Quantum phase transitions and the breakdown of classical general relativity

It is proposed that the infinite-red-shift surface of a black hole is a qua ntum phase transition of the vacuum of space-time analogous to the liquid-v apour critical point of a Bose fluid. The equations of classical general re lativity remain valid arbitrarily close to the horizon yet fail there throu gh the divergence of a characteristic coherence length xi. The integrity of global time. required for conventional quantum mechanics to be defined, is maintained. The metric inside the event horizon is different from that pre dicted by classical general relativity and may be de Sitter space. The devi ations from classical behaviour lead to distinct spectroscopic and bolometr ic signatures that can, in principle, be observed at large distances from t he black hole.