The Neutrino

Ghost Particle of the Atom

In his usual thorough, graceful, magisterial manner Isaac Asimov describes the discovery of the Neutrino, a particle which, invented to make the bookkeeping come out, delightfully deigned to exist.

The first half of this short book describes the nature of the scientific endeavor: careful observation, inference and generalization of principles, which guide further observation and theorizing. These generalizations, labeled Laws of Nature, are so useful that when new observations seem to violate a well-established law, every effort is made to adjust and preserve it by coming up with explanations for the new phenomena that are in accord with the established principles. Only occasionally must these laws be scrapped entire. And sometimes they guide theoreticians to new science.

So with the Neutrino, a particle so small and standoffish that it is very difficult to observe: huge numbers of them stream from the Sun and pass through the Earth without interaction with any other forms of matter, as though the Earth were not there at all. But certain neucleonic interactions could not be properly accounted for; a small amount of energy and linear and angular momenta always seemed to go missing: the theory requires these properties be conversed, but small amounts could not be measured. To preserve the conservation laws, the Neutrino was postulated - massless and without charge, but bearing the missing kinetic energy and momenta.

And having been predicted, it was in time observed.

The book was published in 1966 so the catalogue of physical facts is no longer complete and correct: there is a family of neutrinos and they are not quite massless and their interactions are complex and fascinating. But these are incidental matters to the lay reader, who may come away from this book with an appeciation for the nature of scientific work, the interplay of observation, intuition, deduction, imagination and aesthetic sensibility by which the working of nature may be increasingly deeply understood.