OPPENHEIMER, J. ROBERT

Robert Oppenheimer achieved great distinction in four very different ways: through his personal research, as a teacher, as director of Los Alamos, and as the elder statesman of postwar physics. These different activities belong to different periods, except that his role as teacher overlaps in time with several of these periods. We may therefore review these different contributions separately, while following a chronological order.

J. Robert Oppenheimer was the son of Julius Oppenheimer, who had immigrated as a young man from Germany.1 The fither was a successful businessman, and the family was well-to-do. His mother, the former Ella Freedman, was a painter of near professional standard, and both parents had taste for art and music.

As a boy Oppenheimer showed a wide curiosity and the ability to learn quickly. He went to the Ethical Culture School in New York, a school with high academic standards and liberal ideas. He went as a student to Harvard in 1922, and in spite of following a very broad curriculum, which included classical languages as well as chemistry and physics, he completed the four-year undergraduate course in three years and graduated summa cum laude in 1925.

With all the breadth of his interests, Oppenheimer was quite clear that his own subject was physics. During his undergraduate course he profited much from the contact with Percy Bridgman, an eminent physicist who himself had wide-ranging interests and whose publications dealt with topics far beyond the field of his own experiments; they included philosophical questions.

After graduating, Oppenheimer went to Europe; and during his four years of travel he established himself as a theoretical physicist.

Research in Quantum Mechanics. The year 1925 marked the beginning of an exhilarating period in theoretical physics. During that year Heisenberg’s first paper on the new quantum mechanics appeared, and Dirac started to develop his own version of Heisenberg’s theory in a paper which appeared in the same year. Schrödinger’s first paper on his wave equation was published early in 1926. Up to that time the principles of the quantum theory had been grafted onto the classical equations of mechanics, with which they were not consistent. The resulting rules sometimes gave unique predictions which agreed with observation; sometimes the answers were ambiguous; and sometimes the rules could not be applied at all. The new ideas showed the way of obtaining a logically consistent and mathematically clear description, and it looked as if all the old paradoxes of atomic theory would resolve themselves.

This started a period of intense activity, during which all atomic phenomena had to be reexamined in the light of the new ideas. Oppenheimer’s quickness in grasping new ideas helped him to play a part in this process. His first paper was submitted for publication in May 1926, less than four years from his entering Harvard and less than a year after Heisenherg’s first paper on quantum mechanics.2 It shows him in full command of the new methods, with which he showed that the frequencies and intensities of molecular band spectra could be obtained unambiguously from the new mechanics. A second paper, submitted in July, is concerned with the hydrogen atom;3 by this time he was making use of the full apparatus of matrix mechanics developed by Born. Heisenherg, and F. P. Jordan, of the alternative techniques of Dirac, and of Schrödinger’s wave mechanics. These two papers were written in Cambridge, and he acknowledged help from Ralph H. Fowler and Paul Dirac.

In the second paper Oppenheimer raises the question of the continuous spectrum and discusses the question of how to formulate the normalization of the wave functions for that case. This was the beginning of his interest in a range of problems which were to occupy him for some time.

In 1926 Max horn invited Oppenheimer to come to Göttingen, where he continued his work on transitions in the continuous spectrum, leading to his first calculations of the emission of X rays. He also developed, jointly with Born, the method for handling the electronic, vibrational, and rotational degrees of freedom of molecules, now one of the classical parts of quantum theory, referred to as the “Born-Oppenheimer method.”4 He obtained his Ph.D. degree in the spring of 1927.

