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This work presents a universal and revisited formalism for the entropy of the apparent horizon in modified gravity to investigate the validity of the Generalized Second Law (GSL) of thermodynamics. This revisited horizon entropy is…

General Relativity and Quantum Cosmology · Physics 2025-12-22 Soma Heydari , Parastoo Askari , Kayoomars Karami

Recent developments in observational cosmology have led to attempts to make modifications on both sides of the Einstein equation to explain some of the puzzling new findings. What follows is an examination of the source of gravity that we…

Cosmology and Nongalactic Astrophysics · Physics 2014-01-23 Edward A Spiegel

An alternative approach to Einstein's theory of General Relativity (GR) is reviewed, which is motivated by a range of serious theoretical issues inflicting the theory, such as the cosmological constant problem, presence of non-Machian…

General Physics · Physics 2016-07-13 Ram Gopal Vishwakarma

The peculiarities of the inverse square law of Newtonian gravity in standard Big Bang Cosmology are discussed. It is shown that the incorporation of an additive term to Newtonian gravitation, as the inverse Yukawa-like field, allows remove…

General Relativity and Quantum Cosmology · Physics 2021-12-28 Nelson Falcon

Discovery of a novel thermodynamic aspect of nonrelativistic gravity is reported. Here, initially, an unspecified scalar field potential is considered and treated not as an externally applied field but as a thermodynamic variable on an…

Statistical Mechanics · Physics 2021-11-10 Peter Ván , Sumiyoshi Abe

Non-perturbative theories of quantum gravity inevitably include configurations that fail to resemble physically reasonable spacetimes at large scales. Often, these configurations are entropically dominant and pose an obstacle to obtaining…

General Relativity and Quantum Cosmology · Physics 2008-11-26 Graham Brightwell , Joe Henson , Sumati Surya

Along this review, we focus on the study of several properties of modified gravity theories, in particular on black-hole solutions and its comparison with those solutions in General Relativity, and on Friedmann-Lemaitre-Robertson-Walker…

General Relativity and Quantum Cosmology · Physics 2015-06-05 A. de la Cruz-Dombriz , D. Saez-Gomez

We discuss a large class of phenomenological models incorporating quantum gravity motivated corrections to electrodynamics. The framework is that of electrodynamics in a birefringent and dispersive medium with non-local constitutive…

General Relativity and Quantum Cosmology · Physics 2008-11-26 R. Montemayor , Luis F. Urrutia

This work presents a study of the possibility for extending the well-known results of E.Verlinde concerning the entropic nature of gravity to the ultraviolet region (Planck's energies) and also the derivation of quantum corrections to…

High Energy Physics - Theory · Physics 2013-09-24 A. E. Shalyt-Margolin

Recently a class of alternative theories of gravity which goes under the name f(R) gravity, has received considerable attention, mainly due to its interesting applications in cosmology. However, the phenomenology of such theories is not…

General Relativity and Quantum Cosmology · Physics 2008-11-26 Thomas P. Sotiriou , Stefano Liberati

Recently, it was argued (Eur. Phys. J. C {\bf73}, 2487 (2013)) that the total entropy of a gravitational system should be related to the volume of system instead of the system surface. Here, we show that this new proposal cannot satisfy the…

General Relativity and Quantum Cosmology · Physics 2016-05-17 H. Moradpour

Emergent gravity views spacetime as an entity emergent from a more complete theory of interacting fundamental constituents valid at much finer resolution or higher energies, usually assumed to be above the Planck energy. In this view…

General Relativity and Quantum Cosmology · Physics 2010-03-12 B. L. Hu

I describe the conceptual and mathematical basis of an approach which describes gravity as an emergent phenomenon. Combining principle of equivalence and principle of general covariance with known properties of local Rindler horizons,…

General Relativity and Quantum Cosmology · Physics 2009-11-22 T. Padmanabhan

This paper brings together four distinct but very important physical notions: 1) Entropic force, 2) Entropy-along-a-curve, 3) Tsallis' q-statistics, and 4) Emergent gravitation. We investigate the non additive, classical (Tsallis')…

General Physics · Physics 2018-06-15 D. J. Zamora , M. C. Rocca , A. Plastino , G. L. Ferri

If we assume that the source of thermodynamic system, $\rho$ and $p$, are also the source of gravity, thermal quantities, such as entropy, temperature, and chemical potential, can induce effects of gravity, or gravity can induce thermal…

General Relativity and Quantum Cosmology · Physics 2014-09-12 Rong-Jia Yang

In this contribution to the conference "Beyond Einstein: Historical Perspectives on Geometry, Gravitation and Cosmology in the Twentieth Century", we give a critical status report of attempts to explain the late accelerated expansion of the…

General Relativity and Quantum Cosmology · Physics 2008-10-02 Norbert Straumann

We study the Euclidean gravitational path integral computing the Renyi entropy and analyze its behavior under small variations. We argue that, in Einstein gravity, the extremality condition can be understood from the variational principle…

High Energy Physics - Theory · Physics 2018-12-27 Xi Dong , Aitor Lewkowycz

In this work we derive general quantum phenomenological equations of gravitational dynamics and analyse its features. The derivation uses the formalism developed in thermodynamics of spacetime and introduces low energy quantum gravity…

General Relativity and Quantum Cosmology · Physics 2021-02-03 Ana Alonso-Serrano , Marek Liška

We consider the controversial hypothesis that gravity is an entropic force that has its origin in the thermodynamics of holographic screens. Several key aspects of entropic gravity are discussed. In particular, we revisit and elaborate on…

High Energy Physics - Theory · Physics 2012-05-23 Masud Chaichian , Markku Oksanen , Anca Tureanu

Wald's entropy formula allows one to find the entropy of black holes' event horizon within any diffeomorphism invariant theory of gravity. When applied to general relativity, the formula yields the Bekenstein-Hawking result but, for any…

General Relativity and Quantum Cosmology · Physics 2015-08-24 Fayçal Hammad