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We propose a cosmological model that describes isotropic expansion of inhomogeneous universe. The energy-momentum tensor that creates the spatial inhomogeneity may not affect the uniform expansion scaling factor $a(t)$ in the FLRW-like…

High Energy Physics - Theory · Physics 2014-10-15 Wei-Jian Geng , H. Lu

Primordial gravitational waves are created during the de Sitter phase of an exponentially-expanding (inflationary) universe, due to quantum zero-point vacuum fluctuations. These waves produce fluctuations in the temperature of the Cosmic…

Astrophysics · Physics 2022-09-07 Bruce Allen , Robert Caldwell , Scott Koranda

The Joule-Thomson expansion process is studied for Bardeen-AdS black holes in the extended phase space. Firstly, we get Joule-Thomson coefficient and find that the divergent point of Joule-Thomson coefficient coincides with the zero point…

General Relativity and Quantum Cosmology · Physics 2020-06-03 Cong Li , Pengzhang He , Ping Li , Jian-Bo Deng

We consider the late-time accelerated universe in the Friedmann-Robertson-Walker (FRW) spacetime with a nonzero curvature, and investigate cosmological models when the cosmic fluid is taken to be inhomogeneous and viscous (bulk viscous),…

General Relativity and Quantum Cosmology · Physics 2023-01-18 Iver Brevik , Alexander V. Timoshkin

A way to address the conundrum of Quantum Gravity is to illustrate the potentially fundamental interplay between quantum field theory, curved space-times physics and thermodynamics. So far, when studying moving quantum systems in the…

General Relativity and Quantum Cosmology · Physics 2008-11-26 Nathaniel Obadia

The process of the Joule-Thomson adiabatic expansion within RNED-AdS spacetime is investigated. The isenthalpic P-T diagrams and the inversion temperature were depicted. The inversion temperature depends on the magnetic charge and RNED…

General Physics · Physics 2023-04-06 S. I. Kruglov

In the context of $F(\phi)R$ models of gravity, the conformal invariance of the curvature perturbation on uniform-field slices has been already demonstrated in several publications. In this work we study the curvature perturbation…

General Relativity and Quantum Cosmology · Physics 2023-11-01 José Jaime Terente Díaz , Mindaugas Karčiauskas

The present study explores the thermal evolution and emission properties of neutron stars within the framework of modified $f(R, T)$ gravity by solving the coupled energy-balance and heat-transport equations. We compute stellar mass and…

General Relativity and Quantum Cosmology · Physics 2025-11-27 Charul Rathod , M. Mishra , Prasanta Kumar Das , Captain R. Singh

Considering the nonlinearity of the Yang Mills charge, we investigate the Joule-Thomson expansion for the Einstein-Power-Yang-Mills AdS black holes in the context of the gauge-gravity duality. Under this framework, we calculate the…

High Energy Physics - Theory · Physics 2023-05-24 Yun-Zhi Du , Xiao-Yang Liu , Yang Zhang , Li Zhao , Qiang Gu

The conformal correspondence between FLRW universes in the Einstein and Jordan frames allows for an expansion-collapse duality -- an always expanding Einstein frame universe can have a dual Jordan frame description that is contracting…

General Relativity and Quantum Cosmology · Physics 2023-09-12 Dipayan Mukherjee , Harkirat Singh Sahota

We generalize the theory of the inhomogeneity effect to enable comparison among different inhomogeneous planets. A metric of inhomogeneity based on the cumulative distribution function is applied to investigate the dependence of planetary…

Earth and Planetary Astrophysics · Physics 2023-08-31 Xi Zhang

In the context of f(R, T) gravity theory for the flat Friedmann Lemaitre Robertson Walker (FLRW) model, the accelerating expansion of the universe is investigated using a specific form of the emergent Hubble parameter. Datasets from H(z),…

General Relativity and Quantum Cosmology · Physics 2025-01-16 N. Myrzakulov , S. H. Shekh , Anirudh Pradhan , Archana Dixit

We investigate the thermodynamics of a spatially flat Friedmann-Robertson-Walker (FRW) universe within the framework of Generalized Proca (GP) theory, a comprehensive vector-tensor theory. By adopting two distinct dark energy models in GP,…

General Relativity and Quantum Cosmology · Physics 2026-01-21 Aofei Sang

The idea of Verlinde that gravity is an entropic force caused by information changes associated with the positions of material bodies, is used in the present work for the FRW model of the Universe. Using modified Hawking temperature, the…

General Relativity and Quantum Cosmology · Physics 2016-10-31 Saugata Mitra , Subhajit Saha , Subenoy Chakraborty

Universal thermodynamics for FRW model of the Universe bounded by apparent/event horizon has been considered for massive gravity theory. Assuming Hawking temperature and using the unified first law of thermodynamics on the horizon, modified…

General Relativity and Quantum Cosmology · Physics 2017-02-21 Subhajit Saha , Saugata Mitra , Subenoy Chakraborty

In this work, we study some thermodynamical aspects associated with torsion in a flat FLRW spacetime cosmic evolution. By implementing two Ansatze for the torsion term, we find that the model admits a phantom regime or a quintessence…

General Relativity and Quantum Cosmology · Physics 2020-06-26 Miguel Cruz , Fernando Izaurieta , Samuel Lepe

We investigate the warm inflationary scenario in the Weyl geometric gravity theory, in which the action is constructed by adding matter to the simplest conformally invariant gravitational action in Weyl geometry. The $\tilde{R}^2$ theory…

General Relativity and Quantum Cosmology · Physics 2026-05-19 Runhua Huang , Tiberiu Harko , Shi-Dong Liang , Hong-Hao Zhang , Lei Ming

We define thermodynamic pressure $P$ by work density $W$ as the conjugate quantity of thermodynamic volume $V$ from field equation. We derive the equations of state $P$=$P(V, T)$ for the Friedmann-Robertson-Walker (FRW) universe in Einstein…

General Relativity and Quantum Cosmology · Physics 2022-11-28 Shi-Bei Kong , Haximjan Abdusattar , Yihao Yin , Hongsheng Zhang , Ya-Peng Hu

We explore the thermodynamic and phase transition properties of asymptotically AdS black holes within Einstein-Gauss-Bonnet gravity, focusing on Joule Thomson expansion. Thermodynamics is studied in the extended phase space, where the…

General Relativity and Quantum Cosmology · Physics 2024-10-01 Kartheek Hegde , A. Naveena Kumara , C. L. Ahmed Rizwan , Ajith K. M. , Md Sabir Ali , Shreyas Punacha

In the paper, hep-th/0501055 (R.G. Cai and S.P. Kim, JHEP {\bf 0502}, 050 (2005)), it is shown that by applying the first law of thermodynamics to the apparent horizon of an FRW universe and assuming the geometric entropy given by a quarter…

High Energy Physics - Theory · Physics 2008-11-26 M. Akbar , Rong-Gen Cai