Abstract. We employ the semiclassical approximation to the Wheeler–DeWitt equation in the spatially flat de Sitter Universe to investigate the dynamics of a minimally coupled scalar field near the Planck scale. We find that, contrary to naive intuition, the effects of quantum gravitational fluctuations become negligible and the scalar field states asymptotically approach plane waves at very early times. These states can then be used as initial conditions for the quantum states of matter to show that each mode essentially originated in the minimum energy vacuum. Although the full quantum dynamics cannot be obtained exactly for the case at hand, our results can be considered as supporting the general idea of asymptotic safety in quantum gravity.

Key words: inflation; quantum gravity phenomenology; quantum field theory on curved space; physics of the early universe

Received 15 April 2008, accepted for publication 19 May 2008
Published 18 June 2008