The uses of neutrinos: a historical perspective

Abstract

When Pauli postulated the existence of a new elementary particle, the ‘neutron’, in the late 1930s, he was introducing an entity to fill the gaps in the physics of the day. There was no direct evidence for such a particle; only the need to account for the missing energy in beta decay processes and to explain the statistics of some nuclei. Thus, Pauli's neutron was called into existence to solve problems in the areas of radioactivity and nuclear physics; but, in time, it would prove useful in many other areas of physics. The aim of this paper is to describe the many uses the neutrino has had in physics since its appearance, uses that have determined the ontological status of this elusive particle. Interestingly, the experimental detection of neutrinos 50 years ago was a minor episode in understanding the nature of such particles. As we shall argue, other moments in the biography of the particle proved more significant in determining the uses of neutrinos and their ontology.