Flat space analog for the quantum origin of structure

Abstract

The authors address the question of if the structure of the universe originates from quantum fluctuation, as assumed in inflation, or if classical, thermal fluctuations could lead to the same outcome. They study their previously proposed test (the analytical structure of particular cosmological correlation functions) in flat space where several aspects and details are much better defined. They show that their criterion is completely general and observable and how it is seen in Unruh - de Witt detectors.