Quantum Cosmology

Abstract

Most of the evolution of the Universe is likely to have proceeded classically, in the sense that the dominant phenomenon is the classical expansion while quantum fluctuations are small and can be treated as perturbations. Prior to this stage, however, genuinely quantum phenomena almost certainly took place. Although it is not clear whether they have left any observable foot- prints, it is of interest to try to understand them, as this may shed light on such issues as initial conditions for classical cosmology (are inflationary initial data natural? how long was the inflationary epoch? is open Universe consistent with inflation?), properties of space-time near the cosmological singularity, origin of coupling constants, etc.