I've been so busy lately. See, I'm a teaching assistant, and I'm taking quantum field theory, and I'm working in the lab. And then, yeah, there's Ken.
Lab work takes away from my quantum field theory time. To really understand what I'm learning in QFT, I'd need to teach myself complex analysis (I never took it) and relativity and review a number of other subjects that I have been taught, but never properly learned.
The professor started by talking about physical descriptions of rubber bands (a continuous medium in which for instance, waves can move... You can describe it mathematically with a "field") and then suddenly was talking about particles that go back in time. The idea of quantum field theory is, in a sense, that it makes no real sense to describe a single particle. You have to describe the whole system. All your particles, and the empty space between them, because the energy is constantly being exchanged. Oh, when I say "space" -- time is a dimension, almost but not quite like the others... If that sounds confusing, well, it is.
One class seems like more work than the seven I took in high school. But I don't have the time I need to spend. And it's worse because I really do want to understand this stuff. I'm wondering how the other half dozen in the class are doing, and convinced, of course, that they're all finding it easy. At least one of them is taking two other classes as well as being a TA and research assistant. But I'm used to feeling dumb.
Being a TA takes away from the time I spend in the lab. I'm just starting to understand what's going on there, to understand the point of the things I'm being asked to do. (It turns out that the project I was working on up until now may not really happen, but the new one is more interesting, and I don't really mind.) Right now, I'm working on building a control system for a laser. Now I've never studied control engineering, never heard of an "error signal before," have only a hazy idea of how feedback works. My entire knowledge of electronics comes from ten lectures and a half dozen labs I had in Durham, and here I am building adder and subtractor and integrator circuits with op amps... I can't even remember what an op amp does. I'd really like to understand how the thing I'm building works, but I'd need to relearn my electronics, and teach myself control systems out of a book, or something. I can't seem to keep hold of the various explanations I've been given... I do know that the purpose of it is to stabilize the laser, so that the frequency doesn't change when the temperature goes up or down, or when the pressure changes in the room, or whatever. I also know that if they really needed this right now, Pati and Venketesh and George and Joe could design a circuit in a few minutes. But they want me to learn.
This is the first step in the process of building a slow-light system in a vapor cell, which is the first step toward building a new kind of optical gyroscope. (I've been trying to study optical gyroscopes. It requires a little general relativity, and a lot of interferometry that I've never had. Also, I really struggle the problem of how pulses travel in cavities.) To make slow light you need a stable laser. I am also trying to understand slow light. In our experiment, it will be a side effect of something called "electromagnetically induced transparency." I am trying to understand electromagnetically induced transparency. What I understand so far is that if you use one laser to put all of the atoms in your sample into a superposition state such that the other laser tries to distort them in two directions at once, the atoms won't be distorted by the other laser, and so won't absorb its energy. That specific frequency will be able to pass through the material unabsorbed -- the material will be transparent to that color. But apparently if I send in a pulse made of that color and a lot of nearby colors, the pulse will be transmitted only very slowly. I am not sure why this is so. I do not really understand the way that the index of refraction -- the speed of light in a medium -- depends on the states of the atoms.
Ken has been helping me with this, and with QFT. He's in the same position as I am -- teaching, taking QFT, and working in a lab -- except his teaching assignment is twice as many hours, and he has a two hour a day commute. He's not taking QFT for credit, but he's doing the homework anyway, mostly so he can help me. He wants to learn this stuff too, but if not for me he would probably be trying to do it at a more convenient time.
I don't really feel like either of us is shortchanging the students, since mostly what I do is grade and supervise, and since I've seen Ken in office hours, patiently working through problems and giving advice... His students have a great TA. But we are both resenting the students, for the time they take, and I don't like that either. I don't want to resent my students. I usually like teaching. I usually get more out of it than this.
Meanwhile I haven't been posting to AFP, or to this blog (yes, that's my excuse), nor have I been watching TV (new fall season?) nor even reading much (though Ken and I are going through Catch 22 together...) We've missed concerts and movies we've wanted to see, haven't been down to Chicago since summer. And I haven't been phoning my family lately, although they're used to that...
I kind of thought that after my qualifiers, it would be easier than this. But I guess I didn't choose an easy life.
I chose a rewarding life. I chose teaching, and learning, and building things. I choose to try to balance all of that with meaningful relationships, a personal life, my family, friends, cultural stuff. I guess I shouldn't complain. I've got all of that. I've got an embarrassment of riches. Only I don't have time to enjoy them all...