Princeton University Gravity Initiative Seminar

Abstract: Effective field theories (EFTs) of gravity provide a powerful and well-motivated framework to describe deviations from general relativity. However, their application to dynamical spacetimes has been challenging because the addition of higher-derivative terms generically spoils their well-posedness - the property guaranteeing that solutions exist and are unique.

In this module, I will describe the new prescription of Figueras, Held and Kovacs that renders a general class of EFTs well-posed and stable to evolve within their regime of validity. I will discuss the potential complications arising from additional massive degrees of freedom and initial data, and how these can be managed. This formulation opens up opportunities for numerical study in strong gravity regimes, and preliminary results are already demonstrating its effectiveness in practice. With these results we can properly test EFTs against observation in the challenging regime of binary mergers for the first time.