Speaker
Description
Inflationary spacetimes have been argued to be past geodesically incomplete in many situations. However, whether the geodesic incompleteness implies the existence of an initial spacetime curvature singularity or whether the spacetime may be extended (potentially into another phase of the universe) is generally unknown. Both questions have important physical implications. In this talk, we take a closer look at the geometrical structure of inflationary spacetimes and investigate these very questions. I will first discuss classifying which past inflationary histories have a scalar curvature singularity and which might be extendible and/or non-singular. Then, I will briefly go over derivation of a rigorous extendibility criteria of various regularity classes for quasi-de Sitter spacetimes that evolve from infinite proper time in the past. Finally, I will argue that past-eternal inflationary scenarios are most likely physically singular, except in situations with very special initial conditions.