Oppenheimer remained in Europe until 1929, spending some time with Paul Ehrenfest in Leiden and with Wolfgang Pauli in Zurich; the influence of both these men helped further to deepen his understanding of the subject. He continued with the work on radiative effects in the continuous spectrum. which he recognized as one of the important and difficult problems of the time, and found ways of improving the approximations used, which still serve as a pattern for work in this field. Among his minor papers, one deals with electron pickup by ions, a problem which requires the use of nonorthogonal wave functions.5

In 1929 Oppenheimer accepted academic positions both at the University of California, Berkeley, and at the California Institute of Technology; and between 1929 and 1942 he divided his time between these two institutions. The list of his papers during this period might almost serve as a guide to what was important in physics at that time. He was now at the top of his form in research work, and he knew what was important, so that he did not waste his time on pedantic detail. In some of these papers Oppenheimer struggled with key problems which were not yet ripe for solution, such as the difficulties of the electromagnetic self-energy, or the paradox of the “wrong” statistics of the nitrogen nucleus (wrong because, before the discovery of the neutron, nuclei were believed to consist of protons and electrons).6 But on others he was able to take important steps forward. He saw the importance of Dirac’s idea to avoid the difficulty of negative energy states for electrons by assuming them all filled except for a few holes, which were then positively charged particles. He showed, however, that Dirac could not be right in identifying these as protons, since they would have to have the same mass as electrons.7 Thus he practically predicted the positron three years before its discovery by Carl Anderson.

When cosmic-ray experiments showed serious contradiction with theory, Oppenheimer studied the possibility that this might indicate a breakdown of the accepted quantum theory of radiation.8 When the discovery of the meson resolved the paradox, he took great interest in the properties of the new particle. He also developed, in a paper with J. F. Carlson, an elegant method for investigating electron-photon showers in cosmic rays.9 In the 1930’s the cyclotron and other accelerators opened up the atomic nucleus to serious study, and Oppenheimer participated in asking important questions and in answering some of them. His paper with G. Volkoff shows a very early interest in stars with massive neutron cores.10

During the California period Oppenheimer proved to be an outstanding teacher of theoretical physics. He attracted many pupils, both graduate students and more senior collaborators, many of whom, under his inspiration, became first-rate scholars. His important qualities as a teacher were those which characterized his research: his flair for the key question, his quick understanding, and his readiness to admit ignorance and to invite others to share his struggle for the answer. His influence on his pupils was enhanced by his perceptive interest in people and by his habit of informal and charming hospitality. After his marriage in 1940 his wife, the former Katherine Harrison, helped maintain this easy and warm hospitality.

Oppenheimer still maintained a great breadth of interests, adding even Sanskrit to the languages he could, and did, read. At first his interests were exclusively academic: and he showed little interest in political questions, or in the national and world events of the day. But in the mid-1930’s he became acutely aware of the disturbing state of the world—unemployment at home, Hitler, Mussolini, and the Spanish Civil War in Europe. He became interested in politics and, like many liberal intellectuals of the day, became for a time involved with the ideas of left-wing groups.

The list of publications by Oppenheimer and his group shows a break in 1941, and this marks almost the end of his personal research (the exception being three papers published after the war) but by no means of his influence on the development of physics.

Atomic Energy: Los Alamos . The change was the result of Oppenheimer’s involvement with atomic energy. After the discovery of fission he, like many others, had started thinking about the possibility of the practical release of nuclear energy. With his quick perception he was aware of the importance of fast neutrons for any possible bomb. In 1940 and 1941 the idea of releasing nuclear energy was beginning to be taken seriously. A number of groups in different universities were working on the feasibility of a nuclear reactor, and others on methods for separating uranium isotopes. The latter would ultimately lead to the production of the light isotope (U235) in nearly pure form, and this is capable of sustaining a chain reaction with last neutrons. The reactor work led to the production of plutonium, which can be used for the same purpose. While these efforts were well under way by the beginning of 1942, there was no coordinated work on the design of an atomic weapon, its critical size, methods of detonating it, and so on. Oppenheimer had attended some meetings at which such matters were discussed, and early in 1942 he was asked to take charge of the work on fast neutrons and on the problem of the atomic bomb.

On the theoretical side Oppenheimer assembled at Berkeley a conference of first-rate theoreticians, including Edward Teller, who on that occasion first suggested the possibility of a thermonuclear explosion. The work continued in a theoretical group led by Oppenheimer at Berkeley. The experimental determination of the relevant nuclear data was divided between a large number of small nuclear physics laboratories; this hampered progress, since it was difficult for these groups to maintain adequate contact, particularly in view of the secrecy with which the whole project had to he treated.

