There have been so many semi-popular books about particle physics that it is a challenge to bring much new to bear on the subject. In The Quantum Quark , Andrew Watson bravely tells the story of the theory of the strong force known as quantum chromodynamics (QCD); at least that is what the jacket promises. In practice, it is more a story about modern particle physics and quarks than a definitive history of this fascinating field.
Readers who want to find out about particle physics in the sense of current experiments may find this book helpful, as it is very readable. On occasion it does enter new ground, with a first look at the confusing story of the origins of QCD. But its historical value is limited; there is no list of sources or references, and on several occasions those who have lived through this era on the inside will have to decide whether it is their memories or the author's sources that are in error.
As an example of how the book scratches the surface and has limited value as a historical source, take the origins of the 2004 Nobel Prize in Physics, which was for the discovery of a property that was an essential seed of the modern QCD theory of matter. As such it is a touchstone for this book. The prize was shared by David Gross "and his student Frank Wilczek" at Princeton University and "graduate student David Politzer" at Harvard University. As graduate students do not tend to dream up something that leads to the Nobel prize, readers may well wonder: how did this happen, and not just to one but to two students? Whereas it is clear who directed Wilczek, the stimulus and essential role at a crucial juncture of Politzer's mentor, Sidney Coleman, goes unmentioned. Other comments raise more questions than they answer: "Gross claims that he and Wilczek were the first to publish the master equation of QCD." Well, were they? Is this a verbal claim made to the author, or is it in the literature?
Two pages later we read: "Due to a minus sign in an early version of their calculation, Gross and Wilczek originally thought they had proved the exact opposite." And that is that. Where is this early version to be found? Why did they change their opinion? The fascinating story of Coleman's role is omitted. A book that is puffed as "the story of [QCD] theory" misses one of its central dramas.
Future historians of science should use the "Chronology" in The Quantum Quark with care. The entries reveal the uncertain nature of the book. The chronology includes Thomson's discovery of the electron, Millikan's measurement of its charge, and other pieces of atomic physics that, while interesting and central to a story of 20th-century physics, are far removed from QCD per se. There are several factual errors, for example the history of exotic mesons has its dates and origins confused; the history of lattice computations of glueballs suggests that the IBM-sponsored work of Don Weingarten stands alone; and the idea that the flavour dependence of spin in the neutron and proton arose with the Spin Muon Collaboration (SMC) in 1995 suggests people have short memories. In general, major advances are listed alongside trivialities, with no means of telling which are major and which are not. The final entry, "2003 pentaquark discovered", is an ironic testimony to the authority of the history. I took a poll of experts after the International Hadron Conference in 2003 and only a minority believed in the reality of this particle. Today the sceptical majority is larger still; indeed, the pentaquark fiasco might warrant its own book.
As a broad-brush survey of quark physics for those working in particle physics who want to broaden their vision, The Quantum Quark is readable with useful explanatory analogies. But Watson could have made a deeper contribution to the literature had he chosen a tighter theme. The fascinating and authoritative history of the origins of QCD remains to be written. Anyone who wants to read a profound history of the origins of QCD theory would do well to visit the Nobel Foundation website, where the background to the 2004 Nobel prize is described.
Frank Close is professor of physics, Oxford University, and co-author of The Particle Odyssey .
The Quantum Quark
Author - Andrew Watson
Publisher - Cambridge University Press
Pages - 464
Price - £19.99
ISBN - 0 521 82907 0