The Nine Numbers of the Cosmos by Michael Rowan-Robinson, Oxford University Press, ISBN 0198504446, 拢16.99/$32.50
IN THE beginning was the big bang. Our Universe began at a finite time in the past in a state of unimaginably high density and temperature. And it鈥檚 been expanding and cooling ever since. Cosmologists try to work out what鈥檚 happening in the evolving Universe from this model. But it鈥檚 incomplete. Because we don鈥檛 understand the big bang itself, we can鈥檛 predict many important parameters of the Universe鈥攕uch as its age and density. Instead, we have to rely on observation.
For decades, astronomers have been trying to measure these unknown quantities to find the missing pieces of the cosmic jigsaw. In the past few years dramatic progress has been made, thanks to technological developments like the Hubble Space Telescope. Cosmologists now feel that the answers to many important questions are within reach.
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The Nine Numbers of the Cosmos is a survey of modern cosmology with the missing numbers as its theme. They are: the density of 鈥渙rdinary鈥� or baryonic matter; the Universe鈥檚 anisotropy or lumpiness; the Hubble constant or rate of expansion of the Universe; its age; temperature of the microwave background; the density of non-baryonic cold dark matter; the tilt, the string tension or density of hot dark matter鈥攖hree numbers, two of which are probably zero, that might fix the failures of the cold dark matter model; the cosmological constant; and the Universe鈥檚 star formation history.
It鈥檚 a successful device that focuses attention on a series of well-defined issues. But there are many more than nine numbers to chose from, and I am not convinced that Rowan-Robinson has picked wisely. 鈥淭he Universe鈥檚 star formation history鈥� is not a number at all.
Crucially, none of Rowan-Robinson鈥檚 nine numbers relates to the fact that there must always have been more matter than antimatter in our Universe. If it weren鈥檛 so, we wouldn鈥檛 be here. Matter and antimatter would have annihilated each other, leaving only radiation. What caused this asymmetry is still unknown, but it was vital for our existence.
A few weeks ago Lawrence Krauss reviewed Just Six Numbers (快猫短视频, 4 December 1999, p 48). In that book Martin Rees paints a picture of the Universe in a similar numerological vein to Rowan-Robinson. The two authors do cover some similar ground, but these books are actually quite different in style and scope. Rowan-Robinson has produced a more comprehensive survey of the subject, at the price of a less coherent overall structure. Both convey very well the sense of excitement felt by cosmologists as a complete picture of the cosmos begins to take shape.