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by scott_s 4282 days ago
I don't think that is a response to this work. That is dated February 1. He links to this paper's author, Laura Mersini-Houghton, but he links to a paper and blog post of hers from January. Reading that blog post (http://backreaction.blogspot.com/2014/01/if-it-quacks-like-b...), what she says seems to be in contradiction with the more recent paper she wrote (http://arxiv.org/abs/arXiv:1409.1837).

In her blog post from January, she says:

"What Hawking is saying is essentially that he believes that a matter collapse only leads to a temporary apparent horizon but not to an eternal event horizon. That is an opinion which is shared by many of his colleagues (including me) and there is nothing new about this idea whatsoever."

But in her more recent paper, she says:

"More specifically, we find that collapsing stars slow down their collapse right outside their horizon, while substantially reducing their mass through Hawking radiation. ... The star never crosses its horizon, so neither unitarity nor causality are violated, thereby solving the longstanding information loss paradox. This investigation shows that universally collapsing stars bounce into an expand- ing phase and probably blow up, instead of collapsing to a black hole."

I am not a physicist, but when I read those two statements, they are in contradiction. The first statement says to me: it may not be an absolute horizon, but it is a horizon. The second statement says to me: actually, we never reach any horizon. So I think that the more recent statement means that she has changed her conclusions based on her recent work.

1 comments

I'm confused here. The mere existence of an event horizon - albeit a temporary one - should make a black hole! So "More specifically, we find that collapsing stars slow down their collapse right outside their horizon," by implying that a horizon DOES exist, simply doesn't cut it. Am I missing something?
I believe that's using the concept of a horizon. For an object of a particular mass, we can use our theory to tell us where the event horizon would be, if it collapses past that point. My understanding of this recent paper is that they are saying: it won't collapse past that point.