A massive underground detector aimed at understanding the mysterious ghost particles in our universe has released its first major findings. The Jiangmen Underground Neutrino Observatory in China has made some of the most precise measurements to date of how neutrinos switch between three varieties, or flavors, as they zip through space. Scientists are hoping the detector will help resolve a longstanding mystery: how heavy each neutrino flavor is. The initial results haven’t answered that question just yet, but they show what the detector is capable of. Results were published Wednesday in the journal Nature.