Measurements of the Velocity of Light

Abstract

THE decrease of velocity of light deduced from the red-shifts is of the order of 1 km./sec. in 6,000 years, or 1 in 600,000,000 for thirty years, which is quite consistent with the apparent constancy of the wavelength mentioned by Lord Kitchener. Our observations, being affected by unsuspected systematic errors, and covering only a third of a century, give what is probably a greatly exaggerated rate of slowing down. The remarkable fact is that all the determinations are unanimous in indicating the existence of such a variation, and the red-shifts, if interpreted so as to escape from fantastic results, confirm it.