Frank Wilczek gave an impressive physics colloquium at MIT last month, called “What is Space?” and it really gave me a new view of the physical world. I had read about spontaneous symmetry-breaking in quantum field theory texts, but I had not appreciated that the space around us can be viewed as a condensate. This was also the first time I’ve heard the word “superconductor” used in the sense he meant, but it seems like a somewhat natural generalization after some pondering.
He put up slides of his talk here (warning: this file did not agree with the Firefox on Linux in my office, but I was able to view it in Safari at home), but there were a couple differences between the slides and the lecture he gave. First, he only presented the first 2/3 of the slides, so it was interesting to read the slides that he rejected and tossed to the end. Second, in the talk, he really emphasized the point that truly empty space is a fundamentally explosive medium, because quark-antiquark pairs have negative energy. In particular, the space we see is quite full of such pairs, which mutually repel, so there is an equilibrium concentration. Also, these pairs are made of real particles, and are not virtual (although I don’t understand the significance of this statement). I had never seen this idea before, and I wonder if the negative energy claim is a result of some reasonably recent lattice QCD computations, or if I’ve simply failed to pay attention in the past.
At the end, there were a lot of questions from the audience about extra dimensions and strings, and he ducked all of them. I had been meaning to ask if he expected the nature of the condensates to change in or near the event horizon of a black hole, but unfortunately, I was unable to think of a good way to say it in English words at the time.