16 DOWNFALL OF CLASSICAL PHYSICS 



known to be "wrong" with it is that it is not unique. 

 If we had found that our frame was unsatisfactory and 

 another frame was preferable, that would not have 

 caused a great revolution of thought; but to discover 

 that ours is one of many frames, all of which are equally 

 satisfactory, leads to a change of interpretation of the 

 significance of a frame of location. 



"Commonsense" Objections. Before going further I must 

 answer the critic who objects in the name of common- 

 sense. Space — his space — is so vivid to him. "This 

 object is obviously here; that object is just there. I know 

 it; and I am not going to be shaken by any amount of sci- 

 entific obscurantism about contraction of measuring rods." 

 We have certain preconceived ideas about location 

 in space which have come down to us from ape-like 

 ancestors. They are deeply rooted in our mode of 

 thought, so that it is very difficult to criticise them 

 impartially and to realise the very insecure foundation 

 on which they rest. We commonly suppose that each 

 of the objects surrounding us has a definite location in 

 space and that we are aware of the right location. The 

 objects in my study are actually in the positions where 

 I am "aware" that they are; and if an observer (on 

 another star) surveying the room with measuring rods, 

 etc., makes out a different arrangement of location, he 

 is merely spinning a scientific paradox which does not 

 shake the real facts of location obvious to any man 

 of commonsense. This attitude rejects with contempt 

 the question, How am I aware of the location? If the 

 location is determined by scientific measurements with 

 elaborate precautions, we are ready enough to sug- 

 gest all sorts of ways in which the apparatus might 

 have misbehaved; but if the knowledge of location is 



