Abstract
THE expansion of the universe expected by theory has been strikingly confirmed by radial velocity observations of the spiral nebulae, which, we may remark, is discussed by Dr. R. O. Redman elsewhere in this issue (p. 836), but a serious difficulty immediately arises. The expansion is so fast that it cannot easily be reconciled with an evolutionary age of the universe greater than about 1010 years. Yet all other astronomical evidence requires an age of 1012 or 1013 years. The rate of expansion has been deduced theoretically by Eddington, who finds remarkable agreement with observation, at least so far as order of magnitude is concerned. If he can put his very daring calculations in a form which will command the general assent of mathematicians, they will provide a very strong confirmation of the whole theory of the expanding universe. Two other recent investigations have tried, in very different ways, to dispose altogether of the cosmical constant, the quantity which on Einstein's original theory fixed the amount of the large-scale curvature of the universe. Milne has supposed that the nebulae were formerly bunched together in a quite small region of space and endowed with motions which have produced both their present distances and their present velocities. This does not solve the age difficulty and Sir James feels also that the simplicity of this explanation has been achieved by assuming practically all that is to be explained. On the other hand, the recent work of Einstein and de Sitter suggests that really we know no reason which makes space have any inherent curvature. There seems to be a possibility that the universe is undergoing a series of expansions and contractions, in which case we have all the time we want for its evolution. This appears to Sir James to be the only possibility at present in the field which is not exceedingly difficult to reconcile with our general knowledge of astronomy.
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Expansion of the Universe. Nature 130, 839 (1932). https://doi.org/10.1038/130839b0
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DOI: https://doi.org/10.1038/130839b0