According to this New Scientist article, Stephen Hawking now thinks that information in black holes may not be lost forever. He will make his case at the 17th International Conference on General Relativity and Gravitation in Dublin on 21st July. His last-minute request was granted solely based on his reputation, as details of the new theory are sketchy at best. Hints from a recent Cambridge seminar indicate that Hawking’s ‘new’ black holes may have no well-defined event horizon. Also, the GR17 website gives the following snippet:
The Euclidean path integral over all topologically trivial metrics can be done by time slicing and so is unitary when analytically continued to the Lorentzian. On the other hand, the path integral over all topologically non-trivial metrics is asymptotically independent of the initial state. Thus the total path integral is unitary and information is not lost in the formation and evaporation of black holes. The way the information gets out seems to be that a true event horizon never forms, just an apparent horizon.
A bit above my head, I’m afraid, but hopefully other SciScoop readers can enlighten me as to its meaning. We’ll have to wait until next Wednesday for the full details, but it promises to be an interesting talk.