A thermodynamical analysis of the inhomogeneous FLRW type model: Redefined Bekenstein–Hawking system

2017 ◽  
Vol 14 (11) ◽  
pp. 1750159 ◽  
Author(s):  
Sourav Haldar ◽  
Pritikana Bhandari ◽  
Subenoy Chakraborty
Keyword(s):  
Second Law Of Thermodynamics ◽  
Integral Form ◽  
The Other ◽  
Type Model ◽  
First Law Of Thermodynamics ◽  
Generalized Second Law ◽  
First Choice ◽  
Definition Of ◽  
Thermodynamical Laws ◽  
The Universe

A detailed thermodynamical study has been presented for the inhomogeneous FLRW-type model of the Universe bounded by a horizon with three possible modifications of Bekenstein–Hawking formulation of thermodynamical parameters namely entropy and temperature. For the first choice of the thermodynamical system validity of both the first law of thermodynamics (FLT) and the generalized second law of thermodynamics (GSLT) are examined. Also, the integrability conditions for the exact one-forms in both the thermodynamical laws are analyzed and it is found that they are consistent with each other. On the other hand, for the other two choices of the thermodynamical system to hold the first law of thermodynamics, one must restrict the parameters (in the definition of the thermodynamical variables) in some specific integral form.

scholarly journals Thermodynamics in the Universe Described by the Emergence of Space and the Energy Balance Relation

Entropy ◽  
2019 ◽  
Vol 21 (2) ◽  
pp. 167
Author(s):  
Fei-Quan Tu ◽  
Yi-Xin Chen ◽  
Qi-Hong Huang
Keyword(s):  
Energy Balance ◽  
Present Model ◽  
Thermodynamic Description ◽  
Energy Condition ◽  
Second Law Of Thermodynamics ◽  
Second Law ◽  
First Law Of Thermodynamics ◽  
Generalized Second Law ◽  
Balance Relation ◽  
The Universe

It has previously been shown that it is more common to describe the evolution of the universe based on the emergence of space and the energy balance relation. Here we investigate the thermodynamic properties of the universe described by such a model. We show that the first law of thermodynamics and the generalized second law of thermodynamics (GSLT) are both satisfied and the weak energy condition are also fulfilled for two typical examples. Finally, we examine the physical consistency for the present model. The results show that there exists a good thermodynamic description for such a universe.

The wormhole thermodynamics in f (R ) gravity

2019 ◽  
Vol 35 (04) ◽  
pp. 1950360 ◽  
Author(s):  
A. S. Sefiedgar ◽  
M. Mirzazadeh
Keyword(s):  
Continuity Equation ◽  
Energy Momentum Tensor ◽  
Apparent Horizon ◽  
Second Law Of Thermodynamics ◽  
Momentum Tensor ◽  
Second Law ◽  
Standard Entropy ◽  
Field Equations ◽  
First Law Of Thermodynamics ◽  
Generalized Second Law

Thermodynamics of the evolving Lorentzian wormhole at the apparent horizon is investigated in [Formula: see text] gravity. Redefining the energy density and the pressure, the continuity equation is satisfied and the field equations in [Formula: see text] gravity reduce to the ones in general relativity. However, the energy–momentum tensor includes all the corrections from [Formula: see text] gravity. Therefore, one can apply the standard entropy-area relation within [Formula: see text] gravity. It is shown that there may be an equivalency between the field equations and the first law of thermodynamics. It seems that an equilibrium thermodynamics may be held on the apparent horizon. The validity of the generalized second law of thermodynamics (GSL) is also investigated in the wormholes.

scholarly journals A Study of Universal Thermodynamics in Brane World Scenario

2015 ◽  
Vol 2015 ◽  
pp. 1-9 ◽  
Author(s):  
Saugata Mitra ◽  
Subhajit Saha ◽  
Subenoy Chakraborty
Keyword(s):  
Second Law Of Thermodynamics ◽  
Chaplygin Gas ◽  
Brane World ◽  
Second Law ◽  
Modified Chaplygin Gas ◽  
Thermodynamical Equilibrium ◽  
Brane Model ◽  
Generalized Second Law ◽  
Frw Model ◽  
The Universe

A study of Universal thermodynamics is done in the framework of RSII brane model and DGP brane scenario. The Universe is chosen as FRW model bounded by apparent or event horizon. Assuming extended Hawking temperature on the horizon, the unified first law is examined for perfect fluid (with constant equation of state) and Modified Chaplygin Gas model. As a result there is a modification of Bekenstein entropy on the horizons. Further the validity of the generalized second law of thermodynamics and thermodynamical equilibrium are also investigated.

scholarly journals VISCOUS DARK ENERGY AND GENERALIZED SECOND LAW OF THERMODYNAMICS

2010 ◽  
Vol 19 (07) ◽  
pp. 1205-1215 ◽  
Author(s):  
M. R. SETARE ◽  
A. SHEYKHI
Keyword(s):  
Dark Matter ◽  
Dark Energy ◽  
Time Evolution ◽  
Casimir Effect ◽  
Apparent Horizon ◽  
Second Law Of Thermodynamics ◽  
Second Law ◽  
Total Entropy ◽  
Generalized Second Law ◽  
The Universe

We examine the validity of the generalized second law of thermodynamics in a non-flat universe in the presence of viscous dark energy. First we assume that the universe is filled only with viscous dark energy. Then, we extend our study to the case where there is an interaction between viscous dark energy and pressureless dark matter. We examine the time evolution of the total entropy, including the entropy associated with the apparent horizon and the entropy of the viscous dark energy inside the apparent horizon. Our study shows that the generalized second law of thermodynamics is always protected in a universe filled with interacting viscous dark energy and dark matter in a region enclosed by the apparent horizon. Finally, we show that the the generalized second law of thermodynamics is fulfilled for a universe filled with interacting viscous dark energy and dark matter by taking into account the Casimir effect.

