Louis Anderson, a 16-year-old aspiring biotech entrepreneur, eats dinner with an anarchist, a world-renowned tongue splitter and at least 30 people who have implanted themselves with magnets or radio-frequency identification chips, a.k.a. RFID implants, for fun on a recent Friday night in Tehachapi, Calif. We’re at Grindfest, an annual meetup of biohackers, and Louis has never met a single member of the community in the flesh before, although he’s been planning the trip for two years. They have a lot to talk about. Will artificial intelligence kill us or save us? Will global warming be worse than experts predict? When...