On November 4, 1908, Polish physicist and recipient of the Nobel Peace Prize Joseph Rotblat was born. Rotblat was the only physicist to leave the Manhattan Project (1942–46) on the grounds of conscience. Rotblat’s work on nuclear fallout was a major contribution toward the ratification of the 1963 Partial Nuclear Test Ban Treaty. A signatory of the Russell–Einstein Manifesto (1955), he was secretary-general of the Pugwash Conferences on Science and World Affairs from their founding until 1973.
Joseph Rotblat worked as a domestic electrician in Warsaw after the First World War and got interested in a career as a physicist. Even though he had no formal education, Rotblat began working at a physics department of the Free University of Poland, gaining an MA in 1932 and Doctor of Physics, University of Warsaw in 1938. Rotblat held the position of Research Fellow in the Radiation Laboratory of the Scientific Society of Warsaw and became assistant Director of the Atomic Physics Institute of the Free University of Poland in 1937.
Before the start of the Second World War, Rotblat already conducted experiments showing that neutrons were emitted in the fission process. In early 1939 he envisaged that a large number of fissions could occur and if this happened within a sufficiently short time, then considerable amounts of energy could be released. He went on to calculate that this process could occur in less than a microsecond, and as a consequence would result in an explosion. Rotblat was then invited to study in Paris at the University of Liverpool under James Chadwick.
It was clear to Joseph Rotblat that his work could be used to produce a bomb and with the rise of Nazi Germany he continued because he thought the only way to prevent Nazi Germany from using a nuclear bomb was if Britain had one to act as a deterrent. After the start of the war, he started working explicitly with Chadwick on bomb work. In 1944, Rotblat went with James Chadwick’s group to work on the Manhattan Project to build the first atomic bombs. However, as it became more and more apparent that Germany had abandoned the development of its own bomb that Rotblat asked to leave the project.
James Chadwick was then shown a security dossier in which Rotblat was accused of being a Soviet spy and that, having learnt to fly at Los Alamos, he was suspected of wanting to join the Royal Air Force so that he could fly to Poland and defect to the Soviet Union. In addition, he was accused of visiting someone in Santa Fe and leaving them a blank cheque to finance the formation of a communist cell. Rotblat was able to show that much of the information within the dossier had been fabricated. In reminiscences from 1985 Rotblat tells how a box containing “all my documents” went missing on a train ride from Washington D.C. to New York as he was leaving the country, but the presence of large numbers of Rotblat’s personal papers from Los Alamos now archived at the Churchill Archives Centre “is totally at odds with Rotblat’s account of events”. Joseph Rotblat was not permitted to re-enter the United States until 1964 and he was the only physicist to leave the Manhattan Project on the grounds of conscience, even though others later refused to work on atomic bombs after the defeat of Japan.
Jopeph Rotblat became senior lecturer and acting director of research in nuclear physics at the University of Liverpool and naturalised as a British subject. He also became more interested in the medical and biological uses of radiation and was appointed Professor of Physics at St Bartholomew’s Hospital, London. In 1955, he demonstrated that the contamination caused by the fallout after the Castle Bravo test at Bikini Atoll nuclear test by the United States would have been far greater than that stated officially. He managed to show that the bomb had three stages and showed that the fission phase at the end of the explosion increased the amount of radioactivity a thousandfold. Rotblat’s paper on the matter was taken up by the media and contributed to the public debate that resulted in the ending of atmospheric tests by the Partial Nuclear Test Ban Treaty.
Rotblat believed that scientists should always be concerned with the ethical consequences of their work and he became one of the most prominent critics of the nuclear arms race. He was the youngest signatory of the Russell-Einstein Manifesto in 1955, and chaired the press conference that launched it. Along with Bertrand Russell and others, Rotblat organised the first of the Pugwash Conferences on Science and World Affairs in 1957 and continued to work within their framework until his death. Further, Joseph Rotblat joined with Einstein, Oppenheimer, Russell and other concerned scientists to found the World Academy of Art and Science. After the breakthrough of the Partial Nuclear Test Ban Treaty, Rotblat was in 1965 made a CBE.
At yovisto you can learn more about the Manhattan project in the video “The Moment in Time: The Manhattan Project“.
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