FRAMES OF SPACE 15 



travelling at high speed — whether instruments of a 

 technical kind or, for example, a human retina. In only 

 one respect do I treat my nebular observer as more than 

 a piece of registering apparatus; I assume that he is 

 subject to a common failing of human nature, viz. he 

 takes it for granted that it was his planet that God 

 chiefly had in mind when the universe was created. 

 Hence he is (like my reader perhaps?) disinclined to 

 take seriously the views of location of those people who 

 are so misguided as to move at 1000 miles a second 

 relatively to his parish pump. 



An exceptionally modest observer might take some 

 other planet than his own as the standard of rest. Then 

 he would have to correct all his measurements for the 

 FitzGerald contraction due to his own motion with 

 respect to the standard, and the corrected measures 

 would give the space-frame belonging to the standard 

 planet as the original measures gave the space-frame of 

 his own planet. For him the dilemma is even more 

 pressing, for there is nothing to guide him as to the 

 planet to be selected for the standard of rest. Once 

 he gives up the naive assumption that his own frame is 

 the one and only right frame the question arises, Which 

 then of the innumerable other frames is right? There 

 is no answer, and so far as we can see no possibility of 

 an answer. Meanwhile all his experimental measure- 

 ments are waiting unreduced, because the corrections 

 to be applied to them depend on the answer. I am 

 afraid our modest observer will get rather left behind 

 by his less humble colleagues. 



The trouble that arises is not that we have found 

 anything necessarily wrong with the frame of location 

 that has been employed in our system of physics; it has 

 not led to experimental contradictions. The only thing 



