Quantum Origin of the Event Horizon

An analysis of the Penrose-Carter diagram of the gravitational collapse of a thin shell of radiation in Minkowski spacetime supports the idea of a quantum origin of the event horizon, and therefore of the concomitant collapse process. The analysis is based on the unavoidable presence of a length scale in the conformal compactification of both Minkowski and Schwarzschild spacetimes, which in a natural way can be identified with the Planck length. One should arrive at the same conclusion, however, with a more involved mathematical description, for any other collapse process with a not naked singularity i.e. protected by an event horizon.