This weeks Oculus keynote by John Carmack reminded me of his talk (or lecture) about physics, light and rendering. While the contents might sound heavy, his ability to explain it in an understandable way for anyone is extraordinary.
Understanding the base techniques to emulate parts of reality on computers is comparable to understanding presses and ink for print designers, in my opinion. And just fun to learn.
If you have an afternoon to spare, watch the whole thing and exponentially increase your knowledge on computers, nature and the whole universe.