Entropy and universality of Cardy-Verlinde formula in dark energy universe

By Iver Brevik, Shin'ichi Nojiri, Sergei D. Odintsov, Luciano Vanzo. 2004

188 citations recorded by the source corpus.

We study the entropy of a FRW universe filled with dark energy (cosmological constant, quintessence, or phantom). For the general or time-dependent equation of state $p=w\ensuremath{\rho}$ the entropy is expressed in terms of energy, Casimir energy, and w. The corresponding expression is reminiscent of the 2D conformal field theory (CFT) entropy only for conformal matter. At the same time, the cosmological Cardy-Verlinde formula relating three typical FRW universe entropies remains universal for any type of matter. The same conclusions hold in modified gravity, which represents the gravitational alternative for dark energy and which contains terms that increase at low curvature. It is interesting that black holes in modified gravity are more entropic than those in Einstein gravity. Finally, some hydrodynamical examples testing the new shear viscosity bound, which is expected to be the consequence of the holographic entropy bound, are presented for the early Universe in the plasma era and for the Kasner metric. It seems that the Kasner metric provides a counterexample to the new shear viscosity bound.

Subfields: Astronomy and Astrophysics, Nuclear and High Energy Physics, Statistical and Nonlinear Physics

View Paper: https://www.semanticscholar.org/paper/0e024fc56866f10101545c1bcd5a6d8f14219299

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Citations in the corpus

Phantom energy traversable wormholes (2005, background): “2 phantom thermodynamics leads to a negative entropy (or negative temparature) [16, 17], and the energy density increases to infinity in a finite time [11, 18], at which point the size of the Universe blows up in a finite time.”
Stable dark energy stars (2005, background): “For this case, the cosmic fluid is denoted as phantom energy, and possesses peculiar properties, such as negative temperatures [30] and the energy density increases to infinity in a finite time, resulting in a Big Rip [31].”
Viscous Cosmology for Early- and Late-Time Universe (2017, methodology): “icity we will assume a one-component ﬂuid model, and we assume the bulk viscosity ζ to be constant. For more details, the reader may consult Refs. [86, 87, 154–156], and additionally the related Ref. [157]. We start with the Cardy entropy formula for an (1+1) dimensional CFT: S = 2π r c 6 L0 − c 24”