The Celestial Road to a Holographic Description of Black Holes

Black holes are at the root of the most striking puzzles that arise when attempting to combine quantum mechanics and general relativity; they are therefore thought to be key to a formulation of a theory of quantum gravity. In recent years, progress in our understanding of the elusive quantum nature of black holes has been made thanks to the so-called holographic correspondence, which has provided theoretical physicists with a powerful tool to study quantum gravity. However, these methods are so far only fully developed for anti-de Sitter spacetimes, whereas understanding realistic black holes would require to develop a holographic correspondence for asymptotically flat spacetimes.The aim of this project is to make major steps towards a holographic description of quantum gravity in asymptotically flat spacetimes, and to address some of the unresolved key issues in black hole physics, especially in understanding the mysterious origin of their vast entropy. To do so, I propose to combine two novel emergent ideas: The first is a new approach to holography in flat spacetimes called celestial holography, which proposes that quantum gravity in flat space can be described by a celestial conformal field theory living on the sphere at infinity. The second is based on the recent discovery, in my previous works, of the existence of intriguing infinite-dimensional symmetries that appear close to black holes’ event horizon. The infinite set of asymptotic conservation laws in the presence of horizons is awaiting to be unraveled, as it will reveal unexplored constraints on information flow for black holes in flat spacetimes.Thanks to this unique combination of powerful approaches based on symmetry principles, my research project aims at addressing the challenge of a holographic formulation of spacetimes that include realistic black holes, such as the ones we observe in the sky.