Ignition is close now. Within a year or two the 192 laser beams at the National Ignition Facility (NIF)—the world’s largest and most powerful laser system, a 13-year, $4-billion enterprise—will focus their energy onto a pellet no bigger than a peppercorn. Energy from the laser beams will crush the pellet’s core with such force that the hydrogen isotopes inside will fuse together and release energy, an H-bomb in miniature.