246 ANNUAL EEPOET SMITHSONIAN INSTITUTION, 192 8 



life history, but with a large part of the story of the birth of 

 matter itself. 



Discoveries in the fields of experimental science naturally go 

 hand in hand with that study of the laws of design of the universe 

 which we call theoretical science. One supplements the other, and 

 the strength of one enhances the strength of the other. It is nat- 

 urally around the atom's structure that the thoughts of men have 

 loved to hover. And here, the power to comprehend a new point 

 of view has grown enormously in the last few years. We have a 

 clearer understanding of what understanding means. We were in 

 danger of becoming so enamored of those laws which govern the 

 behavior of matter in bulk as to refuse to admit any other possibili- 

 ties in respect to the laws of the atom. The workings of the coarse- 

 grained things of nature were all about us. Pulleys, springs, water 

 torrents, the waves of the sea, these were things of common experi- 

 ence, and the mind sought contentment in the tliought that the atom 

 might utilize in its structure only things which behaved as these 

 things behaved; and even as a little hill may hide the Alps from 

 one whose life is in its shadow, so there was danger in the known 

 and obvious workings of the common things around us obscuring 

 from our vision the story of that great universe of the atom which 

 lies beyond. Happily, the complacency of our outlook has received, 

 in recent years, one or two serious jolts. First came the theory of 

 relativity, which taught us that a greater elasticity of thought was 

 necessary if we were to understand nature as she is rather than as 

 we might have made her. Then came a series of experimental phe- 

 nomena which seemed to violate all our notions of how things 

 should be, and since we could not alter the experimental phe- 

 nomena we had to alter the notions, and so there arose the so-called 

 quantum theory of atomic structure — one of the most helpful crys- 

 tallizations of thought for correlating the facts that we have ever 

 had. And then, as further search showed this theory to be inade- 

 quate beyond a certain stage, there arose only a couple of years 

 ago, an entirely new way of regarding the atom — a way so radical 

 in its point of view that it is safe to say that had it been put forward 

 15 years ago, it would hardly have attained a hearing. Born in a 

 day of more liberal thought, however, it had no sooner made an ap- 

 pearance than a host of workers arose to welcome it and to develop 

 its consequences, so that to-day there is hardly a physical laboratory 

 in the country which does not contain one or more persons who have 

 acquired the power to think in its terms. 



In speaking of theories being discarded and superseded by others, 

 we must not think of the discarded ones as useless. The situation 

 is not one where we are to think of a certain theory as right 



