Abstract

The neutrino is one of nature's most peculiar particles. It has 1/2 unit of spin but no electric charge, a near-zero rest-mass, and it interacts with other particles only through gravity and the weak interaction. It can pass through light years of lead without an interaction. There is good experimental evidence that the Earth receives only about 1/3 of the neutrinos that the Sun should be producing and sending in our direction.