CHAPTER II

_A modern duel: Einstein and Eddington v. Bergson and Whitehead_

In this battle over the importance of time and process great names stand out as representatives of the two opposed views: Einstein and Bergson, with their lieutenants, Eddington and Whitehead. The two leaders use very different methods. Einstein, as mathematical physicist, suggests that physical laws can best be expressed if we assume that space and time are so similar that physics can make no absolute distinction between them. Thus in relativity theory the symmetry of space involves the symmetry of time, and therefore the reversibility of physical laws, as has been shown by Birkhoff. Bergson, as biologist and philosopher, denies that the view of time which is implicit in relativity mathematics is adequate when a wider range of experience is taken into account.

Einstein starts by excluding all but a very narrow range of physical experience, and finds that he can make successful predictions about light and gravitation by treating the irreversibility of the passage of time as of no importance for scientific measurements. Bergson, by studying a wide range of biological and subjective experience, comes to assert the existence of a creative process, though the inherent limitations of the intellect and of science may leave the essence of this process outside their reach.

Both protagonists have left their flanks exposed, by omitting to present their view as a consistent logical system, Einstein because he is concerned only with the equations that can be empirically tested, and Bergson because his chief interest is non-intellectual. It is here that their lieutenants step forward to develop the two points of view, and hence to intensify the conflict.

Eddington provides a logical basis for the theory of relativity and reveals that the significance of physical laws is not quite what we used to think. They are, he argues, identities which the human mind discovers in its search for something permanent that it can call _matter_ beneath all the changing appearances of the world. We have made matter the real thing by demanding permanence or indestructibility as the basis of physical reality. Now that we know that we have done this it need not trouble us too much to find that absolute unchanging matter doesn’t exist, since this merely means that we started out with a demand that nature cannot fulfil. Unfortunately Eddington doesn’t discuss what alternative demand we might now make in order to build up a more satisfactory system of scientific ideas. But in spite of his enthusiastic support of Einstein’s theory, with its implicit assumption of reversibility, Eddington hesitates at least once in his advocacy of reversible laws, for facts are turning up which suggest that this undiscussed presupposition may not prove valid.[3]

Meantime Whitehead has been at work on the other side, and by sharpening his logic till few can understand him has made the idea of temporal process the basis of all intellectual and scientific thought, whereas up to now process has always presented many difficult problems for the intellect. He proposes that since the conception of matter has been found to be unsatisfactory we must start from the basic idea of process in building up a new physical theory. As a consequence of his line of thought, Whitehead found it necessary to reject some of Einstein’s arguments and to show that Einstein’s law could be reached from quite different postulates. For instance, Whitehead assumed that the motion of light was irreversible, and that light did not travel with the same velocity in the two opposed directions.

So much for one aspect of the conflict, its logical and philosophical basis. But the issue must be decided by appeal to experimental confirmation over the widest range of phenomena. Orthodox physics still assumes reversibility, and has on its side the explicit statement made by Einstein in 1925,[4] but by doing so it excludes at the start any reference to organic processes. Conceptions based on this assumption could never be legitimately applied to life, and all attempts made hitherto to explain the central controlling processes of organisms in terms of classical physics have necessarily failed. We know now that this failure could have been foreseen.

The same objection cannot be made against the basic ideas of Bergson and Whitehead, nor against the new atomic physics as interpreted by Born, as we shall see in a moment. To Bergson and Whitehead, as to many others amongst whom Lloyd Morgan must be mentioned, the process of nature is creative, i.e. it involves the coming into being of the new, the appearance of new combinations essentially precluded before. This probably means that the laws of physics which are to describe what is actually happening in the world must be given irreversible form. For reversible equations make no distinction between to-day and to-morrow, and cannot express the fact that at later moments new forms may emerge, either in the evolution of organisms or of stars. On the other hand irreversible laws can be arranged so as to display time as an active factor in causation, i.e. to emphasize the fact that a certain period of time necessarily has to pass before some new combination can be attained.[5]

The upholders of a real process in nature can appeal to the facts of organic life, human memory, and to biological and stellar evolution. But their case is still weak because fundamental irreversibility has not yet received explicit mathematical formulation suitable for experimental test. When this has been done the intellectual battle will be brought to its decision, and if irreversibility wins the day biology and psychology will find themselves in possession of a physical basis well suited to the facts with which they have to deal.

There is reason to believe that the decision will be made very soon. We saw that the implicit assumption of reversibility underlies all Newtonian conceptions. It may therefore be that the reason why we cannot interpret atomic behaviour in terms of particle motions is that electrical and radiational processes are essentially irreversible. Particle motion and wave propagation--the two ideas on which all modern theories of matter are based--are both represented by mathematical expressions which are essentially reversible since time enters only through the square of ‘dt’. If the quantum processes should prove to be irreversible, we have already found a reason why the old conceptions of particles and waves must be inadequate.

