I didn’t write a summary of the third day of “Quantum Boot Camp” to go with my Day One and Day Two summaries for a simple reason: I would’ve needed to do that on Saturday, and I spent Saturday in transit back to the US. More than that, though, it was harder to summarize than the other two days, because my talk was the middle of three, and thus I spent most of the first talk fiddling with my slides and fretting, and most of the third fighting off the post-talk adrenaline crash.
Happily, Sedeer at Inspiring Science offers a summary of the first two talks, namely Larus Thorlacius from Nordita talking about string theory, and, well, me. So I can crib off that a bit…
The main physics thing I remember from Thorlacius’s talk is that he gave the first explanation of the often-repeated claim that the five sorts of string theories before Witten’s breakthrough in 19mumble are all different aspects of “M-Theory,” a thing that we don’t understand. This is often phrased in a way that makes it seem baffling and unscientific, but Thorlacius presented it as a matter of different corners of parameter space of the larger theory. That is, if you let some of the many (many, many…) adjustable parameters of M-Theory take on a certain range of values, you get an approximate theory with (relatively) tractable solutions that look like one of the previously known string theories. A different set of extreme values for a different set of adjustable parameters gets you a different set of tractable solutions looking like a different string theory. And so on.
So, the puzzling claim about “M-Theory” is just a statement that we can’t write down a perfectly general set of equations covering all possible values of the many adjustable parameters, but we can generate useful equations for several different sets of simplifying approximations. That is something I can get my head around, and now that common claim makes sense to me.
(His explanation of AdS/CFT wasn’t quite as good, alas, but that’s mostly because it didn’t click with me as well as an explanation by somebody at the AAAS meeting several years ago, which focused on the difference in the number of dimensions between the two sides of the duality. But bit by bit, I’m getting a better handle on what the hell they’re talking about…)
The other thing I remember from Thorlacius’s talk was a self-deprecating line about the relationship between theory and experiment, which was (paraphrased): “Theory doesn’t need experiments– it gets along just fine without them. In fact, this is the Achilles heel of theory. You can write down all sorts of wonderful theories, but unfortunately, only a tiny number of theories are actually correct.” I like that a lot.
My talk was on one of my regular obsessions, namely the use of atomic physics techniques to search for exotic physics beyond the Standard Model. We were asked to prepare two 45-minute talks, so I split my summary of experiments into two pieces based on the general approach. The first talk focused on experiments that try to simply detect things that shouldn’t happen, like parity-violating transitions in atoms, or Lorentz-violating interactions between spins and some exotic field. The second was about the use of ultra-precise techniques for measuring frequencies to measure tiny shifts in atomic energy levels and thus detect changes in the fine-structure constant or things like an electric dipole moment of the electron.
The audience was great for both talks, asking lots of questions as we went along, and the first talk came in pretty much right on schedule. The second was always a bit longer, though, and as a result I didn’t really get to go into EDM searches in detail, because I wound up spending a lot of time on atomic clocks. They both seemed to go over very well, though, so I was happy.
(I’ve sent my slides to Sabine, who will post them on the conference web page at some point. If I get really bored, I might upload them to SlideShare and post them here, but no guarantees…)
The third talk was Eddy Ardonne talking about topological insulators, but as mentioned above, I was fighting a severe adrenaline crash, and thus don’t remember much about it. I did like the sports analogy he used, about how football players on opposite sides of the Atlantic would tell you that an American football and a soccer ball are very different things, but a topologist would say there’s no difference between them. Instead, I will shamelessly link to an old post here about topological insulators, which is one of the most enduringly popular things I’ve written, and uses a very similar explanation to what I recall Ardonne saying in his talk.
All in all, the workshop was a very enjoyable experience. It was great to meet a bunch of really smart writers and scientists and talk shop on both sides of the gap. I learned a bunch of interesting things, and had a lot of fun talking to people informally. I hope they continue to run these, and if anybody on this side of the Atlantic would like to fund and host something similar, I’d be all over that, too.