Editing J. Robert Oppenheimer (section)

== Manhattan Project ==
=== Los Alamos ===
{{Main|Project Y}}
On October 9, 1941, two months before the United States entered World War II, President [[Franklin D. Roosevelt]] approved a crash program to develop an [[Nuclear weapon|atomic bomb]]. On October 21, Ernest Lawrence brought Oppenheimer into what became the Manhattan Project. Oppenheimer was assigned to take over the project's specific bomb-design research by [[Arthur Compton]] at the [[Metallurgical Laboratory]].<ref>{{Cite web |title=J. Robert Oppenheimer's Interview |url=https://ahf.nuclearmuseum.org/voices/oral-histories/j-robert-oppenheimers-interview/ |access-date=March 14, 2024 |website=Atomic Heritage Foundation - Nuclear Museum |language=en-US |archive-date=January 4, 2024 |archive-url=https://web.archive.org/web/20240104105947/https://ahf.nuclearmuseum.org/voices/oral-histories/j-robert-oppenheimers-interview/ |url-status=live }}</ref> On May 18, 1942,{{sfn|Hewlett|Anderson|1962|pp=44–46}} [[National Defense Research Committee]] Chairman [[James B. Conant]], who had been one of Oppenheimer's lecturers at Harvard, asked Oppenheimer to take over work on [[fast neutron]] calculations, a task Oppenheimer threw himself into with full vigor. He was given the title "Coordinator of Rapid Rupture"; "rapid rupture" is a technical term that refers to the propagation of a fast neutron chain reaction in an atomic bomb. One of his first acts was to host a summer school for atomic bomb theory in Berkeley. The mix of European physicists and his own students—a group including Serber, [[Emil Konopinski]], [[Felix Bloch]], Hans Bethe, and Edward Teller—kept themselves busy by calculating what needed to be done, and in what order, to make the bomb.{{sfn|Norris|2002|p=240}}{{sfn|Hoddeson|Henriksen|Meade|Westfall|1993|pp=42–44}}

[[File:Oppenheimer-j r.jpg|thumb|upright=0.8|left|Oppenheimer's ID photo from the [[Project Y|Los Alamos Laboratory]]|alt=Mug shot with "K-6" over it.]]
In June 1942, the [[United States Army|U.S. Army]] established the [[Manhattan Engineer District]] to handle its part in the atom bomb project, beginning the process of transferring responsibility from the [[Office of Scientific Research and Development]] to the military.<ref>{{harvnb|Hewlett|Anderson|1962|pp=72–74}}</ref> In September, [[Brigadier General (United States)|Brigadier General]] [[Leslie R. Groves Jr.]], was appointed director of what became known as the Manhattan Project.<ref>{{harvnb|Hewlett|Anderson|1962|pp=81–82}}</ref> By October 12, 1942, Groves and Oppenheimer had decided that for security and cohesion, they needed to establish a centralized, secret research laboratory in a remote location.{{sfn|Hoddeson|Henriksen|Meade|Westfall|1993|pp=57–58}}

Groves selected Oppenheimer to head the project's secret weapons laboratory, although it is not known precisely when.{{sfn|Norris|2002|p=244}} This decision surprised many, because Oppenheimer had left-wing political views and no record as a leader of large projects. Groves worried that because Oppenheimer did not have a Nobel Prize, he might not have had the prestige to direct fellow scientists,{{sfn|Groves|1962|pp=61–63}} but Groves was impressed by Oppenheimer's singular grasp of the practical aspects of the project and by the breadth of his knowledge. As a [[military engineer]], Groves knew that this would be vital in an interdisciplinary project that would involve not just physics but also chemistry, [[metallurgy]], [[explosive weapon|ordnance]], and [[engineering]]. Groves also detected in Oppenheimer something that many others did not, an "overweening ambition",{{sfn|Norris|2002|p=242}} which Groves reckoned would supply the drive necessary to push the project to a successful conclusion.{{sfn|Norris|2002|p=242}} Oppenheimer's past associations were not overlooked, but on July 20, 1943, Groves directed that he receive a security clearance "<!--In accordance with my verbal directions of July 15, it is desired that clearance be issued to Julius Robert Oppenheimer -->without delay irrespective of the information which you have concerning Mr Oppenheimer. He is absolutely essential to the project."<ref>{{harvnb|Groves|1962|p=63}}</ref> Rabi considered Oppenheimer's appointment "a real stroke of genius on the part of General Groves, who was not generally considered to be a genius".{{sfn|Bird|Sherwin|2005|pp=185–187}}

