Universe and Electron
Fundamental Theory. By Sir Arthur Eddington. (Cambridge University Press. 25s.)
SIR ARTHUR EDDINGTON devoted the later years of his life mainly to the development of a theory by which he sought to achieve 2 harmonisation of the two great, and hitherto almost unrelated, de- partments of physical thought—relativity theory and quantum theory. Put briefly, the former may be described as the physics of matter on the large scale, including the largest system of all, the universe, and the latter as the physics of the most elementary par- ticles—protons, electrons and the like—of which the physical world is thought to be composed. The general character of Eddington's theory is only to be understood from the modern point of view, according to which theoretical physics is less a discovery of objectively existing laws of nature than the imaginative creation of concepts in terms of which the observed relations between different phenomena can be expressed in logical form. This point of view is now fairly general, but the distinctive feature of Eddington's outlook is that, whereas to most physicists the concepts of relativity theory are quite distinctfrom those of quantum theory, he saw them as the same concepts in a different form.
To take a single example, astronomers have observed that the Light from distant galaxies differs in a certain systematic way from light in our own galaxy, and they express this in terms of the concept of an "expanding universe." Physicists have observed that elec- trified bodies exert forces on one another, and they express this in terms of concepts of mutually attracting protons and electrons. Eddington held that the concept of an expanding universe was simply a disguised form of the concept of attracting particles, and claimed to have deduced the conception of "rate of recession" of the galaxies mathematically from the conception of "force of attraction" between proton and electron. This means that even if we could never see anything outside the earth, we could deduce the large-scale behaviour of the universe from observations of vacuum tubes. He went even further and claimed that a perfect reasoner, made acquainted with the methods of investigation of the physicist, would not need even the vacuum tubes ; he could deduce the fundamental laws of physics without any observation at all, because those laws expressed con- ditions inherent in the nature of measurement itself, quite apart from the characteristics of the objective system—atom or universe— which was measured.
Eddington did not succeed in making his views generally accepted, partly because, in spite of his great gifts of exposition, others found it too difficult to follow the very individual process of his reasoning, and also partly because the ultimate inevitability of the course of events in the objective world, which seemed to be entailed by his theory, seemed inconsistent with our power to imagine a violation of the laws already derived. This point was the theme of a dis- cussion in Nature a few years ago, initiated by the late Sir James Jeans, which left both parties very much where they were. It was doubtless the hope of being able to present' his views with such a wealth of corroborative evidence as to compel assent that led him to write the book which is now published. The MS was found among his papers after his death and placed in the ablest hands available—those of Sir Edmund Whittaker,—to edit. It was not quite complete ; a note, probably written on the last day of Edding- ton's working life, was appended, giving the intended contents of three further chapters, which would have included the general summing-up of the whole theory. Nevertheless, the volume as it stands carries the subject considerably further than any previous writings, and, whatever the ultimate verdict may be, the evidence that Eddington was on the track of something profoundly important and original is now undeniable.
That is not to say that this account of what he had found is necessarily to be accepted. His deduction of the constants of nature may be perfectly sound, and yet depend ultimately on knowledge obtainable only from experience. That will not be known until the theory is 'made intelligible to the minds of the ordinary theoretical physicists, and it is doubtful if even the present book will make it so. But that he had achieved something which will eventually give us a deeper understanding of the nature of things than has yet been possible it is now difficult to deny. Sir Edmund Whittaker is con- vinced of so much, and the correspondences between the calculated and observed values of physical constants are so numerous and so exact that the conclusion seems unavoidable. One feels anew the loss which the world of science has sustained from the too early
death of this abnormally gifted seer. HERBERT DINGLE.
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