Cosmological Scattering


Scott Melville


Apr 8, 2024






I will outline different approaches to describing 'scattering' on cosmological spacetimes. Scattering - describing what will emerge from a system if a known state is thrown in - plays a foundational role in our understanding of quantum field theory on flat Minkowski spacetime. Fundamental physical properties (e.g.  causality) correspond to distinct mathematical features of the S-matrix and its phase shifts (e.g. analyticity), which have been used to derive many non-trivial constraints on the phenomenology of low-energy particle collisions. The motivation for developing an analogous machinery for curved spacetimes is to achieve the same dictionary between fundamental physical principles and concrete mathematical properties - which can ultimately be used to constrain our cosmological models. Recently, there have been some hints that causality continues to impose powerful (and practically useful) constraints on these non-trivial backgrounds, which I will describe.


Scott Melville is a Stephen Hawking Fellow and Lecturer of Cosmology at Queen Mary University, London. He works on aspects of effective field theory for gravity, cosmology and particle physics.  Melville is known for being an exceptionally clear speaker.

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