Danny Boyle loves dark dilemmas. Whether it's Shallow Grave, his first film, in which London roommates must at one point decide who will chop up a corpse, or the scene in 28 Days Later in which plague survivors must kill one of their own before he can infect the rest, Boyle's films depict thoughtful people weighing terrible choices. In his new sci-fi thriller Sunshine, the sun is dying-fizzling from within by a real physics phenomenon known as a Q-Ball (a supersymmetric atomic nucleus)-and scientists must fly a bomb into its center to reignite it. The film's main villain is the hostility of space, and Boyle's best means of frightening us, as he sees it, is science. (He brought on consultants like CERN physicist and BBC personality Brian Cox to authenticate the danger.) The crew has no chance, by the film's cold calculus, and yet what can humans do-in movies or real life-but struggle on? The director spoke with us about the fragility of Earth, arrogant science and why realism is so scary.