11:00 am–12:00 pm
Please join us:
Gautam Satishchandran’s PhD Thesis Defense
Monday, June 27, 2022 at 11:00 AM CDT
The Memory Effect, Symmetries and Infrared Finite Scattering Theory in Quantum Field Theory and Quantum Gravity ‘
Over the past half-century three seemingly disparate concepts and issues in scattering theory have been shown to be fundamentally related to each other: (1) the gravitational memory effect, which is an observable effect where test masses are permanently displaced due to the passage of a burst of gravitational radiation. (2) the existence of an infinite dimensional group of symmetries of classical and quantum scattering theory. (3) the infrared divergences encountered in quantum scattering theory which renders the conventional S-matrix with massless particles undefined. In this thesis, we explain the origin of these relationships and argue that there is no way to "cure" such IR divergences within the conventional framework of scattering theory. In particular, we argue that there is no preferred Hilbert space representation for scattering in quantum field theory and quantum gravity. We believe that to treat scattering at a fundamental level, it is necessary to reformulate scattering theory from an "algebraic viewpoint" rather than attempt to shoehorn the "in" and "out" states into some fixed Hilbert space. We outline the framework of such an infrared-finite scattering theory.
Committee:
Robert M. Wald (Chair)
Savdeep Sethi
Daniel Holz
David Miller
Gautam will be a postdoctoral fellow at Princeton University in the Princeton Gravity Initiative.