Eternal inflation, energy conditions and the role of decoherent histories

Abstract

Eternal inflation, the idea that there is always a part of the universe that is expanding exponentially, is a frequent feature of inflationary models. It has been argued that eternal inflation requires the violation of energy conditions, creating doubts for the validity of such models. We show that eternal inflation is possible without any energy condition violation, highlighting the important role of decoherence and the selection of states in the inflationary process.