Event Details

Black holes are expected to be effective gravitational descriptions resulting from coarse-graining over a large number of underlying microstates. Here we explore the consequences of this coarse-graining on the phase space of excitations around the black hole. In particular, we study this phase space for an incipient black hole in the half-BPS sector of N=4 Super YangMills theory, both from the AdS and CFT perspectives. On the gravity side, the coarse-graining corresponds to putting a stretched horizon away from the “core” of the solution. As a result, the phase space around the black hole has a new soft/collective mode on the stretched horizon -- i.e., the bulk Wilson line from the asymptotic boundary to the horizon -- which is absent in individual microstates. We then explicitly construct and coarse-grain the phase space in the CFT, and explain the emergence of such a soft mode from the microscopic degrees of freedom of the black hole.