Speaker
Description
Spacetime-symmetry breaking provides a well-motivated avenue for probing departures from general relativity and possible low-energy signatures of quantum gravity. I will discuss theoretical consistency conditions that arise when diffeomorphism symmetry is broken, focusing on the distinction between explicit and spontaneous breaking and the associated constraints on the gravitational dynamics. I will then show how gravitational waves provide complementary observational tests of these scenarios. In particular, symmetry breaking can modify the polarization content and propagation of gravitational waves, as well as the primordial gravitational-wave spectrum. Together, these theoretical and observational considerations illustrate how gravitational-wave measurements can test both the consistency and phenomenology of modified spacetime symmetries.