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Adopting the Landau-Lifshiftz method of classical fluctuations we determine the statistical average strength of the fluctuations of the energy flux on the apparent horizon of a homogeneous and isotropic universe described by Einstein…

General Relativity and Quantum Cosmology · Physics 2018-07-04 Jose P. Mimoso , Diego Pavon

We investigate the thermodynamical properties of the apparent horizon in a fractal universe. We find that one can always rewrite the Friedmann equation of the fractal universe in the form of the entropy balance relation $ \delta Q=T_h…

General Physics · Physics 2015-06-12 Ahmad Sheykhi , Zeinab Teimoori , Bin Wang

Considering the Einstein field equations in Lyra manifold, and applying the unified first law of thermodynamics as well as the Clausius relation to the apparent horizon of FRW universe, we find the entropy of apparent horizon in Lyra…

General Relativity and Quantum Cosmology · Physics 2017-09-12 H. Moradpour , N. Sadeghnezhad , S. Ghaffari , A. Jahan

We show that Jacobson's thermodynamic derivation of Einstein's equations remains valid when local Rindler horizons are treated as finite heat-capacity systems, resolving the unphysical infinite-bath assumption of standard Unruh…

High Energy Physics - Theory · Physics 2026-03-02 F. Barzi , H. El Moumni , K. Masmar

In the context of thermodynamics applied to our cosmological apparent horizon, we explicit in greater details our previous work which established the Friedmann Equations from projection of Hayward's Unified First Law. In particular, we show…

General Relativity and Quantum Cosmology · Physics 2015-02-17 Alexis Helou

An equilibrium picture of thermodynamics is discussed at the apparent horizon of FRW universe in $f(T,T_G)$ gravity, where $T$ represents the torsion invariant and $T_G$ is the teleparallel equivalent of the Gauss-Bonnet term. It is found…

General Relativity and Quantum Cosmology · Physics 2015-11-04 M. Zubair

We analyze spacetimes with horizons and study the thermodynamic aspects of causal horizons, suggesting that the resemblance between gravitational and thermodynamic systems has a deeper quantum mechanical origin. We find that the observer…

General Physics · Physics 2016-10-03 Eric M Howard

The thermodynamical properties of dark energy are usually investigated with the equation of state $\omega =\omega_{0}+\omega_{1}z$. Recent observations show that our universe is accelerating, and the apparent horizon and the event horizon…

Astrophysics · Physics 2008-11-26 Yongping Zhang , Ze-Long Yi , Tong-Jie Zhang , Wenbiao Liu

Recently, a generalized gravity theory was proposed by Harko etal where the Lagrangian density is an arbitrary function of the Ricci scalar R and the trace of the stress-energy tensor T, known as F(R,T) gravity. In their derivation of the…

General Physics · Physics 2015-06-12 Subenoy Chakraborty

With the usual definitions for the entropy and the temperature associated with the apparent horizon, we show that the unified first law on the apparent horizon is equivalent to the Friedmann equation for the scalar--tensor theory with…

General Relativity and Quantum Cosmology · Physics 2015-07-31 Yumei Huang , Yungui Gong , Dicong Liang , Zhu Yi

The thermodynamics-gravity conjecture reveals that one can derive the gravitational field equations by using the first law of thermodynamics and vice versa. Considering the entropy associated with the horizon in the form of non-extensive…

General Relativity and Quantum Cosmology · Physics 2021-11-04 Mahnaz Asghari , Ahmad Sheykhi

It is well known that, for a wide class of spacetimes with horizons, Einstein equations near the horizon can be written as a thermodynamic identity. It is also known that the Einstein tensor acquires a highly symmetric form near static, as…

General Relativity and Quantum Cosmology · Physics 2009-07-30 Dawood Kothawala , T. Padmanabhan

The present work deals with four alternative formulation of Bekenstein system on event horizon in $f(R)$ gravity. While thermodynamical laws holds in universe bounded by apparent horizon, these laws break down on event horizon. With…

General Relativity and Quantum Cosmology · Physics 2016-05-27 Jibitesh Dutta , Saugata Mitra , Binod Chetry

Motivated by the notion that the mathematics of gravity can be reproduced from a statistical requirement of maximal entropy, we study the consequence of introducing an entropic source term in the Einstein-Hilbert action. For a spatially…

General Relativity and Quantum Cosmology · Physics 2024-03-20 Soumya Chakrabarti

Present investigation devoted to the dynamical study of Relativistic Hydrodynamics with some thermodynamical characteristics in $f(R,G)$ gravity towards spatially homogeneous isotropic cosmological model filled with isotropic fluid. We…

General Physics · Physics 2020-04-09 S. H. Shekh , Simran Arora , V. R. Chirde , P. K. Sahoo

We investigate the thermodynamical and causal consistency of cosmological models of the cubic Quasi-Topological Gravity (QTG) in four dimensions, as well as their phenomenological consequences. Specific restrictions on the maximal values of…

General Relativity and Quantum Cosmology · Physics 2013-04-16 U. Camara dS , A. A. Lima , G. M. Sotkov

In this paper we show that the gravitational field equations of $(n+1)$% -dimensional topological black holes with constant horizon curvature, in cubic and quartic quasi-topological gravity, can be recast in the form of the first law of…

General Relativity and Quantum Cosmology · Physics 2015-06-19 A. Sheykhi , M. H. Dehghani , R. Dehghani

It is shown that the differential form of Friedmann equation of a FRW universe can be rewritten as a universal form $dE = TdS + WdV$ at apparent horizon, where $E$ and $V$ are the matter energy and volume inside the apparent horizon (the…

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

We give a short review of the recent developments of entropic cosmology based on two thermodynamic laws of the apparent horizon, namely the first and the second laws of thermodynamics. The first law essentially provides the change of the…

General Relativity and Quantum Cosmology · Physics 2024-09-04 Shin'ichi Nojiri , Sergei D. Odintsov , Tanmoy Paul

Thermodynamics on the horizon of a flat universe at late times is studied in holographic cosmological models that assume an associated entropy on the horizon. In such models, a $\Lambda(t)$ model similar to a time-varying $\Lambda(t)$…

General Relativity and Quantum Cosmology · Physics 2020-01-01 Nobuyoshi Komatsu
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