Science News reports on a paper to be published in Physical Review Letters in which an international team of researchers describes their computer simulation of the most violent collision imaginable: two black holes colliding head-on at nearly light-speed. Even in this extreme scenario, Roger Penrose's weak cosmic censorship hypothesis seems to hold — the resulting black hole (after the gravitational waves have died down) retains its event horizon. "Mathematically, 'naked' singularities, or those without event horizons, can exist, but physicists wouldn't know what to make of them. All known mechanisms for the formation of singularities also create an event horizon, and Penrose conjectured that there must be some physical principle — a 'cosmic censor' — that forbids singularity nakedness ..."