Neutrinos, the only elementary particles with unknown mass, have been given a new upper limit of 0.45 electron volts (eV) by scientists. This is less than one-millionth the mass of an electron, which stands at 511,000 eV. The finding was reported in Science on April 10.
Physicist Susanne Mertens says measuring neutrino mass could provide clues about its origin and shed light on its role in the formation of galaxies. She believes that knowing their mass could reveal whether neutrinos acquire it through the Higgs boson, as other massive particles do, or through another mechanism yet to be discovered.
Source: https://www.nature.com/articles/d41586-025-01157-1