OUE KNOWLEDGE OF ATOMIC NUCLEI 



By G. P. Harnwell, Ph. D. 

 Director of the Laboratory of Physics, University of PennsylvoMia 



The subject which within the past few years has come to be known 

 as "nuclear physics" is an outgrowth and in many ways the culmina- 

 tion of the research in atomic physics which began with the opening 

 of the present century. You are familiar with many of the prac- 

 tical results of this earlier work, though possibly you do not all 

 realize how directly most of our recent technical developments are 

 due to what at first sight seems like a highly impractical and literally 

 intangible field of investigation. In consequence, I would like first 

 to consider briefly why we study atoms and molecules and what evi- 

 dence the pure scientist can offer the engineers, who are applied 

 scientists, and also all the other nontechnical members of society 

 to justify their continued support of pure science. For without this 

 support we cannot continue to make fundamental advances in our 

 knowledge of, and control over, our physical environment. 



The motivations of the pure scientist would appear to many at 

 first thought as whimsical and abstract as the immediate results he 

 achieves. The briefest explanation of why he works is curiosity 

 rather than the necessity of earning a livelihood. The questions he 

 asks are "Why?" and "How?" rather than "What good will come of 

 all this?" The latter is the first query that occurs to most people 

 and is a question that some of us must answer if the aims and results 

 of pure science are to be widely understood. The gap between these 

 points of view is bridged by realizing that the scientist's aim is funda- 

 mentally to gain as wide and deep a knowledge as possible of our 

 physical surroundings. That this alone is a justifiable aim worthy of 

 everyone's support is evident, for the first step toward control over 

 our environment, which results in benefit to all, is a proper under- 

 standing of the phenomena and laws of the physical world. Our 

 civilization, excepting our racial biological inheritance, is largely due 

 to the activities of pure scientists. These scientists have not generally 



1 Presented at the Stated Meeting of the Franklin Institute held Wednesday, Novem- 

 ber 16, 1938. Keprinted by permission from the Journal of the Franklin Institute, vol. 

 227, No. 4, April 1939. 



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