A Rejuvenated Universe Without Initial Singularity

Abstract

Cosmological observations strongly suggest the presence of dark energy which comprises the majority of the current energy density of the universe. The equation of state relating the pressure and energy density of this dark energy, p = w ρ, appears to have w close to -1, with most analyses preferring w<-1 when these values are considered as part of the parameter space. If w<-1 is the future behavior of the dark energy, the scale factor, expansion rate, and energy density of the universe will diverge in a finite time as its apparent expansion age tends to zero. We hypothesize that w>-1 is restored at a late enough time, perhaps due to a phase transition of the dark energy, and show that this produces conditions observationally indistinguishable from a Hot Big Bang. This process of rejuvenation may have occurred in the past, making our universe much older than it appears and eliminating the Big Bang singularity.