scholarly journals Renormalizable and Unitary Model of Quantum Gravity

Symmetry ◽  
2019 ◽  
Vol 11 (11) ◽  
pp. 1334
Author(s):  
S. A. Larin
Keyword(s):  
Quantum Theory ◽  
Quantum Gravity ◽  
Curvature Tensor ◽  
Relativistic Quantum ◽  
Dimensional Regularization ◽  
Graviton Propagator ◽  
Unitary Model ◽  
Theory Of Gravity ◽  
Made In

We consider R + R 2 relativistic quantum gravity with the action where all possible terms quadratic in the curvature tensor are added to the Einstein-Hilbert term. This model was shown to be renormalizable in the work by K.S. Stelle. In this paper, we demonstrate that the R + R 2 model is also unitary contrary to the statements made in the literature, in particular in the work by Stelle. New expressions for the R + R 2 Lagrangian within dimensional regularization and the graviton propagator are derived. We demonstrate that the R + R 2 model is a good candidate for the fundamental quantum theory of gravity.

scholarly journals Fourth-derivative relativistic quantum gravity

2018 ◽  
Vol 191 ◽  
pp. 07002 ◽  
Author(s):  
S.A. Larin
Keyword(s):  
Quantum Theory ◽  
Quantum Gravity ◽  
Curvature Tensor ◽  
Relativistic Quantum ◽  
Dimensional Regularization ◽  
Quantum Theory Of Gravitation ◽  
Graviton Propagator ◽  
Fourth Derivative ◽  
Theory Of Gravitation

We consider relativistic quantum gravity with the action including terms quadratic in the curvature tensor. This model is known to be renormalizable. We demonstrate that the model is also unitary. New expressions for the corresponding Lagrangian and the graviton propagator within dimensional regularization are derived. We argue that the considered model is the proper candidate for the fundamental quantum theory of gravitation.

scholarly journals Higher-derivative relativistic quantum gravity

2018 ◽  
Vol 33 (05) ◽  
pp. 1850028 ◽  
Author(s):  
S. A. Larin
Keyword(s):  
Quantum Theory ◽  
Quantum Gravity ◽  
Curvature Tensor ◽  
Relativistic Quantum ◽  
Dimensional Regularization ◽  
Quantum Theory Of Gravitation ◽  
Higher Derivative ◽  
Graviton Propagator ◽  
Theory Of Gravitation

Relativistic quantum gravity with the action including terms quadratic in the curvature tensor is analyzed. We derive new expressions for the corresponding Lagrangian and the graviton propagator within dimensional regularization. We argue that the considered model is a good candidate for the fundamental quantum theory of gravitation.

scholarly journals Renormalizable and Unitary Lorentz Invariant Model of Quantum Gravity

2021 ◽  
Author(s):  
S. A. Larin
Keyword(s):  
General Relativity ◽  
Quantum Theory ◽  
Quantum Gravity ◽  
Curvature Tensor ◽  
Quantum Theory Of Gravitation ◽  
Proper Choice ◽  
Invariant Model ◽  
Self Consistent ◽  
Theory Of Gravitation

We analyze the R + R2 model of quantum gravity where terms quadratic in the curvature tensor are added to the General Relativity action. This model was recently proved to be a self-consistent quantum theory of gravitation, being both renormalizable and unitary. The model can be made practically indistinguishable from General Relativity at astrophysical and cosmological scales by the proper choice of parameters.

scholarly journals Conceptual Problems in Quantum Gravity and Quantum Cosmology

2013 ◽  
Vol 2013 ◽  
pp. 1-17 ◽  
Author(s):  
Claus Kiefer
Keyword(s):  
Quantum Theory ◽  
Quantum Gravity ◽  
Present Status ◽  
Quantum Cosmology ◽  
Open Problems ◽  
Fundamental Physics ◽  
Main Current ◽  
Conceptual Problems ◽  
Theory Of Gravity ◽  
Conceptual Nature

The search for a consistent and empirically established quantum theory of gravity is among the biggest open problems of fundamental physics. The obstacles are of formal and of conceptual nature. Here, I address the main conceptual problems, discuss their present status, and outline further directions of research. For this purpose, the main current approaches to quantum gravity are briefly reviewed and compared.

scholarly journals Uncertainty relation for quantum gravity

2016 ◽  
Vol 31 (28n29) ◽  
pp. 1645028
Author(s):  
Ya. I. Azimov
Keyword(s):  
Quantum Theory ◽  
Quantum Gravity ◽  
Uncertainty Relation ◽  
Physical Realization ◽  
Non Local ◽  
Theory Of Gravity ◽  
The Physical Realization

Discussion of the physical realization of coordinates demonstrates that the quantum theory of gravity (still absent) should be non-local and, probably, non-commutative as well.

scholarly journals Proposal for a New Quantum Theory of Gravity III: Equations for Quantum Gravity, and the Origin of Spontaneous Localisation

2020 ◽  
Vol 75 (2) ◽  
pp. 143-154 ◽  
Author(s):  
Maithresh Palemkota ◽  
Tejinder P. Singh
Keyword(s):  
General Relativity ◽  
Quantum Theory ◽  
Quantum Gravity ◽  
Equation Of Motion ◽  
Classical General Relativity ◽  
Spectral Action ◽  
Commutative Space ◽  
Theory Of Gravity ◽  
Simple Action ◽  
Spectral Equation

