Corrected entropy of FriedmannRobertsonWalker universe in tunneling method
Abstract
In this paper, we study the thermodynamic quantities of FriedmannRobertsonWalker (FRW) universe by using the tunneling formalism beyond semiclassical approximation developed by Banerjee and Majhi [25]. For this we first calculate the corrected Hawkinglike temperature on apparent horizon by considering both scalar particle and fermion tunneling. With this corrected Hawkinglike temperature, the explicit expressions of the corrected entropy of apparent horizon for various gravity theories including Einstein gravity, GaussBonnet gravity, Lovelock gravity, f(R) gravity and scalartensor gravity, are computed. Our results show that the corrected entropy formula for different gravity theories can be written into a general expression (4.39) of a same form. It is also shown that this expression is also valid for black holes. This might imply that the expression for the corrected entropy derived from tunneling method is independent of gravity theory, spacetime and dimension of the spacetime. Moreover, it is concluded that the basic thermodynamical property that the corrected entropy on apparent horizon is a state function is satisfied by the FRW universe.
 Authors:
 Institute of Theoretical Physics, Lanzhou University, Lanzhou 730000 (China)
 Publication Date:
 OSTI Identifier:
 22273218
 Resource Type:
 Journal Article
 Resource Relation:
 Journal Name: Journal of Cosmology and Astroparticle Physics; Journal Volume: 2009; Journal Issue: 08; Other Information: Country of input: International Atomic Energy Agency (IAEA)
 Country of Publication:
 United States
 Language:
 English
 Subject:
 79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; BLACK HOLES; COSMOLOGICAL MODELS; COSMOLOGY; ENTROPY; FERMIONS; GRAVITATION; SCALARS; SEMICLASSICAL APPROXIMATION; SPACETIME; TENSORS; THERMODYNAMICS; TUNNEL EFFECT; UNIVERSE
Citation Formats
Zhu, Tao, Ren, JiRong, and Li, MingFan, Email: zhut05@lzu.cn, Email: renjr@lzu.edu.cn, Email: limf07@lzu.cn. Corrected entropy of FriedmannRobertsonWalker universe in tunneling method. United States: N. p., 2009.
Web. doi:10.1088/14757516/2009/08/010.
Zhu, Tao, Ren, JiRong, & Li, MingFan, Email: zhut05@lzu.cn, Email: renjr@lzu.edu.cn, Email: limf07@lzu.cn. Corrected entropy of FriedmannRobertsonWalker universe in tunneling method. United States. doi:10.1088/14757516/2009/08/010.
Zhu, Tao, Ren, JiRong, and Li, MingFan, Email: zhut05@lzu.cn, Email: renjr@lzu.edu.cn, Email: limf07@lzu.cn. 2009.
"Corrected entropy of FriedmannRobertsonWalker universe in tunneling method". United States.
doi:10.1088/14757516/2009/08/010.
@article{osti_22273218,
title = {Corrected entropy of FriedmannRobertsonWalker universe in tunneling method},
author = {Zhu, Tao and Ren, JiRong and Li, MingFan, Email: zhut05@lzu.cn, Email: renjr@lzu.edu.cn, Email: limf07@lzu.cn},
abstractNote = {In this paper, we study the thermodynamic quantities of FriedmannRobertsonWalker (FRW) universe by using the tunneling formalism beyond semiclassical approximation developed by Banerjee and Majhi [25]. For this we first calculate the corrected Hawkinglike temperature on apparent horizon by considering both scalar particle and fermion tunneling. With this corrected Hawkinglike temperature, the explicit expressions of the corrected entropy of apparent horizon for various gravity theories including Einstein gravity, GaussBonnet gravity, Lovelock gravity, f(R) gravity and scalartensor gravity, are computed. Our results show that the corrected entropy formula for different gravity theories can be written into a general expression (4.39) of a same form. It is also shown that this expression is also valid for black holes. This might imply that the expression for the corrected entropy derived from tunneling method is independent of gravity theory, spacetime and dimension of the spacetime. Moreover, it is concluded that the basic thermodynamical property that the corrected entropy on apparent horizon is a state function is satisfied by the FRW universe.},
doi = {10.1088/14757516/2009/08/010},
journal = {Journal of Cosmology and Astroparticle Physics},
number = 08,
volume = 2009,
place = {United States},
year = 2009,
month = 8
}

Analog models of gravity have been motivated by the possibility of investigating phenomena not readily accessible in their cosmological counterparts. In this paper, we investigate the analog of cosmological particle creation in a FriedmannRobertsonWalker universe by numerically simulating a BoseEinstein condensate with a timedependent scattering length. In particular, we focus on a twodimensional homogeneous condensate using the classical field method via the truncated Wigner approximation. We show that for various forms of the scaling function the particle production is consistent with the underlying theory in the long wavelength limit. In this context, we further discuss the implications of modified dispersionmore »

Matching of FriedmannLema[cflx i]treRobertsonWalker and Kasner cosmologies
The matching of FriedmannLema[cflx i]treRobertsonWalker spacetimes onto a Kasner vacuum region is investigated. We apply the Darmois junction conditions to show that a spatially flat Einsteinde Sitter region can be joined smoothly to a special case of the Kasner vacuum spacetime. This result suggests an intriguing cosmological model. 
Straight strings and FriedmannRobertsonWalker spacetimes
The embeddability of a straight cosmic string in a FriedmannRobertsonWalker (FRW) universe is examined. Although previous suggestions that an exact embedding for a string with longitudinal tension equal to energy density is impossible are substantiated, it is shown that the deviations of either the external metric from the exact FRW metric or of the internal structure of the string from the exact tension equals energy density are expected to be very small, of the order of the square of the ratio of the string diameter (or the evacuated shell around the string) to the Hubble radius. Thus the lack ofmore » 
Wormhole spectrum of a quantum FriedmannRobertsonWalker cosmology minimally coupled to a powerlaw scalar field and the cosmological constant
The expansion of the wave function of a quantum FriedmannRobertsonWalker cosmology minimally coupled to a scalar field with a powerlaw potential by its scalarfield part decouples the gravitationalfield part into an infinite system of linear homogeneous differential equations (equivalent to a matrix equation). The solutions for the gravitationalfield part are found in the product integral formulation. It is shown that there exists a spectrum of the wave functions exponentially damped for large threegeometries under the condition that the cosmological constant should vanish. These are interpeted as the HawkingPage wormholes.