Saturday, 7 May 2016

The Cosmic Web - J. Richard Gott ****

This is a book about the large-scale structure of the universe. It’s a subject Richard Gott is particularly well qualified to talk about, having been associated with it since the 1970s. When he was still a graduate student he did pioneering work on the gravitational clumping of galaxies into galaxy clusters. Initially it was believed that this clumping tendency would repeat itself in an ever-ascending hierarchy, with stars clumping into galaxies, galaxies into clusters, clusters into superclusters and so on up to the very largest scales. In time, however, both observational and theoretical work led to a much more complex picture – the ‘cosmic web’ of the book’s title.

Topologically, the universe resembles a giant sea sponge. Unlike the hierarchical model, the high density concentrations of matter (corresponding to the body of the sponge) are not isolated clumps, but a single intricately connected structure. At the same time, the low density ‘voids’ running through it are likewise continuously connected – in contrast to the holes in a Swiss cheese, which was another early model that had to be discarded. Gott was among the first people to recognize the sponge-like structure of the universe – in part because, as a precocious high-school student back in the 1960s, he had done a science fair project on topological models of exactly that kind.

There’s no question that Gott is one of the world’s leading experts in this subject – but is he the best person to write a popular science book about it? I think the answer is a qualified ‘yes’. I really enjoyed his writing style, which is as lucid and unadorned as I’ve ever come across in an academic author. The theory never gets too difficult, either – mainly classical dynamics and statistics, with no relativistic or quantum complications. Nevertheless, Gott is not one of those writers who pretends you can have mathematics-free physics. There are no actual equations (except in the small print at the end of the book), but there are plenty of graphs, Greek letters and powers-of-ten numbers. This is not a book for people who are scared of such things.

At one point, Gott recounts an amusing anecdote he heard from the great Russian physicist Yakov Zeldovich, highlighting the benefits of using the median rather than the mean as a statistical measure. Yet he tells it to the reader exactly the way Zeldovich told it to him – without explaining how the mean and median are defined, or what they are used for. If those things are second nature to you, then you’ll appreciate the anecdote… and you’ll probably enjoy the whole book, too. If not, then you may find it heavy going.

This is the sort of book I would have loved when I was an undergraduate, or possibly even as a mind-stretching read in high school. It’s a young audience of future scientists who will probably get the most out of it today – not just for the picture it paints of how the universe is made, but for its unique inside view of four decades of cutting-edge research.

Review by Andrew May

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