AbstractWe present a new, falsifiable quantum theory of gravity, which we name non-commutative matter-gravity. The commutative limit of the theory is classical general relativity. In the first two papers of this series, we have introduced the concept of an atom of space-time-matter (STM), which is described by the spectral action in non-commutative geometry, corresponding to a classical theory of gravity. We used the Connes time parameter, along with the spectral action, to incorporate gravity into trace dynamics. We then derived the spectral equation of motion for the gravity part of the STM atom, which turns out to be the Dirac equation on a non-commutative space. In the present work, we propose how to include the matter (fermionic) part and give a simple action principle for the STM atom. This leads to the equations for a quantum theory of gravity, and also to an explanation for the origin of spontaneous localisation from quantum gravity. We use spontaneous localisation to arrive at the action for classical general relativity (including matter source) from the action for STM atoms.

scholarly journals Outline for a Quantum Theory of Gravity

2019 ◽  
Vol 74 (5) ◽  
pp. 383-386
Author(s):  
Tejinder P. Singh
Keyword(s):  
Quantum Theory ◽  
String Theory ◽  
Quantum Gravity ◽  
Experimental Tests ◽  
World Sheet ◽  
Action Function ◽  
Relativistic Limit ◽  
Metric Tensor ◽  
Theory Of Gravity ◽  
Matrix Dynamics

AbstractBy invoking an asymmetric metric tensor, and borrowing ideas from non-commutative geometry, string theory, and trace dynamics, we propose an action function for quantum gravity. The action is proportional to the four-dimensional non-commutative curvature scalar (which is torsion dependent), which is sourced by the Nambu–Goto world-sheet action for a string plus the Kalb–Ramond string action. This ‘quantum gravity’ is actually a non-commutative classical matrix dynamics, and the only two fundamental constants in the theory are the square of the Planck length and the speed of light. By treating the entity described by this action as a microstate, one constructs the statistical thermodynamics of a large number of such microstates, in the spirit of trace dynamics. Quantum field theory (and ℏ) and quantum general relativity (and G) emerge from the underlying matrix dynamics in the thermodynamic limit. Statistical fluctuations, which are inevitably present about equilibrium, are the source for spontaneous localisation, which drives macroscopic quantum gravitational systems to the classical general relativistic limit. While the mathematical formalism governing these ideas remains to be developed, we hope to highlight here the deep connection between quantum foundations and the sought-for quantum theory of gravity. In the sense described in this article, ongoing experimental tests of spontaneous collapse theories are in fact also tests of string theory!

scholarly journals Quantum Theory of Gravity and Arthur Eddingtons Fundamental Theory

2021 ◽  
Vol 2 (11) ◽  
pp. 1092-1100
Author(s):  
Konstantinov SI
Keyword(s):  
Dark Matter ◽  
Quantum Theory ◽  
Quantum Gravity ◽  
Dark Matter Halo ◽  
Fundamental Theory ◽  
Theories Of Gravity ◽  
Theory Of Gravity ◽  
First Time ◽  
Contraction And Expansion ◽  
The Universe

For the first time, the article presents the Quantum Theory of Gravity, covering not only the microcosm of elementary particles, but also the macrocosm of planets, stars and black holes. This relational approach to gravity was consistently presented in Arthur Eddington's monograph “Fundamental Theory”. In the theory of quantum gravity proposes to consider instead of gravity holes in the curved space-time of Einstein's general relativity, gravitational funnels formed by the rotation of planets, stars and galaxies in a dark matter halo. The change in the gravitational potential in the funnels occurs instantly in all areas of the gravitational funnel space in accordance with the pressure gradient described by the Euler-Bernoulli equation for superfluid continuous media. The new cosmological theory represents the evolution of the universe and dark holes without a singularity. The disordered alternation of the processes of contraction and expansion of individual regions of the infinite Universe realizes the circulation of baryonic and dark matter, which allows it to exist indefinitely, bypassing the state of equilibrium. Numerical modeling allows us to assert that the theory of quantum gravity is the most reliable of the three generally accepted theories of gravity.

scholarly journals Renormalizable and Unitary Lorentz Invariant Model of Quantum Gravity

Universe ◽  
2021 ◽  
Vol 7 (11) ◽  
pp. 435
Author(s):  
Sergey A. Larin
Keyword(s):  
General Relativity ◽  
Quantum Theory ◽  
Quantum Gravity ◽  
Curvature Tensor ◽  
Quantum Theory Of Gravitation ◽  
Proper Choice ◽  
Invariant Model ◽  
Self Consistent ◽  
Theory Of Gravitation

We analyze the R+R2 model of quantum gravity where terms quadratic in the curvature tensor are added to the General Relativity action. This model was recently proved to be a self-consistent quantum theory of gravitation, being both renormalizable and unitary. The model can be made practically indistinguishable from General Relativity at astrophysical and cosmological scales by the proper choice of parameters.

scholarly journals Towards metric-affine quantum gravity

2020 ◽  
Vol 17 (supp01) ◽  
pp. 2040003 ◽  
Author(s):  
Roberto Percacci
Keyword(s):  
Quantum Theory ◽  
Quantum Gravity ◽  
Theory Of Gravity

I review here some motivations to consider a theory of gravity based on independent metric and connection, and its status as a quantum theory.

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