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 GENERALIZED SECOND LAW OF THERMODYNAMICS IN WARPED DGP BRANEWORLD

2010 ◽  
Vol 25 (14) ◽  
pp. 1199-1210 ◽  
Author(s):  
AHMAD SHEYKHI ◽  
BIN WANG
Keyword(s):  
Apparent Horizon ◽  
Second Law Of Thermodynamics ◽  
Matter Field ◽  
Second Law ◽  
Intrinsic Curvature ◽  
First Law Of Thermodynamics ◽  
Generalized Second Law ◽  
Curvature Term ◽  
Horizon Entropy ◽  
Dgp Braneworld

We investigate the validity of the generalized second law of thermodynamics on the (n - 1)-dimensional brane embedded in the (n + 1)-dimensional bulk. We examine the evolution of the apparent horizon entropy extracted through relation between gravitational equation and the first law of thermodynamics together with the matter field entropy inside the apparent horizon. We find that the apparent horizon entropy extracted through connection between gravity and the first law of thermodynamics satisfies the generalized second law of thermodynamics. This result holds regardless of whether there is the intrinsic curvature term on the brane or a cosmological constant in the bulk. The observed satisfaction of the generalized second law provides further support on the thermodynamical interpretation of gravity based on the profound connection between gravity and thermodynamics.

scholarly journals Validity of the Generalized Second Law of Thermodynamics in the Logamediate and Intermediate Scenarios of the Universe

2011 ◽  
Vol 42 (2) ◽  
pp. 266-283 ◽  
Author(s):  
Arundhati Das ◽  
Surajit Chattopadhyay ◽  
Ujjal Debnath
Keyword(s):  
Second Law Of Thermodynamics ◽  
Second Law ◽  
Generalized Second Law ◽  
The Universe

Viscous Ricci dark energy and generalized second law of thermodynamics in modified f(R, T) gravity

2018 ◽  
Vol 33 (38) ◽  
pp. 1850225 ◽  
Author(s):  
C. P. Singh ◽  
Ajay Kumar
Keyword(s):  
Dark Energy ◽  
Apparent Horizon ◽  
Second Law Of Thermodynamics ◽  
Second Law ◽  
Fluid Viscosity ◽  
Ricci Dark Energy ◽  
Evolution Of The Universe ◽  
Generalized Second Law ◽  
The Future ◽  
The Universe

The motivation of this paper is to study the bulk viscosity effect in Ricci dark energy (RDE) model within the framework of modified f(R, T) gravity, where R is the Ricci scalar and T is the trace of the energy–momentum tensor. As most studies assume that the universe is filled with a perfect fluid, viscosity is expected to present at least during some stages, especially in the early stage of the evolution of the universe but it could still become significant in the future. We assume the universe is filled with viscous RDE and pressureless dark matter. We consider the total bulk viscous coefficient is in the form of [Formula: see text][Formula: see text]H, where [Formula: see text] and [Formula: see text] are the constants. We obtain the solutions to the modified field equations by assuming a form f(R, T) = R [Formula: see text] T, where [Formula: see text] is a constant. We find the scale factor and deceleration parameter, and classify all possible evolutions of the universe. We briefly discuss the future finite-time singularity and show that the Big Rip singularity appears in viscous RDE model. We investigate two geometrical diagnostics, statefinder parameter and Om to analyze the dynamics of evolution of the universe. The trajectories of statefinder parameter reveal that the model behaves like quintessence for small [Formula: see text], and for large [Formula: see text] it shows the Chaplygin gas-like. However, in late time both the models approach [Formula: see text]CDM. The model shows a transition from decelerated phase to accelerated phase. Similarly, the Om analysis reveals that the model behaves like quintessence for small [Formula: see text] and phantom-like for large [Formula: see text]. We extend our study to analyze the time evolution of the total entropy and generalized second law of thermodynamics of viscous RDE model in f(R, T) theory inside the apparent horizon. Our study shows that the generalized second law of thermodynamics always preserves in viscous RDE model in a region enclosed by the apparent horizon under the suitable constraints of viscous coefficients.

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