This, more or less: https://en.wikipedia.org/wiki/False_vacuum_decay#Inflation https://en.wikipedia.org/wiki/False_vacuum_decay#Inflation The problem is we're

This, more or less: https://en.wikipedia.org/wiki/False_vacuum_decay#Inflation https://en.wikipedia.org/wiki/False_vacuum_decay#Inflation The problem is we're not sure that's what caused reheating. There's been other suggestions, some of them quite exotic -- a collision with a neighbouring brane, for instance. Still, my bet's on false vacuum decay.