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The year 1998 marked a breakthrough in neutrino physics when Pontecorvo's hypothesis of neutrino oscillations was experimentally confirmed. This phenomenon, predicted by Bruno Pontecorvo in the 1950s, revealed the ability of neutrinos to transform between different types, known as flavors. The discovery provided crucial evidence for the existence of neutrino masses and opened up new avenues for understanding the fundamental properties of these elusive particles.