What does today’s sci-fi mean for our real-life future? Cyberpunk author Neal Stephenson argues that it’s time to get over our love of dystopia. A class at MIT searches sci-fi classics for technologies they can invent right now, although maybe they shouldn’t. Geoengineers take a tip from Carl Sagan — who saw a green future for Mars — to see if we can save Earth. And we meet some scientists who think that if we ever want to see the stars, we’d better start building the starship.