Possible Constraints on the Duration of Inflationary Expansion from Quantum Stress Tensor Fluctuations

TL;DR

Quantum stress tensor fluctuations in deSitter spacetime can grow over time, potentially affecting inflation duration estimates and leading to observable density perturbations in cosmology.

Contribution

This paper introduces a model analyzing how quantum stress tensor fluctuations influence geodesic expansion during inflation, suggesting constraints on inflation duration.

Findings

Fluctuations grow over time in deSitter spacetime.

Growth of fluctuations can produce observable density perturbations.

Potential to set upper bounds on inflation duration.

Abstract

We discuss the effect of quantum stress tensor fluctuations in deSitter spacetime upon the expansion of a congruence of timelike geodesics. We treat a model in which the expansion fluctuations begin on a given hypersurface in deSitter spacetime, and find that this effect tends to grow, in contrast to the situation in flat spacetime. This growth potentially leads to observable consequences in inflationary cosmology in the form of density perturbations which depend upon the duration of the inflationary period. In the context of our model, the effect may be used to place upper bounds on this duration.