In the 1950s, scientists discovered that some neutrinos were missing from certain nuclear reactions. This discrepancy, known as the solar neutrino problem, puzzled scientists for decades. The mystery was finally solved in the 1990s when researchers discovered that neutrinos can change, or oscillate, between three different types: electron neutrinos, muon neutrinos, and tau neutrinos. This oscillation allows neutrinos to escape detection in some experiments, explaining why the number of neutrinos observed was lower than expected. The discovery of neutrino oscillation earned the 2015 Nobel Prize in Physics and provided new insights into the fundamental properties of matter.
