Viscous Cosmology and the Cardy-Verlinde Formula

Abstract

The holographic principle in a radiation dominated universe is extended to incorporate the case of a bulk-viscous cosmic fluid. This corresponds to a nonconformally invariant theory. Generalization of the Cardy-Verlinde entropy formula to the viscous case appears to be possible from a formal point of view, although we question on physical grounds the manner in which the Casimir energy is evaluated in this case. Also, we consider an observation recently made by Youm, namely that the entropy of the universe is no longer expressible in the conventional Cardy-Verlinde form if one relaxes the radiation dominance equation of state and instead merely assumes that the pressure is proportional to the energy density. We show that Youm's generalized entropy formula remains valid when the cosmic fluid is no longer ideal, but endowed with a constant bulk viscosity.

10 pages, no figures. Contribution to the Proceedings of the Second Londrina Winter School "Mathematical Methods in Physics", August 25-30, 2002, Londrina-Parana, Brazil

References in corpus (4)

• Relating Friedmann equation to Cardy formula in universes with cosmological constant
• On the Cardy-Verlinde Entropy Formula in Viscous Cosmology
• A Note on the Cardy-Verlinde Formula
• Cardy-Verlinde Entropy Formula in the Presence of a General Cosmological State Equation

Cited by in corpus (5)

• Black holes, cosmological solutions, future singularities, and their thermodynamical properties in modified gravity theories
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• Cardy-Verlinde formula in FRW Universe with inhomogeneous generalized fluid and dynamical entropy bounds near the future singularity
• Non-Singular Bouncing cosmology from Phantom Scalar-Gauss-Bonnet Coupling: Reconstruction with Observational Insights
• Bjorken expansion in the isotropic Kasner spacetime