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The averaging problem in general relativity is briefly discussed. A new setting of the problem as that of macroscopic description of gravitation is proposed. A covariant space-time averaging procedure is described. The structure of the…

General Relativity and Quantum Cosmology · Physics 2007-05-23 Roustam M. Zalaletdinov

The Galactic Center black hole environment gives us new opportunity to test deviation from General Relativity and black hole physics. In this work we analytically generate the shape of the Galactic Center black hole by using a recently…

General Relativity and Quantum Cosmology · Physics 2026-01-27 Pranjali Bhattacharjee , Sanjeev Kalita , Debojit Paul

Klein-Gordon and Dirac equations are the motion equations for relativistic particles with spin 0 (so-called scalar particles) and 1/2 (electron/positron) respectively. For a free particle, the Dirac equation is derived from the Klein-Gordon…

General Physics · Physics 2009-11-16 Marie-Noëlle Célérier , Laurent Nottale

This work is the extension of author`s research, where the modified theory of induced gravity (MTIG) is proposed. The theory describes two systems (stages): Einstein (ES) and "restructuring" (RS). We consider equations with quadratic…

General Physics · Physics 2019-11-22 Farkhat Zaripov

Chern-Simons (CS) modified gravity is an extension to general relativity (GR) in which the metric is coupled to a scalar field, resulting in modified Einstein field equations. In the dynamical theory, the scalar field is itself sourced by…

High Energy Astrophysical Phenomena · Physics 2011-12-16 Yacine Ali-Haïmoud , Yanbei Chen

Physics invites the idea that space contains energy whose gravitational effect approximates that of Einstein's cosmological constant, Lambda; nowadays the concept is termed dark energy or quintessence. Physics also suggests the dark energy…

Astrophysics · Physics 2008-11-26 P. J. E. Peebles , Bharat Ratra

A new class of solutions of the Einstein field equations in spherical symmetry is found. The new solutions are mathematically described as the metrics admitting separation of variables in area-radius coordinates. Physically, they describe…

General Relativity and Quantum Cosmology · Physics 2009-11-07 Roberto Giambo' , Fabio Giannoni , Giulio Magli , Paolo Piccione

We show that derivation of Friedmann's equations from the Einstein-Hilbert action, paying attention to the requirements of isotropy and homogeneity during the variation, leads to a different interpretation of pressure than what is typically…

General Relativity and Quantum Cosmology · Physics 2021-07-15 Kevin S. Croker , Joel L. Weiner

We propose a quantum gravity-extended form of the classical length contraction law obtained in Special Relativity. More specifically, the framework of our discussion is the UV self-complete theory of quantum gravity. Against this…

High Energy Physics - Theory · Physics 2013-10-01 Antonio Aurilia , Euro Spallucci

An approach to the quantization of gravity in the presence matter is examined which starts from the classical Einstein-Hilbert action and matter approximated by "point" particles minimally coupled to the metric. Upon quantization, the…

General Physics · Physics 2022-05-24 Matej Pavšič

We consider a general class of quantum gravity-inspired, modified gravity theories, where the Einstein-Hilbert action is extended through the addition of all terms quadratic in the curvature tensor coupled to scalar fields with standard…

General Relativity and Quantum Cosmology · Physics 2016-04-12 Kent Yagi , Leo C. Stein , Nicolas Yunes , Takahiro Tanaka

We investigate a slowly rotating black hole solution in a novel Einstein-Maxwell-scalar theory, which is prompted by the classification of general Einstein-Maxwell-scalar theories. The gyromagnetic ratio of this black hole is calculated,…

General Relativity and Quantum Cosmology · Physics 2022-01-05 Jianhui Qiu

In Einstein's gedankenexperiment for measuring space and time, an ensemble of clocks moving through curved spacetime measures geometry by sending signals back and forth, as in the global positioning system (GPS). Combining well-known…

General Relativity and Quantum Cosmology · Physics 2012-10-18 Seth Lloyd

A novel idea is proposed for a natural solution of the dark energy and its cosmic coincidence problem. The existence of local antigravity sources, associated with astrophysical matter configurations distributed throughout the universe, can…

General Relativity and Quantum Cosmology · Physics 2018-07-04 Georgios Kofinas , Vasilios Zarikas

Quasinormal modes of Dirac field in the background of a non-Schwarzschild black holes in theories with higher curvature corrections are investigated in this paper. With the help of the semi-analytic WKB approximation and further using of…

General Relativity and Quantum Cosmology · Physics 2020-01-08 A. F. Zinhailo

We construct and study general static, spherically symmetric, magnetically charged solutions in Einstein-Maxwell-dilaton gravity in four dimensions. That is, taking Einstein gravity coupled to a ${\rm U}(1)$ gauge field and a massless…

High Energy Physics - Theory · Physics 2023-03-24 Achilleas P. Porfyriadis , Grant N. Remmen

The Cosmic Defect theory (CD), which is presented elsewhere in this conference, introduces in the standard Einstein-Hilbert Lagrangian an elastic term accounting for the strain of space-time viewed as a four-dimensional physical continuum.…

General Relativity and Quantum Cosmology · Physics 2014-11-20 Ninfa Radicella , Angelo Tartaglia

In this work, the relativistic phenomena of Lorentz-Fitzgerald contraction and time dilation are derived using a modified distance formula that is appropriate for discrete space. This new distance formula is different than the Pythagorean…

General Physics · Physics 2018-10-03 David Crouse , Joseph Skufca

A Friedmann--Robertson--Walker Universe is studied with a dark energy component represented by a quintessence field. The Lagrangian for this system, hereafter called the Friedmann--Robertson--Walker--quintessence (FRWq) system, is…

General Relativity and Quantum Cosmology · Physics 2017-08-23 Sergio A. Hojman , Felipe A. Asenjo , Carlos A. Rubio

Recent results based on renormalization group approaches to Quantum Gravity suggest that the Newton's and cosmological constants should be treated as dynamical variables whose evolution depend on the characteristic energy scale of the…

General Relativity and Quantum Cosmology · Physics 2018-05-08 S. J. Gabriele Gionti