The decay of hot KK space
  The non-perturbative instabilities of hot Kaluza-Klein spacetime are investigated. In addition to the known instability of hot space (the nucleation of 4D black holes) and the known instability of KK space (the nucleation of bubbles of nothing by quantum tunneling), we find two new instabilities: the nucleation of 5D black holes, and the nucleation of bubbles of nothing by thermal fluctuation. These four instabilities are controlled by two Euclidean instantons, with each instanton doing double duty via two inequivalent analytic continuations; thermodynamic instabilities of one are shown to be related to mechanical instabilities of the other. I also construct bubbles of nothing that are formed by a hybrid process involving both thermal fluctuation and quantum tunneling. There is an exact high-temperature/low-temperature duality that relates the nucleation of black holes to the nucleation of bubbles of nothing. 
Adam R. Brown
hep-th gr-qc