This speculation may indeed be found correct, since Born, one of the leading experts in Quantum Dynamics, asserts that all quantum processes are irreversible and that the apparent reversibility of classical processes is only an approximation due to the fact that their irreversibility happens to be negligible.[4] We may therefore hope that the atomic physicists will soon formulate the quantum laws in a clearly irreversible form which admits of precise experimental test.

But this may take some years, and in the meantime we must look around and see how this issue is affecting current thought. We find the doubt about process presented by Mr Sullivan (in _Gallio_), who has not yet made up his mind to which side science will grant the victory. Thus on one page he writes: “it seems to be true that events do not really take place, we come across them” and suggests that process may be “a totally irrelevant idea when applied to reality”. But later we learn to our surprise that “it seems likely that (in scientific theory) the world will have to be regarded as an evolutionary process, where patterns of value emerge”. However, this inconsistency need not bother us, since we are told that “the teachings of science so far as the spiritual problems of man are concerned are merely irrelevant”.

These views reflect perfectly the uncertainty of the time, and will be looked back on as a precious record of the state of mind which preceded the scientific synthesis. Perhaps the most interesting feature of the essay is the indecision it displays with regard to the spiritual importance of science. This is a relic from the days when there were two worlds, the world of science and the world of religion and art. No one ever knew which of these worlds they were living in, and this is no wonder. For the division was made only because at one time it looked as though the scientific method could only deal with _quantities_, and therefore that science could have nothing to say about values or qualities. This view is no longer tenable. For instance, there is a quality in organic integration which most of us value, and without this and many other such conceptions biology and psychology could not get far.

Before proceeding any further it is necessary to correct a common misunderstanding with regard to the significance of Einstein’s theory of relativity. This theory is mathematical, and is based on a series of postulates which rule out any claim to present an ultimate theory of space and time. One of these postulates[6] asserts that all our physical knowledge can be reduced to the space-time coincidences of pairs of point-events, or in other words the intersection of the world-lines of electrons. No respect for the supreme genius who predicted two experimental results and eliminated the chief discrepancies remaining in Newtonian theory should restrain scientists from pointing out that this postulate assumes something that has never been known to occur, and has no valuable reference to the world of physical experiment. The confirmation of Einstein’s final equations cannot give any validity to this postulate. For it is difficult to think of any physical experience considered by theoretical physics which does not involve the perception of light or colour, and one cannot assume that the perception of light is a perception of coincidences. Light varies in colour and intensity; coincidence in space is too abstract to account for an effect which is subject to variation. Moreover all physical experience requires a certain amount of time, and this fact is neglected if perception is reduced to the recognition of instantaneous coincidences. Even if these two criticisms are left on one side we still have to notice that Einstein’s postulate rules out from the range of physics the important fact that many processes are irreversible. For instance, if we accept Einstein’s definition of physical experience, then the interesting fact that radioactivity is only observed in the form of disintegration, and not also as the reverse process of a spontaneous building up of heavier elements from lighter, has to be left over by physics to be dealt with by some other science.

It almost always happens that the formulations of genius are exaggerated and form the basis of a pernicious orthodoxy, and it has certainly happened to relativity theory. Against a tide of exaggerated praise Whitehead, Larmor, and Bridgman, as well as some Continental astronomers, have debated the general assumption that the theory of relativity is adequate to its task, but those in whose hands the power of orthodoxy lies have not yet answered their criticisms in print. Neglect has always been the weapon by which orthodoxy has unknowingly hindered the advance of new ideas. But while this neglect is easy to understand, it is really remarkable that the postulates of relativity theory were not subjected to closer examination before it was made the basis of wide philosophical speculation. The experimental confirmation of Einstein’s law of gravitation does not guarantee his postulates, since Whitehead has reached a similar law (identical within the accuracy of the observations) from different assumptions.

Einstein’s profound creative intuition and use of a difficult technique compel our deepest respect, but his work should never have been regarded as a _general_ theory of time and space. Not only does he neglect the question of irreversibility but it is very doubtful if periodic processes can be made to fit into his scheme, as has been pointed out by Russell and Bridgman during the last year. Probably Einstein himself has never regarded his theory as more than a stage in the attempt to create a still wider physical synthesis, and we must not interpret in a broad sense his statement that one of the demands of his theory “takes away from space and time the last remnant of physical objectivity”.[6] This could only be true if physical time shared the absolute symmetry of space, i.e. if physical processes were all reversible. But there are processes from which we can obtain an objective criterion of the direction of time, and hence time does retain an element of physical objectivity as distinct from the absolute symmetry of space. One of the most interesting features in the future of physics will be the explanation of the fact that Einstein reached a correct law from postulates of limited validity, and in this connection Whitehead’s alternative derivation may prove to be of importance.