How the Other Half Researches

Over at Cosmic Variance, Sean has an idea for an Undergraduate [Particle Astrophysics and Cosmology] Theory Insitute, a six-week summer course that would cover a bunch of the basic tools and techniques of the field, and prepare students to do theoretical research in those fields. The proposed syllabus:

1. Special relativity, index notation, vectors, tensors.
2. Lagrangian and Hamiltonian mechanics.
3. Classical scalar field theory.
4. Gauge theories and electromagnetism.
5. Basics of Lie groups, SU(n).
6. Non-abelian symmetries.
7. Spontaneous symmetry breakdown, the Higgs mechanism.
8. Topological defects.
9. Spacetime curvature and Einstein's equation.
10. Schwarzschild and Robertson-Walker spacetimes.
11. Basics of field quantization and Feynman diagrams.

The additional words in brackets above are very important because this list is fairly specific to those fields-- lots of theorists have long and successful careers without ever thinking about the Higgs mechanism for their research. It's an interesting list, though, and if Sean finds a backer, I may pose as a non-traditional student and try to attend, because I'd like to know more about those topics than I do.

The problem that this is a solution to is that theoretical physics research tends to require a good deal more background than experimental work does. An experimentalist like myself can hire an undergraduate student, give them a couple of wrenches, and turn them loose on a vacuum system, but students who want to do theoretical work need to know a lot more physics before they can make sense of their results. Of course, as Sean notes, this isn't necessarily a Bad Thing:

There's a perfectly good response to this situation, which is: even if you eventually want to become a theorist, it's a great idea to do experimental research as an undergrad. Maybe you won't be immersed in the kind of work you ultimately want to pursue, but (1) understanding something about how experiments work is an unambiguously good thing, and (2) the important lesson is not in the details of the particular field, but in what it's like to do research, which is almost independent of the type of research you're doing.

I would agree with this, but I'd also turn it around: I think that at some point, every experimentalist should spend a little time doing theoretical work. It doesn't have to be publishable theoretical work, or even all that sophisticated, but at some point during grad school, you should spend a few weeks with a pad of paper or a computer, and try to grind out some theoretical results relevant to your experiments. It's important to know how the other half lives, if only to confirm that you don't want to do what they do.

It's actually pretty common for experimentalists to do baby theory on the side. I don't think there's been a single experiment that I've done where I didn't at some point have to simulate some results, or develop a toy model in order to interpret the data. I'm not going to attempt to claim that banging out some little simulations in Mathematica is exactly equivalent to doing full-on multi-channel quantum scattering calculations to determine collision cross-sections, but it does capture a little of the feel, and give me some appreciation for what theorists actually do. I know how much work I had to put into getting sensible results out of my dinky little toy model, which makes it easier to appreciate just how difficult real theory is.

It's somewhat rarer for theorists to do experimental work, which seems terribly unfair at times. Then again, I've met theorists who wouldn't know which end of a soldering iron to hold, so maybe it's all for the best...

In an ideal world, though, people planning on doing theory would do at least one experimental research project in grad school, and experimentalists would do at least one theory project. And somebody with a bazillion dollars would fund Sean's summer theory institute, so I could sneak in and learn some of this stuff...