When, therefore, the United States government brought the atomic energy work under the auspices of the army and put Colonel (later General) Leslie Groves in charge of the project under the code name “Manhattan District,” Oppenheimer suggested to Groves that the weapon development be concentrated in a single laboratory. This should include the theory and the nuclear physics work as well as the chemical, metallurgical, and ordnance aspects of the project. In this way the different groups could work together effectively.

Groves accepted the proposal, and on Oppenheimer’s advice chose the site of a boys’ boarding school at Los Alamos, New Mexico, a region Oppenheimer knew and loved—he had a ranch there. The remoteness of the site made access and transport problems difficult but seemed to have an advantage in reducing contacts with the outside—and therefore the risk of leakage of information.

Groves not only followed Oppenheimer’s advice in the creation and location of the laboratory, but he selected Oppenheimer as its director. This was a bold decision, since Oppenheimer was a theoretician with no experience of administration or of organizing experimental work. Events proved Groves right, and the work of the laboratory was extremely effective. In the view of most of the wartime members of Los Alamos, its success owed much to Oppenheimer’s leadership.

He attracted a strong team of first-rate scientists, who came because of their respect for Oppenheimer as a scientist and because of his evident sense of purpose. Inside the laboratory he was able to maintain completely free exchange of information between its scientific members; in other words, in exchange for the isolation of the laboratory and the restrictions on travel which its members had to accept, there was none of the “compartmentalization” favored in other atomic energy laboratories for the sake of security. Oppenheimer was able to delegate responsibility and to make people feel they were being trusted. At the same time his quick perception enabled him to remain in touch with all phases of the work. When there were major problems or major decisions to be taken, he guided the discussions of the people concerned in the same spirit of a joint search for the answer in which he had guided the discussions with his students. In the work he did not spare himself, and in response he obtained a sustained effort from all his staff.

It seems that the laboratory was set up just in time, because when the design of the plutonium bomb was ready, enough plutonium was available for the first bomb, The plutonium bomb required a greater design and development effort than the uranium bomb, since the more intense neutron background required a much more rapid assembly from subcritical conditions to the final, highly critical configuration. Failing this, a stray neutron is likely to set off the chain reaction when the assembly is only just critical, giving an explosion of very poor efficiency.

When the test of the first bomb at Alamogordo demonstrated the power of the new weapon, all spectators felt a terrified awe of the new power, mixed with pride and satisfaction at the success of their endeavors. Initially some were more conscious of the one emotion, some of the other. Oppenheimer, whose attitude to his own faults was as unmerciful as to those of others, if not more so, admitted later that he could not resist feeling satisfaction with the key part he had played in the work. Many accounts have quoted the verses from his Sanskrit studies of the Bhagavad-Gita which went through his mind at the time of the test, the first referring to the “radiance of a thousand suns” and the other saying, “I am become Death, the destroyer of worlds.” Besides the awareness of the technical achievement, Oppenheimer clearly did not lose sight of the seriousness of the implications.

None of this was public knowledge until 6 August 1945, when the first uranium bomb was dropped on Hiroshima. The implications of the decision to use the bomb to destroy a city will continue to occupy historians for a long time. Oppenheimer played some part in this decision: he was one of a panel of four scientists (the others being A. H. Compton, E. Fermi, and E. O. Lawrence) who were asked in May 1945 to discuss the case for the military use of the bomb on Japan. They were told that it would he impossible to cancel or delay the planned invasion of Japan, which was sure to be very costly in lives, unless Japan surrendered beforehand. Their opinion, which Oppenheimer supported, was that a demonstration on an uninhabited island would not he effective, and that the only way in which the atom bomb could be used to end the war was by actual use on a “military” target in a populated area. Today, in retrospect, many people, including many scientists, deplore this advice and the use of the bomb. Oppenheimer commented in 1962: “I believe there was very little deliberation ... The actual military plans at that time… were clearly much more terrible in every way and for everyone concerned than the use of the bomb. Nevertheless, my own feeling is that if the bombs were to he used there could have been more effective warning and much less wanton killing.…”11 lie remained for the rest of his life acutely conscious of the responsibility he bore for his part in developing the weapon and in the decision to use it.

