4 i6 SCIENCE PROGRESS 



stars which, by astronomical measurement, are found to be 

 nearer, should ultimately be discovered to be farther. On such 

 a question it is possible to admit evidence. 1 A non-Euclidean 

 aether is as metaphysically possible as a centaur or a hippogriff. 

 A non-Euclidean space is as contradictory as a round square. 

 Our material lines may bend ; our rays of light may bend ; but 

 our straight lines are not straight unless they are straight. It 

 may be that we always see crooked, but that is no reason why 

 we should not think straight. The writer would urge not only 

 that we go back with or remain with Newton, but that we go 

 back to or remain with Euclid. Non-Euclidean geometry, non- 

 Newtonian mechanics, and the Principle of Relativity are admir- 

 able examples of the coherence of thought whatever may be the 

 material supplied to it as foundation, but they must not be mis- 

 taken for reality. 



Some physicists would try to inform us that there is no 

 velocity greater than that of light. It may be that it is so. It 

 may be that the aether of space, which, in spite of the re- 

 lativists, we must emphatically assert is an assumption almost 

 essential to the explanation of the world as we see and know it, 

 imposes an impenetrable barrier upon more rapid motion. Even 

 here, however, there is no sufficient evidence. But the physicist 

 who says that there is anything in velocity that prevents a 

 greater speed than that of light is talking absurdly. Velocity 

 and limit are contradictory concepts. It is a round square and a 

 crooked straight line over again. Nor should it be admitted too 

 hastily that no actual velocity can exceed that of light. Even 

 here the physicist is extrapolating unduly. All experiments on 

 high velocities necessarily have reference to minute electrified 

 particles, and it may be that electrified and non-electrified bodies 

 differ in properties such as these. Moreover, once again, all he 

 can say is that his equations apply only to velocities smaller 

 than that of light. Once again, as so often before in the realm 

 of practical science, we are bound to demur that it is not allow- 

 able to extrapolate an empirical rule one iota beyond the point 

 where it is experimentally proved. Prof. Dewar discovered the 

 importance of this principle when he wrongly estimated the 

 temperature of liquid hydrogen. And the rationale of relativism 



1 It is as well to be explicit and say that I have never heard it suggested that 

 there is any evidence of the kind. The matter here briefly touched I have treated 

 more fully in two articles in Mind, No. 73 and No. 88. 



