Entropy maximization in the emergent gravity paradigm

Abstract

The accelerated expansion of the universe can be interpreted as a quest for satisfying holographic equipartition. It can be expressed by a simple law, ∆V = ∆t (N surf − N bulk ) which leads to the standard Friedmann equation. This novel idea suggested by Padmanabhan in the context of general relativity has been generalized by Cai and Yang et al. to Gauss-Bonnet and Lovelock gravities for a spatially flat universe in different methods. We investigate the consistency of these generalizations with the constraints imposed by the maximum entropy principle. Interestingly, both these generalizations imply entropy maximization even if their basic assumptions are different.Further, we analyze the consistency of Verlinde's emergent gravity with the maximum entropy principle in the cosmological context. In particular, we consider the generalization suggested by Shu and Gong, in which an energy flux through the horizon is assumed, in addition. Even though the conceptual formulations are different, these two emergent perspectives of gravity describes a universe which behaves as an ordinary macroscopic system. Our results provide further support to the emergent gravity paradigm.

Horizon thermodynamics in holographic cosmological models with a power-law term

“…In particular, the entropy should approach a certain maximum value consistent with their constraints, i.e., S < 0 [52]. A certain type of universe, e.g., a de Sitter universe [58][59][60][61]65], behaves as an ordinary macroscopic system [59]. For related studies, see, e.g., the works of Pavón and Radicella [58], Mimoso and Pavón [59], and Krishna and Mathew [60,61].…”

“…Similar discussions are given in Refs. [58][59][60][61][62][63][64][65]. In this way, we can study the evolution of the entropy on the horizon.…”

“…The second law of thermodynamics has been extensively studied from a cosmological viewpoint [38][39][40][41][42][43][44][45][53][54][55][56][57]. The maximization of entropy has recently attracted attention [58][59][60][61][62][63][64][65]. For example, Mimoso and Pavón have examined the maximization of entropy in the universe with a de Sitter era and have shown that the universe behaves as an ordinary macroscopic system at least in the last stage [59].…”

“…For example, Mimoso and Pavón have examined the maximization of entropy in the universe with a de Sitter era and have shown that the universe behaves as an ordinary macroscopic system at least in the last stage [59]. Krishna and Mathew have investigated entropy maximization and the holographic equipartition law [60,61]. Bamba et al have exam-ined thermodynamic equilibrium conditions for several entropies in Rastall gravity [62].…”

Entropy production due to adiabatic particle creation in a holographic dissipative cosmology

“…To explain the accelerated expansion, astrophysicists have proposed several cosmological models [3]: e.g., ΛCDM (Lambda cold dark matter) models, Λ(t)CDM models (i.e., a timevarying Λ(t) cosmology) [4][5][6][7][8][9], bulk viscous models [10][11][12][13][14], and the creation of CDM (CCDM) models [15][16][17][18][19][20][21][22][23][24][25][26], as well as other scenarios . The evolution of the universe has been recently examined from a thermodynamic viewpoint, using such models [41][42][43][44][45][46][47][48][49][50][51][52][53][54][55][56][57][58][59].…”