Dissertation/Thesis Abstract

Beyond Semiclassical Gravity: Quantum Stress Tensor Fluctuations in the Vacuum
by Schiappacasse, Enrico D., Ph.D., Tufts University, 2018, 73; 10812605
Abstract (Summary)

Large vacuum fluctuations of a quantum stress tensor can be described by the asymptotic behavior of its probability distribution. Here we focus on stress tensor operators which have been averaged with a sampling function in time. The Minkowski vacuum state is not an eigenstate of the time-averaged operator, but can be expanded in terms of its eigenstates. We calculate the probability distribution and the cumulative probability distribution for obtaining a given value in a measurement of the time-averaged operator taken in the vacuum state. In these calculations, we use the normal ordered square of the time derivative of a massless scalar field in Minkowski spacetime as an example of a stress tensor operator. We analyze the rate of decrease of the tail of the probability distribution for different temporal sampling functions, such as compactly supported functions and the Lorentzian function. We find that the tails decrease relatively slowly, as exponentials of fractional powers, in agreement with previous work using the moments of the distribution. Our results lead additional support to the conclusion that large vacuum stress tensor fluctuations are more probable than large thermal fluctuations, and may have observable effects.

Indexing (document details)
Advisor: Ford, Lawrence H.
Commitee: Hertzberg, Mark P., Hsiang, Jen-Tsung, Love, Peter J., Olum, Ken D., Vilenkin, Alexander V.
School: Tufts University
Department: Physics
School Location: United States -- Massachusetts
Source: DAI-B 79/10(E), Dissertation Abstracts International
Subjects: Quantum physics, Theoretical physics, Particle physics
Keywords: Compactly supported functions, Probability distribution, Quantum stress tensor fluctuations, Semiclassical gravity
Publication Number: 10812605
ISBN: 9780438020788
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