This is the second in a scattered series of episodes that I'm in aggregate titling "20 Minute Lessons in 20th Century Physics." Tune in this week, and I'll give you a brief introduction to general relativity. This episode makes lots of references to special relativity (ep. 22 -- March, 2006), so make sure you've listened to that episode first if you're new to the podcast. The graphic for this week's show comes courtesy of Nick Strobel's Astronomy Notes.