A Newtonian Model for the Quantum Gravitational Back-Reaction on Inflation

Abstract

Quantum gravitational back-reaction offers a simultaneous explanation for why the cosmological constant is so small and a natural model of inflation in which scalars play no role. In this talk I review previous work and present a simple model of the mechanism in which the induced stress tensor behaves like negative vacuum energy with a density proportional to $-\Lambda/{8\pi G} \cdot (G \Lambda)^2 \cdot H t$. The model also highlights the essential role of causality in back-reaction.Comment: 4 pages, LaTeX 2.6, no figures. Talk given at the International Meeting on Quantum Gravity and Spectral Geometry, Naples, Italy, July 2-7, 200