Editing Andrei Sakharov (section)

===Soviet program of nuclear weapons===
{{main|RDS-37|Tsar Bomba}}
After [[World War II]], he researched [[cosmic ray]]s. In mid-1948 he participated in the [[Soviet atomic bomb project]] under [[Igor Kurchatov]] and [[Igor Tamm]]. Sakharov's study group at FIAN in 1948 came up with a second concept in August–September 1948.<ref name=":0">Zaloga, Steve (17 February 2002). ''The Kremlin's Nuclear Sword: The Rise and Fall of Russia's Strategic Nuclear Forces 1945–2000''. Smithsonian Books. {{ISBN|1588340074}}.</ref> Adding a shell of natural, unenriched uranium around the deuterium would increase the deuterium concentration at the uranium-deuterium boundary and the overall yield of the device, because the natural uranium would capture neutrons and itself fission as part of the thermonuclear reaction. This idea of a layered fission-fusion-fission bomb led Sakharov to call it the ''sloika'', or layered cake.<ref name=":0" /> The first Soviet atomic device was tested on August 29, 1949. After moving to [[Sarov]] in 1950, Sakharov played a key role in the development of the first megaton-range Soviet hydrogen bomb using a design known as ''Sakharov's Third Idea'' in Russia and the [[History of the Teller–Ulam design|Teller–Ulam design]] in the United States. Before his ''Third Idea'', Sakharov tried a "layer cake" of alternating layers of fission and fusion fuel. The results were disappointing, yielding no more than a typical fission bomb. However the design was seen to be worth pursuing because deuterium is abundant and uranium is scarce, and he had no idea how powerful the US design was. Sakharov realised that in order to cause the explosion of one side of the fuel to symmetrically compress the fusion fuel, a mirror could be used to reflect the radiation. The details had not been officially declassified in Russia when Sakharov was writing his memoirs, but in the Teller–Ulam design, soft X-rays emitted by the fission bomb were focused onto a cylinder of lithium deuteride to compress it symmetrically. This is called [[radiation implosion]]. The Teller–Ulam design also had a secondary fission device inside the fusion cylinder to assist with the compression of the fusion fuel and generate neutrons to convert some of the lithium to tritium, producing a mixture of deuterium and tritium.<ref>{{cite book|author=Sakharov, Andrei|title=Memoirs|publisher=Vintage|date=1992|isbn=978-0679735953}}</ref><ref>{{cite book|author1=Gorelik, Gennady |author2=Bouis, Antonina |title=The world of Andrei Sakharov: a Russian physicist's path to freedom|date=2005|publisher=Oxford University Press|isbn=978-0195156201}}</ref> Sakharov's idea was first tested as [[RDS-37]] in 1955. A larger variation of the same design which Sakharov worked on was the 50&nbsp;Mt [[Tsar Bomba]] of October 1961, which was the most powerful nuclear device ever detonated.

Sakharov saw "striking parallels" between his fate and those of [[J. Robert Oppenheimer]] and [[Edward Teller]] in the US. Sakharov believed that in this "tragic confrontation of two outstanding people", both deserved respect, because "each of them was certain he had right on his side and was morally obligated to go to the end in the name of truth." While Sakharov strongly disagreed with Teller over [[Nuclear weapons testing|nuclear testing in the atmosphere]] and the [[Strategic Defense Initiative]], he believed that American academics had been unfair to Teller's resolve to get the H-bomb for the United States since "all steps by the Americans of a temporary or permanent rejection of developing thermonuclear weapons would have been seen either as a clever feint, or as the manifestation of stupidity. In both cases, the reaction would have been the same – avoid the trap and immediately take advantage of the enemy's stupidity."{{citation needed|date=April 2024}}

Sakharov never felt that by creating nuclear weapons he had "known sin", in Oppenheimer's expression. He later wrote:
{{blockquote|text=After more than forty years, we have had no [[third world war]], and the [[Mutual assured destruction|balance of nuclear terror]]&nbsp;... may have helped to prevent one. But I am not at all sure of this; back then, in those long-gone years, the question didn't even arise. What most troubles me now is the instability of the balance, the extreme peril of the current situation, the appalling waste of the arms race&nbsp;... Each of us has a responsibility to think about this in global terms, with tolerance, trust, and candor, free from ideological dogmatism, parochial interests, or national egotism."|source=Andrei Sakharov<ref name="people">{{cite encyclopedia|url=http://people.bu.edu/gorelik/AIP_Sakharov_Photo_Chrono/SakharovAndrei_NDSB_uned.htm|title=Andrei Sakharov|first=Gennady|last=Gorelik|encyclopedia=New dictionary of scientific biography|date=2008|editor-first=Noretta|editor-last=Koertge|publisher=Charles Scribner's Sons/Thomson Gale|location=Detroit|access-date=July 12, 2011|archive-date=February 15, 2019|archive-url=https://web.archive.org/web/20190215033444/http://people.bu.edu/gorelik/AIP_Sakharov_Photo_Chrono/SakharovAndrei_NDSB_uned.htm|url-status=dead}}</ref>}}