Just got back from teaching my Physics 678 class. I can’t really tell you the title, since I don’t really know it myself. How so?, you ask….Well, what happened is this:
The semester started, and I showed up to teach what I thought was supposed to be the second part of a graduate string theory class, as long promised. (The bit where I do my standard dog-and-pony show about D-branes, etc, now that they know about basic perturbative string theory from my colleague Nick Warner’s class last year. Sort of an extended version of courses I’ve given at Summer Schools at several places around the planet.)
The first warning sign was that I looked on the online schedule to see where my class was to be held (small classes often end up in surprise mystery buildings all over campus…I like this because I get to learn of new teaching spaces over in the Humanities territories, for example), and saw that the title of the course was something like “Introduction to Relativistic Field Theory”. Hmmm…. problem there was that there is no course on the books entitled “String Theory, part II: Non-perturbative aspects”, so the schedulers did the best they could.
So I showed up for the first class (this is three weeks ago now), and sure enough, there are the six or seven graduate students from Nick’s class…. but there are four or five students from the condensed matter group, and from the quantum information groups, part of CSI (I kid you not [update: you see, that's the group's name, see an earlier post]) over in Electrical Engineering! They saw a course with that title and, understandably, thought it was a good chance to learn some Relativistic Field Theory.
So what to do…. Choices:
(1) Treat the unprepared students (who have not done any field theory) as noise, and just carry on regardless? Plus point: I get to use my standard notes…little or no preparaton…more time for research…. Minus point: I can’t bear to have people in my class who aren’t getting anything out of it. It would drive me nuts!
(2) Teach a Relativistic Quantum Field Theory course…. Plus point: Tony Zee’s book is an excellent introduction; I’ve taught the second half before (to most of those folks from Nick’ class) so it can’t be too hard to make notes for the first half…. Minus point: the students and faculty high energy physics group (my people) would have me hung, drawn and quartered, and then taken out and shot with very slowly moving blunt bullets.
(3) Do something else at the last minute.
Well, I chose (3). Because I’m an idiot, I suppose. But it’s a challenge. so I’m writing a whole new course as I go along…sometimes on the bus on the way to teach the class. What would the title be? I’m not sure yet, since I have no idea where I’m going, but I’m trying to put in a little bit for everybody from the three camps. They’ve agreed to be grown up and so some reading on each other’s topics from time to time, to fill in a bit of background. So for example, the first day (since I abandoned my notes), we sat together and traded our recommendations for some of the best bits of background reading on topics in condensed matter theory, quantum information theory, and high energy theory. Next class, we traded mini explanations for what were central concepts in each topic that showed up in our reading…. all very touchy-feely.
So in choosing (3), what am I lecturing on? Well, I’m trying to cut a path through some material that is of interest and value to several camps, no matter what area of theoretical physics you come from….. (apologies to the uninitiated for the unexplained terms in the next few paragraphs):
So we started with the Ising model, and focussed on to phase transitions. Then we focused on the second order phase transition (a “critical point”) and have lingered around that point for a while learning language of statistical physics, and converting it into bits of quantum field theory as well. We’ve understood the onset of scale invariance at such a point, (conformal invariance is to follow), and then scaling operators, critical exponents, the idea of irrelevant, relevant and marginal operators, their scaling dimensions, etc. Then we’ve taken a tour of various types of critical behaviour, understood the central idea of universal behaviour, critical exponents, scaling laws…..even discussed the fact that this shows up in real physics all over the place…. This week we learned about several of the fun things that theoretical physicists have done to define all sort of statistical models and phase transitions generalising the Ising model, such as the Potts models, the Lee-Yang model, etc….culminating in the RSOS/IRF models, built from the A-D-E Dynkin diagrams of the simply laced Lie algebras….this latter allowed me to digress on Lie Algebras, Dynkin diagrams and all that good stuff…sneakily introducing the diagrams for the affine cases too.
Of course, little do they know what all this is leading up to….so much apparently specialized condensed matter physics and group theory is preparation for what I consider to be among the most interesting snd important topics in string theory too! Perturbative and non-perturbative. It’ll sneak up on them in a rather nice way…
This will lay the groundwork for more conformal field theory, and we’ll worry about edge effects, and theories with boundary, and finite size effects….(so that’ll be one way of understanding D-branes sneaking up in the background, among others…..)
We’ll also spend some time on various integrable systems (unpacking properties of things already seen above, and doing more), study solitons of various sorts, in various dimensions. Again, these will be all for their own sake, and will teach a lot about field theory….but there’ll be important aspects of string theory just on the cusp of all of this too, and I’ll bring this out when we’re ready…..
You know, it sounds like its a jumble of stuff, but there are some important themes, techniques and language that get sewn together by all this stuff, and gets left out of a lot of standard courses….I’m having fun just talking about the fun stuff I think that we’re going to do….
So, it’s time consuming, and it’s a challenge to keep everyone catered for, but so far I think I’ve been up to the challenge…. three weeks gone, only another twelve or so of “winging it” to go! (None of them read this blog, so I think I’m safe….)
-cvj
September 14th, 2005 at 3:12 pm
Good luck Clifford, if I never see you again for some reason, it was nice knowing you…
(on the other hand, I wish I could take that class myself).
