Black Holes Part III

After a few weeks of waiting, I finally got to hear Stephen Hawking live and in person talking about his ideas for solving the so-called “Black Hole Information Paradox” (which I talked about in one earlier post and on another about my trip to BBC World. Hawking came to Imperial College for a meeting celebrating the 60th birthday of Theoretical Physics Professor Chris Isham.

The basic idea seems more or less simple (at least for those of you with a vague understandinf of Quantum Mechanics and General Relativity). Previously, people have thought about Black Holes which evolved in a so-called “classical” universe — that is, one in which the weird quantum mechanical uncertainties only apply to the black hole itself, but not to the large-scale properties of space and time. Hawking seems to have calculated the additional effect of quantum mechanics on the spacetime as a whole, and realized that when we make measurements “at infinity” (i.e, far from the black hole), we can’t actually be sure when, where and even if the black hole has actually formed. In some of the universes that may have happened, information is indeed lost, and in some it isn’t. but when all of the possibilities are combined together using the rules of quantum mechanics, the net effect on our measurements is that all of the information that falls into the hole is (statistically) recoverable. The catch (aside from the fact that I may have completely misunderstood Hawking’s entire talk) is that the calculation rests upon a conjecture about the properties of quantum fields (that is, all the kinds of particles we know about) have a specific form in those Universes that have so-called non-trivial topology (wormholes, loops, etc., between different points and times).

Not sure if this makes any sense at all — again, my apologies if I’ve completely misconstrued or misunderstood the argument!