Wednesday, March 31, 2004
Spacetime and Black Holes
This quarter I don't get to moonlight in the humanities; I actually have to teach a physics course. But it's a fun one: Spacetime and Black Holes, an introduction to general relativity for undergraduates. GR is Einstein's theory of gravity; it can be summed up in the simple statement "Gravity is the curvature of spacetime." It plays a crucial role in understanding black holes and neutron stars, the big bang and the accelerating universe, gravitational waves, and every attempt to quantize gravity.
Teaching GR to undergraduates is still unusual; at many places it isn't even a core graduate course. (Of course, these days they're teaching undergraduates string theory.) For a long time GR was somewhat outside the main action of physics, since our experiments didn't probe into regimes where it was important. That's certainly changed in recent years. GR also has something of a reputation for being difficult, which is quite untrue; it's intrinsically very straightforward, but the relevant mathematics (tensor analysis, differential geometry) is just so different than that used in other areas of physics that it seems like a big investment to learn.
This quarter I'll be using Jim Hartle's new book, which is a fantastically useful text. He approaches the subject with a physics-first attitude that allows the student to get to the fun parts without spending months learning formalism. (If they want to do that, they should take the graduate course and buy my book.) We just state without demonstration what the spacetime around a star or black hole looks like, and then dive right in to understanding its features. I've never actually taught it this way before, so it's something of an experiment. The worry is that the students will fear that they're getting a watered-down version of the true story, which really isn't the case. By the end they'll get the whole shootin' match. If I would just quit blogging and write my lecture, anyway.