THE MAN IN THE LIFT 113 



velocity of the lift is ever-increasing — accelerated. Can 

 we extend to accelerated frames our principle that 

 Nature is indifferent to frames of space and time, so 

 that no one frame is superior to any other? I think we 

 can. The only doubt that arises is whether we should 

 not regard the frame of the man in the lift as superior 

 to, instead of being merely coequal with, our usual 

 frame. 



When we stand on the ground the molecules of the 

 ground support us by hammering on the soles of our 

 boots with force equivalent to some ten stone weight. 

 But for this we should sink through the interstices of 

 the floor. We are being continuously and vigorously 

 buffeted. Now this can scarcely be regarded as the ideal 

 condition for a judicial contemplation of our natural 

 surroundings, and it would not be surprising if our 

 senses suffering from this treatment gave a jaundiced 

 view of the world. Our bodies are to be regarded as 

 scientific instruments used to survey the world. We 

 should not willingly allow anyone to hammer on a 

 galvanometer when it was being used for observation; 

 and similarly it is preferable to avoid a hammering on 

 one's body when it is being used as a channel of scien- 

 tific knowledge. We get rid of this hammering when 

 we cease to be supported. 



Let us then take a leap over a precipice so that we 

 may contemplate Nature undisturbed. Or if that seems 

 to you an odd way of convincing yourself that bodies do 

 not fall,* let us enter the runaway lift again. Here 

 nothing need be supported; our bodies, our galvano- 



* So far as I can tell (without experimental trial) the man who jumped 

 over a precipice would soon lose all conception of falling; he would only 

 notice that the surrounding objects were impelled past him with ever- 

 increasing speed. 



