Minimal conditions for the creation of a Friedman-Robertson-Walker universe from a "bounce"

TL;DR

This paper explores the minimal physical conditions needed for a universe to emerge from a bounce rather than a singularity, highlighting the necessity of violating the strong energy condition around the bounce.

Contribution

It provides a general, model-independent analysis of the conditions for a cosmological bounce, emphasizing the violation of the SEC and presenting an inflation-inspired bounce model.

Findings

A bounce requires violation of the strong energy condition.

Other energy conditions can be satisfied during the bounce.

An inflation-inspired model naturally supports a big bounce.

Abstract

We investigate the minimal conditions under which the creation of our universe might arise due to a "bounce" from a previous collapse, rather than an explosion from a big-bang singularity. Such a bounce is sometimes referred to as a Tolman wormhole. We subject the bounce to a general model-independent analysis along the lines of that applied to the Morris-Thorne traversable wormholes, and show that there is always an open temporal region surrounding the bounce over which the strong energy condition (SEC) must be violated. On the other hand, all the other energy conditions can easily be satisfied. In particular, we exhibit an inflation-inspired model in which a big bounce is "natural".