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Alan H. Guth


The quest for a new theory of cosmic origins

Book review by Anthony Campbell. Copyright © Anthony Campbell (2001).

Alan Guth is famous as the chief originator of the inflation theory of the beginning of the universe. According to this, the universe underwent an almost inconceivably rapid expansion within a minute fraction of a second after its presumed beginning in the Big Bang. The theory resolves a number of difficulties in the earlier account. Probably most readers of popular science books and articles will be familiar with the concept of inflation in a general way, but they will neverthless find this book well worth reading. Guth is of course ideally qualified to write an insider's account of how the idea arose and developed, and an additional bonus is that he writes well. He sets the story in its human context, with pen portraits (and some photographs) of the dramatis personae, and he also presents an intellectually demanding, but very rewarding, explanation of the physics itself.

A difficulty that any popularizer of physics faces is the choice whether to include mathematics. As publishers know, if equations appear in a book its sales plummet, so authors are generally asked to avoid them. Guth has done this, but he nevertheless does not shrink from describing difficult ideas. This is particularly true of chapters 8 and 9, which deal with the concepts of a GUT (grand unified theory) and magnetic monopoles. However, the explanations are presented in an attractive manner, with good diagrams, and there is also a valuable glossary as well as a number of appendices in which related ideas such as black body radiation and gravitational energy are outlined. Anyone who does wish to go into the mathematics can follow up the references in the extensive notes. This is first-class science writing, in which the difficult ideas are not shirked but are made comprehensible for non-mathematical readers who are prepared to concentrate. This is not light reading, but the rewards are considerable.

One of the most startling implications of the inflation scenario is that the observable universe which we can see with our instruments must be only a tiny part of the universe that actually exists. Moreover, there are theoretical reasons for thinking that there may be offshoots from our own universe, which Guth calls pocket universes. These would bud off from one another endlessly, to produce an infinite number of universes, each of which originates in a Big Bang in the same way as our own. Although Guth doesn't mention it, I was reminded here of the Mandelbrot series. What is perhaps rather disappointing philosophically is that this process probably does not extend indefinitely into the past, so even if our universe is not the first in the series, a first universe there must have been. Although the debate is still not closed, it seems unlikely that the inflationary universe is eternal.

Until about twenty years ago speculation about the origin of the universe seemed destined to remain just that—speculation, barely distinguishable from mythology. Probably every human culture that has existed has had its stories about how the universe came to be. These are the various creation myths. Some critics of science claim that modern cosmology is simply another creation myth, one adapted to our own time. There is, however, a vital difference. Although we cannot observe directly what happened at moments close to the origin of the universe, theories such as inflation make testable predictions about the universe we see today, and modern cosmology is therefore science, not mythology. Inflation, Guth claims, although still not accepted fact, is well on its way to becoming so. And, looking beyond inflation itself, he hints at even more tantalizing vistas of possibility: the existence of something rather than nothing may come to be seen as the inevitable consequence of the laws of physics. As Guth remarks, that will leave us with one deep question: what determines the laws of physics?

%T The Inflationary Universe
%S The quest for a new theory of cosmic origins
%A Alan H. Guth
%I Vintage
%C London
%D 1998
%G ISBN 0-09-995950-X
%P xv + 358 pp
%K science, physics, cosmology
%O paperback, illustrated

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