The buzz is that Hawking has a new idea about how to resolve the “Black Hole Information Paradox”, the well known incompatibility between standard ideas about black holes and the unitary time evolution of the wave function that is fundamental to quantum mechanics. Evidently Hawking has asked to give a talk about this at GR17, a big conference on general relativity that will be held July 18-23 in Dublin.
The abstract for his talk goes like this:
“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.”
I can’t tell exactly what that means either, so I guess we’ll have to wait for the talk. My own prejudice about quantum field theory is that the relation between the Euclidean and Minkowski space formulations of quantum field theory is actually much more interesting and subtle than people think. It’s not just a technical trick. So I’ll be interested to see what Hawking has to say about this.
Something else at the conference that may be interesting will be Sir Roger Penrose’s public talk entitled “Fashion, Faith and Fantasy in Modern Physical Theories”. Guess what he is referring to by “Fashion”.