2003/05/22 by Tanmay Vachaspati, Vachaspati, Tanmay
Physics and Astronomy · #Astrophysics (astro-ph) #FOS: Physical sciences #astro-ph
paper · pdf · doi:10.48550/arxiv.astro-ph/0305439
Talk presented at Davis Inflation Meeting, 2003 (astro-ph/0304225)
arxiv created 2003/05/22 · arxiv updated 2009/12/01
Eternal inflation is shown to require violations of the Null Energy Condition (NEC) on superhorizon scales. With light scalar fields as the matter sources in a de Sitter background, there can be no classical or semiclassical violations of the NEC. However, quantum fluctuations of the energy-momentum tensor, described by an expectation value of four field operators, do lead to large-scale NEC violations. The backreaction of such quantum fluctuations on the inflating spacetime is generally deduced at a heuristic level and leads to the eternal inflation scenario. A rigorous treatment of the backreaction will necessarily include fluctuations of the metric, and several new effects are expected to come into play.