Colliding with a Crunching Bubble

TL;DR

This paper explores the interactions between Lambda=0 bubbles and crunching Lambda<0 bubbles in eternal inflation, revealing conditions under which the former survive or are affected, with implications for cosmic structure and black hole formation.

Contribution

It provides new insights into bubble collision outcomes in eternal inflation, especially regarding the role of domain wall tension and BPS bounds.

Findings

Supersymmetric Lambda=0 bubbles are resilient to certain collisions.

Domain walls with tension above the BPS bound are expelled and do not affect the bubble.

When the BPS bound is saturated, collisions can lead to black hole horizons.

Abstract

In the context of eternal inflation we discuss the fate of Lambda = 0 bubbles when they collide with Lambda < 0 crunching bubbles. When the Lambda = 0 bubble is supersymmetric, it is not completely destroyed by collisions. If the domain wall separating the bubbles has higher tension than the BPS bound, it is expelled from the Lambda = 0 bubble and does not alter its long time behavior. If the domain wall saturates the BPS bound, then it stays inside the Lambda = 0 bubble and removes a finite fraction of future infinity. In this case, the crunch singularity is hidden behind the horizon of a stable hyperbolic black hole.