Correlations Beyond the Cosmological Horizon

Abstract

It normally is taken for granted in arguments in cosmology that phenomena which occur in spacetime regions which ”lie outside of each other’s horizon” must be uncorrelated, since no causal communication can occur between the regions. However, it is a fundamental feature of quantum field theory that correlations between observable quantities occur over all spacetime regions, including regions lying outside each other’s horizon. It is possible that such correlations play an important role in processes occurring in the early universe.