Frequency Spectra and Probability Distributions for Quantum Fluctuations

Abstract

This paper discusses two distinct, but related issues in quantum fluctuation effects. The first is the frequency spectrum which can be assigned to one loop quantum processes. The formal spectrum is a flat one, but the finite quantum effects can be associated with a rapidly oscillating spectrum, as in the case of the Casimir effect. The leads to the speculation that one might be able to dramatically change the final answer by upsetting the delicate cancellation which usually occurs. The second issue is the probability distribution for quantum fluctuations. It is well known that quantities which are linear in a free quantum field have a Gaussian distribution. Here it will be argued that quadratic quantities, such as the quantum stress tensor, must have a skewed distribution. Some possible implications of this result for inflationary cosmology will be discussed. In particular, this might be a source for non-Gaussianity.