The first detection of gravitational waves in 2015 marked the beginning of a new era in astrophysics. Over the past decade, observations of hundreds of black hole and neutron star collisions have not only deepened our understanding of compact objects but also enabled us to test Einstein's general theory of relativity in the most extreme conditions known: the warped, dynamic spacetime near merging black holes. In this talk, I will give a brief overview of gravitational-wave discoveries, with a focus on how we use the final "ringdown" phase of black hole mergers to probe the fundamental nature of gravity and spacetime. I will also discuss how gravitational-wave observations are opening a new window into the dark sector of the universe. Gravitational-wave astronomy has become a powerful probe of strong-field gravity and a promising avenue for discovering new physics beyond the Standard Model.

Dr Ling (Lilli) Sun is an academic and a DECRA fellow at the Centre for Gravitational Astrophysics at the Australian National University, where she works on gravitational-wave research within the LIGO–Virgo–KAGRA Collaboration. She is also a Chief Investigator of the ARC Centre of Excellence for Gravitational-Wave Discovery (OzGrav). She received her PhD in Physics from the University of Melbourne in 2018, followed by a postdoctoral appointment at the California Institute of Technology, before joining ANU in late 2020. Her research focuses on gravitational-wave data analysis and using gravitational-wave observations to explore fundamental physics, including black hole spectroscopy, black hole superradiance, ultralight dark matter, and gravitational-wave detector science.