From Big Crunch to Big Bang

TL;DR

This paper explores conditions under which a contracting universe can transition into an expanding universe, proposing models based on M-theory that could lead to new cosmological scenarios.

Contribution

It introduces a framework within 11-dimensional M-theory for a universe bounce from contraction to expansion, offering a novel approach to cosmological modeling.

Findings

A contracting universe can transition to expansion via a bounce in M-theory.

The model reduces to heterotic string theory at the bounce.

Potential to simplify and modify ekpyrotic scenarios.

Abstract

We consider conditions under which a universe contracting towards a big crunch can make a transition to an expanding big bang universe. A promising example is 11-dimensional M-theory in which the eleventh dimension collapses, bounces, and re-expands. At the bounce, the model can reduce to a weakly coupled heterotic string theory and, we conjecture, it may be possible to follow the transition from contraction to expansion. The possibility opens the door to new classes of cosmological models. For example, we discuss how it suggests a major simplification and modification of the recently proposed ekpyrotic scenario.