 One form that such a naked singularity could take is that of a white hole, which is a time-reversed black hole. Imagine taking a film of a black hole forming from the collapse of a massive object, say, a star, with light, dust, rockets, astronauts and old socks falling into it during its subsequent evolution. Now imagine that film being run backwards. This is the picture of a white hole: one starts with a naked singularity, out of which might appear people, rockets, socks—anything at all—with eventually a star bursting forth. Absolutely nothing in the causal past of such a white hole would determine what would pop out of it, since, as follows from the No Hair Theorems  (section 3.2),  items that fall into a black hole leave no trace on the future outside of it. (This description should feel familiar to the canny reader: it is the same as the way that increase of entropy in ordinary thermodynamics as embodied in the Second Law makes retrodiction impossible; the relationship of black holes to thermodynamics is discussed in  section 5.)  Because the field equations of general relativity do not pick out a preferred direction of time, if the formation of a black hole is allowed by the laws of spacetime and gravity, then those laws also permit white holes. 