New data slash estimated neutrino mass

The most advanced neutrino weigh-in so far has put a new upper limit on the enigmatic particle’s mass, capping it at 0.45 electron volts (eV) — less than one-millionth the mass of an electron. Researchers studied 259 days’ worth of data to arrive at the new estimate, which cut the previous best measurement almost in half. Neutrinos are the only elementary particles whose mass is unknown. Measuring it could provide a crucial clue to how the particle acquires its mass in the first place.