They may be about to change their minds, however. Two researchers in the US are pointing out that physicists have swept some "humiliating" problems with black holes under the carpet. By confronting these problems, they say, they have found an alternative fate for a collapsing star.
Emil Mottola of theLos Alamos National Laboratory in New Mexico and Pawel Mazur of the University of South Carolina in Columbia think it mightturn into an exotic bubble of superdense matter, an object they call a gravastar.
I read this somewheere
Try here. You might also find out why we think there are black holes, even though we've never seen them.