String Theory seminar - Andrea Puhm Seminar

Abstract: The holographic principle is a powerful tool in gaining insight into quantum gravity for spacetimes with a negative cosmological constant, but it is an outstanding question how generally it applies. I will review recent advances in celestial holography which conjectures that quantum gravity in spacetimes with flat asymptotics is dual to a co-dimension two conformal field theory on the celestial sphere at null infinity. Recasting the S-matrix, which is the basic observable in quantum gravity, in a basis of boost (rather than energy) eigenstates indeed reveals similarities with CFT correlation functions. I will highlight several intriguing and some puzzling features and discuss celestial holography for general spacetime dimensions and for non-trivial asymptotically flat backgrounds of Kerr-Schild type which include the Coulomb field of a static and spinning charge, the Schwarzschild and Kerr geometry as well as electromagnetic and gravitational shockwaves.