Just heard about this podcast/video about how the technology in science fiction (or futurist concepts like Dyson Spheres) might actually work. I've only listened to one episode so far, but it is pretty interesting. Not too heavy on things like math, while still trying to figure out how a society might attempt to do something without violating the laws of physics. One downside is that the guy doing it sounds a bit like Elmer Fudd. Not so bad that it's annoying, but enough that it takes a bit of time to get used to.