Quasinormal modes and pole-skipping in holographic theories

A black hole spacetime has characteristic excitations called quasinormal modes. Using the AdS/CFT duality, the quasinormal modes of a AdS black hole correspond to the collective modes of the thermal state of a strongly interacting quantum field theory. While the complete spectrum of quasinormal modes depends upon the details of the spacetime, in this talk I will explain that exact constraints on the spectrum can be obtained by studying just the dynamics near the event horizon. In the dual quantum field theories this is related to a phenomenon called pole-skipping, and leads to a universal relation between hydrodynamics and chaos in such theories.