Bounces, turnarounds and singularities in bimetric gravity

TL;DR

This paper explores cosmological solutions in bimetric gravity, showing how matter content influences universe behaviors and identifying extremality events across interconnected spaces.

Contribution

It demonstrates that cosmological dynamics in bimetric gravity can be characterized without assuming matter coupling to only one metric, revealing inter-universe event correlations.

Findings

Cosmologies can be described by matter content in the uninhabited space.

Extremality events in one universe imply similar events in the other.

Some conclusions are independent of matter distribution.

Abstract

In this letter, we consider cosmological solutions of bimetric theory without assuming that only one metric is coupled to gravity. We conclude that any cosmology can be described by fixing the matter content of the space that we are not inhabiting. On the other hand, we show that some conclusions can still be extracted independently of the matter content filling both spaces. In particular, we can conclude the occurrence of some extremality events in one universe if we know that they take place in the other space.