WHAT IS A NEUTRINO?
Neutrinos are among the most abundant—as well as the most elusive—elementary particles in the universe. These ultralight subatomic particles are the basis for all matter. Also known as ghost particles, they have no charge and pass through matter easily. They’re also so tiny that no one could be certain they even had mass until Takaaki Kajita and Arthur B. Mcdonald proved it around the turn of the century. But it took until 2019 for a group of international researchers in Karlsruhe, Germany—using the sophisticated KATRIN detector— to thoroughly examine neutrinos and thereby establish their mass.