Recently, I read in the journal Nature that Stephen Hawking wrote a paper claiming that black holes do not exist.  How is this possible? Please explain it to me because I didn't understand what he said.

References:


Article in Nature News: Stephen Hawking: 'There are no black holes' (Zeeya Merali, January 24, 2014).
S. Hawking, Information Preservation and Weather Forecasting for Black Holes, arXiv:1401.5761.


The paper by Dr. Stephen Hawking doesn't say that black holes don't exist. What he says is that black holes can exist without "event horizons". To understand what an event horizon is, we first have to understand what is meant by escape velocity. This last one is the speed you need to escape a body. Now, here is where the event horizon and the escape velocity comes in play: the event horizon is the boundary between where the speed needed to escape a black hole is less than that of light, and where the speed needed to escape a black hole is greater than the speed of light.
 

So Hawking says that  instead of event horizon, there may be "apparent horizons" that would hold light and information only temporarily before releasing them back into space in a "garbled form".
