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We analyze the properties of the electric and magnetic fields in different reference frames within a cosmological background space-time. First, we investigate the conformal properties of the electromagnetic fields and charge currents,…

General Relativity and Quantum Cosmology · Physics 2019-03-27 Luciano Combi , Gustavo E. Romero

In this work, we explored warm inflation in the background of $f(R,T)$ gravity in the strong dissipation regime. Considering scalar field for FLRW universe, we derived modified field equations. We then deduced slow-roll parameters under…

General Relativity and Quantum Cosmology · Physics 2023-11-07 Biswajit Deb , Sabina Yeasmin , Atri Deshamukhya

In this work we study the Joule-Thomson expansion for uncharged black holes in a noncommutative scenario characterized by a parameter $\theta$, which is present in the horizon function. We calculate the inversion temperature for some values…

High Energy Physics - Theory · Physics 2021-11-03 J. P. Morais Graça , Eduardo Folco Capossoli , Henrique Boschi-Filho

We study the thermodynamics of Bose-Einstein condensation in a weakly interacting quasi-homogeneous atomic gas, prepared in an optical-box trap. We characterise the critical point for condensation and observe saturation of the thermal…

We presented a sound foundation of thermodynamics for a Friedmann-Robertson-Walker (FRW) universe from the first principle in ground-breaking work [Hu et al., JHEP12 (2022) 168]. Based on such an approach, we explore the thermodynamics of…

General Relativity and Quantum Cosmology · Physics 2025-07-09 Yue Chu , Shi-Bei Kong , Yang Liu , Hongsheng Zhang , Ya-Peng Hu

The temperature correction to the free energy of the gravitational field is considered which does not depend on the Planck energy physics. The leading correction may be interpreted in terms of the temperature dependent effective…

General Relativity and Quantum Cosmology · Physics 2009-11-10 G. E. Volovik , A. I. Zelnikov

The Friedman-Robertson-Walker (FRW) space-time exhibits particle creation similar to Hawking radiation of a black hole. In this essay we show that this FRW Hawking radiation leads to an effective negative pressure fluid which can drive an…

General Relativity and Quantum Cosmology · Physics 2012-11-20 Sujoy Kumar Modak , Douglas Singleton

We study the most general cosmological model with real scalar field which is minimally coupled to gravity. Our calculations are based on Friedmann-Lemaitre-Robertson-Walker (FLRW) background metric. Field equations consist of three…

General Relativity and Quantum Cosmology · Physics 2023-03-22 Medine Ildes , Metin Arik

We study the process of relaxation back to thermal equilibrium in $(1+1)$-dimensional conformal field theory at finite temperature. When the size of the system is much larger than the inverse temperature, perturbations decay exponentially…

High Energy Physics - Theory · Physics 2009-11-07 Danny Birmingham , Ivo Sachs , Sergey N. Solodukhin

The expansion of the Universe in $f(R,T)$ gravity is studied. We consider functions of the form $f(R,T)=R+\lambda T^\epsilon$ where $\epsilon<1$. We find that for all models with $\epsilon<0$, the Universe transitions to exponential growth…

General Relativity and Quantum Cosmology · Physics 2026-03-26 Vincent R. Siggia , Eric D. Carlson , P. Lee Pryor

The concept of smooth deformations of a Riemannian manifolds, recently evidenced by the solution of the Poincar\'e conjecture, is applied to Einstein's gravitational theory and in particular to the standard FLRW cosmology. We present a…

General Relativity and Quantum Cosmology · Physics 2015-03-17 M. D. Maia , A. J. S. Capistrano , J. S. Alcaniz , Edmundo M. Monte

In this Letter, we study analytically the evolutions of the flat Friedmann-Lemaitre-Robertson-Walker (FLRW) universe and its linear perturbations in the framework of {\em the dressed metric approach} in loop quantum cosmology (LQC).…

General Relativity and Quantum Cosmology · Physics 2017-09-21 Tao Zhu , Anzhong Wang , Klaus Kirsten , Gerald Cleaver , Qin Sheng

We present two-dimensional simulations for the cooling of neutron stars with strong magnetic fields (B > 1e13 Gauss). We study how the cooling curves are influenced by magnetic field decay. We show that the Joule heating effects are very…

Astrophysics · Physics 2008-03-05 Deborah N. Aguilera , José A. Pons , Juan A. Miralles

The thermodynamical aspects of the conformal time scale factor duality (SFD) of cosmological models within Einstein Gravity are investigated. We derive the SFD transformations of the thermodynamical quantities describing the thermal…

High Energy Physics - Theory · Physics 2017-03-01 G. M. Sotkov , A. L. Alves Lima , U. Camara da Silva

The actual accelerated expansion of the universe continues being a mystery in physics. Some models had been proposed for this explanations, among them the dark energy, which however has problems of experimental character as well as…

General Relativity and Quantum Cosmology · Physics 2012-11-13 Alejandro Guarnizo

The fluctuations of spacetime geometries at finite temperature are evaluated within the linearized theory of gravity. These fluctuations are described by the probability distribution of various configurations of the gravitational field. The…

General Relativity and Quantum Cosmology · Physics 2015-10-13 Iwo Bialynicki-Birula

We argue that a scalar field in de Sitter spacetime should feel explicit thermal effects associated with its curvature. Starting from the Bunch-Davies vacuum and a scalar field with small mass compared to the de Sitter curvature, we use the…

High Energy Physics - Theory · Physics 2025-12-08 Nikos Irges , Antonis Kalogirou , Fotis Koutroulis

The method of a conformal transformation is applied to a general class of single field inflation models with non-minimal coupling to gravity and non-standard kinetic terms, in order to reduce the cosmological perturbative calculation to the…

General Relativity and Quantum Cosmology · Physics 2012-03-19 Takahiro Kubota , Nobuhiko Misumi , Wade Naylor , Naoya Okuda

Physical equivalence between different conformal frames in scalar-tensor theory of gravity is a known fact. However, assuming that matter minimally couples to the metric of a particular frame, which we call the matter Jordan frame, the…

General Relativity and Quantum Cosmology · Physics 2015-10-16 Guillem Domènech , Misao Sasaki

We analyze the thermal fluctuations of a free, conformally invariant, Maxwell quantum field (photon) interacting with a cosmological background spacetime, in the framework of quantum field theory in curved spacetimes and semiclassical and…

General Relativity and Quantum Cosmology · Physics 2025-07-01 Markus B. Fröb , Dražen Glavan , Paolo Meda