A Physicist in Deep Waters
To the plain man the world of physics is indeed a perplexing one. A few years ago he was told he need but show a little patience; soon the laboratory door would be opened and there would be disclosed to him a working model of the ultimate pro- cesses of Nature. Alas, this promise has not been fulfilled ! A close investigation has shown that the rigid distinction between space and time, and between matter and energy, which the restricted circumstances of our terrestrial existence has taught ns to make, cannot be recognized in atomic and cosmic processes. Hence it is inherently impossible to represent the ultimate processes of Nature by means of models (or by visual images), for in them these rigid distinctions are neces- sarily embodied. The earth on which we live is so infinitesi- mally small compared with the immensity of the universe, and our senses are so much too gross to perceive its finer structure, that our conceptions of the physical world are essentially parochial. It is hardly surprising, therefore, that what lies beyond the range of our normal everyday experience should appear to us as incomprehensible as fire would appear to a mermaid, or an Income Tax assessment to a South Sea Islander.
The plain man is now told that the underlying processes of Nature do not admit of being represented by any model or image, but can only be understood in terms of mathematical conceptions of which he, as a plain man, has no knowledge. But this does not mean that he must remain completely unsatisfied and be sent empty away. Such of the conclusions of physics and astronomy as can be referred to everyday conceptions may be explained to him ; he may also be told where his conceptions cease to be applicable, and even at what point on his horizon the mathematical physicists disappeared on their journey of discovery.
England is particularly fortunate in having a number of physicists of the first rank, who are prepared from time to time to set aside their specialised studies and describe their conclusions in round terms. Prominent amongst these is Sir James Jeans, who, rather more than a year ago, delighted the civilized world with the publication of The Universe Around Us. In this book he most brilliantly explained not only the main conclusions at which astronomy and physics had arrived, but also as much of the evidence as it was possible to explain in terms of current conceptions and images. In his latest book, The Mysterious Universe, Sir James Jeans begins by summarising much that is in his earlier book, but carries us further by developing several physical problems which had not been primarily relevant to its main theme. In this the very high standard which he set himself with his earlier book is admirably maintained. But this introductory part of the book cannot be judged on its scientific merits alone, as it is written to lead up to a climax in the last chapter (" In Deep Waters "), in which the conclusions of modern mathematical physics are given a metaphysical interpretation.
Two conclusions are especially emphasized in the earlier part of the book : first, that the universe (as it appears to be running down towards a final state of thermo-dynamic ex- haustion) must have been the product of a special act of creation at a time not infinitely distant ; and second, that the underlying processes of Nature cannot be represented (or, indeed, inferred from results of experiment) except in terms of pure mathematics. On these two conclusions he bases an eschatological doctrine in which the beliefs of Moses and Pythagoras are curiously compounded, which is to the effect that the universe must have been created " from outside" by a Mathematician-Creator. The statement of this is as follows :-
" Modern scientific theory compels us to think of the Creator as working outside time and space, which arc part of his creation, just as the artist is outside his canvas . . The creation must have been an act of thought. Indeed, the finiteness of time and space almost compel us, of themselves, to picture the creation as an act of thought . . . We discover that the universe shows evidence of a designing or controlling power that has something in common with our own individual minds—not, so far as we have discovered, emotion, morality or aesthetic appreciation, but is tendency to think in a way which, for want of a better word, we describe as mathematical."
Even when it is not philosophically enlightening, it is always psychologically interesting to see a distinguished scientist plunging into metaphysical waters in search of a revelation which he may seem to discern in its depths. The conclusion with which Sir James Jeans emerges from his immersion suggests that he has but rediscovered the bone which he happened to be carrying before he took the plunge. In doing so he can claim to be in good company with Plato, to whom the world seemed intelligible only as the expression of a moral idea, and also with the duck in Alice in Wonderland, which said " I know what ' it' means when I find a thing. It is usually a frog or a worm."
As Sir James Jeans points out in the preface, " everyone may claim the right to draw his own conclusions from the facts presented by modern science." Nevertheless, it is a pity that an author who commands such authority on scientific grounds should not have recognised that philosophy is as difficult a subject as physics, and deserves to be approached with as much respect. Sir James Jeans assumes that science underwent a fundamental change when it was recognized that the underlying principles of nature could not be repre- sented by images or models, but only by mathematical concep- tions which had no counterpart in the world of every day expe- rience and imagery. But this is not so : the change was is purely domestic one, and did not touch the essential faith of the scientist in " the Uniformity of Nature." Thus Helmholtz, who clearly recognized the nature of science, meant to be taken literally when he declared that "The final aim of all Natural Science is to resolve itself into mechanics." The new Quant Mechanics, moreover, as its name rightly implies, is as mechanis- tic as the mechanics of Newton. Though it does not lend itself to illustration by means of models, its fundamental assumption is that the record of the world as obtained by measurement (of what Sir Arthur Eddington refers to as pointer readings) can be embraced in a mathematical scheme. It seems likely that all science, including biology, cannot proceed except by adopting mechanistic assumptions, but this does not alter the fact that the metaphysical validity of mechanistic principles cannot be maintained. Thus any eschatology which rests on the naive assumption that the world is completely intelligible in mechanistic terms and which ignores the possibility that concrete events may spring from a deep and unfathomable mystery, cannot be valid.
It is interesting to observe that Sir James Jeans's final conclusion in some respects resembles that of Sir Arthur Eddington, who wrote that " all through the physical world runs that unknown content, which must surely be the stuff of our consciousness." But Eddington concludes on a less speculative note by saying: "We have found a footprint on the shores of the unknown; we have devised profound • theories one after another to account for its origin. At last we have succeeded in reconstructing the creature that made the
footprint, and lo ! it is our own." JOHN Pus.r:v.
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