# Bubble of nothing Bubbles of nothing are novel solutions in General Relativity. The term “nothing” here is used quite literally: there is not even spacetime itself! These bubbles typically arise as an instability in some spacetime, such as the original [[0169 Kaluza-Klein|Kaluza-Klein]] vacuum. To establish them as the outcome of some instability, one needs to find an [[0478 Instanton|instanton]] that mediates the transition from the original state to the bubble. In this case, the instanton is related to the Lorentzian bubble solution via analytic continuation. Once bubbles of nothing are formed, they can expand, collapse, or remain static. The static ones are usually understood as candidates for the ground (lowest energy) state because ground states are expected to be static. ## Refs - instability of the [[0169 Kaluza-Klein|KK]] vacuum: [[1981#Witten]] - flat bubbles - [[1982#Witten]] expanding - static: product of time and a Euclidean BH - AdS expanding bubbles - [[AharonyFabingerHorowitzSilverstein2002]][](https://arxiv.org/abs/hep-th/0204158) - [[BirminghamRinaldi2002]][](https://arxiv.org/abs/hep-th/0205246) - [[2002#Balasubramanian, Ross]] - [[Cai2002]] - [[RossTitchener2004]][](https://arxiv.org/abs/hep-th/0411128) - [[BalasubramanianLarjoSimon2005]][](http://arxiv.org/abs/hep-th/0502111) - [[HeRozali2007]][](http://arxiv.org/abs/hep-th/0703220) - [[HutasoitKumarRafferty2009]][](https://arxiv.org/abs/0902.1658) - AdS soliton - can be viewed as a bubble in 4D - [[1998#Horowitz, Myers]] - static bubbles - [[2006#Copsey, Horowitz]] - stabilised by magnetic charge: [[StotynMann2011]] - with an extra de Sitter factor - [[2020#Dibitetto, Petri, Schillo]] - under T-duality in bosonic string theory - [[2023#Delgado]] - with a conical singularity - [[2024#Ookouchi, Sato, Tsukahara]]: including conical singularities leads to higher decay rate ![[A0003 Dark bubble in a book.png]]