no. 09 (2015): 1542008. http://dx.doi.org/10.1142/s0218271815420080.

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We discuss the relation between perturbative gauge theory and perturbative gravity, and look at how this relation extends to some exact classical solutions. First, we give an overview of the double copy prescription that takes gauge theory amplitudes into gravity amplitudes, which has been crucial to progress in perturbative studies of supergravity. Then, we review how the self-dual sectors provide an important insight into the relation between the theories. A key role is played by a kinematic algebraic structure mirroring the color structure. Finally, we review how these ideas extend to some

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38

Jones, KRW. "Newtonian Quantum Gravity." Australian Journal of Physics 48, no. 6 (1995): 1055. http://dx.doi.org/10.1071/ph951055.

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We develop a nonlinear quantum theory of Newtonian gravity consistent with an objective interpretation of the wavefunction. Inspired by the ideas of Schrodinger, and Bell, we seek a dimensional reduction procedure to map complex wavefunctions in configuration space onto a family of observable fields in space-time. Consideration of quasi-classical conservation laws selects the reduced one-body quantities as the basis for an explicit quasi-classical coarse-graining. These we interpret as describing the objective reality of the laboratory. Thereafter, we examine what may stand in the role of the

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Nojiri, Shin'ichi, and Sergei D. Odintsov. "Effective Lagrangian and Static Black Holes in 2-D Dilatonic Gravity Inspired by Quantum Effects." Modern Physics Letters A 12, no. 13 (1997): 925–35. http://dx.doi.org/10.1142/s0217732397000959.

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We study the effective action in 2-D dilaton-Maxwell quantum gravity. Working with the one-loop renormalizable subset of such theories, we construct the improved effective Lagrangian which contains curvature under logarithm. This effective Lagrangian leads to new classical dilatonic gravity inspired by quantum effects. The static black holes (BH) solutions which may play the role of a remnant after the Hawking radiation for such theory are carefully investigated. The effective Lagrangian for Gross–Neveu-dilaton gravity is also constructed (in 1/N expansion).

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40

Escors, David, and Grazyna Kochan. "The Uncertainty Principle and the Minimal Space–Time Length Element." Physics 4, no. 4 (2022): 1230–40. http://dx.doi.org/10.3390/physics4040079.

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Quantum gravity theories rely on a minimal measurable length for their formulations, which clashes with the classical formulation of the uncertainty principle and with Lorentz invariance from general relativity. These incompatibilities led to the development of the generalized uncertainty principle (GUP) from string theories and its various modifications. GUP and covariant formulations of the uncertainty principle are discussed, together with implications for space–time quantization.

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SHIRAISHI, KIYOSHI. "U(∞) GAUGE THEORY FROM HIGHER DIMENSIONS." International Journal of Modern Physics A 07, no. 24 (1992): 6025–37. http://dx.doi.org/10.1142/s0217751x92002738.

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We show that classical U (∞) gauge theories can be obtained from the dimensional reduction of a certain class of higher-derivative theories. In general, the exact symmetry is attained in the limit of degenerate metric; otherwise, the infinite-dimensional symmetry can be taken as spontaneously broken. Monopole solutions are examined in the model for scalar and gauge fields. An extension to gravity is also discussed.

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BAPTISTA, JOSÉ PLÍNIO, ANTÔNIO BRASIL BATISTA, and JÚLIO CÉSAR FABRIS. "ON THE SIGNATURE OF EXTRA DIMENSIONS: THE CLASSICAL CASE." International Journal of Modern Physics D 02, no. 04 (1993): 431–41. http://dx.doi.org/10.1142/s0218271893000301.

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We consider multidimensional theories where the extra dimensions are permitted to be time-like. The study is carried out entirely on the classical level. The inexistence of any effect due to the changing of signature of internal dimensions is shown in the case of a pure geometric theory with a flat internal space; when the internal manifold has an intrinsic curvature or when an external field is coupled to gravity, some solutions that are unphysical with a space-like internal manifold become physical with a time-like one. The case where gravity is coupled to a Maxwell-type field in five dimens

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Ziaeepour, Houri. "Comparing Quantum Gravity Models: String Theory, Loop Quantum Gravity, and Entanglement Gravity versus SU(∞)-QGR." Symmetry 14, no. 1 (2022): 58. http://dx.doi.org/10.3390/sym14010058.

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In a previous article we proposed a new model for quantum gravity (QGR) and cosmology, dubbed SU(∞)-QGR. One of the axioms of this model is that Hilbert spaces of the Universe and its subsystems represent the SU(∞) symmetry group. In this framework, the classical spacetime is interpreted as being the parameter space characterizing states of the SU(∞) representing Hilbert spaces. Using quantum uncertainty relations, it is shown that the parameter space—the spacetime—has a 3+1 dimensional Lorentzian geometry. Here, after a review of SU(∞)-QGR, including a demonstration that its classical limit i

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BOJOWALD, MARTIN, and AURELIANO SKIRZEWSKI. "QUANTUM GRAVITY AND HIGHER CURVATURE ACTIONS." International Journal of Geometric Methods in Modern Physics 04, no. 01 (2007): 25–52. http://dx.doi.org/10.1142/s0219887807001941.

