A late-accelerating universe with no dark energy - and a finite-temperature big bang

TL;DR

This paper explores a modified brane-world cosmology combining infra-red and ultra-violet effects, resulting in a universe that accelerates without dark energy and begins with a finite-density singularity instead of a hot big bang.

Contribution

It introduces a novel brane-world model with Gauss-Bonnet corrections that preserves late-time acceleration without dark energy and proposes a universe origin different from the traditional hot big bang.

Findings

Universe exhibits late acceleration without dark energy.

Early universe starts from a finite-density singularity.

No hot big bang, replaced by a sudden curvature singularity.

Abstract

Brane-world models offer the possibility of explaining the late acceleration of the universe via infra-red modifications to General Relativity, rather than a dark energy field. However, one also expects ultra-violet modifications to General Relativity, when high-energy stringy effects in the early universe begin to grow. We generalize the DGP brane-world model via an ultra-violet modification, in the form of a Gauss-Bonnet term in the bulk action. The combination of infra-red and ultra-violet modifications produces an intriguing cosmology. The DGP feature of late-time acceleration without dark energy is preserved, but there is an entirely new feature - there is no hot big bang in the early universe. The universe starts with finite density and pressure, from a "sudden" curvature singularity.