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A new mechanism for causing naked singularities is found in an effective superstring theory. We investigate the gravitational collapse in a spherically symmetric Einstein-Maxwell-dilaton system in the presence of a pure cosmological…

General Relativity and Quantum Cosmology · Physics 2010-11-19 Kengo Maeda , Takashi Torii , Makoto Narita

We examine the motion of a charged particle in the vicinity of a weakly magnetized naked singularity. The escape velocity and energy of the particle moving around the naked singularity after being kicked by another particle or photon are…

General Relativity and Quantum Cosmology · Physics 2015-11-19 Gulmina Zaman Babar , Mubasher Jamil , Yen-Kheng Lim

We study the characteristics of azimuthally propagating electromagnetic fields in a cylindrical cavity. It is found that under certain conditions, the transverse components of the electromagnetic field are singular at the center of the…

Classical Physics · Physics 2023-05-17 Mustafa Bakr , Smain Amari

An equation of motion is derived for a topologically cylindrical worldsheet of lightlike electromagnetic current, embedded in 3+1 dimensions in a smooth external electromagnetic field. Then it is shown that the static circle of uniformly…

Classical Physics · Physics 2012-12-24 J. Margulies

We establish a framework to construct spherically symmetric and static solutions in $f(R)$ gravity coupled with nonlinear electromagnetic fields. We present two new specific solutions and discuss the energy conditions. We calculate some…

General Relativity and Quantum Cosmology · Physics 2025-09-09 Yongben Shi , Rong-Jia Yang

The Temporal Fluctuation Model proposed in present paper represents an attempt for a unitary vision for gravity, inertia and electromagnetism. We obtain the main results of General Relativity and Electromagnetism and the theory, until now,…

General Physics · Physics 2007-05-23 Viorel Drafta

The interactions of gravitons with spin-1 matter are calculated in parallel with the well known photon case. It is shown that graviton scattering amplitudes can be factorized into a product of familiar electromagnetic forms, and cross…

General Relativity and Quantum Cosmology · Physics 2017-04-07 N. E. J. Bjerrum-Bohr , Barry R. Holstein , John F. Donoghue , Ludovic Planté , Pierre Vanhove

We present a classical theory of gravity, which is singularity free at short distances and reduces to General Relativity at large distances. We discuss its implications.

General Relativity and Quantum Cosmology · Physics 2025-02-19 Saurya Das , Mitja Fridman , Sourav Sur

A systematic search for different viable models of the dark energy universe, all of which give rise to finite-time, future singularities, is undertaken, with the purpose to try to find a solution to this common problem. After some work, a…

High Energy Physics - Theory · Physics 2015-05-27 A. J. López-Revelles , E. Elizalde

The discovery of the accelerated expansion of the universe highlighted General Relativity's inability to naturally account for dark energy without invoking a finely tuned cosmological constant. In response, a wide range of alternative…

General Relativity and Quantum Cosmology · Physics 2025-11-11 P. A. G. Monteiro , C. J. A. P. Martins

We conduct a preliminary investigation into the phenomenological implications of Einsteinian cubic gravity (ECG), a 4-dimensional theory of gravity cubic in curvature of interest for its unique formulation and properties. We find an…

General Relativity and Quantum Cosmology · Physics 2018-04-13 Robie A. Hennigar , Mohammad Bagher Jahani Poshteh , Robert B. Mann

We discuss the dynamics of a spherically symmetric dark radiation vaccum in the Randall-Sundrum brane world scenario. Under certain natural assumptions we show that the Einstein equations on the brane form a closed system. For a de Sitter…

High Energy Physics - Theory · Physics 2017-08-23 Rui Neves , Cenalo Vaz

Why are "analogue spacetimes'' interesting? For the purposes of this workshop the answer is simple: Analogue spacetimes provide one with physically well-defined and physically well-understood concrete models of many of the phenomena that…

General Relativity and Quantum Cosmology · Physics 2009-04-14 Matt Visser , Silke Weinfurtner

Black hole spacetimes that exhibit integrable singularities have gained considerable interest as alternatives to both regular and singular black holes. Unlike most known regular black hole solutions, these models evade the formation of an…

General Relativity and Quantum Cosmology · Physics 2025-08-15 Julio Arrechea , Stefano Liberati , Hooman Neshat , Vania Vellucci

Gravitational collapse is one of the most fruitful subjects in gravitational physics. It is well known that singularity formation is inevitable in complete gravitational collapse. It was conjectured that such a singularity should be hidden…

General Relativity and Quantum Cosmology · Physics 2010-05-12 Tomohiro Harada , Hideo Iguchi , Ken-ichi Nakao

Motivated by some recent speculative attempts to model the dark energy, scalar fields with negative kinetic energy coupled to gravity without a cosmological constant are considered. It is shown that in the presence of an ordinary fluid, any…

High Energy Physics - Theory · Physics 2007-05-23 G. W. Gibbons

There has been much recent work on quantum inequalities to constrain negative energy. These are uncertainty principle-type restrictions on the magnitude and duration of negative energy densities or fluxes. We consider several examples of…

General Relativity and Quantum Cosmology · Physics 2016-08-25 L. H. Ford , Michael J. Pfenning , Thomas A. Roman

There are known models of spherical gravitational collapse in which the collapse ends in a naked shell-focusing singularity for some initial data. If a massless scalar field is quantized on the classical background provided by such a star,…

General Relativity and Quantum Cosmology · Physics 2009-12-31 Tomohiro Harada , Hideo Iguchi , Ken-ichi Nakao , T. P. Singh , Takahiro Tanaka , Cenalo Vaz

Non-minimally coupled Y(R)-Maxwell gravity which have some interesting solutions may be used to understand dark matter, dark energy, the origin of cosmic magnetic field and the evaluation of the universe. We give some new solutions to the…

General Relativity and Quantum Cosmology · Physics 2013-04-09 Özcan Sert

A theorem, giving necessary and sufficient condition for naked singularity formation in spherically symmetric non static spacetimes under hypotheses of physical acceptability, is formulated and proved. The theorem relates existence of…

General Relativity and Quantum Cosmology · Physics 2017-08-23 Roberto Giambo' , Fabio Giannoni , Giulio Magli , Paolo Piccione