Open Collections

Waterfield, Conor

University of British Columbia

Stochastic gravity is an extension of semiclassical gravity in which general relativity and quantum field theory are combined using the Schwinger-Keldysh formalism. This approach opens up the ability to study problems where quantum fluctuations are important in semiclassical gravity. This framework has been used to demonstrate the possibility of parametric resonance between fluctuating quantum fields and spacetime causing an accelerated expansion of the universe. This may be one possible solution to the cosmological constant problem. In this thesis, I focus on both understanding the consequences of stochastic gravity models and developing consistent calculation methods. Fluctuating spacetime may indicate the possibility of scattering. Regularization techniques must be used in quantum field theory calculations. A method that involves a UV cutoff and maintains Lorentz invariance may be one useful approach. Scattering is studied through various approaches; as a form of Rayleigh scattering, as a result of interacting field theories, and as a direct influence on geodesics. Quantum field theory approaches to the scattering of geodesics are determined to be a small effect and are not predicted in the framework of semiclassical gravity or stochastic gravity. The study of geodesic deviation in interferometer experiments gives some indication that parametric resonance effects could have a significant role in stochastic gravity. The possibility of using Pauli-Villars as a Lorentz invariant approach to regularize quantum fields in stochastic gravity calculations is explored. The Pauli-Villars regularization scheme is shown to have significant problems when applied to stochastic gravity, such as failures in second-order stress-energy tensor terms and restrictions due to the kinematic properties of negative-norm fields.

Text

2023-08-30

Attribution-NonCommercial-NoDerivatives 4.0 International

http://hdl.handle.net/2429/85706

Physics

University of British Columbia

UBCV

http://creativecommons.org/licenses/by-nc-nd/4.0/