Primordial Neutrinos

This review discusses in detail the connection between cosmological observations and neutrino physics. Neutrinos decouple from thermal contact in the early universe at a temperature of order 1 MeV, which coincides with the temperature at which light-element synthesis occurs. Observations of light-element abundances therefore provide important information about properties such as neutrino energy density and chemical potential. Precision observations of the cosmic microwave background and large-scale structure of galaxies can be used to probe neutrino masses with greater precision than current laboratory experiments. This review discusses current cosmological bounds on neutrino properties, as well as possible bounds from upcoming measurements.