Soon after the US dropped two nuclear bomb on Japan in 1945, a group of physicists at the University of Pennsylvania decided to investigate for themselves how nuclear fission and the bomb might work using non-classified materials. In doing so, they ventured into classified territory and raised questions about the nature of science and secrecy.
To what degree would nuclear research become shackled by the requirements of national security? Would the open circulation of new scientific knowledge cease if that knowledge was relevant to nuclear fission? Those questions were hardly idle speculation: From the fall of 1945 through the summer of 1946, the US Congress was crafting new, unprecedented legislation that would legally define the bounds of open scientific research and even free speech. The idea of restricting open scientific communication “may seem drastic and far-reaching,” President Harry S. Truman argued in an October 1945 statement exhorting Congress to rapid action. But, he said, the atomic bomb “involves forces of nature too dangerous to fit into any of our usual concepts.”
The former Manhattan Project scientists who founded what would eventually become the Federation of American Scientists were adamantly opposed to keeping nuclear technology a closed field. From early on they argued that there was, as they put it, “no secret to be kept.” Attempting to control the spread of nuclear weapons by controlling scientific information would be fruitless: Soviet scientists were just as capable as US scientists when it came to discovering the truths of the physical world. The best that secrecy could hope to do would be to slightly impede the work of another nuclear power. Whatever time was bought by such impediment, they argued, would come at a steep price in US scientific productivity, because science required open lines of communication to flourish.
At the University of Pennsylvania were nine scientists sympathetic to that message. All had been involved with wartime work, but in the area of radar, not the bomb. Because they had not been part of the Manhattan Project in any way, they were under no legal obligation to maintain secrecy; they were simply informed private citizens. In the fall of 1945, they tried to figure out the technical details behind the bomb.