It has been said that a true work of art looks good from afar and close up. John Barrow's The Constants of Nature passes this test. His subject is grand: the cosmos and its spawning of life. But the book is liberally leavened with human interest and fascinating or simply amusing pieces of information. Moreover, Barrow has the knack of writing for the general public while including material that will be new and insightful for professional scientists.
Besides being a well-regarded researcher in cosmology and the origins of life, he takes a deep interest in the foundations of mathematics and physics. He is also clearly something of a magpie or beachcomber, constantly on the lookout for those titbits of information that enliven his books. Perhaps only Richard Dawkins and Paul Davies among British working scientists have done more to bring science to the public. And, as an apprentice magpie, let me add this: Barrow, when a teenager, won a UK junior mile championship, beating Steve Ovett.
There are three main themes in the book. The first begins with an account of the recognition and measurement of the constants of nature, such as the speed of light, Newton's gravitational constant and the quantum of action.
Then comes the story of the introduction of physically meaningful units, as opposed to anthropocentric units such as the foot and ounce, appropriate for their measurement. This was part of the majestic "march to objective truth" on which scientists, especially in the Victorian age, saw themselves as banner carriers. The ideal was to get a view of nature as she is and not as glimpsed through our distorting eyes.
Key figures were the engaging and original Irish scientist George Johnstone Stoney and Max Planck, the discoverer of the quantum of action. For this reason, Planck's system of units has become far better known, and Stoney, an uncle of Alan Turing (a sample of Barrow's beachcombing), has been nearly forgotten. Barrow shows how the Planck units lay bare a vast panorama, stretching from the microscopic to the macroscopic frontiers of knowledge and to the edge of space, time and the universe.
His second theme is life and how we humans might have clambered onto our strange stage. This is the cue for revisiting the anthropic cosmological principle, about which Barrow and Frank Tipler published an eponymous bestseller in 1986. British relativist Brandon Carter had previously formulated the "anthropic principle". His aim was to counter the claim that our universe is characterised by implausibly unlikely values of the constants of nature, as various people, notably the physicist Dirac, had suggested. Carter argued that universes with constants significantly different from ours would be inhospitable to any form of life. Only special universes can engender life. But observers must be present if any universe is to be observed, so we must not be surprised to find ours is special.
Bertrand Russell said that the key to longevity was to choose one's ancestors with care. According to Carter, observers choose their universe.
Because it smacks of gerrymandering, Carter's principle attracts flak, some well directed. But Barrow makes a strong case. It is the combinations of constants that are dimensionless, and therefore have values independent of the units of length, time and mass used to measure them, that count. Some, including key numbers in mathematics, such as pi, have values around unity.
Chemistry and life are characterised largely by the so-called fine-structure constant 1/137.0360... and the proton-electron mass ratio 1836.11... These are literally constants of life, since they permit living things to function, but they cannot be varied too much or death beckons.
Moreover, nuclear forces have to be extraordinarily fine tuned to permit the existence of carbon, vital for life. And cosmology is dominated by enigmatic multiples of the astronomically large number 10 to the power of 40. All these numbers enable the universe to host life but they seem bizarre. So there may be a role for the anthropic principle. I am left wondering what it is all about but glad Barrow has made me think.
The third main theme of The Constants of Nature is whether those constants are truly constant. Confirmation of change would drastically change physics. Several distinguished scientists have argued the likelihood of change, but hitherto all evidence has pointed to a remarkable stability. A nice twist to the story is that Barrow himself is part of a team of astronomers who may have made the very first real detection of a change in the fine-structure constant. He is working hard to make the title of his own book obsolete. That does not make it any the less worth reading.
Julian Barbour is an independent theoretical physicist and the author of The End of Time and The Discovery of Dynamics.
The Constants of Nature: From Alpha to Omega
Author - John Barrow
ISBN - 0 224 06135 6
Publisher - Cape
Price - £17.99
Pages - 352