A unified picture of cosmological entropy on apparent horizon in F(R, G) gravity

2017 ◽  
Vol 32 (33) ◽  
pp. 1750182 ◽  
Author(s):  
Ali İhsan Keskin ◽  
Irfan Acikgoz
Keyword(s):  
Apparent Horizon ◽  
Second Law Of Thermodynamics ◽  
Hawking Temperature ◽  
Second Law ◽  
Field Equations ◽  
Frw Universe ◽  
Generalized Second Law ◽  
History Of ◽  
The Universe ◽  
Friedmann Robertson Walker

In this study, the validity of the generalized second law of thermodynamics (GSLT) has been investigated in F(R, G) gravity. We consider that the boundary of the universe is surrounded by an apparent horizon in the spatially flat Friedmann–Robertson–Walker (FRW) universe, and we take into account the Hawking temperature on the horizons. The unified solutions of the field equations corresponding to gravity theory have been applied to the validity of the GSLT frame, and in this way, both the solutions have been verified and all the expansion history of the universe has been shown in a unified picture.

Cosmology in scalar–tensor–vector theory via thermodynamics

2018 ◽  
Vol 33 (24) ◽  
pp. 1850137 ◽  
Author(s):  
Onur Siginc ◽  
Mustafa Salti ◽  
Hilmi Yanar ◽  
Oktay Aydogdu
Keyword(s):  
Apparent Horizon ◽  
Second Law Of Thermodynamics ◽  
Entropy Function ◽  
Second Law ◽  
Generalized Second Law ◽  
Vector Theory ◽  
Theory Of Gravity ◽  
The Universe ◽  
Non Equilibrium

Assuming the universe as a thermodynamical system, the second law of thermodynamics can be extended to another form including the sum of matter and horizon entropies, which is called the generalized second law of thermodynamics. The generalized form of the second law (GSL) is universal which means it holds both in non-equilibrium and equilibrium pictures of thermodynamics. Considering the universe is bounded by a dynamical apparent horizon, we investigate the nature of entropy function for the validity of GSL in the scalar–tensor–vector (STEVE) theory of gravity.

scholarly journals Diffusive Bejan number and second law of thermodynamics toward a new dimensionless formulation of fluid dynamics laws

2019 ◽  
Vol 23 (6 Part B) ◽  
pp. 4005-4022 ◽  
Author(s):  
Michele Trancossi ◽  
Jose Pascoa
Keyword(s):  
Fluid Dynamics ◽  
Entropy Generation ◽  
Fluid Dynamic ◽  
Second Law Of Thermodynamics ◽  
Integral Form ◽  
Second Law ◽  
Bejan Number ◽  
Definition Of ◽  
New Formulation ◽  
Dimensionless Formulation

In a recent paper, Liversage and Trancossi have defined a new formulation of drag as a function of the dimensionless Bejan and Reynolds numbers. Further analysis of this hypothesis has permitted to obtain a new dimensionless formulation of the fundamental equations of fluid dynamics in their integral form. The resulting equations have been deeply discussed for the thermodynamic definition of Bejan number evidencing that the proposed formulation allows solving fluid dynamic problems in terms of entropy generation, allowing an effective optimization of design in terms of the Second law of thermodynamics. Some samples are discussed evidencing how the new formulation can support the generation of an optimized configuration of fluidic devices and that the optimized configurations allow minimizing the entropy generation.

scholarly journals The Spirit as the Subject Carrying out the Sublation of Nature

2009 ◽  
Vol 30 (1-2) ◽  
pp. 19-31
Author(s):  
Gilles Marmasse
Keyword(s):  
The Other ◽  
General Hypothesis ◽  
Know How ◽  
Rational Nature ◽  
The Subject ◽  
The Absolute ◽  
The One ◽  
Definition Of ◽  
The Universe

In this paper, I will try to propose a general characterisation of the spirit in Hegel'sEncyclopaedia. This characterisation is based on the opposition between nature and spirit. More precisely, in my view the Hegelian spirit can be defined as the activity of bringing the natural exteriority back to a living totality.We know that for Hegel the notion of spirit takes so many shapes that their unity is difficult to find. For instance, what does the soul in the subjective spirit, property in the objective spirit and the cult of the Greek gods in the absolute spirit have in common? Furthermore, when we consider property, for example, the problem is knowing if the spirit is here constituted by the owner, by the deeds of ownership or by the living relationship between the owner and the possessed goods.Moreover, the Hegelian spirit is a philosophical descendant of several different traditions. The question is, therefore, to know how these traditions are linked in the Hegelian notion. I will present these briefly before stating my general hypothesis about the definition of the spirit.First, the Hegelian spirit is connected to thenoûsof the Greek philosophers (the Latinspiritus, intellectus). Thenoûs— on the one hand, an immaterial entity leading the universe, and, on the other, a faculty of the soul — is most often distinguished by its separate and rational nature. For Hegel too, the spirit, as a non-perceptible entity, constitutes the freest and most rational stage in the development of the Idea.

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