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The spatially homogeneous perfect fluid solutions by Kompanneets-Chernov-Kantowski-Sachs are interpreted as a thermodynamic perfect fluid in isentropic evolution, namely, the isentropic limit of their non-homogeneous generalizations, the…

General Relativity and Quantum Cosmology · Physics 2026-02-11 Salvador Mengual , Joan Josep Ferrando

A generalized entropy arising in the context of superstatistics is obtained for an ideal gas. The curvature scalar associated to the thermodynamic space generated by this modified entropy is calculated using two formalisms of the geometric…

Statistical Mechanics · Physics 2018-04-18 J. L. López , O. Obregón , J. Torres-Arenas

Two different physical systems are said to be thermodynamically equiv- alent if one of the thermodynamic potentials of the first system is pro- portional to the corresponding potential of the second system after expressing the state…

Statistical Mechanics · Physics 2015-06-04 Salvino Ciccariello

The ideal gas laws are derived from the democritian concept of corpuscles moving in vacuum plus a principle of simplicity, namely that these laws are independent of the laws of motion aside from the law of energy conservation. A single…

Classical Physics · Physics 2013-04-23 Jacques Arnaud , Laurent Chusseau , Fabrice Philippe

The ideal (i.e. noninteracting), homogeneous Fermi gas, with its characteristic sharp Fermi surface in the momentum distribution, is a fundamental concept relevant to the behavior of many systems. With trapped Fermi gases of ultracold…

Quantum Gases · Physics 2012-09-10 T. E. Drake , Y. Sagi , R. Paudel , J. T. Stewart , J. P. Gaebler , D. S. Jin

Einstein's equations of General Relativity form a highly nonlinear system, so most exact solutions rely on symmetry assumptions. Spherically symmetric spacetimes have been particularly important, providing a tractable yet physically rich…

General Relativity and Quantum Cosmology · Physics 2026-01-08 Salvador Mengual

Microcanonical equations for several thermodynamic properties of a system, suitable for molecular dynamics simulations, are derived from the nonextensive Tsallis entropy functional. Two possible definitions of temperature, the usual one and…

Statistical Mechanics · Physics 2011-03-21 J. Carrete , L. M. Varela , L. J. Gallego

We analyze the interpretation of the spherically symmetric perfect fluid solutions that admit a flat synchronization orthogonal to the fluid flow as a thermodynamic perfect fluid in local thermal equilibrium. The ideal gas sonic condition…

General Relativity and Quantum Cosmology · Physics 2022-06-09 Salvador Mengual , Joan Josep Ferrando

We show that under rather general assumptions on the form of the entropy function, the energy balance equation for a system in thermodynamic equilibrium is equivalent to a set of nonlinear equations of hydrodynamic type. This set of…

Exactly Solvable and Integrable Systems · Physics 2012-10-01 Giuseppe De Nittis , Antonio Moro

A criterion is presented and discussed to detect when a divergence-free perfect fluid energy tensor in the space-time describes an evolution in local thermal equilibrium. This criterion is applied to the class II Szafron-Szekeres perfect…

General Relativity and Quantum Cosmology · Physics 2007-05-23 Bartolomé Coll , Joan Josep Ferrando

We study the thermodynamics of the universe containing perfect fluid with equation of state $p=\omega\rho,\omega$ is variable. Here we choose $\omega$ to be a function of the red shift variable $z$ and four different choices of $\omega$ has…

General Relativity and Quantum Cosmology · Physics 2014-11-20 Nairwita Mazumder , Subenoy Chakraborty

A family of parabolic Szekeres-Szafron class II solutions in local thermal equilibrium is studied and their associated thermodynamics are obtained. The subfamily with the hydrodynamic behavior of a generic ideal gas (defined by the equation…

General Relativity and Quantum Cosmology · Physics 2019-10-16 Bartolomé Coll , Joan Josep Ferrando , Juan Antonio Sáez

An equation of state for an ideal gas with a small number of particles is studied. The resulting equation is found to differ from that expected in conventional thermodynamics, which is strikingly illustrated when considering the traditional…

Statistical Mechanics · Physics 2011-11-09 Tsuyoshi Hondou

The staid subject of exact static spherically symmetric perfect fluid solutions of Einstein's equations has been reinvigorated in the last decade. We now have several solution generating techniques which give rise to new exact solutions.…

General Relativity and Quantum Cosmology · Physics 2008-11-26 Kayll Lake

Here we consider our universe as inhomogeneous spherically symmetric Lemaitre-Tolman-Bondi Model and analyze the thermodynamics of this model of the universe. The trapping horizon is calculated and is found to coincide with the apparent…

General Relativity and Quantum Cosmology · Physics 2011-05-09 Subenoy Chakraborty , Nairwita Mazumder , Ritabrata Biswas

The equilibrium and fluctuations of an ideal gas in a rigid container are studied by every student of statistical mechanics. Here we study the less well-known case when the box is floating freely; in particular we determine the fluctuations…

Astrophysics of Galaxies · Physics 2021-08-11 Scott Tremaine , Bence Kocsis , Abraham Loeb

In this paper, we examine the thermodynamic features of an exotic fluid known as modified cosmic Chaplygin gas in the context of homogeneous isotropic universe model. For this purpose, the behavior of physical parameters are discussed that…

General Relativity and Quantum Cosmology · Physics 2018-10-05 M. Sharif , Sara Ashraf

The approach of an ideal gas to equilibrium is simulated through a generalization of the Ehrenfest ball-and-box model. In the present model, the interior of each box is discretized, {\it i.e.}, balls/particles live in cells whose occupation…

Statistical Mechanics · Physics 2009-11-10 S. Prestipino

A Bose gas in an external potential is studied by means of the local density approximation. Analytical results are derived for the thermodynamic properties of an ideal Bose gas in a generic power-law trapping potential, and their dependence…

Statistical Mechanics · Physics 2008-02-03 Hualin Shi , Wei-Mou Zheng

We theoretically examine equilibrium properties of the harmonically trapped ideal Bose and Fermi gases in the quantum degeneracy regime. We analyze thermodynamic characteristics of gases with a finite number of atoms by means of the known…

Quantum Gases · Physics 2021-12-06 Valeriia Bilokon , Elvira Bilokon , Alexander Peletminskii , Andrii Sotnikov