Singularity scattering laws for bouncing cosmologies: a brief overview

Abstract: For contracting/expanding bouncing cosmologies, the formulation of junction conditions at a bouncing was recently revisited by the author in collaboration with B. Le Floch and G. Veneziano. The regime of interest here is the so-called quiescent regime, in which a monotone behavior of the metric is observed and asymptotic expansions can be derived. Here, we overview our new methodology based on the notion of {\sl singularity scattering maps} and {\sl cyclic spacetimes}, and we present our main conclusions. In particular, we provide a classification of all allowed bouncing junction conditions, including three universal laws.