19::0] TiiE Theop.y of Relativity 37 



mathematically speaking, as well as the future. This seems absurd, 

 and corresponds to nothing real in our experience, so far as we 

 know, but these equations we are discussing have proved true in so 

 many ways that we eagerly anticipate their further interpretation. 

 New tests for straightness of lines, for simultaneity of events, 

 etc., have been adopted, and everything seems queer and unfamiliar. 

 Straight lines, according to Relativity, appear crooked to us, and vice 

 versa. Spheres in motion become oblate spheroids, and we feel like 

 the prisoner in Gilbert and Sullivan's opera, condemned always to 

 play on a warped table, "on a cloth untrue, with a twisted cue, 

 and elliptical billiard balls." 



According to this theory, also, the greatest possible velocity in 

 space is that of light, — 186,000 miles per second. Even if a shell 

 were fired with a velocity of 100,000 miles per second directly for- 

 ward from a gun mounted on a car moving with the same velocity of 

 100,000 miles per second, the resultant velocity of the shell would 

 not be 200,000 miles per second, as we should expect, but only 150,000. 

 No combination of any number of velocities impressed upon a body 

 can exceed the velocity of light. The new definitions of physical terms 

 are equally puzzling, as for example: "Matter does not cause the 

 curvature of space, — it is the curvature." Again, Einstein has prac- 

 tically ignored in his theory the idea of force as the condition for 

 change of motion, which was possibly the greatest contribution made 

 by Galileo to the science of dj-namics, and in spite of the fact that 

 some physicists hold force to be perhaps the most basic of all the ideas 

 of mechanics. As already said, the ether, which Planck calls a "child 

 of sorrow," is, in the eyes of relativists, hopelessl}^ discredited. 



The work of Einstein is epoch-making. Just as for sixty years 

 everything in physics has had to square with Maxwell's equations, — 

 even Einstein's theory, — so now there is already seen a tendency to 

 make our thinking square with Einstein's equations. Just what results 

 will come out of the new theory it is impossible to say. The Einstein 

 mechanics have shown at least some power of exploration of intra- 

 atomic space, which Newtonian mechanics could not do, and this may 

 assist us in the development of a rational theory of atomic structure 

 better than any theory we now have. 



But we are not to stop here. The English are actively preparing 

 to make even more accurate observations in Australia during the 



