The Particle Odyssey by Frank Close, Michael Marten and Christine Sutton, Oxford University Press, 拢29.95, ISBN 0198504861 Reviewed by Stephen Battersby
THE very first fundamental particle was discovered in 1897, when physicistJ. J. Thomson showed that the mysterious 鈥渃athode rays鈥� come in little pieces, now known as electrons. He used a vacuum tube, plus some electrodes and magnets.
The last fundamental particle in the Standard Model of particle physicsis a fleeting and rare entity called the tau neutrino.It was finally spotted a hundred and three years later at Fermilab in Chicago. They used a vacuum tube, plus some electrodes and magnets.
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The Fermilab machine is, though, about 20,000 times longer than Thomson鈥檚 cathode ray tube. Like other modern particle accelerators, it is highly sophisticated both in the way it boosts particles to colossal energies and in the way that it tracks the debris that flies off when they collide. How Thomson鈥檚 simple glass tube evolved into these intricate monsters, and how they have shown us the nature of matter, are the main themes of The Particle Odyssey.
The book is filled with images of particle tracks, the pictures that tell physicists about the subatomic world. It isn鈥檛 so easy for anyone else to interpret them, but often that doesn鈥檛 matter, for as the authors put it, 鈥渢hese pictures show that the subatomic world is real and accessible; they also have their own peculiar beauty鈥�. The diagrams are excellent too. One shows cosmic rays cascading over a landscape of significant mountains 鈥� a montage of those where laboratories have analysed these extraterrestrial invaders.
Just occasionally I felt a little lost among the avalanche of different particles and machines, and wasn鈥檛 immediately sure where each one fits in to the grand theoretical scheme. I would have appreciated some sketches of how quarks build up protons, neutrons and other baryons 鈥� and how they rearrange themselves in collisions to produce new particles. But the real strength of The Particle Odyssey is in describing the progress of experiments. How, for example, something as mundane as an improved photographic emulsion allowed physicists to discover a whole new world of particles in the 1940s; or how a more radical idea led to the first modern-style particle accelerator, the cyclotron.
And I鈥檝e never appreciated the sheer scale of the new machines as vividly as I do now. One detector being built for the LHC, the next giant accelerator, generates a strong magnetic field. How strong? 鈥淭he magnetic field stores 2.4 thousand million joules of energy 鈥� enough to melt 18 tonnes of gold.鈥