ABSTRACT
The evidence for neutrinos changing from one flavor to another flavor, initially hinted at by atmospheric neutrinos and solar neutrinos, has also dramatically increased in the 21st century. While the initial hints for neutrino oscillations came from natural sources of neutrinos such as atmospheric and solar neutrinos, increasingly precise measurements of neutrino oscillation properties are being made with manmade sources of neutrinos, namely accelerator-generated beams and nuclear reactors. Additionally, the oscillations of electron antineutrinos have been seen with reactor neutrinos. An exciting frontier in neutrino physics in the 21st century does not involve probing the properties of the neutrino itself, but rather using neutrinos to probe distant astrophysical phenomena. While much of the first 90 years of the history of neutrinos centered on probing the fundamental properties of the neutrino itself, in the 21st century we are moving toward harnessing the unique properties of the neutrinos to increase our understanding of the Universe.
