210 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1952 



that the electrical circuit will oscillate ; and in a similar kind of way, 

 the ball and spring oscillate. You know that if the electrical circuit 

 is stimulated by an external force of frequency equal to its own, it 

 will resonate and build up a big amplitude; and for exactly similar 

 reasons, the ball on the end of the spring builds up an amplitude 

 when subjected to an external force which harmonizes with the system 

 in frequency. Thus, since you understand all about the nature of 

 the electrical oscillations of the circuit, you ought to be able to stim- 

 ulate your brains to the point of understanding why and how a ball 

 bobs up and down on the end of a spring in oil." 



No longer does the engineer seek to understand his electrical prob- 

 lems through mechanical ones, but when he gets a mechanical problem, 

 the first thing he does is to seek the electrical analogue and think in 

 terms of that — he seeks the equivalent electrical circuit. And so this 

 concept, reality, is indeed like a chameleon, changing its color to 

 harmonize with the setting of its time. Ah ! reality, what an elusive 

 thing it is and how its search has tormented mankind from time 

 immemorial. Reality, that will-o'-the-wisp of philosophy ! You may 

 think you have it in your hand but find that you have merely the 

 shadow of something else. You will pursue that something else; 

 you will clutch it, and again it will feel real until you find that your 

 consciousness of its touch is no more than the tingle of your own 

 blood as your hands clasp upon it. Reality is the most alluring of 

 all courtesans, for she makes herself what you would have her at the 

 moment; but she is no rock on which to anchor your soul, for her 

 substance is of the stuff of shadows; she has no existence outside 

 your own dreams and is oft no more than the reflection of your own 

 thoughts shining upon the face of nature. 



The concepts which one is willing to accept into his category of 

 thinking and to regard as natural without further inquiry as to their 

 origin change with the epoch, and today the average mathematical 

 physicist at any rate encounters no obstacle in classical electro- 

 dynamics. Indeed, he would be very content and feel that he had a 

 very understandable picture of nature if all atomic phenomena could 

 be brought into a picture in which classical electrodynamics was 

 the only controller of that picture. Today, however, he finds him- 

 self driven to new realms of abstraction in understanding the atom. 

 If he had been forced into these realms 100 years ago, he probably 

 would have given up and have felt that if he were to have no further 

 security in the matter of what I might call common-sense understand- 

 ableness, he might as well go back another couple of hundred years 

 and join with the forces of the astrologers or the alchemists. How- 

 ever, realizing what has happened to his mental accommodation in the 

 past, first through Newtonian dynamics — which was by no means a 



