Last week, inside a gold-plated drum in a Northern California lab, a group of scientists briefly recreated the physics that power the sun. Their late-night experiment involved firing 192 lasers into the capsule, which contained a peppercorn-sized pellet filled with hydrogen atoms. Some of those atoms, which ordinarily repel, were smushed together and fused, a process that produces energy. By standards of Earth-bound fusion reactions, it was a lot of energy. For years, scientists have done this type of experiment only to see it fall short of the energy used to cook the fuel. This time, at long last, they exceeded it.
That feat, known as ignition, is a huge win for those who study fusion. Scientists have only had to gaze up at the stars to know that such a power source is possible—that combining two hydrogen atoms to produce one helium atom entails a loss of mass, and