On December 5, 2022, scientists at the National Ignition Facility in Livermore, California, fired 192 superpowered lasers at a tiny capsule. The capsule contained hydrogen (H) atoms—the smallest units of an element. In a fraction of a second, extreme heat and pressure caused pairs of hydrogen atoms to fuse together, forming the element helium (He). This reaction is called nuclear fusion. It’s the same reaction that happens inside the sun to produce heat and light. During this particular experiment, something historic happened: For the first time, scientists achieved a fusion reaction that produced more energy than they’d put in.
Some scientists believe that nuclear fusion could someday be used to generate massive amounts of energy without creating pollution. Though there’s still a long way to go in its development, this breakthrough is an important step. “It’s a huge turning point for fusion energy,” says Kelli Humbird, a physicist who worked on the project.