Physicists get closer than ever to measuring the elusive neutrino

Ghost-like particles called neutrinos hardly ever interact with normal matter, giving the teensy apparitions supreme hiding powers. They are so elusive that, in the decades since their initial discovery, physicists still haven’t pinned down their mass. But recently, by plopping them onto a 200-ton “neutrino scale,” scientists have put a new limit on the neutrino’s mass.

The result: It’s very, very small.