they say you can never go back

Note: Last week I was traveling, bouncing from one experience to another and all the while trying to stuff them all into my head. This week I want to get at least a quick entry about each of these, before I leave town again. This is the second in a series of five very distinct settings I got to experience on this trip.


They say you can never go back. It’s a good warning to heed, especially since it’s been 20 years since I graduated from college. I’m a different person, the school’s a different place. The faculty are different people.

Most of them.

It turns out that last week I was able to go back to the same lecture room, the same course, the same professor as when I took my very first college physics course. They’ve painted and the chairs are nicer, but so much of what I know as the archetype of a physics class was completely reinforced. It was a strange combination of nostalgia and something out of the twilight zone.

My main host, though, was just starting his career as a faculty member during my junior year of a physics major. Michael quickly became an obvious choice of someone to work with, both during a summer research experience and as an advisor for my senior thesis. I went to his Thermodynamics course earlier that day. There’s lots about this that affected me, but I had a few especially poignant realizations as a result of Michael’s class.

First, the students are the same students that I attended school with. That is, they tote the same water bottles, carry essentials in the same backpacks, take notes with pencil and spiral bound notebooks, an occasional giant eraser at the ready. They ask the same questions and seemed to live the same dorm lives. For all the technical advances we’ve made in the last two decades, the nuts and bolts of the tradition remain the same. There was a dry erase board instead of a chalk board at the front of the room, and there was an image from the web that Michael had ready to show, but he never got that far. Frankly, there wasn’t that much that needed to be different, in spite of the hype that there is this new generation of students who have different demands and attention spans.

Second, and especially important to me, is the fact that I understood the presentation of that 60-minute class in a completely new and wonderful way. This was, essentially, a presentation on how we think about the states of all the particles in a room, all the directions they can be moving, and how to represent this. It’s not easy nor obvious, so you have to come up with a special convention. But to get there, you should start with the most basic, a single particle in a small box with a single dimension. And then it gets infinitely more complicated. There are ways to derive this, ways to paint the picture of how we portray n particles and what the possibilities for them might be. And Michael showed a derivation of this, and it landed upon the right relationship.

But here’s the amazing thing: What the presentation landed on, what Michael spent the 60 minutes to derive, was not the important thing. That’s what struck me.

If you exist as a physics student, you see your share of derivations like this one, and the tendency is to believe that the derivation and the result are what’s important. They are, but only to an extent. What’s more important is how you think in order to get to that place. What Michael was demonstrating, whether he knew it or not, was the perspective and state of mind of a physicist. We all do this a little differently; Michael likes to personify the particle in a box, and imagine that additional particles add to a party of particles, and we have to find a way to describe the state of this party. This is just the hook, though. It’s all the metaphor and analogy and emoting that the presenter of this derivation describes that are the important pieces. These are the glimpses into how the physics professor thinks about the physical situation and tries to find a way to model it.

It’s a little deflating to get to the end of a derivation and then have your professor tell you that he never expects you to re-create this on your own. On the other hand, it’s freeing. You don’t have to invent something from scratch. But you should have the opportunity to experience it. When I was a student I never understood why that should be. Now, a lot older (twice as old!) and a little more mature, I realize that physics professors are not passing on information, but a way of thinking and approaching problems.

Finally, the last bit of lesson I took away from my going back into a classroom of my former professors was that I should (we all should) do this more often. I didn’t sit in on Thermodynamics to remediate my understanding, although it didn’t hurt. Instead, it was enjoyable to see another presentation and personification of the topic. We very, very rarely take the opportunity to visit others’ classes, and it’s a shame. Besides feeling good about myself because I understood what was going on in an upper level physics course, I got to learn a new way of characterizing an idea.

At the end of the day, I got to give a presentation of my own work back to my old department. Much of it was on how we learn from others’ perspectives, so my day felt like a coherent story arc. However, it took me a while to realize and accept a funny thing that was happening: I was being held up as an expert in a field, rather than as a student there. It’s an odd feeling, especially as I’d spent the day learning so much.