Surviving the crash: assessing the aftermath of cosmic bubble collisions

Understand

This paper is the third in a series investigating the possibility that if we reside in an inflationary "bubble universe", we might observe the effects of collisions with other such bubbles.

• Here, we study the interior structure of a bubble collision spacetime, focusing on the issue of where observers can reside.
• Numerical simulations indicate that if the inter-bubble domain wall accelerates away, infinite spacelike surfaces of homogeneity develop to the future of the collision; this strongly suggests that observers can have collisions to their past, and previous results then imply that this is very likely.
• However, for observers at nearly all locations, the restoration of homogeneity relegates any observable effects to a vanishingly small region on the sky.