How strings solve the apparent contradiction between black holes and quantum coherence

Abstract

Computations in the calculable small coupling regime of string theories and the general consensus that no new physics has to be invoked in continuing to the large coupling (black hole) regime, suggest the following picture. Quantum states are not black holes even if energy distributions would suggest so. Black holes appear as macrostates, i.e. with the same procedure that blures the quantum coherence of microstates. It is also discussed how a spacetime description—and thus geometry, causal properties and event horizons—may stem from decoherence in the pregeometric approach represented by string theories.