Neutrinos pass through the entire planet without stopping. They travel billions of light-years from colliding black holes and exploding stars without being absorbed or deflected, arriving intact and pointing straight back at their source. But catching enough of them to learn anything requires a detector the size of a city. So researchers buried antennas 150 to 200 meters beneath the South Pole and used a cubic kilometer of Antarctic ice as the detector. When a high-energy particle slams into ice, it triggers a cascade of secondary particles that radiate at radio frequencies — a phenomenon predicted by Soviet physicist Gurgen Askaryan in 1962. That's what the Askaryan Radio Array (ARA) was built to catch. In 2019, ARA recorded 13 unexplained radio signals from below the ice. Separating genuine signals from the radio noise of nearby Amundsen-Scott South Pole Station took years of new simulation tools.…