STANDS SCIENCE WHEBE SHE DID? THOMAS 247 



the only difficulty beiiio; that it presupposes the nebulae have had 

 their great velocities from all time, whereas most of us like to think 

 of all the stars being formed out of one primeval mass. But 

 Professor Milne has elaborated his theory to a form in which very 

 strange things happen. In his universe all observers in uniform rela- 

 tive motion observe identical world pictures. The observable volume 

 of the universe is finite, but the system has no age and no radius — 

 onl}' an age and a radius when a particular observer is specified at a 

 particular stage of his experiences. What we call " creation " in the 

 past history of any one observer reappears on the confines of the 

 observable system, where, however, the particles become invisible 

 owing to recession with the speed of light. It is all passing strange. 

 Such in broad outline are some of the problems the physicists of 

 today are trying to solve. They will be solved only by the closest 

 cooperation of experimenter and mathematician, theoretician, and 

 empiricist. The way in which fact and theory are intertw'ined was 

 well shown by a paper reatl by Prof. Dayton Miller. Given on the 

 last day, and unentered on the original program, it has not secured 

 the attention it deserves. As is well known, the theory of relativity 

 is based ultimately on the Michelson-Morley experiment of 1887. 

 Professor Miller showed that even Michelson and Morley did not get 

 the completely null result assumed by the theory of relativity, while 

 he and Morley have repeated the experiment since and have always 

 obtained a positive effect, which appears to vary with the time of 

 day. Unless some explanation is forthcoming, the theory of rela- 

 tivity will need considerable modification in the light of these experi- 

 ments. At Leicester, Lord Rutherford suggested that the facts are 

 all-important, and theory must be kept in its place. Sir Arthur 

 Eddington seemed to suggest that if the facts do not agree with the 

 theory, tant pis pour les faits. Lord Rutherford is not so obviously 

 right as appears at a first glance, for facts are generally discovered 

 only under the guidance of some theory. But we may rest assured 

 that if the difficult but entrancing problems of modern physics are 

 to be solved, it will be by the perfect union of fact and theory, and 

 that alone. 



