THE THEORY OF RELATIVITY 447 



whither will all this discussion of relativity lead us, and what is the chief 

 end and aim and hope of those interested in the relativity theory. The 

 answer will depend upon the point of view. To the mathematician the 

 whole theory presents a consistent mathematical structure, based on 

 certain assumed or demonstrated fundamental postulates. As a finished 

 piece of mathematical investigation, it is, and of necessity must remain, 

 of theoretical interest, even though it be finally abandoned by the 

 physicists. The theory has been particularly pleasing to the mathe- 

 matician in that it is a generalization of the Newtonian mechanics, and 

 includes this latter as a special case. Many of the important formulas of 

 the relativity mechanics, which contain the constant denoting the veloc- 

 ity of light become, on putting this velocity equal to infinity, the ordi- 

 nary formulas of the Newtonian mechanics. Generality is to the mathe- 

 matician what the philosopher's stone was to the alchemist, and just as 

 the search for the one laid the foundation of modern chemistry, so is the 

 striving after the other responsible for many of the advances in 

 mathematics. 



On the other hand, those physicists who have advocated the theory of 

 relativity see in it a further advance in the long attempt to rightly ex- 

 plain the universe. The whole history of physics, is, to use a somewhat 

 doubtful figure of speech, strewn with the wrecks of discarded theories. 

 One does not have to go back to the middle ages to find amusing reading 

 in the description of these theories, which were seriously entertained and 

 discarded only with the greatest reluctance. But all the arguments of 

 the wise, and all the sophistries of the foolish, could not prevent the 

 abandoning of a theory, if a few stubborn facts were not in agreement 

 with it. Of all the theories worked out by man's ingenuity, no one has 

 seemed more sure of immortality than the one we know as the Newtonian 

 mechanics. But the moment a single fact appears which this system 

 fails to explain, then to the physicist with a conscience this theory is 

 only a makeshift until a better one is devised. Now this better one may 

 not be the relativity mechanics — its opponents are insisting rather 

 loudly that it is not. But in any case, the entire discussion has had 

 one result pleasing alike to the friends and foes of relativity. It has 

 forced upon us a fresh study of the fundamental ideas of physical theory, 

 and will give us without doubt, a more satisfactory foundation for the 

 superstructure which grows more and more elaborate. 



It can well happen that scientists, some generations hence, will 

 read of the. relativity mechanics with the same amused tolerance which 

 marks our attitude towards, for example, Newton's theory of fits of easy 

 transmission and reflection in his theory of the propagation of light. 

 But whatever theory may be current at that future time, it will owe 

 much to the fact that in the early years of the twentieth century, this 

 same relativity theory was so insistent and plausible, that mathe- 