The Aftermath of the Bomb: Princeton . At the end of 1945 Oppenheimer returned to California. This did not mean, however, returning to an ivory tower. He was by now a national figure, and his advice much in demand; he was also very seriously concerned with the issues raised by the invention of atomic weapons. He took part in the drafting of the “AchesonLilienthal Report,” which proposed the international control of atomic energy. Most of the language of this report is undoubtedly Oppenheimer’s and so, probably, are many of its ideas. The authors of this report wrote it in a generous spirit: international control of the new weapons would be used to ensure peace and to prevent any nation’s threatening another with the formidable new weapons. It probably never had much chance of becoming a political reality. A proposal embodying the outline of the report, but hardly its spirit, was presented to the United Nations by Bernard Baruch as the “Baruch Plan,” but nothing came of it.

In 1946 the Atomic Energy Commission was set up under the McMahon Act, which provided for civilian control of atomic energy. The first proposal, the May-Johnson Bill, which would have led to military control, was defeated very largely because of the opposition from scientists, although Oppenheimer was prepared to accept it. The commission appointed a General Advisory Committee, with Oppenheimer as chairman; and he served in that capacity until 1952. The committee did more than give technical advice; it had great influence on the policy of the commission. Oppenheimer’s role as chairman was not to dominate opinion but to clarify the issues and to formulate people’s thoughts. In addition to the General Advisory Committee, he served on numerous other committees concerned with policy questions relating to atomic weapons and defense.

In October 1947, Oppenheimer moved to Princeton, New Jersey, to become director of the Institute for Advanced Study. Until then the Institute had been a kind of retreat for great scientists and scholars who wanted to get on with their studies in peace. Under Oppenheimer’s regime the population of the Institute grew in number, and it included many young scientists, mostly as short-term members for a year or two. They included many visitors from other countries. Oppenheimer was an active member of the physics department and usually presided at seminar meetings.

Under Oppenheimer’s influence the physics group became one of the centers at which the current problems of modern physics were most clearly understood. Many colleagues came to discuss their ideas with Oppenheimer, and to do so meant exposing one’s thoughts to penetrating scrutiny and sometimes to withering criticism. Oppenheimer now had less time for physics than in the prewar days, and he had to form his judgments more rapidly. He was fallible, and there were occasions when he violently and effectively attacked some unfortunate speaker whose ideas were perhaps not proved hut were worth debating: there were other instances when he hailed as very promising ideas which later proved barren.

The early Princeton years were a time when there was again a buoyant optimism in physics. The theory of electrons and their electromagnetic field had been stagnant for many years because of the infinities predicted by quantum theory for the field energy of a point charge. The discovery of the “Lamb shift” in the hydrogen spectrum showed that there were some questions to which theoretical answers were needed, and the attempts to find the answers showed how one could bypass the troublesome infinities. S. Tomonaga, J. Schwinger. R. P. Feynman, and F. J. Dyson developed consistent formulations for the new form of the theory, and it was hoped that they could be extended to the proton and neutron and their interactions with the newly discovered meson field. It was a time of intense debte and discussion, and much of this took place at small ad hoc meetings of theoreticians, at which Oppenheimer was at his best in guiding discussion and in helping people to understand each other (and sometimes themselves). The phrase he used in an interview to describe the work at the Institute, “What we do not know we try to explain to each other,“ is very appropriate for these sessions. He had always had a remarkable gift for finding the right phrase, and he had now become an absolute master of the epigram.

While he did not resume personal research on any substantial scale (he was coauthor of three papers on physics after the war, one of them being a criticism of somebody else’s theory), Oppenheimer’s participation in meetings at the Institute and elsewhere was still a major factor in the development of ideas in physics.

As director of the institute, Oppenheimer was responsible also for the policy in other fields, including pure mathematics and history. Here the breadth of his knowledge was a unique qualification, lie did not, of course, take part in the work of the other groups as he did in physics, hut he could understand what was being done and could comment in a manner respected by the experts.

