Cosmic acceleration from first principles

TL;DR

This paper proposes a first-principles entropic acceleration theory based on general relativity that explains cosmic acceleration without a cosmological constant, potentially resolving the H_0 tension and the coincidence problem.

Contribution

It introduces a covariant non-equilibrium entropic acceleration model in FLRW cosmology that reproduces observed acceleration without a cosmological constant.

Findings

Reproduces $ m extit{ extbf{Λ}}$CDM-like acceleration

Suggests a higher present Hubble rate, addressing the H_0 tension

Eliminates the need for a cosmological constant

Abstract

General relativistic entropic acceleration theory may explain the present cosmic acceleration from first principles without the need of introducing a cosmological constant. Following the covariant formulation of non-equilibrium phenomena in the context of a homogeneous and isotropic Friedmann-Lemaitre-Robertson-Walker (FLRW) metric, we find that the growth of entropy associated with the causal horizon of our universe (inside a finite bubble in eternal inflation) induces an acceleration that is essentially indistinguishable from that of $\Lambda$CDM, except for a slightly larger present rate of expansion compared to what would be expected from the CMB in $\Lambda$CDM, possibly solving the so-called $H_0$ tension. The matter content of the universe is unchanged and the coincidence problem is resolved since it is the growth of the causal horizon of matter that introduces this new relativistic entropic force. The cosmological constant is made unnecessary and the future hypersurface is Minkowsky rather than de Sitter.