# Quarks and Gluons: a Century of Particle Charges

1 April 2001

by M Y Han (Duke), World Scientific Publishing, 168pp, ISBN 981 02 3704 9 hbk $34/£21, ISBN 981 02 3745 6 pbk)$16/£10.

This is a readable little book on particle physics and is aimed at those with no previous exposure to the subject. It starts with the discovery of the electron in 1897 and works its way more or less historically up to the present. That means, of course, that it contains a lot about leptons and photons as well as the quarks and gluons of the title.

The guiding theme is the discovery of different kinds of conserved charges – first electric charge, then baryon number and the lepton numbers, and finally the more subtle kind of charges that are the source of the colour force between the quarks.

Like Stephen Hawking, the author manages to avoid all equations, except E = mc2. The style is chatty and colloquial (American), which will have some non-native English readers running for their phrase books. For example, correct predictions are “right on the money”, and when the terminology seems comical the reader is exhorted to “get a grip on yourself”. Nevertheless, as one would expect from a leading contributor to the field, Han takes care to get things right even when using simple language, as for example in his discussion of spin.

The jacket says that the book will be “both accessible to the layperson and of value to the expert”. I imagine that the latter refers to its value in helping us to communicate with non-experts.

I have some misgivings about this book, mainly because of its insistence on discussing only those charges that are (within current limits) absolutely conserved leaves the reader with the impression that nothing much is understood about the weak interaction. The author even says that the weak charges have yet to be identified. All of the beautiful developments of electroweak unification are omitted. Also, there is no mention of the exciting possibilities that lie in the near future. This makes the subject seem a bit moribund and musty. For example, we are told that the discovery of the pion in 1947 was “one of the last hurrahs” of cosmic-ray physics, whereas in fact that field continues to show astonishing vitality, with neutrino studies, ultrahigh-energy primaries and other fascinating phenomena promising a rich future.