Editing Joseph Rotblat (section)

== Manhattan Project ==
While still in Poland, Rotblat had realised that [[nuclear fission]] might possibly be used to produce an [[atomic bomb]]. He first thought that he should "put the whole thing out of my mind",<ref name=Abe>{{cite web|url=http://www.irwinabrams.com/books/excerpts/annual95.html|first=Irwin|last=Abrams|title=The 1995 Nobel Peace Prize For Joseph Rotblat and the Pugwash Conference on Science And World Affairs|access-date=2 March 2007|archive-date=20 February 2012|archive-url=https://web.archive.org/web/20120220065400/http://www.irwinabrams.com/books/excerpts/annual95.html|url-status=live}}</ref> but 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. He worked with Chadwick on [[Tube Alloys]], the British atomic bomb project.<ref name=Abe />

In February 1944, Rotblat joined the [[Los Alamos Laboratory]] as part of Chadwick's [[British contribution to the Manhattan Project|British Mission]] to the [[Manhattan Project]].<ref name=Abe /> Although he was upset by the morality of the project, he believed the allies needed to be able to threaten retaliation in case Germany developed the bomb.<ref name="natureobit"/> The usual condition for people to work on the Manhattan Project was that they had to become [[US citizen]]s or [[British subject]]s. Rotblat declined, and the condition was waived.<ref name=telegraph>{{cite news|url=https://www.telegraph.co.uk/news/obituaries/1497409/Professor-Sir-Joseph-Rotblat.html|newspaper=[[The Daily Telegraph]]|title=Professor Sir Joseph Rotblat|date=2 September 2005|access-date=2 April 2018|archive-date=3 December 2017|archive-url=https://web.archive.org/web/20171203134907/http://www.telegraph.co.uk/news/obituaries/1497409/Professor-Sir-Joseph-Rotblat.html|url-status=live}}</ref> At Los Alamos, he was befriended by [[Stan Ulam]], a fellow Polish-Jewish scientist, with whom he was able to converse in Polish. Rotblat worked in [[Egon Bretscher]]'s group, investigating whether high-energy [[gamma rays]] produced by nuclear fission would interfere with the [[nuclear chain reaction]] process, and then with [[Robert R. Wilson]]'s cyclotron group.{{sfn|Brown|2012|pp=47–49}}

Rotblat continued to have strong reservations about the use of science to develop such a devastating weapon. In 1985, he related that, at a private dinner at the Chadwicks' house at Los Alamos in March 1944, he was shocked to hear the director of the Manhattan Project, [[Major General (United States)|Major General]] [[Leslie R. Groves, Jr.]], say words to the effect that the real purpose in making the bomb was to subdue the Soviets. Indeed, Groves testified under oath at the 1954 hearing about [[J. Robert Oppenheimer]]'s security record that "there was never, from about two weeks from the time I took charge of this project, any illusion on my part but that Russia was our enemy and that the project was conducted on that basis."<ref name=Groves1954>{{
cite book
|author = United States Atomic Energy Commission and J. Robert Oppenheimer
|year = 1971
|title = In the Matter of J. Robert Oppenheimer
|publisher = Cambridge, MA: MIT Press
|pages = 173
}}</ref><ref name="Leaving the Bomb Project" /> Despite Groves' testimony, in response to a suggestion by Andrew Brown that Groves' remark may have been made to test Rotblat's loyalty, [[Barton Bernstein]], who had questioned the accuracy of Rotblat's memory, commented in a letter to Brown: "It's an interesting, responsible interpretation, and cannot be dismissed, though I'm not prepared to embrace it."{{sfn|Brown|2012|p=295}}

By the end of 1944, it was also apparent that Germany had abandoned the development of its own bomb in 1942. Rotblat then asked to leave the project on grounds of conscience and returned to Liverpool.<ref name="natureobit">{{Cite journal
| last1 = Milne | first1 = S.
| last2 = Hinde | first2 = R.
| doi = 10.1038/437634a
| title = Obituary: Joseph Rotblat (1908–2005) Physicist who committed his life to the cause of nuclear disarmament
| journal = Nature
| volume = 437
| issue = 7059
| pages = 634
| year = 2005
| pmid = 16193034
| bibcode = 2005Natur.437..634M
| s2cid = 29764779
| doi-access = free
}}</ref>

Chadwick learned that the chief of security held a security dossier in which Rotblat was accused of intending to return to England so that he could be flown over Poland and parachute into Soviet territory to pass on the secrets of the atomic bomb. He was also accused of visiting someone in [[Santa Fe, New Mexico|Santa Fe]] and leaving them a blank cheque to finance the formation of a communist cell.<ref name=Abe />

Rotblat was able to show that much of the information within the dossier had been fabricated.<ref name=Abe /> In addition, FBI records show that in 1950, Rotblat's friend in Santa Fe was tracked down in California, and she flatly denied the story; the cheque had never been cashed and had been left to pay for items not available in the UK during the war. In 1985, Rotblat recounted 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,<ref name="Leaving the Bomb Project">{{cite journal |last=Rotblat |first=Joseph |title=Leaving the Bomb Project |journal=Bulletin of the Atomic Scientists |date=August 1985 |url=https://books.google.com/books?id=uwYAAAAAMBAJ&pg=PA16 |volume=41 |issue=7 |pages=16–19 |doi=10.1080/00963402.1985.11455991 |bibcode=1985BuAtS..41g..16R |access-date=31 October 2020 |archive-date=10 January 2021 |archive-url=https://web.archive.org/web/20210110181332/https://books.google.com/books?id=uwYAAAAAMBAJ&pg=PA16 |url-status=live |url-access=subscription }}</ref> 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".<ref>{{cite journal |last=Underwood |first=Martin |title=Joseph Rotblat's Archive: Some Anomalies and Difficulties |journal=AIP History Newsletter |year=2011 |volume=43 |pages=5–7|url=https://www.aip.org/sites/default/files/history/files/newsletter-pdf/Summer2011HistoryNewsletter.pdf}}</ref><ref>{{Cite journal
| last1 = Underwood | first1 = M. C.
| title = Joseph Rotblat, the Bomb and Anomalies from His Archive
| doi = 10.1007/s11948-011-9345-4
| journal = Science and Engineering Ethics
| volume = 19
| issue = 2
| pages = 487–90
| year = 2011
| pmid = 22190230
| s2cid = 32392242
}}</ref>