Abstract
A CENTRAL NEWS message from New York states that a well defined periodic variation in the speed of light has been registered in the experiments now being carried out at Mount Wilson which were begun by Michelson. The message refers to a passage in the annual report of the director of the Mount Wilson Observatory, which was received in Great Britain some time ago. As is well known, Michelson found that atmospheric irregularities, the astronomer's ‘bad seeing’, interfered with his attempts to determine the velocity of light using long bases, from Mount Wilson to neighbouring peaks. He was led to the heroic task of constructing a vacuum base a mile long, and a tunnel of thirty-six inch diameter and a mile long was constructed. It is so well made that a vacuum of two or three millimetres of mercury can be maintained in it. The last report stated that it was hoped to conclude the work in August, so that we may hope for full details before very long. The periodic term that the report mentions is presumably of a purely instrumental character. Our readers will remember that it has sometimes been urged that the precise observations of the velocity of light which have been made from time to time do show a definite secular change of the velocity (see, for example, Ghenry de Bray, NATURE, 120, 602, Oct. 22, 1927, and 127, 522, April 4, 1931), but the view has so far found little support from men of science generally.
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Determinations of the Speed of Light. Nature 132, 307 (1933). https://doi.org/10.1038/132307a0
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DOI: https://doi.org/10.1038/132307a0