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We extend the thermodynamic derivation of gravity in the Jacobson framework by generalizing the Clausius relation through a nontrivial entropy functional. We show that entropy deformations appear as modifications of the effective…

General Relativity and Quantum Cosmology · Physics 2026-04-14 H. R. Fazlollahi

In this work, two originally separate adjustments for the Friedmann equations are concurrently considered. Firstly, the fractal structure of the black hole horizon region is imposed by the Barrow entropy. The second adjustment is the…

General Relativity and Quantum Cosmology · Physics 2024-06-13 Tuhina Ghorui , Prabir Rudra , Farook Rahaman

Modified gravity (MG) theories predict, in general, that the ratio of gravitational wave (GW) to electromagnetic (EM) luminosity distances, $\Xi$, differs from its general relativity (GR) value of unity at cosmological scales, thus…

General Relativity and Quantum Cosmology · Physics 2021-05-28 Isabela S. Matos , Maurício O. Calvão , Ioav Waga

We discuss the galaxy clustering based on thermodynamics and statistical mechanics in the expanding universe in a modified theory of gravity. The modified general relativity (MGR) is developed using the regular line element field to…

General Physics · Physics 2023-02-15 Abdul W. Khanday , Sudhaker Upadhyay , Prince A. Ganai

As a classical approach, the dynamics of the Universe, influenced by its dark components, are unveiled through prior modifications of Einstein's equations. Cosmography, on the other hand, is a highly efficient tool for reconstructing any…

General Relativity and Quantum Cosmology · Physics 2024-07-19 Sai Swagat Mishra , N. S. Kavya , P. K. Sahoo , V. Venkatesha

We investigate the cosmological implications of Tsallis entropy in two widely discussed frameworks: the Cai-Kim thermodynamic derivation of the Friedman equations and the Tsallis holographic dark energy (HDE) scenario, considering both the…

Cosmology and Nongalactic Astrophysics · Physics 2026-03-06 Pedro M. Ibarbo-Perlaza. , J. Bayron Orjuela-Quintana , Jose L. Palacios-Córdoba , César A. Valenzuela-Toledo

The basic objective of this investigation is to explore the impact of a novel gravitational modification, specifically, the $f(\mathcal{G}, \mathbf{T}^2)$ (where $\mathbf{T}^2 \equiv T_{\alpha\beta}T^{\alpha\beta}$, $T^{\alpha\beta}$…

General Relativity and Quantum Cosmology · Physics 2022-04-12 Z. Yousaf , M. Z. Bhatti , S. Khan , P. K. Sahoo

We present a unified framework that combines early- and late-Universe observations to constrain three functional realizations of f(T,B) gravity: the linear, quadratic, and general power-law models. First, constraints on deviations from the…

Cosmology and Nongalactic Astrophysics · Physics 2026-01-27 Yahia Al-Omar , Majida Nahili , Nidal Chamoun

We make a first principle study of gravitational pressure in cosmic thermodynamics. The pressure is directly derived from the unified first law, in fact the Einstein field equation in spherically symmetric spacetime. By using this pressure,…

General Relativity and Quantum Cosmology · Physics 2023-01-18 Haximjan Abdusattar , Shi-Bei Kong , Wen-Long You , Hongsheng Zhang , Ya-Peng Hu

In this paper, we obtain the law of emergence with Tsallis entropy from the thermodynamic laws. We first derive the law of emergence from the equilibrium description of the unified first law and Clausius relation. However, it has been shown…

General Relativity and Quantum Cosmology · Physics 2023-01-02 M. Dheepika , Hassan Basari V. T. , Titus K. Mathew

We construct $F(T,\left(\nabla{T}\right)^2,\Box {T})$ gravitational modifications, which are novel classes of modified theories arising from higher-derivative torsional terms in the action, and are different than their curvature analogue.…

General Relativity and Quantum Cosmology · Physics 2016-10-19 Giovanni Otalora , Emmanuel N. Saridakis

Utilizing Kaniadakis entropy associated with the apparent horizon of the Friedmann-Robertson-Walker (FRW) Universe and applying the emergence of cosmic space paradigm, we deduce the modified Friedmann equation for a non-flat…

General Relativity and Quantum Cosmology · Physics 2024-05-08 Pranav Prasanthan , Sarath Nelleri , Navaneeth Poonthottathil , Sreejith E K

In this paper, we study the model of $f(T, B)$ gravity with viscous fluid in flat-FRW metric, in which $T$ and $B$ are torsion scalar and boundary term, respectively. We obtain the Friedmann equations in the framework of modified…

General Relativity and Quantum Cosmology · Physics 2019-09-02 A. Pourbagher , Alireza Amani

In this article, we investigate the thermodynamic stability of the FRW universe for two examples, Tsallis entropy and loop quantum gravity, by considering non-extensive statistical mechanics. The heat capacity, free energy and pressure of…

General Relativity and Quantum Cosmology · Physics 2022-01-03 Yang Liu

Inspired by the Wald-Kodama entropy $S=A/(4G_{\text{eff}})$ where $A$ is the horizon area and $G_{\text{eff}}$ is the effective gravitational coupling strength in modified gravity with field equation $R_{\mu\nu}-Rg_{\mu\nu}/2=$ $8\pi…

General Relativity and Quantum Cosmology · Physics 2015-07-14 David Wenjie Tian , Ivan Booth

Inspired by String T-duality and taking into account the zero-point length correction, $l_0$, to the gravitational potential, we construct modified Friedmann equations by applying the first law of thermodynamics on the apparent horizon of…

General Relativity and Quantum Cosmology · Physics 2024-12-17 Giuseppe Gaetano Luciano , Ahmad Sheykhi

We perform observational confrontation and cosmographic analysis of $f(T,T_G)$ gravity and cosmology. This higher-order torsional gravity is based on both the torsion scalar, as well as on the teleparallel equivalent of the Gauss--Bonnet…

General Relativity and Quantum Cosmology · Physics 2024-10-15 Harshna Balhara , J. K. Singh , Shaily , Emmanuel N. Saridakis

In this paper, we investigate the thermodynamic aspects of quadratic gravity in a $D$-dimensional Friedmann-Lemaitre-Robertson-Walker (FLRW) universe. First, we derive the field equations and the effective energy-momentum tensor for…

General Relativity and Quantum Cosmology · Physics 2025-07-17 Navid Safarzadeh Ilkhchi , Amin Rezaei Akbarieh , Yaghoub Heydarzade

First and second laws of black hole thermodynamics are examined at the apparent horizon of FRW spacetime in $f(R,R_{\alpha\beta}R^{\alpha\beta} ,\phi)$ gravity, where $R$, $R_{\alpha\beta}R^{\alpha\beta}$ and $\phi$ are the Ricci scalar,…

General Relativity and Quantum Cosmology · Physics 2016-11-17 M. Zubair , Farzana Kousar , Sebastian Bahamonde

In this paper, we investigate some exact cosmological models in Myrzakulov $F(T,Q)$ gravity or the Myrzakulov gravity-III (MG-III) proposed in [arXiv:1205.5266], with observational constraints. The MG-III gravity is some kind of unification…

General Relativity and Quantum Cosmology · Physics 2024-09-05 Dinesh Chandra Maurya , K. Yesmakhanova , R. Myrzakulov , G. Nugmanova