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200 papers

We discuss the linearization of Einstein equations in the presence of a cosmological constant, by expanding the solution for the metric around a flat Minkowski space-time. We demonstrate that one can find consistent solutions to the…

General Relativity and Quantum Cosmology · Physics 2010-04-14 Jose Bernabeu , Catalina Espinoza , Nick E. Mavromatos

Recent results on solutions of the Einstein equations with matter are surveyed and a number of open questions are stated. The first group of results presented concern asymptotically flat spacetimes, both stationary and dynamical. Then there…

General Relativity and Quantum Cosmology · Physics 2007-05-23 Alan D. Rendall

We propose a formulation of gravity theory in the form of a field theory in a flat space-time with a number of dimensions greater than four. Configurations of the field under consideration describe the splitting of this space-time into a…

General Relativity and Quantum Cosmology · Physics 2015-06-03 S. A. Paston

In Einstein's general relativity, with its nonlinear field equations, the discoveries and analyzes of various specific explicit solutions made a great impact on understanding many of the unforeseen features of the theory. Some solutions…

General Relativity and Quantum Cosmology · Physics 2007-05-23 Jiri Bicak

In a class of generalized Einstein's gravity theories we derive the equations and general asymptotic solutions describing the evolution of the perturbed universe in unified forms. Our gravity theory considers general couplings between the…

General Relativity and Quantum Cosmology · Physics 2009-10-28 J. Hwang

We briefly review the current status of nonlocal gravity (NLG), which is a classical nonlocal generalization of Einstein's theory of gravitation based on a certain analogy with the nonlocal electrodynamics of media. Nonlocal gravity thus…

General Relativity and Quantum Cosmology · Physics 2020-01-20 Bahram Mashhoon , Friedrich W. Hehl

One of the greatest problems of standard cosmology is the Big Bang singularity. Previously it has been shown that non-local ghostfree higher-derivative modifications of Einstein gravity in the ultra-violet regime can admit non-singular…

High Energy Physics - Theory · Physics 2010-12-03 Tirthabir Biswas , Tomi Koivisto , Anupam Mazumdar

We study the solutions of the semiclassical Einstein equation in flat cosmological spacetimes driven by a massive conformally coupled scalar field. In particular, we show that it is possible to give initial conditions at finite time to get…

Mathematical Physics · Physics 2015-03-10 Nicola Pinamonti , Daniel Siemssen

We argue that in a nonlinear gravity theory, which according to well-known results is dynamically equivalent to a self-gravitating scalar field in General Relativity, the true physical variables are exactly those which describe the…

General Relativity and Quantum Cosmology · Physics 2010-11-01 Guido Magnano , Leszek M. Sokolowski

Nonlocal gravity (NLG) is a classical nonlocal generalization of Einstein's theory of gravitation developed in close analogy with the nonlocal electrodynamics of media. It appears that the nonlocal aspect of the universal gravitational…

General Relativity and Quantum Cosmology · Physics 2022-09-12 Mahmood Roshan , Bahram Mashhoon

We showed that the principle of nongravitating vacuum energy, when formulated in the first order formalism, solves the cosmological constant problem. The most appealing formulation of the theory displays a local symmetry associated with the…

General Relativity and Quantum Cosmology · Physics 2011-09-09 E. I. Guendelman , A. B. Kaganovich

This research is an extension of the author's article \cite{zar}, in which conformally invariant generalization of string theory was suggested to higher-dimensional objects. Special cases of the proposed theory are Einstein's theory of…

General Relativity and Quantum Cosmology · Physics 2014-10-13 Farkhat Zaripov

The intrinsic metric symmetries for energy-momentum in warped space-time universally reinforce strict spatial flatness in the GR metric formalism. The passive/active energy-charge for the 1686, 1913, and 1915 gravitational laws maintains…

Mathematical Physics · Physics 2008-05-13 Igor Bulyzhenkov

Utilizing various gauges of the radial coordinate we give a description of static spherically symmetric space-times with point singularity at the center and vacuum outside the singularity. We show that in general relativity (GR) there exist…

General Relativity and Quantum Cosmology · Physics 2007-05-23 Plamen Fiziev

When Einstein's equations for an asymptotically flat, vacuum spacetime are reexpressed in terms of an appropriate conformal metric that is regular at (future) null infinity, they develop apparently singular terms in the associated conformal…

General Relativity and Quantum Cosmology · Physics 2009-06-01 Vincent Moncrief , Oliver Rinne

This paper investigates the existence and stability of Einstein universe in the context of $f(R,T,Q)$ gravity, where $Q=R_{\mu\nu}T^{\mu\nu}$. Considering linear homogeneous perturbations around scale factor and energy density, we formulate…

General Relativity and Quantum Cosmology · Physics 2018-12-19 M. Sharif , Arfa Waseem

Nonlocal gravity is a promising super-renormalizable or finite quantum gravity theory consistent with unitarity. In this paper, we focus on the classical equations of motion and explicitly show that a particular subclass of G\"{o}del-type…

General Relativity and Quantum Cosmology · Physics 2026-05-05 Zhe Zhao , Leonardo Modesto , Cosimo Bambi

We hereby study the properties of a large class of weakly nonlocal gravitational theories around the (anti-) de Sitter spacetime background. In particular, we explicitly prove that the kinetic operator for the graviton field has the same…

High Energy Physics - Theory · Physics 2018-08-16 Alexey S. Koshelev , K. Sravan Kumar , Leonardo Modesto , Leslaw Rachwal

Mathematical modeling of gravitating configurations of physical fields is one of the priority directions of the modern theory of gravity. Most of the exact solutions constructed within the framework of the general relativity are static or…

General Relativity and Quantum Cosmology · Physics 2019-12-03 Ju V Tchemarina , E G Alekseeva , A N Tsirulev , N K Nuraliev

The quantum gravity is formulated based on principle of local gauge invariance. The model discussed in this paper has local gravitational gauge symmetry and gravitational field appears as gauge field. The problems on quantization and…

High Energy Physics - Theory · Physics 2007-05-23 Ning Wu