The label of science fiction is thrown onto a lot of things these days. Pretty much anything set in space or has the presence of an alternate dimension is considered science fiction, which isn't necessarily wrong, it's just a slight over generalization. At its core, I personally think that science fiction is all about creating well formed worlds that are complete with its own set of rules and attributes. It's about creating a world with its own internal logic, which then becomes the primary driver for telling a very specific story. And with Sunshine, Danny Boyle's created a world that fits this criteria perfectly. The high concept tale of a team of scientists/astronauts trying to save the world from a dying sun is intriguing on the surface, and what follows over the course of the next 107 minutes goes from intriguing to flat out crazy. Another point about Sunshine is that the characters are memorable and equally as well formed as the world they inhabit. It's always a tough balancing act when you're dealing with a complex storyline and multiple characters, with characterization usually getting the shorter end of the stick. I would even say that this is often a problem for science fiction movies in general. With Sunshine, this isn't really a problem at all and you really do feel a genuine sense of fear and concern for the livelihood of the Icarus crew. It doesn't hurt that the entire ethnically-diverse cast was excellent. The soundtrack is also a complete takeover when it needs to be, and haunting throughout the rest of the film. Science fiction doesn't really get better than this.