This book is the story of neutrinos, those ghostly sub-atomic particles created in the hearts of stars as a by-product of certain types of nuclear decay processes, but which are also produced from radioactive decay in the rocks beneath your feet and which stream out in their countless trillions from violent events in the Universe such as supernovae and collisions between neutron stars.
Neutrinos, however, are so insubstantial so as to be almost not there at all. They interact very weakly with ordinary, baryonic matter, so that they could pass through a sheet of lead light-years thick as if it were not there. Billions of them pass through your body every second: mostly from the Sun, but also up from the ground, as they pass through the Earth en route through the galaxy, or start life in our planet’s radioactive rocks, and from energetic cosmic ray decay events in the atmosphere. The neutrino, in fact, is so difficult to detect that Wolfgang Pauli, the physicist whose calculations first identified that the radioactive beta decay process, as known in the early 20th century, was missing a particle (or to be more exact two) because the sums just didn’t add up, said that he had done something terrible – he had invented a particle which cannot be detected.
To understand exactly why there was a need for the neutrino, it’s first necessary to consider the physics of the late nineteenth and early twentieth century, so Frank Close gives us a brief and interesting history of the study of radioactivity, from the Curies to Rutherford. By 1932, the neutrino - Italian for “little neutron” – was firmly established in theory, despite meeting initial resistance from the scientific community (and in particular Niels Bohr). Although Pauli’s “invention” was initially a fairly vague idea, Enrico Fermi made it real by coming up with a theory for neutron production, and then Bruno Pontecorvo – not a name I was familiar with before reading this book – suggested a way in which the elusive neutrino could be detected, by looking for the faint radioactivity emitted when a neutrino strikes a chlorine atom, converting it to radioactive argon, in a vast tank of cleaning fluid. Pontecorvo’s shadow, it turned out, loomed large over the whole field of neutrino study for half a century, and his life was a poignant mix of professional triumphs and tragedies. His contributions to the field were immense, but he decided to leave America for the Soviet Union in the 1950s, and, despite winning the Stalin Prize, never had access to the laboratories and other resources furnished to American scientists, thus losing out in both recognition and experiment. Pontecorvo died in 1993, almost unknown to a younger generation of scientists in the West, but undoubtedly the giant in the field of neutrino study.
As you might have gathered, I really enjoyed this book. It’s a cracking detective story, as so many great science stories are. Frank Close explains the science in simple terms, although it is true that a familiarity with nuclear processes might come in useful when reading it. Several times I found myself skipping sections about muons and pions and the finer details of radioactive decay, for example, and as a non-scientist I was not, to be honest, able to make much sense of some of the explanatory diagrams. But this is a minor quibble, because this is a highly-recommended book. Close's writing style is clear and informative, but it may be a tad too dry for some (although it's infinitely preferable, in my opinion, to Hawking's jocular manner). This is actually quite a short book (and physically quite small too - it fits in a large pocket) which manages to tell the neutrino story in succinct chapters without verbiage.
Anyone interested in physics, astronomy, astrophysics and the history of 20th-century science should read it.
Hardback: 182 pages.
