Non-interacting Quantum Field Theory in Riemannian Signature

Explore a General Relativity seminar presentation where Stanford researcher Mikhail Molodyk delves into the construction of quantum field theory analogues in Riemannian signature. Learn about recent microlocal advances in wave operators on spacetimes, focusing on four distinct Fredholm inverses that correspond to retarded, advanced, Feynman, and anti-Feynman propagators in quantum field theory. Discover how this construction applies to Riemannian manifolds with two asymptotically conic ends, examining quantum fields that satisfy the Helmholtz equation and utilize scattering data to build states meeting the Hadamard condition. Gain insights into the analytic structure of the theory, understanding why Feynman propagators are as natural as advanced/retarded ones, and examine key differences between Feynman propagators defined as distinguished inverses versus time-ordered expectations.