Throughout the postwar period Oppenheimer wrote and lectured much. At first the subject was predominantly atomic energy and its implications, and the scheme for its international control. Later he became more concerned with the relations between the scientist and society and, from this, with the problem of conveying an adequate understanding of science to the layman. In his Reith lectures on the B.B.C., “Science and the Common Understanding,” he attempted to set out what science is about.12 The language of such lectures was probably not easily followed in detail by the nonscientist, hut it had a poetic quality which to many listeners brought the subject closer.

The “Oppenheimer Case.” In December 1953, Oppenheimer was informed that his security clearance—that is, his access to secret information—was being withdrawn, because of accusations that his loyalty was in doubt. He exerted his right to ask for hearings, and he was exposed to the grueling experience of over three weeks’ quasi-judicial hearings, in which all his past was exposed to detailed scrutiny. The charges were in part his opposition in 1949 to a crash program for developing the hydrogen bomb, and in part his contacts or associations in the late 1930’s and early 1940’s with Communists and fellow travelers, contacts which had been known to the A.E.C. many years before and had then not been considered sufficiently derogatory to impede his clearance.

It is impossible to understand how these charges could he raised without remembering the atmosphere of hysterical fear of Communism of the Joseph McCarthy era and also without noting that Oppenheimer had made many enemies, who were delighted at this opportunity of curbing his influence. Some of these enemies were people he had bested in public debate, whom his devastating logic had not only shown to be wrong but also made to appear ridiculous. Others were people interested in military policy who feared his influence, which could act contrary to their interests.

The hearings before the three-man Personnel Security Board were originally intended to be confidential, but eventually the transcript was published.13 It remains an interesting historical document. The board found that Oppenheimer was “a loyal citizen” but, by a two-to-one majority, that he was to blame for opposing the hydrogen-bomb program and later was lacking in enthusiasm for it.

The report of the board went to the Atomic Energy Commission. The commissioners did not uphold the board’s (majority) decision censuring Oppenheimer for his views on the hydrogen bomb—this would have caused a powerful reaction in the scientific community—but confirmed the withdrawal of his clearance, in a majority verdict, mainly on grounds of “defects of character.” This was opposed by one of the commissioners, the physicist Henry Smyth, who wrote a minority report in favor of Oppenheimer and criticizing the arguments of his colleagues.14

Oppenheimer continued as director of the Institute and with his writing and lecturing. On many occasions audiences at his lectures gave him ovations clearly intended to express their sympathy for him and their indignation at the treatment he had received.

In 1963, when the McCarthy era was an embarrassing memory, when many of the people who had conducted the Oppenheimer investigation and made decisions had been succeeded by others, and when tempers had cooled, it was decided to make a gesture of reconciliation. Oppenheimer was given the Enrico Fermi Award for 1963, a prize of high prestige awarded by the Atomic Energy Commission. The award is usually conferred by the president, and John F. Kennedy had the intention of doing so when he was assassinated. It was then conferred by Lyndon Johnson, and Oppenheimer acknowledged it with the words he had intended to say to President Kennedy: “I think it is just possible... that it has taken some charity and some courage for you to make this award today.”

Oppenheimer knew for almost a year that he had throat cancer, and he could contemplate this fact and talk about it as lucidly as about a conclusion in physics.

NOTES

1. There has been controversy whether in “J. Robert” the “J” stood for “’Julius,” P. M. Stern (footnote at the beginning of ch. 2 of the book cited in the bibliography) quotes evidence that this was the case. We use the style Oppenheimer used, with the explanation that the letter J “stood for nothing”.

13. United States Atomic Energy Commission, In the Matter of J. Robert Oppenheimer. Transcript of Hearings Before the Personnel Security Board(Washington, D.C., 1954).

14. United States Atomic Energy Commission, In the Matter of J. Robert Oppenheimer. Text of Principal Documents (Washington, D.C., 1954).

BIBLIOGRAPHY

I Original Works. A full list of Oppenheimer’s writings can be found in the article by H. A. Bethe, in Biographical Memoirs of Fellows of the Royal Society, 14 (1968), 391-416.

