WHATS OLD AND WHATS NEW ABOUT NEUTRINOS

To save the laws of conservation of energy, linear and angular momentu m, Pauli suggested the possible existence of an elementary particle po ssessing ito electric charge and very little mass called the neutrino, which was entitled in beta-decay of the nuclei. Subsequent work over the decades has proved the existence of this particle and has proved i rs importance not only to the physics of elementary particles but also to astrophysics and cosmology. This article is triggered by the recen t experiments which show that the neutrinos of one flavour, as they sp eed through space, periodically transmogrify onto other flavors. This discovery is comparable to the discovery of the electron in that it pr ovides the basis to new physics beyond the currently accepted Standard Model.