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We give a set of local geometric conditions on a spacetime metric which are necessary and sufficient for it to be a null electrovacuum, that is, the metric is part of a solution to the Einstein-Maxwell equations with a null electromagnetic…

General Relativity and Quantum Cosmology · Physics 2015-06-16 C. G. Torre

We explore how quantum properties of spacetime, specifically the curvature of momentum space, can backreact on classical gravity within a tractable semiclassical (2+1)-dimensional framework with a negative cosmological constant. Motivated…

General Relativity and Quantum Cosmology · Physics 2026-05-13 Partha Nandi , Mainak Roy , Langa Horoto , Frederik G. Scholtz , Biswajit Chakraborty

We explore the weak-field phenomenology of a compact star spacetime modified by quantum gravitational corrections derived from the effective field theoretical (EFT) approach by Calmet et al. [1]. These corrections, encoded in non-local…

General Relativity and Quantum Cosmology · Physics 2026-02-10 Reggie C. Pantig , Ali Ovgun , Gaetano Lambiase

The presence of a non-zero cosmological term in Einstein field equations can be interpreted as the physical possibility for preferred reference frames without breaking of general covariance. This possibility is used in the process of…

General Relativity and Quantum Cosmology · Physics 2009-08-11 Clovis Jacinto de Matos

The constructive gravity programme applied to electrodynamics with vacuum birefringence yields the---up to unknown gravitational constants---unique compatible gravity theory for the underlying non-metric geometry. Starting from a…

General Relativity and Quantum Cosmology · Physics 2020-09-17 Nils Alex

This thesis concerns the split of Einstein's field equations (EFE's) with respect to nowhere null hypersurfaces. Areas covered include A) the foundations of relativity, deriving geometrodynamics from relational first principles and showing…

General Relativity and Quantum Cosmology · Physics 2007-05-23 E. Anderson

We derive specific properties of electromagnetism when gravitational effects are not negligible and analyze their impact on new physics at the horizons of black holes. We show that a neutral configuration of charges in a region of high…

High Energy Physics - Theory · Physics 2023-12-20 Pierre Heidmann , Madhur Mehta

The Einstein theories of space-time and gravity as well the stander cosmology are reconstructed thoroughly in this paper based on flat reference frame. The rational parts of the Einstein theories are reserved while the irrational parts…

General Physics · Physics 2007-05-23 Mei Xiaochun

Emergent modified gravity presents a new set of generally covariant gravitational theories in which the space-time metric is not directly given by one of the fundamental fields. A metric compatible with the modified dynamics of gravity is…

General Relativity and Quantum Cosmology · Physics 2024-04-09 Martin Bojowald , Erick I. Duque

The nonlocal electrodynamics of uniformly rotating systems is presented and its predictions are discussed. In this case, due to paucity of experimental data, the nonlocal theory cannot be directly confronted with observation at present. The…

High Energy Physics - Theory · Physics 2010-11-19 Bahram Mashhoon

This paper aims at investigating the influence of space-time curvature on the uncertainty relation. In particular, relying on previous findings, we assume the quantum wave function to be confined to a geodesic ball on a given space-like…

General Relativity and Quantum Cosmology · Physics 2021-06-02 Luciano Petruzziello , Fabian Wagner

In this work we study the effects of non-minimal coupling between electromagnetism and gravity, which are motivated by quantum effects such as vacuum polarization. We investigate the modification of both asymptotically dipole and uniform…

General Relativity and Quantum Cosmology · Physics 2023-03-20 Kumar Ravi , Petar Pavlović , Andrey Saveliev

In this second part of our series of two papers, where spacetime is modelled by a graph, where Planck size quantum black holes lie on the vertices, we consider the thermodynamics of spacetime. We formulate an equation which tells in which…

General Relativity and Quantum Cosmology · Physics 2009-10-21 J. Makela

The paper uses geometrical arguments to derive equations with relevance for cosmology; 5-dimensional spacetime is assumed because it has been shown in other works to provide a setting for significant unification of different areas of…

General Physics · Physics 2008-01-29 Jose B. Almeida

The geometric potential in quantum mechanics has been attracted attention recently, providing a formalism to investigate the influence of curvature in the context of low-dimensional systems. In this paper, we study the consequences of a…

The geodesic equations are considered in static mass imbedded in a uniform electromagnetic field. Due to electromagnetic field horizon shrinks and geodesics are modified. By analyzing the behavior of the effective potentials for the…

General Physics · Physics 2019-07-24 A. Al-Badawi , M. Q. Owaidat , S. Tarawneh

An axiomatic approach to electrodynamics reveals that Maxwell electrodynamics is just one instance of a variety of theories for which the name electrodynamics is justified. They all have in common that their fundamental input are Maxwell's…

Mathematical Physics · Physics 2016-08-04 Christian Pfeifer , Daniel Siemssen

In this paper, we investigate the effects of electromagnetic field on the isotropic spherical gravastar models in metric $f(R,T)$ gravity. For this purpose, we have explored singularity-free exact models of relativistic spheres with a…

General Relativity and Quantum Cosmology · Physics 2020-03-03 Z. Yousaf , Kazuharu Bamba , M. Z. Bhatti , U. Ghafoor

In this paper, we study the geodesic motion in spherically symmetric electro-vacuum Euclidean solutions of the Einstein equation. There are two kinds of such solutions: the Euclidean Reissner-Nordstr\"{o}m (ERN) metrics, and the…

General Relativity and Quantum Cosmology · Physics 2024-04-17 Arthur Garnier

Electromagnetic waves propagate in the Schwarzschild spacetime like in a nonuniform medium with a varying refraction index. A fraction of the radiation scatters off the curvature of the geometry. The energy of the backscattered part of an…

General Relativity and Quantum Cosmology · Physics 2009-10-31 Edward Malec