QUANTUM COHERENCE IN 2 DIMENSIONS

The formation and evaporation of two-dimensional black holes are discu ssed. It is shown that if the radiation in minimal scalars has positiv e energy, there must be a global event horizon or a naked singularity. The former would imply loss of quantum coherence while the latter wou ld lead to an even worse breakdown of predictability. CPT invariance w ould suggest that there ought to be past horizons as well. A way in wh ich this could happen with wormholes is described.