II. Secondary Literature. There is as yet no booklength biography of Oppenheimer. Among his obituary notices the most important are the one by Bethe, cited above, and the record of speeches at a memorial meeting by R. Serber, V. F. Weisskopf, A. Pais, and G. T. Seaborg, inPhysics Today, 20 , no. 10 (Oct. 1967), 34-53. The dual biography by Nuel Pharr Davis, Lawrence and Oppenheimer (New York, 1968), has been strongly criticized by many reviewers—for instance, F. Oppenheimer, in Physics Today, 22 , no. 2 (Feb. 1969), 77-80.

Numerous books are primarily concerned with the “Oppenheimer case“ but bring in much biographical material. The most scholarly of these is P. M. Stern, The Oppenheimer Case; Security on Trial (New York, 1969). In addition there are C. P. Curtis, The Oppenheimer Case. The Trial of a Security System (New York, 1955); and J. Major, The Oppenheimer Hearing (London, 1971). H. Chevalier, Oppenheimer, The Story of a Friendship (New York, 1965), criticizes Oppenheimer for his conduct when questioned on security; it also contains many interesting facets of Oppenheimer’s life at Berkeley.

There is also a considerable literature on the history of the Manhattan Project, including Oppenheimer’s part in it. The official record is A History of the United States Atomic Energy Commission, 1, R. G. Hewlett and D. E. Anderson, Jr., The New World (University Park, Pa., 1962), II, R. G. Hewlett and F. Duncan, Atomic Shield (University Park, Pa., 1969). Other examples are Leslie R. Groves, Now It Can Be To Id (New York, 1962); Lewis L. Strauss, Men and Decisions (New York, 1962); D. E. Lilienthal, Journals, II, The Atomic Energy Years 1945-1950 (New York, 1964), and III, The Venturesome Years 1950-1955 (New York, 1966); and L. Givoanetti and F. Freed, The Decision to Drop the Bomb (New York, 1965).

Rudolf Peierls

Cite this article Pick a style below, and copy the text for your bibliography.

Citation styles

Encyclopedia.com gives you the ability to cite reference entries and articles according to common styles from the Modern Language Association (MLA), The Chicago Manual of Style, and the American Psychological Association (APA).

Within the “Cite this article” tool, pick a style to see how all available information looks when formatted according to that style. Then, copy and paste the text into your bibliography or works cited list.

Because each style has its own formatting nuances that evolve over time and not all information is available for every reference entry or article, Encyclopedia.com cannot guarantee each citation it generates. Therefore, it’s best to use Encyclopedia.com citations as a starting point before checking the style against your school or publication’s requirements and the most-recent information available at these sites:

Modern Language Association

The Chicago Manual of Style

American Psychological Association

Notes:

Most online reference entries and articles do not have page numbers. Therefore, that information is unavailable for most Encyclopedia.com content. However, the date of retrieval is often important. Refer to each style’s convention regarding the best way to format page numbers and retrieval dates.

In addition to the MLA, Chicago, and APA styles, your school, university, publication, or institution may have its own requirements for citations. Therefore, be sure to refer to those guidelines when editing your bibliography or works cited list.

Oppenheimer, J. Robert

OPPENHEIMER, J. ROBERT

(b. New York, New York, 22 April 1904; d. Princeton, New Jersey, 18 February 1967)

theoretical physics. For the original article on Oppenheimer see DSB, vol. 10.

The important aspects of Oppenheimer’s life were accurately and perceptively highlighted in Rudolf Peierls’s 1970 DSB entry. Since its writing, many of the details of Oppenheimer’s life have come into much sharper focus by virtue of the publication by Alice Kimball Smith and Charles Weiner of many of the letters he wrote before 1945 to his teachers, to his brother, and to his friends; and by virtue of the availability of his extensive Nachlass in the archives of the Library of Congress.

