While I have divided this topic into three subsections, there is
considerable overlap. The primary questions can be formulated as
the cosmic censorship conjecture. The weak cosmic censorship
conjecture [154] requires a singularity formed from regular, asymptotically flat
initial data to be hidden from an external observer by an event
horizon. An excellent review of the meaning and status of weak
cosmic censorship has been given by Wald [178]. Counter examples have been known for a long time but tend to
be dismissed as unrealistic in some way. The strong form of the
cosmic censorship conjecture [155] forbids timelike singularities, even within black holes.