On the initial singularity and extendibility of flat quasi-de Sitter spacetimes

Understand

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 paper, we take a closer look at the geometrical structure of inflationary spacetimes and investigate these very questions.