The speed of gravity
I gather it's been more or less proven that gravity moves at the speed of light, and not instanteously (or at an infinite speed) as has been previously suggested. This is the sort of issue that makes me wish I'd stuck with Physics and Math in college, since I find both subjects really fascinating but can't even hope to comprehend 10% of them.
This is how deluded I am: I was reading a book (for the layperson, natch) about string theory, and got so excited that I bought a little volume at my local used book store about tensor calculus. Riiiight. This is the person who dropped out of calculus in first year of college because I couldn't score more than 20% on any of the tests due to a complete inability to figure out limits. Sadly, it was one of those things where I understood the explanation and could follow along in class, but as soon as I had to do a proof on my own it was like my brain turned into molasses. Very humbling. I remember thinking, "this is what stupid people feel like."
Anyway, since I never seem to learn from the past, I thought I might try and slog through this paper online: The Speed of Gravity – What the Experiments Say.