Black holes are at the root of the most striking puzzles that arise when attempting to combine the principles of quantum mechanics and Einstein’s theory of gravitation; 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 principle. The latter establishes that the behavior of gravity in a given region of space is actually entirely encoded in terms of a different system, which lives only along the edge of that region. As such, it provides physicists with a dictionary that translates complicated problems into accessible ones. However, the holographic principle has not been developed yet for realistic kinds of spacetimes, such as the ones describing the universe we live in. The first overall objective of this research project is to fill this gap by developing a holographic correspondence for spacetimes which are of relevance for most astrophysical purposes; those spacetimes are the so-called asymptotically flat spacetimes.
The second overall objective of this project is to address some of the unresolved key issues in black hole physics, especially the mysterious origin of their vast entropy. The approach taken in this project is based on a recently discovered intriguing set of infinite symmetries (called ‘soft hair’) that appear close to black hole horizons. These symmetries were previously overlooked, and were hence expected to give important novel insights into the physics of black holes as they strongly constraint physical processes that occur in their vicinity.
We live an exceptional period to study black holes: we now have access to astrophysical observations of a very high accuracy, while the Event Horizon Telescope is providing us with genuine black hole images, including the one in the center of nearby galaxies. The importance of this research project comes from the deep implications of its outcomes in our understanding of black hole physics, and the fact that the discoveries made about the holographic nature of asymptotically flat spacetimes unveil new connections between physical theories and shed new light on the fascinating universal features of gauge theories and gravity.
The conclusions of this Marie Sklodowska-Curie (MSC) action are: 1) infinite-dimensional symmetries give fundamental insights on the universal principles that organize the degrees of freedom in gravitational theories; 2) the interconnection between black hole and asymptotic symmetries is key in order to unveil the fundamental holographic nature of black holes.
