Scientists have been working for more than 50 years to duplicate the process by which the sun generates energy, namely fusing together hydrogen.
It's not just heat that does the trick, but extremely high pressure. One way to experiment on Earth has been to zap tiny fuel-filled capsules with lasers to make them compress, which packs the material inside tighter and tighter together.
At some point, the resulting nuclear fusion takes off like wildfire, creating a cascade of reactions and bringing the dream of power plants that produce more energy than they consume one giant leap closer to reality.
Scientists report a small but significant step this week when, for the first time, the amount of energy produced by fusing deuterium-tritium ions exceeded what was naturally stored inside the fuel.
Previously, the capsules, which start out at just 2 mm in diameter and end up less than the width of a human hair, blew apart before that state of fusion could be achieved.
"The pressures in this tiny little spot are 150 billion atmospheres. The density of the fuel that we finally achieve in these experiments is 2.5 to three times the density of the center of the sun," said physicist Omar Hurricane, with the Lawrence Livermore National Laboratory.