In
cosmology, the concept of
eternal inflation describes a multiverse composed of numerous distinct regions, often referred to as pocket universes or
inflationary zones, one of which contains the
observable universe. According to
astrophysicist Jean-Luc Lehners of the Princeton Center for Theoretical Science, eternal inflation may give rise to multiple such regions. In a 2012 publication, Lehners examined how pocket universes can emerge from the dynamics of eternal inflation and proposed that their subsequent evolution may follow different cosmological scenarios, including slow-roll inflation, cyclic cosmology, or emergent models such as Galilean genesis. He further discussed how the question of which type of universe is most probable depends on the choice of measure used to regulate the infinities associated with eternal inflation. Lehners argues that several leading measure proposals, including the global light-cone cutoff and the causal diamond measure, predict a higher probability of inhabiting a pocket universe that begins with a relatively small Hubble expansion rate. Such predictions are consistent with models involving emergent or cyclic cosmological evolution. Cyclic pocket universes may be particularly favored in this framework, as repeated cosmological cycles could produce habitable conditions multiple times within a single region. ==In media==