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We demonstrate that there does exist an equilibrium description of thermodynamics on the apparent horizon in the expanding cosmological background for a wide class of modified gravity theories with the Lagrangian density $f(R, \phi, X)$,…

General Relativity and Quantum Cosmology · Physics 2011-08-05 Kazuharu Bamba , Chao-Qiang Geng , Shinji Tsujikawa

Thermodynamic interpretations of gravity often arise from applying the Clausius relation to spacetime horizons. In modified gravity theories with higher-order equations of motion, such as f(R) and scalar-tensor gravity, this relation…

General Relativity and Quantum Cosmology · Physics 2026-04-07 Vishnu A Pai , Vishnu S Namboothiri , Titus K Mathew

The present work reveals a direct correspondence between modified theories of gravity (cosmology) and entropic cosmology based on the thermodynamics of apparent horizon. It turns out that due to the total differentiable property of entropy,…

General Relativity and Quantum Cosmology · Physics 2025-07-01 Shin'ichi Nojiri , Sergei D. Odintsov , Tanmoy Paul , Soumitra SenGupta

It was shown recently that, in the case of Schwarschild black hole, one can obtain the correct thermodynamic relations by studying a model quantum system and using a particular duality transformation. We study this approach further for the…

General Relativity and Quantum Cosmology · Physics 2009-03-19 Sudipta Sarkar , T. Padmanabhan

We review thermodynamic properties of modified gravity theories such as $F(R)$ gravity and $f(T)$ gravity, where $R$ is the scalar curvature and $T$ is the torsion scalar in teleparallelism. In particular, we explore the equivalence between…

General Relativity and Quantum Cosmology · Physics 2016-06-22 Kazuharu Bamba

It has previously been shown that the Einstein equation can be derived from the requirement that the Clausius relation dS = dQ/T hold for all local acceleration horizons through each spacetime point, where dS is one quarter the horizon area…

General Relativity and Quantum Cosmology · Physics 2011-05-05 Christopher Eling , Raf Guedens , Ted Jacobson

We study the relation between the thermodynamics and field equations of generalized gravity theories on the dynamical trapping horizon with sphere symmetry. We assume the entropy of dynamical horizon as the Noether charge associated with…

General Relativity and Quantum Cosmology · Physics 2010-05-12 Shao-Feng Wu , Xian-Hui Ge , Peng-Ming Zhang , Guo-Hong Yang

Applying Clausius relation with energy-supply defined by the unified first law of thermodynamics formalism to the apparent horizon of a massive cosmological model proposed lately, the corrected entropic formula of the apparent horizon is…

General Relativity and Quantum Cosmology · Physics 2013-04-19 Hui Li , Yi Zhang

We explore thermodynamics of the apparent horizon in $f(T)$ gravity with both equilibrium and non-equilibrium descriptions. We find the same dual equilibrium/non-equilibrium formulation for $f(T)$ as for $f(R)$ gravity. In particular, we…

General Relativity and Quantum Cosmology · Physics 2015-05-30 Kazuharu Bamba , Chao-Qiang Geng

The thermodynamics of the Universe is restudied by requiring its compatibility with the holographic-style gravitational equations which govern the dynamics of both the cosmological apparent horizon and the entire Universe, and possible…

General Relativity and Quantum Cosmology · Physics 2015-07-29 David Wenjie Tian , Ivan Booth

Starting from the first law of thermodynamics, $dE=T_hdS_h+WdV$, at apparent horizon of a FRW universe, and assuming that the associated entropy with apparent horizon has a quantum corrected relation, $S=\frac{A}{4G}-\alpha \ln…

High Energy Physics - Theory · Physics 2011-02-09 Ahmad Sheykhi

In this work we apply the gravity-thermodynamics approach for the case of generalized mass-to-horizon entropy, which is a two-parameter extension of Bekenstein-Hawking entropy that arises from the extended mass-to-horizon relation, that is…

General Relativity and Quantum Cosmology · Physics 2025-04-01 Spyros Basilakos , Andreas Lymperis , Maria Petronikolou , Emmanuel N. Saridakis

We investigate the cosmological implications of generalized mass-to-horizon entropy, a two-parameter extension of the standard Bekenstein entropy based on the mass-to-horizon relation. Assuming the entropy balance relation, we derive the…

General Relativity and Quantum Cosmology · Physics 2026-05-26 Smeehan S Shameeem , Priyesh K , Krishna P. B , Titus K Mathew

We derive the equation of matter density perturbations on sub-horizon scales for a general Lagrangian density f(R, phi, X) that is a function of a Ricci scalar R, a scalar field phi and a kinetic term X=-(nabla phi)^2/2. This is useful to…

Astrophysics · Physics 2008-12-18 Shinji Tsujikawa

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

We propose a modified gravity theory by extending the Einstein-Hilbert action with an arbitrary function of the Ricci scalar and the Kretschmann scalar invariants. The resulting modified Friedmann equations for a spatially flat FRW universe…

General Relativity and Quantum Cosmology · Physics 2026-05-29 A. Dehyadegari , A. Sheykhi

In the context of the teleparallel equivalent of general relativity the concept of gravitational pressure and gravitational energy-momentum arisen in a natural way. In the case of a Friedmann-Lemaitre-Robertson-Walker space FLRW we obtain…

General Relativity and Quantum Cosmology · Physics 2018-02-19 J. F. da Rocha-Neto , B. R. Morais

Spacetimes with horizons show a resemblance to thermodynamic systems and it is possible to associate the notions of temperature and entropy with them. Several aspects of this connection are reviewed in a manner appropriate for broad…

General Relativity and Quantum Cosmology · Physics 2008-11-26 T. Padmanabhan

In this work, we explore the effect at cosmological level of the extra contribution arising from the Geodetic Brane Gravity model within a thermodynamical perspective. As already known, the universe seen as an extended object embedded…

High Energy Physics - Theory · Physics 2026-01-27 Gilberto Aguilar-Pérez , Giovany Cruz , Miguel Cruz , Efraín Rojas

The conception of gravity as an emergent phenomenon, rooted in the thermodynamics of spacetime, offers a radical departure from its geometric description. This paper investigates the emergence of cosmic space by synthesizing two key…

General Relativity and Quantum Cosmology · Physics 2026-01-05 Ahmad Sheykhi
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