Scientists in China have almost finished building a massive underground detector to sniff out mysterious particles called neutrinos. Neutrinos are tiny, cosmic particles with a mind-bogglingly small mass, but they’re found all around us. Researchers want to study them to get a clearer understanding of how the universe came to be. The Jiangmen Underground Neutrino Observatory will go online next year and will study the neutrinos produced from collisions inside two nuclear power plants. Similar detectors are being built in Japan and the United States. They’re set to start data collection in 2027 and 2031.