Technical Talk

Scattering amplitudes provide a powerful framework for studying fundamental interactions, offering deep insights into both quantum field theory and quantum gravity. In this talk, I will discuss how modern amplitude techniques, particularly in the context of gravitational effective field theories, can be employed to compute classical observables relevant to the current era of gravitational wave physics. Focusing on soft graviton theorems—universal features of the gravitational S-matrix—I will show how they govern the low-frequency behavior of gravitational radiation in classical scattering processes.

Specifically, I will demonstrate how to derive the gravitational waveforms emitted during the scattering and fragmentation of massive objects, where complicated non-linear gravitational dynamics and non-gravitational interactions may take place. Remarkably, despite these complexities, the soft graviton theorem predicts the asymptotic late and early time behaviors of the waveform, including its power-law fall-off and logarithmic corrections, solely in terms of the momenta and intrinsic spins of the incoming and outgoing objects, without requiring detailed knowledge of the intermediate dynamics. I will outline the derivation of these results, explore their implications in gravitational tail memory predictions, and discuss potential observational consequences and generalizations.