Out of this World: Colliding Universes, Branes, Strings, and Other Wild Ideas of Modern Physics

  • Stephen Webb
Copernicus: 2004. 308 pp. €29.95, £17.50, $27.50 0387029303 | ISBN: 0-387-02930-3

“This book is about some really wild ideas,” is how Out of This World begins, so readers cannot say they have not been warned. I lost count of the number of times that ‘wild’ was juxtaposed with ‘ideas’, although other adjectives, including ‘outrageous’, ‘phenomenal’ and ‘outlandish’ are also used to describe the “amazing recent theories” on hidden dimensions, branes and modern particle physics.

The book is about high-energy physics; if readers have enough energy of their own, they might pick up some of the sense of excitement in the current research, but they shouldn't expect suddenly to see the light. I remember seminars where the speaker attempts to review the field in the first three minutes to set the stage for the presentation; those who know the field don't need it, and those who don't aren't likely to learn much. Too often I was left with this feeling as I ploughed through this book: we are given brief glimpses of the standard model, grand unification theories and supersymmetry, superstrings and more.

Stephen Webb tries to describe the panoply of particle physics without using equations, which is a noble aim. He must have read widely to achieve this, although on occasion his sources can be rather visible; an allusion to the strength of the weak force being like Cleopatra falling off her barge in 50 BC but not yet hitting the water rang a bell, for example. The book falls short of existing books, such as Brian Greene's The Elegant Universe (W. W. Norton, 1999), which covers much of the material with greater assurance. There is too much in Webb's book that raises doubts about the reliability of the material and suggests that Out of This World is out of its depth.

Here is a sample, by no means exhaustive. The book states that a particle with “zero rest (sic) mass” always travels at the speed of light. Poorly drawn or incorrectly labelled diagrams violate electric charge, illegally convert quarks into leptons, or show the strength of the weak force, an SU(2) structure, strengthening at energies above 100GeV, whereas it actually starts to become feeble again.

There is the wild idea that “on average, two quarks in a free neutron come close enough to exchange a W boson about once every ten minutes”. If the author is equating the ten-minute half-life of the neutron with the chance that the W boson can initiate the “weak” beta decay, this is misleading. The typical lifetime of a particle resisting beta decay is of the order of nanoseconds or less: the longer lifetime of the neutron is mainly due to the fact that the combined masses of proton and electron, into which the neutron decays, are so close to that of the free neutron that there is almost no ‘phase space’ available.

To popularize using metaphor requires the author to have a deep understanding of the material. To do this over some 300 pages without using equations is a challenge of the highest order, so it is perhaps not surprising that Webb does not always succeed. Readers might have found it easier to persevere if he had shown less ambition, following the maxim that ‘less is more’. The book does provide a sense of the development of ideas, and how the frontiers of current mathematical particle physics are developing, but the descriptions are patchy and the “wild ideas” rather overstated. Without a sense of irony, the dust-jacket puff reads: “Then, in a series of increasingly astonishing chapters...”. Astonishing indeed!