Science meme - first cut

Inspired by mrpjantarctica's comment on my last post, here's a first cut at a "which scientific topics do you understand?" meme. Currently, it needs a lot of work: it's heavily biased towards topics that I know about, and topic selection's a bit dodgy even within those. So, can any of you suggest some better topics, or things I've missed? I'd particularly appreciate suggestions from chemists and statisticians, because currently those sections just serve to show my ignorance of those subjects! Hopefully I'll be able to post a completed list later today, and then we can start spreading it around.

( Instructions and list )