left-handed neutrino

A left-handed neutrino is a tiny, nearly massless particle that interacts very weakly with matter, allowing it to pass through most materials unnoticed. The term "left-handed" refers to the particle's intrinsic spin orientation relative to its direction of motion—its spin is aligned opposite to its movement. Neutrinos come in different types ("flavors") and are fundamental components of the universe, playing key roles in processes like nuclear reactions in stars. The designation "left-handed" is part of how physicists classify these particles based on their spin and movement, reflecting detailed properties observed in particle physics experiments.