Exact Results in Quantum Theory

I will talk about joint work with András Vasy on defining a global Feynman propagator for massive Klein-Gordon fields on asymptotically flat spacetimes. The propagator is defined as an inverse of the Klein-Gordon operator producing solutions which are, in a precise sense, asymptotically positive-frequency in the future and negative-frequency in the past. We use microlocal analysis on a spacetime compactification with distinct boundaries at spacelike, null, and timelike infinity, based on a pseudodifferential calculus introduced by Sussman. This allows an extension of previous constructions of propagators to radiative perturbations of Minkowski spacetime. Zoom link: https://uw-edu-pl.zoom.us/j/2780321940