neutrino mass

Neutrino mass refers to the small, but finite, amount of mass that neutrinos—tiny particles produced in nuclear reactions like those in the Sun—possess. For a long time, scientists believed neutrinos had no mass, but experiments showed they do, albeit very small. This mass allows neutrinos to change their type (or flavor) as they travel, a phenomenon known as "oscillation." Understanding neutrino mass is important because it helps us learn more about the fundamental properties of matter, the universe's evolution, and why there's more matter than antimatter.