Over in Twitterland, we have a question from WillyB:
If you had to pick one topic to cover in Physics, which do you think is the most important for the gen. public?
This sounds like a job for the Internet! To the polling machine!
While several of the options allow linear superpositions of solutions, this is a purely classical poll, so you may choose only one answer. Though you should, of course, feel free to bitch about the choices in the comments.