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Effective equations are often useful to extract physical information from quantum theories without having to face all technical and conceptual difficulties. One can then describe aspects of the quantum system by equations of classical type, which correct the classical equations by modified coefficients and higher derivative terms. In gravity, for instance, one expects terms with higher powers of curvature. Such higher derivative formulations are discussed here with an emphasis on the role of degrees of freedom and on differences between Lagrangian and Hamiltonian treatments. A general scheme i

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Acquaviva, Giovanni, Alfredo Iorio, Pablo Pais, and Luca Smaldone. "Hunting Quantum Gravity with Analogs: The Case of Graphene." Universe 8, no. 9 (2022): 455. http://dx.doi.org/10.3390/universe8090455.

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Analogs of fundamental physical phenomena can be used in two ways. One way consists in reproducing specific aspects of the classical or quantum gravity of quantum fields in curved space or of other high-energy scenarios on lower-energy corresponding systems. The “reverse way” consists in building fundamental physical theories, for instance, quantum gravity models, inspired by the lower-energy corresponding systems. Here, we present the case of graphene and other Dirac materials.

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GEYER, B., D. M. GITMAN, P. M. LAVROV, and P. YU MOSHIN. "ON PROBLEMS OF THE LAGRANGIAN QUANTIZATION OF W3-GRAVITY." International Journal of Modern Physics A 18, no. 27 (2003): 5099–125. http://dx.doi.org/10.1142/s0217751x0301526x.

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We consider the two-dimensional model of W3-gravity within Lagrangian quantization methods for general gauge theories. We use the Batalin–Vilkovisky formalism to study the arbitrariness in the realization of the gauge algebra. We obtain a one-parametric nonanalytic extension of the gauge algebra, and a corresponding solution of the classical master equation, related via an anticanonical transformation to a solution corresponding to an analytic realization. We investigate the possibility of closed solutions of the classical master equation in the Sp (2)-covariant formalism and show that such so

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Aste, Andreas. "Perturbative quantum gauge invariance: where the ghosts come from." Canadian Journal of Physics 83, no. 2 (2005): 139–63. http://dx.doi.org/10.1139/p04-064.

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A condensed introduction to quantum gauge theories is given in the perturbative S-matrix framework, with path-integral methods used nowhere. This approach emphasizes the fact that it is not necessary to start from classical gauge theories that are then subject to quantization: it is possible, instead, to recover the classical group structure and coupling properties from purely quantum-mechanical principles. As a main tool, we use a free-field version of the BecchiRouetStoraTyutin gauge transformation, which contains no interaction terms related to a coupling constant. This free gauge transf

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MÜLLER, DANIEL, MÁRCIO E. S. ALVES, and JOSÉ C. N. de ARAUJO. "THE ISOTROPIZATION PROCESS IN THE QUADRATIC GRAVITY." International Journal of Modern Physics D 23, no. 02 (2014): 1450019. http://dx.doi.org/10.1142/s0218271814500199.

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It is believed that soon after the Planck era, spacetime should have a semi-classical nature. Therefore, it is unavoidable to modify the theory of general relativity or look for alternative theories of gravitation. An interesting possibility found in the literature considers two geometric counter-terms to regularize the divergences of the effective action. These counter-terms are responsible for a higher-order derivative metric theory of gravitation. In the present paper, we investigate how isotropization occurs. For this reason a single solution is chosen throughout this paper. We obtain pert

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Pinto, Fabrizio. "Gravitational Dispersion Forces and Gravity Quantization." Symmetry 13, no. 1 (2020): 40. http://dx.doi.org/10.3390/sym13010040.

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The parallel development of the theories of electrodynamical and gravitational dispersion forces reveals important differences. The former arose earlier than the formulation of quantum electrodynamics so that expressions for the unretarded, van der Waals forces were obtained by treating the field as classical. Even after the derivation of quantum electrodynamics, semiclassical considerations continued to play a critical role in the interpretation of the full results, including in the retarded regime. On the other hand, recent predictions about the existence of gravitational dispersion forces w

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YU, HOI-LAI. "NOETHER CHARGES, BLACK HOLES AND THE IMMIRZI PARAMETER." International Journal of Modern Physics B 21, no. 23n24 (2007): 3990–92. http://dx.doi.org/10.1142/s0217979207045074.

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We have shown that terms in the action which won't contribute to local equation of motions do contribute to globally conversed physical quantities in classical theories of gravity due to general coordinate covariance. This observation allows one to determining the Immirzi parameter in the Ashtekar variable formulation of gravitational theories even at classical level. Applying Wald's Noether charge approach and identifying the entropy on black hole horizon as the Noether charge for translation, one can demonstrate explicitly that the Immirzi parameter does make its contributions through the bo

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