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In an abstract setting of a general classical mechanical system as a model for the universe we set up a general formalism for a law behind the second law of thermodynamics, i.e. really for "initial conditions". We propose a unification with…

High Energy Physics - Theory · Physics 2009-11-11 Holger B. Nielsen , Masao Ninomiya

A system composed of identical spins and described by a quantum mechanical pure state is analyzed within the statistical framework presented in Part I of this work. We explicitly derive the typical values of the entropy, of the energy, and…

Quantum Physics · Physics 2010-07-22 Barbara Fresch , Giorgio J. Moro

Entropic cosmology assumes several forms of entropy on the horizon of the universe, where the entropy can be considered to behave as if it were related to the exchange (the transfer) of energy. To discuss this exchangeability, the…

General Relativity and Quantum Cosmology · Physics 2016-02-19 Nobuyoshi Komatsu , Shigeo Kimura

This paper explores the non-equilibrium behavior of thermodynamics at the apparent horizon of isotropic and homogeneous universe model in $f(\mathcal{G},T)$ gravity ($\mathcal{G}$ and $T$ represent the Gauss-Bonnet invariant and trace of…

General Relativity and Quantum Cosmology · Physics 2018-03-13 M. Sharif , Ayesha Ikram

This paper investigates the thermodynamic evolution of the universe within the framework of a quadratic equation of state (EoS). Building upon the basis of the quadratic EoS model, as a phenomenological extension to dark energy models, we…

Cosmology and Nongalactic Astrophysics · Physics 2025-10-28 A. Shahriar , M. Abbasiyan-Motlaq , M. Mohsenzadeh , E. Yusofi

We derive a generalization of the Second Law of Thermodynamics that uses Bayesian updates to explicitly incorporate the effects of a measurement of a system at some point in its evolution. By allowing an experimenter's knowledge to be…

Statistical Mechanics · Physics 2017-04-04 Anthony Bartolotta , Sean M. Carroll , Stefan Leichenauer , Jason Pollack

The investigation of modifications to the FLRW cosmology resulting from the consideration of a general entropy for the cosmological apparent horizon is the subject of this study. Building upon the work of Nojiri and collaborators in 2022,…

General Relativity and Quantum Cosmology · Physics 2023-07-26 A. Khodam-Mohammadi , M. Monshizadeh

It is generally believed that inflationary cosmology explains the isotropy, large scale homogeneity and flatness as well as predicting the deviations from homogeneity of our universe. We show that this is not the only cosmology which can…

High Energy Physics - Theory · Physics 2007-05-23 J. W. Moffat

In this paper, we intend to evaluate and analyze the statefinder parameters in $f(T)$ cosmology. Friedmann equation in $f(T)$ model is taken, and the statefinder parameters ${r,s}$ are calculated. We consider a model of $f(T)$ which…

General Physics · Physics 2012-11-13 Mubasher Jamil , Davood Momeni , Ratbay Myrzakulov , Prabir Rudra

Entropy is a fundamental concept from Thermodynamics and it can be used to study models on context of Creation Cold Dark Matter (CCDM). From conditions on the first ($\dot{S}\geq0$)\footnote{Throughout the present work we will use dots to…

General Relativity and Quantum Cosmology · Physics 2020-12-02 R. Valentim , J. F. Jesus

Recently, we have investigated the dynamics of the universe in tachyon cosmology with non-minimal coupling to matter \cite{faraj}-\cite{faraj3}. In particular, for the interacting holographic dark energy (IHDE), the model is studied in…

General Relativity and Quantum Cosmology · Physics 2016-07-26 H. Farajollahi , A. Ravanpak , M. Abolghasemi

We investigate the generalized second law (GSL) of thermodynamics in the framework of $f(R)$-gravity. We consider a FRW universe filled only with ordinary matter enclosed by the dynamical apparent horizon with the Hawking temperature. For a…

General Physics · Physics 2012-06-05 K. Karami , M. S. Khaledian , N. Abdollahi

We consider a spatially flat Friedmann-Lemaitre-Robertson-Walker space time and investigate the second law and the generalized second law of thermodynamics for apparent horizon in generalized modified Gauss Bonnet theory of gravity (whose…

General Relativity and Quantum Cosmology · Physics 2011-01-17 H. Mohseni Sadjadi

The state function entropy and its quantum thermodynamical implication for two typical dissipative systems with anomalous spectral densities are studied by investigating on their low-temperature quantum behavior. In all cases it is found…

Statistical Mechanics · Physics 2015-06-03 Chun-Yang Wang , An-Qi Zhao , Xiang-Mu Kong , Jing-Dong Bao

We show that there exists a natural way to define a condition of generalized thermal equilibrium between systems governed by Tsallis thermostatistics, under the hypotheses that i) the coupling between the systems is weak, ii) the structure…

Statistical Mechanics · Physics 2007-09-17 Massimo Marino

The entanglement between the position and coin state of a $N$-dimensional quantum walker is shown to lead to a thermodynamic theory. The entropy, in this thermodynamics, is associated to the reduced density operator for the evolution of…

Quantum Physics · Physics 2015-06-22 Alejandro Romanelli , Raul Donangelo , Renato Portugal , Franklin L. Marquezino

Regardless of studies and debates over a century, the statistical origin of the second law of thermodynamics still remains illusive. One essential obstacle is the lack of a proper theoretical formalism for non-equilibrium entropy. Here I…

Statistical Mechanics · Physics 2017-10-18 Xiangjun Xing

Entropy is a quantity for counting physical degrees of freedom in a system. At a finite temperature, one can use thermal entropy to study thermodynamical properties. At zero temperature, entanglement entropy is expected to provide a…

High Energy Physics - Theory · Physics 2018-10-29 Chen-Te Ma

We provide an explicit calculation of the evolution of the cosmic entanglement entropy in the early universe before the matter dominant era. This is made possible by invoking the generalized Chaplygin gas (GCG) model, which has the…

General Relativity and Quantum Cosmology · Physics 2011-12-08 Pisin Chen , Yuezhen Niu

We consider the particle creation scenario in the dynamical Chern-Simons modified gravity in the presence of perfect fluid equation of state $p=(\gamma-1)\rho$. By assuming various modified entropies (Bekenstein, logarithmic, power law…

General Relativity and Quantum Cosmology · Physics 2018-10-15 Abdul Jawad , Shamaila Rani , Salman Rafique