July 27, 2005

Physics Education—Specialization and Fundamentals

Posted by Arcane Gazebo at July 27, 2005 2:56 PM

In a post at Cosmic Variance, Sean Carroll makes a side remark that, "Sadly, there are still plenty of physics grad students who have never been exposed to [general relativity]."

I'm one of those students, and I've always had the vague sense that GR is something I should know about, since it's one of the pillars of modern physics and a fundamental part of our understanding of the universe. It's because of the highly specialized nature of most physics research that a lot of students don't take a GR course—it simply isn't relevant to a lot of subfields. Likewise, I could say something like "Sadly, there are still plenty of physics grad students who have never been exposed to the BCS theory of superconductivity."

But the more I think about it the less defensible it is that I've not had much contact with GR. I'll spend at least six years in grad school, and for most of that time I won't be taking any classes, just doing research. Surely I could take a little time to audit a GR course? (In fact, a student who recently graduated from our group did exactly this.) It seems more than a little ridiculous to accumulate all the tools necessary to comprehend one of mankind's greatest intellectual achievements, a profound description of nature, and then not make any attempt to learn it. That's a pretty high level of incuriosity. I think there's a certain amount of information overload the first few years in grad school, that made it feel like such a relief to be "done" with classes and just take some data for a while. But I seem to be past that stage.

And while I'm at it, it would be nice to know more about quantum field theory and the Standard Model...

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I, too, missed out on General relativity, though I looked into it enough to know that I didn't understand enough about Tensors to really get it.

On the other hand, I got some exposure to the Standard Model/QFT in the High Energy Physics class I took super-senior year. I found the class fascinating and cool (the time was well spent just so I can say I understand how Feynman diagrams work =] ). But the grunge required was excessive; I did at least a couple problem sets in LaTeX just so I could copy-and-paste things around instead of writing them over and over again. If my memory is correct, the grunge really gets out of hand with quantum chromo-dynamics.

I ocassionally crack open the HEP textbook we used (Griffiths' Introduction to Elementary Particles, if I remember correctly) just to refresh my memory. Fun times.

Posted by: Jonathan Adams | July 27, 2005 3:44 PM

I've heard similar things re:grunge about Berkeley's QFT/Standard Model sequence. That probably helped deter me from it my second year. (It's not like I avoided mathematical tedium by taking graduate solid state, but I was going to take that anyway.)

I think as an undergrad GR would have been too much for me, but some of the grad classes I've taken since then have laid the mathematical foundations. At least, I think they have... maybe I'll find out.

Posted by: Arcane Gazebo | July 27, 2005 5:59 PM

I audited QFT for two semesters (we used Peskin and Schroder). It is cool stuff and the idea behind Feynman diagrams can be used, in principle, for _anything_ with a Green's function description lurking in there. (I once saw a talk using Feynman diagrams for KAM theory---awesome stuff!) The extreme level of grunge of actually computing diagrams (even the simplest ones) is actually quite famous in several respects. (It used to be that going to a certain order in perturbation theory essentially guaranteed a publication. That may still be true, but the order is certainly higher now, especially with the computer algebra algorithms now available for this stuff.) There's at least one well-known sign error that persisted for several years as a result. (Somebody attempted to "duplicate" the painful calculation and found the error.)

As for GR, that has been on my list of things to learn for several years (it's asymptotically on my list, as it were). I don't feel guilty about not having been sufficiently exposed (beyond the few applications to GR we did in Ma 109 back in the day and the couple relevant journal papers I've read by mathematicians who do GR), but I _do_ feel like I'm missing out.

I do feel guilty about not knowing E & M at the level of Jackson. That stuff slipped through the cracks, although I do have a copy of Jackson. I was going to audit the relevant course at Cornell and Georgia Tech once I actually had time, but in each case the class was too early in the morning for my tastes (8:30 am at Cornell!). I could do this now, but I think that instead I'll audit the year-long quantum computation course that Preskill teaches because (1) it's not like I can learn that from an expert at any university and (2) I was hired by the Center for the Physics of Information (who's the CPI now?) and it would be good if I actually knew _something_ about the physics of information. (Actually, my collaborators and I just came up with a very cool way, _in theory_ of course, that a certain BEC system might be very useful for a quantum computer, but I'd like to learn this stuff more extensively and take advantage of the fact that I'm here. (There's a way cool connection between quantum computation and quantum chaos that I'd like to be better equipped to study...)

In terms of a broader point, by the way, it will always be true that there will be subjects within one's discipline that one "should" know. This is hardly confined to physics. Also, there are disciplines within physics that are highly important and potentially accessible that are typically almost invisible in the undergraduate curricula. One example is continuum mechanics (this fact was harped on by Jerry Gollub in a recent Physics Today article, and I very much agree with him on this), which every engineering major learns about in some undergrad class but physicists are usually exposed as grad students instead (if at all).

Maybe I'll eventually learn GR, but the list of things I want to learn (in physics and other subjects) is just so long that I don't know if that will ever happen. Then again, it would be cool to audit a class by Kip Thorne if he's teaching it while I'm around.

Posted by: Mason | July 27, 2005 6:38 PM
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