String Theory and Atomic Physics

Physics, as Clifford Johnson recently reminded us, has a strongly pragmatic side to its personality: “If that ten dimensional scenario describes your four dimensional physics and helps you understand your experiments, and there’s no sign of something simpler that’s doing as good a job, what do you care?” As that “ten dimensional” bit might suggest, the particular subject in question involves string theory, and whether tools from that field can be applied in places where they were not originally expected to work. From one perspective, this is almost like payback time: the first investigations of string theory, back in the 1970s, were trying to understand nuclear physics, and only later were their results discovered to be useful in attacking the quantum gravity problem. Now that the mathematical results of quantum-gravity research have been turned around and applied to nuclear physics again, it’s like coming home — déjà vu, with a twist.

This is quintessential science history: tangled up, twisted around and downright weird. Naturally, I love it.

Shamit Kachru (Stanford University) has an article on this issue in the American Physical Society’s new online publication, called simply Physics, a journal intended to track trends and illustrate highlights of interdisciplinary research. Kachru’s essay, “Glimmers of a connection between string theory and atomic physics,” does not focus on the nuclear physics applications currently being investigated, but rather explores a more recent line of inquiry: the application of string theory to phase transitions in big aggregates of atoms. Screwing around with lithium atoms in a magnetic trap is, by most standards, considerably more convenient than building a giant particle accelerator, so if you can get your math to cough up predictions, you can test them with a tabletop experiment.

(Well, maybe you’ll need a large table.)

If you’ve grown used to hearing string theory advertised as a way to solve quantum gravity, this might sound like cheating. Justification-by-spinoff is always a risky approach. It’s as if NASA said, “We’re still stalled on that going-to-the-Moon business, but — hey — here’s TANG!” But, if your spinoff involves something like understanding high-temperature superconductivity, one might argue that a better analogy would be trying for the Moon and getting weather satellites and GPS along the way.

Moreover, one should not forget that without Tang, we could not have invented the Buzzed Aldrin.