Oppenheimer favored a location for the laboratory in New Mexico, not far from his ranch. On November 16, 1942, he, Groves and others toured a prospective site. Oppenheimer feared that the high cliffs surrounding it would feel claustrophobic, and there was concern about possible flooding. He then suggested a site he knew well: a flat [[mesa]] near [[Santa Fe, New Mexico]], which was the site of a private boys' school, the [[Los Alamos Ranch School]]. The engineers were concerned about the poor access road and the water supply but otherwise felt that it was ideal.{{sfn|Groves|1962|pp=66–67}} The [[Project Y|Los Alamos Laboratory]] was built on the site of the school, taking over some of its buildings, while many new buildings were erected in great haste. At the laboratory, Oppenheimer assembled a group of the top physicists of the time, whom he called the "luminaries".{{sfn|Smith|Weiner|1980|p=227}}

Los Alamos was initially supposed to be a military laboratory, and Oppenheimer and other researchers were to be commissioned into the Army. He went so far as to order himself a lieutenant colonel's uniform and take the Army physical test, which he failed. Army doctors considered him underweight at {{convert|128|lb}}, diagnosed his chronic cough as tuberculosis, and were concerned about his chronic [[lumbosacral joint]] pain.<ref name="Bird & Sherwin, p. 210">{{harvnb|Bird|Sherwin|2005|p=210}}</ref> The plan to commission scientists fell through when Rabi and [[Robert Bacher]] balked at the idea. Conant, Groves, and Oppenheimer devised a compromise whereby the University of California operated the laboratory under contract to the [[United States Department of War|War Department]].<ref>{{harvnb|Hewlett|Anderson|1962|pp=230–232}}</ref> It soon turned out that Oppenheimer had hugely underestimated the magnitude of the project: Los Alamos grew from a few hundred people in 1943 to over 6,000 in 1945.<ref name="Bird & Sherwin, p. 210" />

Oppenheimer at first had difficulty with the organizational division of large groups but rapidly learned the art of large-scale administration after he took up permanent residence at Los Alamos. He was noted for his mastery of all scientific aspects of the project and for his efforts to control the inevitable cultural conflicts between scientists and the military. [[Victor Weisskopf]] wrote:

{{blockquote|Oppenheimer directed these studies, theoretical and experimental, in the real sense of the words. Here his uncanny speed in grasping the main points of any subject was a decisive factor; he could acquaint himself with the essential details of every part of the work.

He did not direct from the head office. He was intellectually and physically present at each decisive step. He was present in the laboratory or in the seminar rooms, when a new effect was measured, when a new idea was conceived. It was not that he contributed so many ideas or suggestions; he did so sometimes, but his main influence came from something else. It was his continuous and intense presence, which produced a sense of direct participation in all of us; it created that unique atmosphere of enthusiasm and challenge that pervaded the place throughout its time.<ref>{{harvnb|Bethe|1968a}}; reprinted as {{harvnb|Bethe|1997|p=190}}</ref>
}}

===Bomb design===
[[File:Groves and Oppenheimer.jpg|thumb|right|upright=1.0|[[Leslie Groves]], military head of the Manhattan Project, with Oppenheimer in 1942|alt=two men, one in military uniform and another in a suit, having a discussion]]
At this point in the war, there was considerable anxiety among the scientists that the [[German nuclear weapons program]] might be progressing faster than the Manhattan Project.<ref>{{harvnb|Bird|Sherwin|2005|pp=221–222}}</ref>{{sfn|Rhodes|1986|pp=511–512}} In a letter dated May 25, 1943, Oppenheimer responded to a proposal by Fermi to use radioactive materials to poison German food supplies. Oppenheimer asked Fermi whether he could produce enough strontium without letting too many in on the secret. Oppenheimer continued, "I think we should not attempt a plan unless we can poison food sufficient to kill a half a million men."{{sfn|Rhodes|1986|pp=510–511}}

In 1943, development efforts were directed to a [[plutonium]] [[gun-type fission weapon]] called "[[Thin Man (nuclear bomb)|Thin Man]]". Initial research on the properties of plutonium was done using cyclotron-generated [[plutonium-239]], which was extremely pure but could be created only in tiny amounts. When Los Alamos received the first sample of plutonium from the [[X-10 Graphite Reactor]] in April 1944, a problem was discovered: reactor-bred plutonium had a higher concentration of [[plutonium-240]] (five times that of "cyclotron" plutonium), making it unsuitable for use in a gun-type weapon.<ref>{{harvnb|Hoddeson|Henriksen|Meade|Westfall|1993|pp=226–229}}</ref>