The detailed investigations and analyses by historians of the Ethical Culture Society and of its school; of the Sanskrit texts Oppenheimer studied and their canonical meaning; of the organizational structure of Los Alamos and of the technical work carried out there; of Oppenheimer’s directorship of Los Alamos, and later of the Institute for Advanced Study; of the details of his governmental advisory activities after World War II, by which time he had become a Cold Warrior; of the illegal behind-the-scene activities of J. Edgar Hoover and his Federal Bureau of Investigation (FBI), and the plotting of Lewis Strauss before the special Atomic Energy Commission (AEC) board was set up to inquire as to Oppenheimer’s suitability for a security clearance; of the machinations and illegal actions carried out by the prosecution during the “inquiry” that terminated with the revocation of his clearance in 1954; and of his subsequent activities as a public intellectual and an influential member of the Congress for Cultural Freedom, have resulted in a much more nuanced, context-dependent, and questioning portrait of the man.

Biographical Advances . Since 2000, five biographies have been published that have perceptively described all aspects of his life. All devote some chapters to a depiction of the familial, educational, social, and psychological circumstances that resulted in the precocious, brilliant, arrogant, emotionally immature, privileged Oppenheimer entering adulthood with an almost pathologically “splintered personality,” as Isador Rabi had put it.

For their biography of Oppenheimer, Kai Bird and Martin J. Sherwood unraveled the deep crisis Oppenheimer underwent during 1925–1926, the academic year he spent at Cambridge after his graduation from Harvard. Oppenheimer’s frustration in his work with Joseph John Thomson at the Cavendish, his general unhappiness with the Cambridge culture, anxieties caused by some sexual encounters, and the cooling of his friendship with some of his Harvard classmates because of their getting married, were catalysts in the breakdown. He became deeply depressed, and jealous of the success of some of the people around him, in particular of Patrick Blackett, a young experimental physicist at the Cavendish some three years his senior who had become his tutor and something of a mentor to him. Sometime in the fall of 1925 he actually left a “poisoned apple” on Blackett’s desk, an apple laced with some chemical, possibly cyanide, that might well have caused Blackett great harm. Fortunately, his deed was discovered and Blackett did not eat the apple. But Oppenheimer was hauled before the university authorities and nearly expelled. Only the intervention of his parents, and the promise that he would seek psychiatric help prevented his expulsion. He recovered, immersed himself in the work of Werner Heisenberg, Paul Dirac, and Erwin Schrödinger, and wrote two papers on the application of quantum mechanics to the vibrational and rotational spectra of molecules before leaving Cambridge in late summer 1926 to accept Max Born’s invitation to come work with him in Göttingen.

Historians now also have a much better account of all of Oppenheimer’s scientific activities during the 1930s, including his astrophysical researches that culminated with his investigations of the formation of what are now known as black holes, the final state of massive stars once they have exhausted their nuclear fuel and implode under gravitational attraction. And they also have a more deeply probing assessment of his involvement with left-wing politics during the 1930s, with such causes as the Spanish Republicans, the California Farm Workers, and the American Federation of Teachers, a branch of which he helped found at Berkeley. Oppenheimer was a member of a group that met regularly to discuss issues of the day. Three out of the four members of that group, which evidently was a secret cell of the Communist Party, were members of the Party. Many of his close friends; his brother and sister-inlaw; the woman who had introduced him to left-wing politics and to whom he considered himself engaged for a while, Jean Tatlock; his wife, Katherine “Kitty” Puening Harrison; all had been or were members of the Communist Party. There is no proof that Oppenheimer ever became a card-carrying member of the party or that he accepted party discipline, though he supported many of its activities through Party channels. The possibility that he had been a Communist during the late 1930s, and might even have perjured himself in denying this, has been raised by respected and knowledgeable historians. The issue is not likely to be resolved as it hinges on what various people thought at the time on the basis of his participation of various Communist Party–supported or Party-initiated activities. On the question of perjury, it surely hinges on what Oppenheimer believed. If he thought that signing a card or paying dues_____. both of which he made it a point never to do_____. were the key criteria for membership, then his denial that he ever was a member would not be perjury, regardless of what other people thought.

