New Year, New Class: Gen Ed Relativity

The new academic year starts this week-- first day of classes is Wednesday-- and I'm dealing with the usual chaos associated with the influx of a new class of students. Who now look to me only a tiny bit older than SteelyKid and the Pip in the above picture (and if you think that sharing that extremely cute photo is part of the motivation for this post, well, you're not wrong...).

This year, the madness of the new term is complicated by having been away for essentially all of August, and by the fact that I'm teaching an entirely new class this term: Astronomy 052: Relativity, Black Holes, and Quasars. This is likely to be a little short on the quasar content, but the title was picked by the only guy who's taught this before, who is a radio astronomer studying active galactic nuclei....

I'm taking a very different approach to this, in keeping with my past musings about liberal education. I'm not using anything textbook-ish, because I figure that's likely to be deeply unappealing to the target audience of non-science majors. Instead, I'm going with more popular books: Einstein's Clocks, Poincaré's Maps by Peter Galison, Why Does E=mc2? by Cox and Forshaw (despite its flaws, the explanation of everything in terms of spacetime is excellent, and nearly unique in the accessible-to-non-majors book market), and Kip Thorne's Black Holes and Time Warps, because it's as good and detailed a popular treatment of general relativity and black holes as I could find. (Will's Was Einstein Right has a great focus on experiments, so I'll probably draw on it for lecture material, but I'm not sure it would work for this audience)(*).

I like to start most classes with a big-picture overview of the goals for the term, and when I was putting the first class's notes together, I listed these under the header of "Busting Myths." Specifically, I'd like to correct a few popular misconceptions:

1) Relativity is really difficult to understand. In fact, the central idea of the theory fits on a bumper sticker: The Laws of Physics Do Not Depend On How You're Moving. Working out all the math is really hard, granted, but the core of the theory is incredibly simple.

2) Relativity is the product of Einstein's genius. Einstein was a sharp guy, no doubt-- if anything, his contributions to quantum physics are probably underrated-- but he wasn't the only one thinking about this stuff, or getting close to the theory. In some sense, Special Relativity is probably best viewed as a particularly compelling synthesis of stuff other people had already done.

3) Relativity is arcane and abstract. In fact, the theory is intensely practical, right from the start, with its focus on what can be measured and how those things are measured. And relativity has been confirmed by any number of real-world experiments, and even has practical consequences for things like GPS.

The current plan is to spend the first couple of classes setting up the basic idea, going back to Galileo and then up through Maxwell's Equations and the Michelson-Morley experiment. Then a week or two of Galison's history, talking about Poincar&eactue;'s contributions and the practical issues of clock synchronization. I may try to figure a way to turn David Mermin's trains-of-unsynchronized-clocks thing into a class activity. Then a bit of spacetime diagram physics, leading into Cox and Forshaw, and a midterm exam at the end of special relativity. After which, the equivalence principle and general relativity, building up to talking about black holes at the end of the term. You'll note that this gets vaguer as we go on, because I only really have a solid image of the first few weeks...

(Nothing can possibly go wrong with this, right?)

Anyway, that's the general plan and approach; we'll see how well it survives contact with the 30-odd econ and history majors I have on the class roster right now. I may or may not do further reports as the term progresses; we'll see how busy I am.


* - The obvious book question: I decided against assigning my own book, because that always feels like a bit of a dick move. It also doesn't quite take the right sort of approach to fit with what I want to try in the class. I will mention it in class on the first day, but I figure if I made them all buy it, I'd be guaranteed a bunch of disgruntled comments about that at the end of the term...


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There also seems to be an impression among some laymen that relativity was a huge and unexpected departure from what went before. I had to school a commenter on Respectful Insolence who brought up that trope. I gave him the short version of what I infer is your lesson plan for the first week or two.

It will be interesting to see how this works as a gen ed subject. The econ majors shouldn't be as math-phobic as some, but you're still going to have to pull this off without calculus.

By Eric Lund (not verified) on 08 Sep 2014 #permalink

First grade. Wow. I'm having a flashback to a hotel lobby and a tiny bundle of beauty in my arms. Sigh.


I teach a class on special relativity for first-year physics majors, designed to avoid calculus. You can find all the class materials on-line at

Perhaps some of this might be useful to you. Feel free to help yourself.

By Michael Richmond (not verified) on 10 Sep 2014 #permalink