THE LAST FIFTY YEARS

(Written for the American Physical Society's 1976 United States Bicentennial volume commemorating American physicists)

It would be impossible to commemorate all the notable American physicists of the last fifty years within one volume, for there have been so many of them. Until the 1920's only two or three dozen physics Ph.D.'s were granted each year in the United States, but by the 1970's the number had risen to over a thousand per year. This exponential rise in the training of physicists was parallelled by equally steep growth in the numbers of working physicists and their production of research. The American Physical Society, which had 59 members when it was founded in 1899 and some 1800 members in 1926, had over 28,000 in 1976. The increasing population of physicists, and its diversity, were also shown by the founding of new organizations such as the Optical Society of America (1916), the Society of Rheology (1929), the Acoustical Society of America (1929), the American Association of Physics Teachers (1930), the American Crystallographic Association (1949), and the American Association of Physicists in Medicine (1958); many other physicists could be found in older groups such as the American Astronomical Society and the engineering societies. A number of these organizations became members of the American Institute of Physics, which since 1931 printed journals and managed related matters which were more efficiently done jointly.

The world economic and political catastrophes of the 1930's did not retard the growth of American physics. Despite budget problems during the Great Depression, laboratories maintained their work and welcomed physicists who emigrated from Europe and elsewhere. Albert Einstein, Enrico Fermi, and over a hundred more of the world's finest physicists found refuge in the United States. While these emigres brought their talents, America more than any other country gave them the opportunity to use them. Even without this addition, by 1940 the United States would have been the equal in physics of any country in the world, thanks to the spectacular rise in the number and quality of native-trained people, but with the aid of the emigres America rose to predominance. An example: When nuclear fission was discovered and many papers were published in 1939 to follow up the discovery, almost twice as many of these were published in the United States as in any other nation, a substantial number of them by refugee physicists.

The Second World War forced a pause in physics education and publication but brought an enormous leap in funding. Working on radar at the MIT Radiation Laboratory, on nuclear weapons within the huge Manhattan Project, and on other equally important research, physicists drew for the first time on the full resources of the government. In many ways their work helped to shorten the war.

Government support continued after the war. Laboratories within the federal government were nothing new—the National Bureau of Standards and others had done valuable physics research since around the turn of the century. But now government contracts, supplementing increased state and local funds and foundation grants, became a major source of support for physics laboratories. Most spectacular among these were the great new particle accelerators, mostly descended from the cyclotron laboratory that Ernest O. Lawrence had created at Berkeley, California in the 1930's. Some scientists were worried by the trend towards costly apparatus and huge, anonymous research teams, but there was no denying the high level that discovery was reaching in the United States. Of the 46 people who won a Nobel prize in physics up to 1940, only six had been American; but of the 57 winners since, 28 were American. (Five more emigrated to the United States after doing the work for which they won the prize.) No other nation in modern times has so dominated a field of science.

Less celebrated but no less important than the advance in basic science was the progress of applied physics. This was carried out particularly by people in industry, who in 1976 amounted to about a fifth of the over 20,000 Ph.D. physicists employed in the United States. Advances in applied physics profoundly affected the country's mode of life and its standing in the world economy. Also noteworthy was the progress of physics education. Before the First World War less than a tenth of American youths graduated from high school and only a small fraction of those went on to college, while in the 1970's physicists were meeting the challenge of instructing a much larger part of the population, and doing it with greatly improved curricula.

By the 1960's foresighted people were pointing out that if the exponential growth of physics was extrapolated for another two centuries, there would have to be more physicists than people in America; at some point the growth would have to level off. But it was equally clear that the science of physics had become so woven into the national life, so fundamental to American industry, defense, education and ways of thought, that it would long retain the central position it had so painstakingly won.

— Spencer Weart 1976