Page:Popular Science Monthly Volume 77.djvu/111



IN a recent letter to the New York Nation, Professor William James, in describing the philosophy of M. Emile Boutroux, makes the statement that "theories result from psychological variations, just as Roosevelts and Rockefellers result from biological variations." Of the entities of science he says:

Considering the prevalence of such philosophical views, and the fact that many persons believe that physics is now undergoing a sort of crisis, in which many of our most cherished ideas are about to be relegated to the scrap-heap, I believe it to be not without profit to consider the past and present condition of our views with regard to the luminiferous ether, and to cautiously forecast their future.

Certainly the postulate of the existence of the ether has been until very recently one of the fundamentals of physics (including astronomy). At the congresses of arts and sciences held at Si Louis in 1904, the subject of physics was, like all Gaul, divided into three parts, physics of matter, physics of ether, physics of the electron, and although this division was, I believe, not made by a physicist, this must have made little difference. In an interesting book published less than a year ago by Sir Oliver Lodge, entitled "The Ether of Space," the properties of the ether are set forth with a concreteness and dogmatic manner that is now becoming unfashionable, and relieves that writer