Andrew Jaffe: Leaves on the Line

I'm not sure why anybody would care, but here's my blog for all to see.

Joanne and I went to see the new show of works by Gabriel Orozco at the Serpentine Gallery. He's most famous for a human skull, inked over with a pattern of criss-crossing diamonds. It's beautiful, it's about mortality, geometry, and it's about imposing our will upon the world (and vice versa). Orozco is a painter, a photographer, a sculptor, zigzagging across the lines between geometry (his cut-up airline-ticket collages), formal beauty (the gorgeous manipulated photo of sun-dappled leaves opening the show) and the conceptual (hanging drier-lint).

At about 4pm, the phone rang -- it was the BBC! Apparently, an editor there had read in New Scientist that Stephen Hawking had solved the "Black Hole Information Paradox." So -- despite the fact that he won't be presenting the results until the GR17 meeting in Dublin next week -- I'm off to the BBC to tell them all I know about Hawking and the Black Hole Information Paradox.

More on my encounter with big media later...

I just spent about three minutes talking to the BBC World 6 o'clock news anchor (Nik Gowing) about Black Holes, quantum mechanics, and information. (And allowed the BBC's budget to shuttle me from Imperial College to White City and finally to Paddington.) He was perhaps less interested in the science than in Hawking's bet with John Preskill (which Hawking will actually lose if his new idea turns out to be correct).

The question, and the paradox, is this. The first ingredient is that, in Einstein's General Relativity, "Black Holes have no hair". That is, no matter what you throw into them (TV sets, The New York Times, mud) all that's left at the end of the day is the total mass, total charge, and total angular momentum (that is, how fast it's spinning) of what was thrown in.

The second ingredient is Quantum Mechanics, in particular a property of quantum mechanics called "unitarity" which, in this context, means that you can't take a highly-ordered system (the TV sets, newspapers, or mud) and make it into an unordered system without acting on it from outside. This is fine in a classical black hole: all that information, all that order, is locked away inside the black hole, inaccessible to the rest of the Universe.

The paradox comes from Hawking's own work: Black Holes are not actually black, but if sitting there in the vacuum of space, actually radiate away at a particular temperature (known as the 'Hawking Temperature') related to the mass of the Black Hole. In this original theory, the radiation is completely featureless, a so-called "black body" -- radiation with much less order than whatever was originally thrown into the black hole. So here's the paradox, then. Throw stuff into a black hole, wait long enough, and you find that the universe is a much less ordered place than it started.

Physicists have been thinking about this problem ever since Hawking's original calculation, and many solutions have been proposed; we won't know until next week (or perhaps after that when all the peer-review dust has settled) if this proposal is the right answer and (perhaps more importantly) whether it gives any insight into the more fundamental problems underlying the paradox: the relationship of General Relativity and Quantum Mechanics, the role of information in fundamental physics, and the meaning or probability.

Of course I didn't get to say all this to the BBC. I know the chances of anyone reading this having seen my "performance" is pretty slim, but if you have, please leave me a comment!! (And let me know if my version was any better than Hawking himself on "Newsnight"!)

Jo and I went to the BBC Proms last night, and saw a new commision from John Casken, Symphony 'Broken Consort'; Ravel's Piano Concerto in G Major; and Stravinski's Firebird Suite, all performed by the BBC Philharmonic, conducted by Gianandrea Noseda. The BBC Phil was OK, hard to judge with the slightly murky sound from our vantage across the room.

For 'Broken Consort' they were augmented by a "Gypsy Ensemble" (compete with red sashes on the men and flowing skirts on the women amongst the formally-dressed Philharmonic) of accordion, mandolin, led-outfitted electric violin and 'cimbalon', which seems to be the guts of a harpsichord played with zither-like hammers. They had some fine moments of almost-Asian music, but it failed to grip your ears or your emotions for much of the piece.

The best instrumentalist was Pierre-Laurent Aimard's piano on the Ravel concerto--jaunty, fluid, perfect, but somehow relaxed at the same time (perhaps aided by his all-black but still informal outfit). Much of the work is familiar and even a tiny little kitsch, but the piano made me want to devote a few years to learning how to play even a little like that (last year Aimard produced a fantastic CD combining Ligeti's piano Etudes, Steve Reich and African singing (a bizarre combination actually suggested by Ligeti). And it's nice that the Proms really are popular entertainment, or at least not the same hifalutin' culture that classical music usually seems. Usual rules don't apply; we could eat and drink in the hall. People even committed the great sin of applauding between movements (nobody knew how many movements there were in the opening Casken piece...) without any approbation (I am reminded of the opposite experience: at a symphony performance in San Francisco, an Asian couple had the temerity to applaud between movements and were hissed by the crowd each time. But why not applaud? Why not show your approval?)