Mikheyev-Smirnov-Wolfenstein (MSW) effect

The Mikheyev-Smirnov-Wolfenstein (MSW) effect describes how neutrinos, which are nearly massless particles, change their identity as they travel through matter, such as the Earth or the Sun. Neutrinos come in three types, or "flavors." As they interact with matter, the likelihood of a neutrino transitioning from one flavor to another varies depending on its energy and the density of the matter it passes through. This phenomenon helps explain why fewer solar neutrinos are detected on Earth than expected, providing insights into neutrino mass and the processes powering the Sun and other stars.