The authors are members of the professional staff of TRW Space Technology Laboratories in Redondo Beach, California. Mr. Branigan is editor of his firm's quarterly Space Log publication. Dr. LeGalley served as editor of Space Science and co‐editor of the recently released books, Space Exploration and Space Physics.
This review of the recent evolutionary history of particle physics is based on a paper prepared for delivery in Washington, D.C., on October 22, 1963, as part of a program of invited lectures presented during the centennial celebration of the National Academy of Sciences. Professor Chew's paper, together with others presented on that occasion, will be published in the forthcoming Proceedings of the Academy's centennial meeting.