In July 1944, Oppenheimer abandoned the Thin Man gun design in favor of an [[Nuclear weapon design#Implosion-type |implosion-type]] weapon; a smaller version of Thin Man became [[Little Boy]]. Using chemical [[explosive lens]]es, a sub-critical sphere of fissile material could be squeezed into a smaller and denser form. The metal needed to travel only very short distances, so the critical mass would be assembled in much less time.<ref>{{harvnb|Hewlett|Anderson|1962|pp=312–313}}</ref> In August 1944, Oppenheimer implemented a sweeping reorganization of the Los Alamos laboratory to focus on implosion.<ref>{{harvnb|Hoddeson|Henriksen|Meade|Westfall|1993|pp=245–248}}</ref> He concentrated the development efforts on the gun-type device, but now with a simpler design that only had to work with [[highly enriched uranium]], in a single group. This device became [[Little Boy]] in February 1945.<ref>{{harvnb|Hoddeson|Henriksen|Meade|Westfall|1993|pp=248–249}}</ref> After a mammoth research effort, the more complex design of the implosion device, known as the "Christy gadget" after [[Robert Christy]], another student of Oppenheimer's,<ref>{{cite web |url=http://www.nuclearfiles.org/menu/library/biographies/bio_christy-robert.htm |title=Nuclear Files: Library: Biographies: Robert Christy |publisher=[[Nuclear Age Peace Foundation]] |access-date=March 8, 2011 |archive-url=https://web.archive.org/web/20060522003123/http://www.nuclearfiles.org/menu/library/biographies/bio_christy-robert.htm |archive-date=May 22, 2006 |url-status=dead }}</ref> was finalized as [[Fat Man]] in a meeting in Oppenheimer's office on February 28, 1945.<ref>{{harvnb|Hoddeson|Henriksen|Meade|Westfall|1993|p=312}}</ref>

In May 1945, an [[Interim Committee]] was created to advise and report on wartime and postwar policies regarding the use of nuclear energy. The Interim Committee established a scientific panel consisting of Oppenheimer, [[Arthur Compton]], Fermi, and Lawrence to advise it on scientific issues. In its presentation to the Interim Committee, the panel offered its opinion not just on an atomic bomb's likely physical effects but also on its likely military and political impact.<ref>{{harvnb|Jones|1985|pp=530–532}}</ref> This included opinions on such sensitive issues as whether the Soviet Union should be advised of the weapon in advance of its use against Japan.<ref>{{harvnb|Rhodes|1986|pp=642–643}}</ref>

=== Trinity ===
{{Main|Trinity (nuclear test)}}
[[File:Trinity Detonation T&B.jpg|thumb|upright=1.2|left|The [[Trinity (nuclear test)|Trinity test]] was the first detonation of a nuclear device.{{sfn|Jungk|1958|p=201}}|alt=a large mushroom-shaped cloud forming after a nuclear explosion]]

In the early morning hours of July 16, 1945, near [[Alamogordo, New Mexico]], the work at Los Alamos culminated in the test of the world's first [[nuclear weapon]]. Oppenheimer had code-named the site "[[Trinity (nuclear test)|Trinity]]" in mid-1944, saying later that the name came from [[John Donne]]'s ''[[Holy Sonnets]]''; he had been introduced to Donne's work in the 1930s by Jean Tatlock, who killed herself in January 1944.{{sfn|Herken|2002|pp=128–129}}{{sfn|Streshinsky|Klaus|2013|pp=194, 211}}

Brigadier General [[Thomas Farrell (United States Army officer)|Thomas Farrell]], who was present in the control bunker with Oppenheimer, recalled:

{{blockquote|Dr. Oppenheimer, on whom had rested a very heavy burden, grew tenser as the last seconds ticked off. He scarcely breathed. He held on to a post to steady himself. For the last few seconds, he stared directly ahead and then when the announcer shouted "Now!" and there came this tremendous burst of light followed shortly thereafter by the deep growling roar of the explosion, his face relaxed into an expression of tremendous relief.<ref>{{harvnb|Szasz|1984|p=88}}</ref>}}

