Particles and pyrotechnics

Frank Close recommends this journey through red-shifting, the pair production of electrons and positrons, the Universe and everything.

一月 31, 2008


The big mystery about antimatter, as far as scientists are concerned, is why there isn't more of it in the Universe. The public's fascination with it is a result of its pyrotechnic ability to destroy matter, releasing energy far more efficiently than any known process, with who knows what implications. It is this that excites followers of Star Trek, Hollywood producers and all those who believe that the military are secretly preparing antimatter weapons.

The cover of this book, with a shadowy detective peering through a magnifying glass against a backdrop of the night sky, makes it look like a potboiler of the previously mentioned variety. Be warned: don't judge a book by its cover. This is a serious and well-researched exposition of particle physics and cosmology that shows how science came upon antimatter and is now trying to understand the asymmetry between matter and antimatter in the Universe.

If you know some physics already, then this book has much to offer. But if you want a popular, easy-to-read book dealing with the weirdness of antimatter, you should look elsewhere.

The fundamental particles and the forces that work on them to make the macroscopic Universe are described by the standard model. While this describes known phenomena to remarkable accuracy, there are unanswered questions that hint at a new physics "beyond the standard model", which many suspect will be revealed at experiments about to start at the Large Hadron Collider at Cern.

The dominance of matter in the Universe is one such mystery. There are examples involving arcane particles endowed with strangeness showing that matter and antimatter can be subtly asymmetric, and recent discoveries involving bottom particles have reinforced this. However, such phenomena while suggestive are not able quantitatively to resolve the mystery.

Helen Quinn and Yossi Nir tell the story of the standard model and illustrate current ideas about what might lie beyond. If you want to know where physics stands at the start of the LHC era and already have some training in physics, this is a good place to begin.

A nice feature is the occasional inclusion of personal recollections about the development of the standard model and of the scientists involved, which adds charm to the narrative both literally and metaphorically. These will be appreciated by both general readers and those with prior knowledge of the field. However, the former may sometimes find themselves struggling in the deep waters of physics, which, though interesting to scientists, are not always absolutely essential for the specific journey that the book is focused on.

If I have a criticism, it is that the authors seem at times uncertain which readership they are aiming at. Concepts such as Hamiltonian, Lagrangian, local and global gauge invariance, and phrases such as "when temperature drops below their mass" or that electromagnetic radiation "is gradually red-shifting, and thus cooling, due to the expansion of the Universe" may be meat and drink to professional physicists but not to readers who need to be told that 10^N is 1 followed by N zeroes. However, if the intervening steps that link temperature and mass or red-shifting and cooling are familiar to you, then this book will fascinate.

It also has an appendix with a timeline of physics, which is useful, but the text might need a couple of minor revisions. The solar neutrino pioneer Ray Davis died in May 2006, and the pair production of electrons and positrons is attributed to Anderson, the discoverer of the positron, whereas this is usually credited to Blackett and Occhialini.

For trained scientists who are not particle physicists, this is one of the best overviews of how the standard model has emerged, what its successes are and, more important for this tale, what its limits are. Particle physicists too will find it a useful summary of their field. It will also be essential reading for students of physics who want to know what research in theoretical particle physics is doing, with not too many strings attached.

The Mystery of the Missing Antimatter

By Helen Quinn and Yossi Nir

Princeton University Press 292pp, £17.95

ISBN 9780691133096

Published 1 January 2008

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