Einstein equations with fluctuating volume

Abstract

We develop a simple model for a study of classical fields in the background of a fluctuating spacetime volume. It is applied for a formulation of the Einstein equations with a perfect-fluid source. We investigate the particular case of a Friedmann-Lemaître-Robertson-Walker cosmology and show that the resulting field equations can lead to solutions which avoid the initial Big Bang singularity. By interpreting the fluctuations as a result of the presence of quantum spacetime, we conclude that classical singularities can be avoided even within a semiclassical model that includes quantum effects in a very simple manner.