Covariant entropy conjecture and concordance cosmological models

TL;DR

This paper tests a covariant entropy conjecture on cosmological models with a positive cosmological constant, revealing strong constraints and an upper bound on the cosmological constant relevant to the universe.

Contribution

It applies the covariant entropy conjecture to concordance cosmological models, deriving constraints and an upper bound on the cosmological constant.

Findings

Rules out models disfavored by the anthropic principle

Imposes an upper bound of 10^{-60} on the cosmological constant

Provides a macroscopic perspective on the cosmological constant problem

Abstract

Recently a covariant entropy conjecture has been proposed for dynamical horizons. We apply this conjecture to concordance cosmological models, namely, those cosmological models filled with perfect fluids, in the presence of a positive cosmological constant. As a result, we find this conjecture has a severe constraint power. Not only does this conjecture rule out those cosmological models disfavored by the anthropic principle, but also it imposes an upper bound $10^{-60}$ on the cosmological constant for our own universe, which thus provides an alternative macroscopic perspective for understanding the long-standing cosmological constant problem.