Atish Dabholkar, of the International Centre for Theoretical Physics, presents this IAS High Energy Theory Seminar on how quantum fields behave near horizons in string theory. He starts from a quantum field of arbitrary mass and spin sitting in the static patch of de Sitter spacetime, showing that its Euclidean partition function picks up contributions from edge modes localized on the horizon, written in terms of the Harish-Chandra character of the de Sitter group. Taking the flat limit and summing over the full tower of string fields, he arrives at the partition function of edge modes near a Minkowski-Rindler horizon, and applies the Kronecker limit formula to produce a modular invariant one-loop result. The calculation extends a known result for a massive vector boson in a spontaneously broken gauge theory to the infinite string spectrum, and comes out ultraviolet finite with a clear state-counting interpretation. The talk is aimed at researchers already fluent in string theory and horizon thermodynamics.