ABSTRACT
Neutrino properties can be deduced from cosmology as they affect, for example, the cosmic microwave background and large scale structures of the Universe as well as Big Bang nucleosynthesis. Neutrinos from neutralino–antineutralino annihilation in the Earth are being sought by looking for vertical upward-going muons. Weakly interacting particles, such as light neutrinos, can escape without interaction from areas of high density to areas of low density, which can erase small scale perturbations entirely. Analogous to the photon background, a cosmic neutrino background should also exist. The very small cross-section of relic neutrinos has so far thwarted, but an experimental attempt in the form of the PTOLEMY project is ongoing. The chapter provides information on very important support of the Big Bang model, namely the synthesis of the light elements in the early universe.
