order and regularity. This implies the existence of a “fundamental” reference frame, or “medium,” or “ether,” whatever we prefer to call it. The introduction of such a conception has been of great value in the study of stellar motions.
Professor H. Bateman: The Michelson-Morley experiment maybe regarded as a test of the laws of reflection by a moving mirror. For the general case in which the source of light is moving relative to the earth, the question resolves itself into two: (i) Is the image of a moving point source of light a single moving point source of light as in the classical electromagnetic theory? (2) Are the spacetime co-ordinates of a point source and its image connected by the relations ,
x' = x—- 2C (x — ut) t' — t—(x — ut) , c2 — u2 v J c2 — u2 v J ’
yr = y zf = z (u = velocity of mirror) ,
of the classical electromagnetic theory and the theory of relativity?
On the assumption that the first question is to be answered in the affirmative, various modifications of the equations connecting the space-time co-ordinates of a point source and its image might be tried on the arrangements of mirrors in the Michelson-Morley experiment. The interference fringes may in each case be regarded as the fringes produced by light coming directly from certain image sources and traveling in accordance with certain assumed laws of propagation which are also under test. The general problem is still more complicated by the contraction of the apparatus. The first question of the sharpness of the image of a point source which is moving relative to the mirror is difficult to settle experimentally on account of the lack of point sources of light moving at a high speed and at some distance from the earth. The velocity of a shooting star may be forty-five miles a second, but this is probably too small for the production of lack of sharpness in the image.
Director Adams closed the conference, thanking all the speakers for their contributions.
Carnegie Institution of Washington Mount Wilson Observatory April 1928