Violations of the Weak Energy Condition in Inflating Spacetimes

TL;DR

This paper discusses how many inflating spacetimes likely violate the weak energy condition, potentially allowing for non-singular, past-eternal cosmological models, though constructing such models remains challenging.

Contribution

It highlights the possibility that inflating spacetimes violate energy conditions and explores implications for non-singular cosmological models.

Findings

Many future-eternal inflating spacetimes violate the weak energy condition

Such spacetimes may not satisfy known averaged energy conditions

Constructing satisfactory non-singular, past-eternal models remains unresolved

Abstract

We argue that many future-eternal inflating spacetimes are likely to violate the weak energy condition. It is possible that such spacetimes may not enforce any of the known averaged conditions either. If this is indeed the case, it may open the door to constructing non-singular, past-eternal inflating cosmologies. Simple non-singular models are, however, unsatisfactory, and it is not clear if satisfactory models can be built that solve the problem of the initial singularity.