98 Master Minds of Modern Science 



movement it contracts by a two-hundred-millionth part 

 of its length. 



Nineteen miles per second seems a great speed, but we 

 have all been travelling at that speed all our lives. 

 Indeed, we have been travelling faster, for our planet has 

 two additional movements — its spin on its axis, and the 

 speed at which it is being carried through space by its 

 master, the sun. 



Please do not imagine that there is anything strange 

 about this contraction. A rod of steel or wood may seem 

 to us a solid object, yet it is of course nothing of the sort, 

 for it is merely a swarm of molecules in active motion, 

 separated one from another by quite considerable spaces. 

 Every time that its position is changed changes are made 

 in the magnetic forces which hold its particles together, 

 and their delicate balance is upset. Really the wonder 

 is not that there is a change, but that the change is so 

 small. 



Now you will begin to understand that measurement of 

 length or distance is relative to direction. 



Increase the speed of our planet. Make it one hundred 

 and sixty-one thousand miles per second, and your rod, 

 when turned, will contract to half its former length. So 

 far as known, there is no planet which moves at such 

 a speed as one hundred and sixty-one thousand miles a 

 second, yet we have observed a nebula which is moving 

 at one thousand miles a second, and if there were a planet 

 in this system moving at the same speed its inhabitants 

 would find that even this rate of speed was enough to 

 upset entirely the accuracy of their measurements. 



Now perhaps you will think that we are going to give 

 you a simple explanation of Einstein's theories, and tell 

 you why it is that he has come to the conclusion that 

 space is " finite yet unbounded/ ' We are sorry. We 

 cannot do it. We have applied to several scientists who 

 themselves do understand the Relativity and Quantum 



