Gravity waves from cosmic bubble collisions

TL;DR

This paper explores how bubble collisions in a universe with reduced symmetry can generate gravity waves, potentially detectable through B-mode polarization in the cosmic microwave background, offering a new observational window.

Contribution

It introduces a novel scenario where bubble collisions produce gravity waves in a universe with two large spatial dimensions, highlighting their potential observational signatures.

Findings

Bubble collisions generate gravity waves due to reduced symmetry.

Gravity waves could dominate over inflationary background in CMB polarization.

Potential detectability of these gravity waves through B-mode polarization.

Abstract

Our local Hubble volume might be contained within a bubble that nucleated in a false vacuum with only two large spatial dimensions. We study bubble collisions in this scenario and find that they generate gravity waves, which are made possible in this context by the reduced symmetry of the global geometry. These gravity waves would produce B-mode polarization in the cosmic microwave background, which could in principle dominate over the inflationary background.