Simon DeDeo is a theoretical physicist and very smart guy, who started out as a cosmologist and has made the transition to complexity theorist at the Santa Fe Institute. (He's not smart because he made that transition, it just so happens that both statements are true.) This summer he gave a series of three lectures at SFI's Complex Systems Summer School, on the general topics of Emergence and Complexity. These are big ideas, and obviously one cannot say everything interesting there is to say about them in three lectures, but Simon manages to cover a lot of extremely important and fascinating topics such as coarse-graining, renormalization, computation, and effective theories. Worth a listen!