Strings and black holes

I review some recent work (done in collaboration with G. Veneziano) which c larifies the existence of a correspondence between self-gravitating fundame ntal string states and Schwarzschild black holes. The main result is a deta iled calculation showing that self gravity causes a typical string state of mass M to shrink, as the string coupling g(2) increases, down to a compact string state whose mass, size, entropy and luminosity match (for the criti cal value g(c)(2) similar to (M root alpha')(-1)) those of a Schwarzschild black hole. This confirms the idea that the entropy of black holes can be a ccounted for by counting string states, and suggests that the level spacing of the quantum states of Schwarzschild black holes is exponentially small, and very much blurred by radiative effects.