Explore the fascinating world of neutrinos and their cosmic influence in this 48-minute conference talk by George Fuller from UCSD. Delve into the Nobel Prize-winning discovery of neutrino masses and flavor mixing, and understand how these elusive particles are key to particle physics, nuclear physics, and astrophysics. Learn about the weak nuclear force, electron neutrinos, and weak interactions as you journey through topics like stellar evolution, supernova explosions, and the early universe. Discover how neutrinos interact with gravitation to shape the cosmos, from the formation of stars to the expansion of the universe. Gain insights into the cosmic microwave background radiation, the size of the universe, and the role of neutrinos in the primordial soup. This talk, part of the Neutrinos and New Physics Teachers' Conference at KITP, offers a comprehensive exploration of cutting-edge neutrino research and its implications for our understanding of the universe.