Relativity and the Displacement of Fraunhofer Lines

Abstract

IN view of the uncertainty in the interpretation of Einstein's equations in the matter of the displacement of solar spectrum lines, and of the hope which has been expressed that experimental spectroscopic evidence may be forthcoming which will settle the point at issue; it may be of interest to give a brief account of the present state of the problem from the experimental point of view. There are really three questions to which answers are required:—(1) Is there any means whereby the displacements of solar lines relative to those of terrestrial origin may be disentangled from such disturbing causes as pressure, varying arc conditions, density gradients, etc.? (2) If so, what do the outstanding displacements amount to? (3) To what extent are they due to gravitation and line-of-sight motion respectively?