THe universe is around 14 billion years matter falling into the singularity appear to take infinite time. So how would two black holes have had the time to complete a merger under those conditions? According to my understanding of GR we should be able to see mergers still in progress as the time reference at the event horizon and at the singularlity with itas infinite density would give us the apearance of infinite time taken which is well beyond the age of the Universe. Would the event horizon simply shift in size and encompass both singularities essentailly entailing two seperate singularities inside one event horizon? If I recall Hawkings radiation this process also takes a long time to reduce a large Black hole to nothing. So even if all the matter was pulled away from the smaller black hole to the larger, The smaller black hole would still not have had enough time to reduce to nothing. or am I correct in that last statement?