Oppenheimer's brother Frank recalled Oppenheimer's first words as "I guess it worked."<ref>{{cite journal |last1=Bernstein |first1=Jeremy |title=Letters : Bomb in the Head |journal=London Review of Books |date=April 26, 2018 |volume=40 |issue=8 |url=https://www.lrb.co.uk/the-paper/v40/n08/letters |access-date=January 10, 2022 |issn=0260-9592 |archive-date=July 15, 2023 |archive-url=https://web.archive.org/web/20230715054555/https://www.lrb.co.uk/the-paper/v40/n08/letters |url-status=live }}</ref><ref name="WP-20220722">{{cite news |last=Johnson |first=Mark |title=How Oppenheimer weighed the odds of an atomic bomb test ending Earth |url=https://www.washingtonpost.com/science/2023/07/22/oppenheimer-manhattan-project-history-atomic-bomb-test/ |date=July 22, 2023 |newspaper=[[The Washington Post]] |url-status=live |archiveurl=https://archive.today/20230722123414/https://www.washingtonpost.com/science/2023/07/22/oppenheimer-manhattan-project-history-atomic-bomb-test/ |archivedate=July 22, 2023 |accessdate=July 22, 2023 }}</ref>

{{external media |float=right|width=18em<!--<<expressing width in ems--> |video1=[https://www.atomicarchive.com/media/videos/oppenheimer.html Oppenheimer recalling his thoughts after witnessing the Trinity test] }}
[[File:Trinity Test - Oppenheimer and Groves at Ground Zero 002.jpg|thumb|right|upright=0.8|Oppenheimer and Groves at the remains of the Trinity test tower. Oppenheimer is wearing his trademark broad-brimmed hat; white overshoes protect against [[nuclear fallout|fallout]].<ref>{{cite magazine |magazine=[[Time (magazine)|Time]] |date=September 17, 1945 |url=http://www.time.com/time/magazine/article/0,9171,854500-2,00.html |archive-url=https://web.archive.org/web/20110629043245/http://www.time.com/time/magazine/article/0,9171,854500-2,00.html |url-status=dead |archive-date=June 29, 2011 |url-access=subscription |title=Science: Atomic Footprint |access-date=March 16, 2011 }}</ref>|alt=Two men, one in a suit and hat and the other in military uniform, stand in front of twisted metal whilst wearing white overshoes]]

According to a 1949 magazine profile, while witnessing the explosion Oppenheimer thought of verses from the ''[[Bhagavad Gita]]'': "If the radiance of a thousand suns were to burst at once into the sky, that would be like the splendor of the mighty one{{nbsp}}... Now I am become Death, the shatterer of worlds."<ref name="life-1949">{{cite news | url=https://books.google.com/books?id=GVIEAAAAMBAJ&dq=oppenheimer+%22if+the+radiance+of+a+thousand+suns+were+to+%22&pg=PA133 | title=J. Robert Oppenheimer | author-first=Lincoln | author-last=Barnett | magazine=[[Life (magazine)|Life]] | date=October 10, 1949 | page=133 | access-date=July 31, 2023 | archive-date=August 9, 2023 | archive-url=https://web.archive.org/web/20230809204214/https://books.google.com/books?id=GVIEAAAAMBAJ&dq=oppenheimer+%22if+the+radiance+of+a+thousand+suns+were+to+%22&pg=PA133 | url-status=live }}</ref> In 1965 he recalled the moment this way:

{{Cquote|We knew the world would not be the same. A few people laughed, a few people cried. Most people were silent. I remembered the line from the Hindu scripture, the ''Bhagavad Gita''; Vishnu is trying to persuade [[Arjuna|the Prince]] that he should do his duty and, to impress him, takes on [[Vishvarupa|his multi-armed form]] and says, "Now I am become Death, the destroyer of worlds." I suppose we all thought that, one way or another.<ref>{{cite AV media |url=https://www.atomicarchive.com/media/videos/oppenheimer.html | title = 'Now I am become death...' | people=Oppenheimer, J.R. |year=1965 |type=video |access-date = November 19, 2021 |publisher = Atomic Archive | archive-date = May 16, 2008 | archive-url=https://web.archive.org/web/20080516104658/http://www.atomicarchive.com/Movies/Movie8.shtml | url-status = live }}</ref>{{refn|group=note|"If the radiance{{nbsp}}..." is ''Bhagavad Gita'' verse XI,12 ({{IAST|divi sūryasahasrasya bhavedyugapadutthitā / yadi bhāḥ sadṛṥī sā syādbhāsastasya mahātmanaḥ}});<ref>{{cite web |url=https://www.gitasupersite.iitk.ac.in/srimad?language=dv&field_chapter_value=11&field_nsutra_value=12&choose=1 |date=September 2, 2017 |title=Bhagavad Gita XI.12 |publisher=Gita Supersite by [[Indian Institute of Technology Kanpur]] |access-date=April 25, 2023 |archive-date=August 4, 2023 |archive-url=https://web.archive.org/web/20230804015213/https://www.gitasupersite.iitk.ac.in/srimad?language=dv&field_chapter_value=11&field_nsutra_value=12&choose=1 |url-status=live }}</ref><ref>{{cite web |access-date=October 24, 2012 |url=http://www.asitis.com/11/12.html |title=Chapter 11. The Universal Form, text 12 |work=Bhagavad As It Is |archive-date=August 4, 2013 |archive-url=https://web.archive.org/web/20130804075758/http://www.asitis.com/11/12.html |url-status=live }}</ref> "Now I am become Death{{nbsp}}..." is verse XI,32.({{IAST|kālo'smi lokakṣayakṛtpravṛddho lokānsamāhartumiha pravṛttaḥ}})

