What exactly did he discover?

John Ziman

  • ‘Subtle is the Lord’: The Science and Life of Albert Einstein by Abraham Pais
    Oxford, 552 pp, £15.00, October 1982, ISBN 0 19 853907 X
  • The Cosmic Code: Quantum Physics as the Language of Nature by Heinz Pagels
    Joseph, 370 pp, £10.95, March 1983, ISBN 0 7181 2217 8
  • Philosophy and the New Physics by Jonathan Powers
    Methuen, 203 pp, £3.95, December 1982, ISBN 0 416 73480 4
  • Albert Einstein: The Centennial Symposium in Jerusalem edited by Gerald Holton and Yehuda Elkana
    Princeton, 439 pp, £24.70, August 1982, ISBN 0 06 908299 5

It is less than three decades since Albert Einstein died, yet many different personae have been supposed behind the familiar mild exterior. Nobody would impute any lack of psychic integrity in the man himself. True enough, he was a peculiarly self-contained person whose inner life was always opaque, even to his most intimate companions. But there was no harsh discontinuity or irreconcilable inconsistency in his temperament, and we have no reason to suppose that he was nervously guarding some guilty secret like Newton’s heretical Unitarianism. His private and public activities are amply documented, and are seldom inexplicable to an intelligent and imaginative observer. Yet even in his scientific work, Einstein can be represented as playing several different roles, in several quite different dramas.

Abraham Pais is a distinguished theoretical physicist who knew Einstein well in his later years at Princeton. The personal and political aspects of his life are dealt with at length in a sympathetic spirit, but this is an intellectual biography, and will long hold its place as the authoritative account of his scientific achievements. It is extraordinarily well done. For anyone who can read the standard language of physics, this is a fascinating book. Here are the famous formulae that we have had to learn or to teach, here are the subtle concepts and profound arguments that we have all had to master, seen in their moments of discovery, when all is glory. It is all familiar, and yet it is a pleasure to be told it all again.

Consider him, first, in the role of iconoclast, or revolutionary. The theory of relativity upset everybody’s settled notions of the uniqueness and universality of space and time. Not, of course, that people took an entirely conservative attitude towards their everyday co-ordinates. Even in 1905, the passengers on a steamship to Australia did not try to carry with them, all the way from Britain, the exact moment of twelve noon, or the direction of Nor’Nor’East. In the end, that would have meant lunching at midnight, standing on their heads. Life on a rotating planet is more conveniently ordered according to local space-time conventions, which vary systematically from place to place. But the ship’s navigator had his chronometer set to Greenwich time, and knew how to orient the ship in relation to the celestial sphere of the fixed stars. For what had always seemed convincing philosophical reasons, these were considered unambiguous, absolute co-ordinates. Any event, anywhere in the universe, could in principle be located at a particular point, at a particular moment, in this complete, unique framework.

It was very shocking, then, to have young Einstein point out that this was not a very convenient scheme for talking physics when one is dealing with objects that are travelling at very high speeds. Even as a schoolboy he had tried to imagine what an electromagnetic wave – that is, a beam of light – would seem like if one tried to catch up with it and observe it as if it were nearly at rest. This almost unthinkable conception was somehow unphysical: the observer on the high-speed space-ship would be seeing something that was not permitted by the laws of physics. The only way to make scientific sense of such a situation was to conjecture that the observer would automatically carry around with him his own personal framework of space and time, in which the light would still appear to be travelling at its usual enormous speed. Every scientist, on every moving space-ship or planet, would naturally prefer to plot the events of the universe on a slightly different map, according to a slightly different calendar. Every world-view was thus, in some degree, relative to the situation of the viewer.

At first this sounds reasonable enough; the perspective from Sydney is not by any means the same as it is from London. But when Einstein insisted that clocks on fast-moving vehicles would appear to be running fast or slow, depending on the point of view, this was clearly prejudicial to good scientific order and discipline. In fact, he was lucky in his radicalism. Other theoretical physicists, older and better-established, had been having similar dangerous thoughts. Einstein brought this revolution to a head, but he did not make it quite alone. Nor was it quite as anarchical as many people seem to think. Different observers certainly prefer to use different maps and clocks, but these are not arbitrary or idiosyncratic. They are all related to one another by strict mathematical formulae, just as a map on Mercator’s projection is precisely related to a map of the same region on a stereographic projection. All that Einstein was saying was that there is no special, no unique point of view, corresponding, say, to a point at rest in the ether. Strange physical phenomena might be observed on bodies moving nearly at the speed of light, but most of the ordinary laws of physics remain unchanged. As in all the best revolutions, the classical achievements of the past were preserved and enhanced.

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