Update: Lemaitre vs. Hubble

We've previously celebrated Father Georges-Henri Lemaitre on this very blog, for taking seriously the idea of the Big Bang. His name has come up again in the post expressing thanks for Hubble's Law -- several commenters, including John Farrell, who wrote the book and should know -- mentioned that it was actually Lemaitre, not Hubble, who first derived the law. That offered me a chance to haughtily dismiss these folks as being unable to distinguish between a theoretical prediction (Lemaitre was one of the first to understand the equations governing relativistic cosmology) and an observational discovery. But it turns out that Lemaitre did actually look at the data! Shows you how much you should listen to me. I received an email from Albert Bosma that cleared up the issue a bit. Indeed, it was not just a theoretical prediction (as I had wrongly presumed) -- Lemaitre definitely used data to ...