Low on flavour, big on impact

One of the triumphs of astronomy in the 20th century was that the Big Bang theory became established as the explanation of the origin of the universe. Edwin Hubble discovered the receding galaxies; Martin Ryle realised that the more distant galaxies of the past were more densely packed than those nearby and of the present. These observations proved the expansion of the universe. George Lemaitre used Albert Einstein's theory of general relativity to relate the expansion and distance in the universe to the force of gravity in it. Arno Penzias and Robert Wilson discovered the cosmic microwave background, predicted by George Gamow decades beforehand as the remnant of the Big Bang fireball.

As the century closed, the Cosmic Background Explorer (Cobe) satellite detected the irregularities of the cosmic microwave background, the beginnings of the formation of the structures - galaxies, stars - that eventually produced you and me.

All these amazing discoveries were acclaimed, including by the award of Nobel prizes. They added up to a surprisingly uniform consensus among cosmologists about the model of the Big Bang, even though it was being tested quantitatively at what might loosely be called the 10 per cent level.

As the millennium turned, however, and the observations were pressed to the 1 per cent level, the standard model started to produce startling ideas.

Cobe's successor, the WMAP satellite, measured the fluctuations of the cosmic microwave background more accurately. The Hubble space telescope, in conjunction with the largest ground-based telescopes, probed the expansion of the universe at ever greater distances, looking ever further back in time. Together these observations, interpreted by the Big Bang model, indicated that 95 per cent of the matter of the universe was of an unknown and invisible kind. Additionally, the space of the universe was a source of previously unsuspected energy that, released into its expansion, is causing it to accelerate. In the face of these almost incredible outcomes, cosmologists are asking whether the Big Bang theory has been pressed beyond its limits. Alternatively, the same cosmologists are buckling down to pursue these ideas and hunt down the new science that they hold in prospect.

Pedro Ferreira is a young cosmologist at Oxford University, and he has written this critical view of how the story fits together - he calls his book a "primer of cosmology". It is a brave book of popular science, uncompromisingly scientific in its approach. Here are no funny stories of eccentric scientists, and the only cute historical picture is on the dust jacket. There are no beautiful, coloured pictures of galaxies and nebulae - there are, however, illustrations by Jem Finer, the artist-in-residence at Oxford's astrophysics department. They are scientist's line diagrams, of the kind sketched on envelopes and paper napkins but executed with confidence. The text, too, is science-speak - the ideas are the most important elements, not the way the ideas are expressed. In fact, the style is not particularly elegant, with few eye-catching figures of speech. There are, however, no equations - well, there is one, but it is spelt out into a sentence so it does not look like one.

So, the book is plain-vanilla popular science, faithful to scientific culture, except for the maths. Those who would like scientists to adopt a non-scientific culture to communicate will not want to read this book. If Ferreira had done so, the book would not be as clear as it is. If you want to be entertained by stories and literature, this is not the book for you.

If you want to know about modern cosmology, it is a good book to read.

Paul Murdin is a senior fellow at the Institute of Astronomy, Cambridge University.