TEE THEORY OF RELATIVITY 445 



mathematician and physicist could read without too great an expendi- 

 ture of time and energy, and with few exceptions, only those which 

 could be found in a rather meager scientific library. 



In spite of the fact that the relativity theory rests on a firm basis 

 of experiment, and upon logical deductions from such experiments, and 

 notwithstanding also that this theory is remarkably self-consistent, and 

 is in fact the only theory which at present seems to agree with all the 

 facts, nevertheless it perhaps goes without saying that it has not been 

 universally accepted. Some objections to the theory have been ad- 

 vanced by men of good standing in the world of physics, and a fair 

 and impartial presentation of the subject would of necessity include a 

 brief statement of these objections. I shall not attempt to answer 

 these objections. Those who have adopted the relativity theory seem 

 in no wise concerned with the arguments put forward against it. In 

 fact, if there is one thing which impresses the reader of the articles on 

 relativity, it is the calm assurance of the advocates of this theory that 

 they are right. Naturally the theory and its consequences have been 

 criticized by a host of persons of small scientific training, but it will 

 not be necessary to mention these arguments. They are the sort of ob- 

 jections which no doubt Galileo had to meet and answer in his famous 

 controversy with the Inquisition. Fortunately for the cause of science, 

 however, the authority back of these arguments is not what it was in 

 Galileo's time, for it is not at all certain just how many of those who 

 have enthusiastically embraced relativity would go to prison in defence 

 of the dogma that one man's now is another man's past, or would allow 

 themselves to be led to the stake rather than deny the doctrine that the 

 length of a yardstick depends upon whether one happens to be measur- 

 ing north and south with it, or east and west. 



In general it may be said that the chief objection to the relativity 

 theory is that it is too artificial. The end and aim of the science of 

 physics is to describe the phenomena which occur in nature, in the 

 simplest manner which is consistent with completeness, and the object- 

 ors to the relativity theory urge that this theory and especially its 

 consequences, are not simple and intelligible to the average intellect. 

 Consider, for example, the theory which explains the behavior of a gas 

 by means of solid elastic spheres. This theory may be clumsy, but it is 

 readily understood, rests upon an analogy with things which can be 

 seen and felt, in other words is built up of elements essentially simple. 

 But the objectors to the relativity theory say that it is based on ideas of 

 time and space which are not now and which never can be intelligible to 

 the human mind. They claim that the universe has a real existence 

 quite apart from what any one thinks about it, and that this real uni- 

 verse, through the human senses, impresses upon the normal mind cer- 

 tain simple notions which can not be changed at will. Minkowski's 



