Following the groundbreaking first detection by both LIGO observatories of gravitational waves in 2015, a new era of gravitational wave astronomy has begun. The waves strong enough for us to detect on Earth are caused by the orbit, deceleration and merger of pairs of extremely massive objects: primarily black holes, but also neutron stars. We seek to predict the gravitational waves emitted by these mergers and thus learn about the black holes and neutron stars themselves - how they form, their internal composition - and Einstein’s theory of gravity.
The Worldline Quantum Field Theory (WQFT) is a new formalism that uses tools and technologies from QFT - particularly scattering amplitudes - to help describe these gravitational merger events. Tackling the gravitational two-body problem has considerable overlap with our description of fundamental particles scattering in collider experiments, and the WQFT provides a streamlined framework for accessing the classical regime. In this talk I will discuss the WQFT’s fundamentals, its past and future applications to gravitational wave physics and its supersymmetric extension to describe spinning black holes and neutron stars.