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 GENERALIZED SECOND LAW OF THERMODYNAMICS IN THE PRESENCE OF INTERACTING DBI-ESSENCE AND OTHER DARK ENERGIES

2010 ◽  
Vol 25 (30) ◽  
pp. 5557-5566 ◽  
Author(s):  
SURAJIT CHATTOPADHYAY ◽  
UJJAL DEBNATH
Keyword(s):  
Dark Energy ◽  
Event Horizon ◽  
Second Law Of Thermodynamics ◽  
Chaplygin Gas ◽  
Second Law ◽  
Modified Chaplygin Gas ◽  
Tachyonic Field ◽  
New Agegraphic Dark Energy ◽  
Generalized Second Law ◽  
Increasing Function

In the present work we investigated the validity of the generalized second law (GSL) of thermodynamics in the presence of interaction between DBI-essence and other four candidates of dark energy, namely the modified Chaplygin gas, hessence, tachyonic field and new agegraphic dark energy. It has been observed that the GSL breaks down in the presence of the interactions. However, the event horizon remains to be an increasing function of time.

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 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.

Modified Chaplygin gas equation of state on viscous dissipative extended holographic Ricci dark energy and the cosmological consequences

2016 ◽  
Vol 26 (06) ◽  
pp. 1750042 ◽  
Author(s):  
Surajit Chattopadhyay
Keyword(s):  
Dark Energy ◽  
Bulk Viscosity ◽  
Cold Dark Matter ◽  
Viscosity Coefficient ◽  
Chaplygin Gas ◽  
Modified Chaplygin Gas ◽  
Ricci Dark Energy ◽  
Dissipative Term ◽  
Generalized Second Law ◽  
The Universe

The present paper reports a study on modified Chaplygin gas (MCG)-based reconstruction scheme for extended holographic Ricci dark energy (EHRDE) in the presence of viscous type dissipative term. The dissipative effect has been described by using Eckart approach. Under the assumption that the universe is filled with MCG–EHRDE under the influence of bulk viscosity we have studied the cosmological dynamics, where the bulk viscosity coefficient has been chosen in a particular time varying form [Formula: see text], where [Formula: see text] and [Formula: see text] are constant coefficients and [Formula: see text] is the Hubble parameter. Furthermore, we have reconstructed the potential and dynamics of viscous MCG–EHRDE as scalar field. Thereafter we have studied the statefinder trajectories to discern its departure from [Formula: see text] cold dark matter ([Formula: see text]CDM) and finally investigated validity of the generalized second law (GSL) of thermodynamics considering event horizon as the enveloping horizon of the universe.

scholarly journals Phenomenologically varying Λ and a toy model for the universe

2014 ◽  
Vol 92 (11) ◽  
pp. 1494-1500 ◽  
Author(s):  
M. Khurshudyan ◽  
J. Sadeghi ◽  
E. Chubaryan ◽  
H. Farahani
Keyword(s):  
Dark Energy ◽  
Second Law Of Thermodynamics ◽  
Chaplygin Gas ◽  
Barotropic Fluid ◽  
Physical Conditions ◽  
Ghost Dark Energy ◽  
Generalized Second Law ◽  
Varying Λ ◽  
First Time ◽  
The Universe

We consider a model of the Universe with variable G and Λ. The subject of interest is a phenomenological model for Λ proposed and considered in this article for the first time (to our knowledge), with the assumption that ghost dark energy exists and interacts with the Universe through Λ. We consider the possibility that there exist unusual connections between different components of the fluids in Universe. We would like to stress that this is simply an assumption and could be very far from reality. This model is interesting phenomenologically and mathematically but we will not discuss physical conditions or possibilities of implementing the modifications. To test our assumption and to observe the behavior of the Universe, we will consider toy models filled by a barotropic fluid and modified Chaplyagin gas. Finally, we will consider interaction between barotropic fluid or Chaplygin gas and ghost dark energy as a separate scenario. The statefinder diagnostic provided stability analysis of the models. All free parameters of the model are fixed to satisfy the generalized second law of thermodynamics.

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