Narrator: In 1939, Joseph Rotblat, a Polish nuclear physicist, was working in England. He became concerned that it might be possible to develop an atomic bomb, and went to consult with Ludwik Wertenstein, his former supervisor in Poland, when home for a visit. Here’s how he later described the results of the visit:
Rotblat: The idea of a nuclear weapon had not occurred to him, but when I showed him my calculations, he could not find anything scientifically wrong with them. On the moral issue, however, he was unwilling to advise me. He himself would never engage in this type of work, but he would not try to influence me. It had to be left to my own conscience.
The war broke out two days after I returned to Liverpool. Within a few weeks Poland was overrun. The stories that Hitler’s military strength was all bluff, that his tanks were painted cardboard, turned out to be wishful thinking. The might of Germany stood revealed, and the whole of our civilization was in mortal peril. My scruples were finally overcome.
Narrator: Rotblat began leading a laboratory in Liverpool where he conducted experiments to determine the feasibility of building a uranium bomb. Eventually he, along with several other physicists working in Britain, joined the Manhattan Project in Los Alamos.
Rotblat: In March 1944 I experienced a disagreeable shock…. During one [casual] conversation, [the general in charge of the project] said that, of course, the real purpose in making the bomb was to subdue the Soviets. (Whatever his exact words, his real meaning was clear.) While I had no illusions about the Stalin regime—after all, it was his pact with Hitler that enabled the latter to invade Poland—I felt deeply the sense of betrayal of an ally. Remember, this was said at a time when thousands of Russians were dying every day on the Eastern Front, tying down the Germans and giving the Allies time to prepare for a landing on the continent of Europe. Until then I had thought that our work was to prevent a Nazi victory, and now I was told that the weapon we were preparing was intended for use against the people who were making extreme sacrifices for that very aim. […]
When it became evident, toward the end of 1944, that the Germans had abandoned their bomb project, the whole purpose of my being in Los Alamos ceased to be, and I asked for permission to leave and return to Britain. […]
Work on the atom bomb convinced me that even pure research soon finds application of one kind or another. If so, I wanted to decide myself how my work should be applied. I chose an aspect of nuclear physics which I knew would definitely be beneficial to humanity: the applications to medicine. Thus I completely changed the direction of my research and spent the rest of my academic career working in a medical college and hospital.
While this gave me personal satisfaction, I was increasingly concerned about the political aspects of the development of nuclear weapons, particularly the hydrogen bomb.
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