By Elizabeth Gibney
After spending three months trying to blow up a star, Hans-Thomas Janka and his team finally saw what they had been waiting for. Like the world’s most patient pyromaniacs, they watched their massive stellar simulation — rendered in painstaking detail — inch closer to detonation. Each day, their supercomputer ticked through just 5 milliseconds of the star’s life.
But perseverance has its rewards. In the team’s previous attempts to make a realistic simulation, the stellar fireworks always petered out. This time, in 2015, Janka watched as the shock wave needed to drive the explosion continued to grow; the mock star was going supernova1. “That was the moment we recognized that, OK, now we are at the point we longed to be at for two decades,” says Janka, a theoretical astrophysicist at the Max Planck Institute for Astrophysics in Garching, Germany. “We were on the path to clarifying the explosion mechanism of these massive stars.”
For more than half a century, physicists have suspected that the heat produced by elusive particles called neutrinos, created in the core of a star, could generate a blast that radiates more energy in a single second than the Sun will in its lifetime. But they have had trouble proving that hypothesis. The detonation process is so complex — incorporating general relativity, fluid dynamics, nuclear and other physics — that computers have struggled to mimic the mechanism in silico. And that poses a problem. “If you can’t reproduce it,” Janka says, “that means you don’t understand it.”
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