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We have investigated the thermodynamical properties of the Universe with dark energy. Adopting the usual assumption in deriving the constant co-moving entropy density that the physical volume and the temperature are independent, we observed…

General Relativity and Quantum Cosmology · Physics 2010-10-27 Yungui Gong , Bin Wang , Anzhong Wang

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

It is argued that the spatial homogeneity of the early universe need not be explained as having evolved from a previous inhomogeneous state. Rather, a homogeneous cosmic initial condition follows from the Second Law of Thermodynamics…

General Relativity and Quantum Cosmology · Physics 2018-06-21 Lucas Lolli Savi

We disclose the thermodynamical properties of the apparent horizon in a nonsingular universe. We take into account the zero-point length correction to the gravitational potential and derive the modified entropy expression that includes…

General Relativity and Quantum Cosmology · Physics 2025-05-06 Ahmad Sheykhi , Leila Liravi , Kimet Jusufi

We investigate the laws of thermodynamics in an accelerating universe driven by dark energy with a time-dependent equation of state. In the case we consider that the physically relevant part of the Universe is that envelopped by the…

General Relativity and Quantum Cosmology · Physics 2009-11-11 Bin Wang , Yungui Gong , Elcio Abdalla

Recent observations show that our universe is accelerating by dark energy, so it is important to investigate the thermodynamical properties of it. The Undulant Universe is a model with equation of state $\omega(a)=-\cos(b\ln a)$ for dark…

Astrophysics · Physics 2010-06-18 Tian Lan , Tong-Jie Zhang , Bao-Quan Wang

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

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

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

We apply the gravity-thermodynamics conjecture, namely the first law of thermodynamics on the Universe horizon, but using the generalized Kaniadakis entropy instead of the standard Bekenstein-Hawking one. The former is a one-parameter…

General Relativity and Quantum Cosmology · Physics 2021-12-07 Andreas Lymperis , Spyros Basilakos , Emmanuel N. Saridakis

We discuss the concept of measurement in cosmology from the relativistic and quantum mechanical points of view. The uncertainty principle within the particle horizon, excludes the momentum of particles to be less than $\pi\hbar H/c$. This…

Astrophysics · Physics 2007-05-23 S. Rahvar , M. Sadegh Movahed , M Saadat

There is a paradox in the standard model of cosmology. How can matter in the early universe have been in thermal equilibrium, indicating maximum entropy, but the initial state also have been low entropy (the "past hypothesis"), so as to…

General Relativity and Quantum Cosmology · Physics 2023-12-21 Jordan Scharnhorst , Anthony Aguirre

An accelerated universe should naturally have a vacuum energy density determined by its dynamical curvature. The cosmological constant is most likely a temporary description of a dynamical variable that has been drastically evolving from…

General Relativity and Quantum Cosmology · Physics 2015-10-28 Joan Sola

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

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

A common feature in the thermodynamic analysis of homogeneous and isotropic world models is the assumption that the temperature of the fluids inside the cosmic horizon (including dark energy) coincides with the temperature of the latter,…

General Relativity and Quantum Cosmology · Physics 2016-11-18 José Pedro Mimoso , Diego Pavón

Assuming that the background geometry is filled with free gas consisting of matter and radiation and no phase transitions being occurred in the early Universe, we discuss the thermodynamics of this {\it closed} system using classical…

General Relativity and Quantum Cosmology · Physics 2015-05-30 A. Tawfik , H. Magdy

This paper continues the building of the cosmological theory that was introduced in two earlier papers under the title A Dust Universe Solution to the Dark Energy Problem. The model introduced in this theory has existence before time zero…

General Physics · Physics 2010-02-21 James G. Gilson

It will be shown that a given realization of nonlinear electrodynamics, used as source of Einstein's equations, generates a cosmological model with interesting features, namely a phase of current cosmic acceleration, and the absence of an…

General Relativity and Quantum Cosmology · Physics 2008-11-26 M. Novello , E. Goulart , J. M. Salim , S. E. Perez Bergliaffa

We discuss cosmological models for an eternal universe. Physical observables show no singularity from the infinite past to the infinite future. While the universe is evolving, there is no beginning and no end - the universe exists forever.…

General Relativity and Quantum Cosmology · Physics 2014-08-27 C. Wetterich
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