ASSAULT ON ATOMS 



By Arthub H. Compton 



[With 2 plates] 



Twenty-five hundred years ago, Thales, the first true scientist of 

 ancient Greece, undertook to solve the problem, " Of what and how 

 is the world made? " Almost a hundred generations have passed and 

 the problem is not yet solved. 



Democritus and his followers thought they had found the solution. 

 Everj'thing is made of atoms. "According to convention there is a 

 sweet and a bitter, a hot and a cold, and according to convention 

 there is color. In truth there are atoms and a void." Thus, in terms 

 of motions of minute particles the ancient Atomists accounted for 

 their world. Mountains and seas, trees and people, even life and 

 thoughts, were thus explained. 



But Socrates and Plato would have none of their atoms. Did they 

 not in Democritus' hands rob men of their personality? Atoms are 

 thus worse than useless, for they destroy the basis of morality. Here 

 in Athens, around the question of atoms, was staged the first great 

 battle between science and religion. Epicurus and Lucretius took 

 up the cudgels on behalf of the atomists, but Plato carried the day, 

 and atoms were forgotten until the revival of scientific thought dur- 

 ing the Renaissance. Though our present day atouiic theories are 

 based on much firmer foundations than those of Democritus, they 

 owe their origin to his ideas, transmitted down through the 

 centuries. 



A few 3'ears ago we were camped beside a mountain lake in the 

 foothills of the Himalayas, studying cosmic rays. The warm air 

 from the plains of India was carried up over a range of mountains, 

 and came down again into the beautiful Vale of Kashmir. Clouds 

 were continuall}^ forming as the air, cooled by expansion as it came 

 up the mountain side, became supersaturated with moisture. But 

 after passing the peak of the range, the air was warmed by com- 



1 Read before the American Philosophical Society, Apr. 23, 1931. Reprinted by per- 

 mission from Proceedings of the American Philosophical Society, vol. 70, No. 3, 1931. 



287 