Actually, I had a similar story here, for some reason the first field theory class is called “quantum electrodynamics” inviting all kinds of students that expect to learn, quite surprisingly, about quantum electrodynamics (e.g quantum optics experimentalists). Field theory, Feynman diagrams etc. is not a bad thing to learn, but I doubt you need this much for photonics, say…
Inquiring about changing the name of the course elicited a few incidents of hysterical laughter…
September 14th, 2005 at 3:36 pm
Clifford,
Sounds like a great course. Now if all string theorists would start teaching courses like this, physics might start getting somewhere again….
September 14th, 2005 at 3:45 pm
You’re doing that and research and gardening and blogging, too?
September 14th, 2005 at 5:20 pm
Arun: For some of the day, sure… Then there’s all the other stuff on various committees, called “service”….and then the sun sets, and I prowl the streets at night, either as gentleman party-goer physicist or in costume, fighting crime and saving the world.
All standard professor stuff that we all do….no? ….
-cvj
September 14th, 2005 at 8:08 pm
Clifford,
I can see the gradual progression of a TV mini-series here, where our protagonist, a hero-blogger if you will, fights evil through his brilliant writing, all the while educating the public about the benefits of science…
(who will play you?)
September 14th, 2005 at 8:14 pm
“(who will play you?)”
Oh! There’s role for me in this mini-series? What am I, a sort of sidekick or advisor to the hero-blogger? …
Is this fiction, documentary, or “reality” tv, by the way?
-cvj
September 14th, 2005 at 8:18 pm
Clifford, you are the evil scientist of course.
(distinctions between these 3 types of TV shows are fairly minimal, you choose…)
September 15th, 2005 at 1:01 am
Ah…. so you know about my secret hideout and laboratory, etc. Hmmm.
And by the way…don’t give up on me….you will be hearing from me about the physics we discussed earlier! And I just took a raft of graduate students for coffee and gave them a long run-down of that circle of ideas, so we’ll see how it goes….
Cheers,
-cvj
September 15th, 2005 at 1:50 am
“raft” of students, my goodness…I only have a handful…
sounds good, we’ll be in touch, no hurry (this feels like a private email, but after 2-3 back and forth comemnts like we had, this thread is safely ours…)
best,
Moshe
September 15th, 2005 at 3:12 am
Great course. You’re really brave!
I have to admit that the first time I understood renormalization beyond the “uhoh, integrals diverge…let’s play some dodgy math tricks, throw in counter terms…results look ok but couplings run” stage was in fact in a condensed matter context (although in a study group with other HEP grad students). It helped a lot that for the 1D Ising model you can write down the exact block spin transformation.
And you can even do duality…nonperturbative physics…everything there…
Did you realize that there are D-branes in condensed matter physics? The Kondo effect is an example: There you have a localised spin degree of freedom and scatter electrons off it. At leading order this is dominated by s-wave scattering so there is really only one spacial coordinate, the radius. So at criticality, you have a CFT in r and t and r is restricted to r>0. So you have a boundary CFT and that has boundary states that look, smell and feel like D-branes.
September 15th, 2005 at 9:26 am
Hi Robert,
Oh yes…duality and D-branes are all very visible in this context….. All part of the agenda.
Thanks!
-cvj
September 15th, 2005 at 2:46 pm
Why not post some vblogs of your time lecturing (copy-right permissible) for this class? Of all those teaching that I can think of, who else could better introduce the core d’esprit of D-brane action?
September 16th, 2005 at 8:28 am
Ashton….thanks! No time to try to implement the vblog thing!
-cvj
September 17th, 2005 at 11:33 am
#3 :: Glist
“Our shine experts have now created the fifth dimension in shine: Glist 5!” – It’s the scientific breakthrough of the 21st century and you can put it in your dishwasher. That’s what they’re telling me in the UK. Can you h…
November 30th, 2005 at 10:38 pm
[...] Well, I got up early to prepare the final exam for that course I was telling you about a while back. It was not a take-home. Those have their place, but I also like trying to set interesting exams in the classroom, where both the examiner (me) and the examined (them) have a good time. I remember this from my days as a student. I loved interesting exams. You come in the room, the scene of possible triumph or disaster. You’ve prepared, and you’re as ready as you will ever be, and the teacher hands out the papers, and then it is you vs the examiner. Fixed time, and all you have is you, your pen, and your brain. (And your sweat.) You turn over the paper and begin…. Excellent drama! [...]
January 8th, 2007 at 5:12 pm
[...] Anyway, so I’m going to try to cover a broad (but not too broad) and interlocking set of topics for them, but not trot out too much of the standard stuff – at least not too linearly anyway. The last time I did this “staying away from the standard stuff”, (see this post) I went quite far in that aim and I don’t think it was well received, since the stringy students wanted standard stringy stuff, and could not see why I spent all that time talking about critical phenomena, scaling, phase transitions, and low dimensional field theory – the condensed matter students probably liked it a bit, but it might not have been “nuts and bolts” enough for them. (I like to think that they’ll thank me one day for giving them a broader education, but I’m sure they won’t see it this way.) So a lot of people are going to show up to try to find out what I’m going to talk about before they register. Wimps. [...]