Oppenheimer had read the ''Bhagavad Gita'' in the original [[Sanskrit]], and the translation is his own.<ref name="Hijiya">{{harvnb|Hijiya|2000}}</ref><ref>{{cite web |access-date=October 24, 2012 |url=http://www.asitis.com/11/32.html |title=Chapter 11. The Universal Form, text 32 |work=Bhagavad As It Is |archive-date=November 17, 2012 |archive-url=https://web.archive.org/web/20121117120052/http://www.asitis.com/11/32.html |url-status=live }}</ref> In the literature, "shatterer" is usually given rather than "destroyer," because "shatterer" appears in the first printed rendition of Oppenheimer's anecdote (in [[Time (magazine)|''Time'' magazine]], November 8, 1948).<ref name="Eternal Apprentice"/> The "shatterer" version later appeared in [[Robert Jungk]]'s ''Brighter than a Thousand Suns: A Personal History of the Atomic Scientists'' (1958),<ref name="Jungk, p. 201">{{harvnb|Jungk|1958|p=201}}</ref> which was based on an interview with Oppenheimer.<ref>{{harvnb|Hijiya|2000|pp=123–124}}</ref>|name="quote" }}
}}

Rabi described seeing Oppenheimer somewhat later: "I'll never forget his walk ... like ''[[High Noon]]''&nbsp;... this kind of strut. He had done it."{{sfn|Monk|2012|pp=456–457}} Despite many scientists' opposition to using the bomb on Japan, Compton, Fermi, and Oppenheimer believed that a test explosion would not convince Japan to surrender.<ref>{{cite web |title=Debate over how to use the bomb |url=https://www.osti.gov/opennet/manhattan-project-history/Events/1945/debate.htm |website=The Manhattan Project |publisher=U.S. Department of Energy History Office |access-date=September 13, 2023 |archive-date=September 2, 2023 |archive-url=https://web.archive.org/web/20230902103805/https://www.osti.gov/opennet/manhattan-project-history/Events/1945/debate.htm |url-status=live }}</ref> At an August 6 assembly at Los Alamos, the evening of the [[Atomic bombings of Hiroshima and Nagasaki|atomic bombing of Hiroshima]], Oppenheimer took to the stage and clasped his hands together "like a prize-winning boxer" while the crowd cheered. He expressed regret that the weapon was ready too late for use against Nazi Germany.{{sfn|Monk|2012|pp=467–468}}

On August 17, however, Oppenheimer traveled to Washington to hand-deliver a letter to Secretary of War [[Henry L. Stimson]] expressing his revulsion and his wish to see nuclear weapons banned.{{sfn|Monk|2012|p=476}} In October he met with President [[Harry S. Truman]], who dismissed Oppenheimer's concern about an arms race with the [[Soviet Union]] and belief that atomic energy should be under international control. Truman became infuriated when Oppenheimer said, "Mr. President, I feel I have blood on my hands", responding that he (Truman) bore sole responsibility for the decision to use atomic weapons against Japan, and later said, "I don't want to see that son of a bitch in this office ever again."{{sfn|Monk|2012|pp=493–494}}{{sfn|Bird|Sherwin|2005|pp=331–332}}

For his services as director of Los Alamos, Oppenheimer was awarded the [[Medal for Merit]] by Truman in 1946.<ref>{{cite news |last1=Bella |first1=Timothy |title=The atomic bombings left Oppenheimer shattered: 'I have blood on my hands' |url=https://www.washingtonpost.com/history/2023/07/21/oppenheimer-truman-atomic-bomb-guilt/ |newspaper=[[The Washington Post]] |date=July 21, 2023 |access-date=August 18, 2023 |archive-date=August 13, 2023 |archive-url=https://web.archive.org/web/20230813140643/https://www.washingtonpost.com/history/2023/07/21/oppenheimer-truman-atomic-bomb-guilt/ |url-status=live }}</ref>