Accelerating expansion and change of signature

TL;DR

This paper proposes that the universe's accelerated expansion and sudden singularities could be explained by a regular change in the spacetime signature on brane-worlds within an AdS5 framework, suggesting a transition from Lorentzian to Euclidean signature.

Contribution

It introduces a novel explanation for sudden singularities via regular signature change in brane-world models, supported by an explicit example satisfying energy conditions.

Findings

Sudden singularities can be explained by signature change in brane-worlds.

The model remains fully regular during the signature transition.

The example satisfies both weak and strong energy conditions.

Abstract

We show that some types of sudden singularities admit a natural explanation in terms of regular changes of signature on brane-worlds in AdS$_{5}$. The present accelerated expansion of the Universe and its possible ending at a sudden singularity may therefore simply be an indication that our braneworld is about to change its Lorentzian signature to an Euclidean one, while remaining fully regular. An explicit example of this behaviour satisfying the weak and strong energy conditions is presented.