Los Alamos . In his fine “sociological biography” Charles Thorpe makes clear the dynamics involved in the construction of the complex organization of Los Alamos and the simultaneous molding of Oppenheimer’s role and authority as its charismatic director. It was a recursive process. The organizational order, the assignment of authority, Oppenheimer’s charismatic role and identity were emergent properties of the social and professional interactions of scientists, technicians, military personnel and all the other people that had been brought together to accomplish the military mission of building an atomic bomb and of Oppenheimer’s interaction with them. Thorpe also highlights the complementary roles at Los Alamos of Oppenheimer and Gen. Leslie Grove and the nature of their relationship and interactions.

This greater insight into the actions and character of Oppenheimer is the result of recent scholarship that has provided a much better understanding of the context in which his actions took place: scientists as political activists in the United States during the 1930s; the prewar Berkeley milieu; Los Alamos; the post–World War II loyalty-security regime; McCarthyism; the Cold War regime and its impact on intellectuals in the United States and in Europe. Oppenheimer’s staunch anticommunism and his deep distrust of the Soviet Union after World War II have been documented by meticulous research. How these views affected his political stand relating to the international control of nuclear energy and nuclear weapons after the rejection of the Acheson-Lilienthal plan by Bernard

Baruch, a close advisor of President Harry S. Truman, and the Soviet’s rejection of the Baruch proposal have been clarified by the researches of James Hershberg and others. Similarly, Priscilla McMillan has written a careful and sensitive chronicle and analysis of the deliberate campaign to destroy Oppenheimer that led to the “inquiry” he underwent_____. a campaign that was responsible for initiating the nuclear arms race between the United States and the Soviet Union that plagued the world for fifty years. Finally, Charles Thorpe’s investigation of Oppenheimer’s activities in the Congress for Cultural Freedom has revealed an important facet of his life in the aftermath of the revocation of his clearance.

All this recent scholarship corroborates what Cathryn Carson states in the Introduction to Reappraising Oppenheimer, the book which she and David Hollinger edited and which is the best entry into recent scholarship on Oppenheimer: “If we can see Oppenheimer in his complexity as something more than a singular individual_____. as a man mirroring and responding to a panoply of contradictory forces_____. then we may come closer to capturing his sense that the life he lived had significance beyond its individual confines” (Carson and Hollinger, p. 9).

SUPPLEMENTARY BIBLIOGRAPHY

Oppenheimer’s papers are located in the Manuscript Division of the Library of Congress. His papers relating to his directorship of the Institute of Advanced Study (IAS) are located at the IAS. A useful short bibliography compiled on the occasion of a Centennial Conference at Berkeley is available from http://ohst.berkeley.edu/oppenheimer/biblio.html.

WORKS BY OPPENHEIMER

Robert Oppenheimer: Letters and Recollections. Edited by Alice Kimball Smith and Charles Weiner. Cambridge, MA: Harvard University Press. 1980. Many of his pre-1945 letters and a list of his scientific and other published papers.

OTHER SOURCES

Biographical Works Bernstein, Jeremy. Oppenheimer: Portrait of an Enigma. Chicago: Ivan R. Dee, 2004. Provides perspectives on Oppenheimer’s strengths as a physicist, written by a member of the contemporary physics community.

Bird, Kai, and Martin J. Sherwin. American Prometheus: The Triumph and Tragedy of J. Robert Oppenheimer. New York: Knopf, 2005. Full of detail, the result of almost twenty-five years of scholarship and more than two hundred interviews with Oppenheimer’s students, associates, friends, and family.

Carson, Cathryn, and David A. Hollinger, eds. Reappraising Oppenheimer: Centennial Studies and Reflections. Berkeley: Office for History of Science and Technology, University of California, Berkeley, 2005. The best entry into the writings on J. Robert Oppenheimer. The book also gives a valuable reassessment of Oppenheimer’s place in the history of the United States during the twentieth century.

Cassidy, David C. J. Robert Oppenheimer and the American Century. New York: Pi Press, 2005. Good description of the changing relationship between science and government.

Herken, Gregg. Brotherhood of the Bomb: The Tangled Lives and Loyalties of Robert Oppenheimer, Ernest Lawrence, and Edward Teller. New York: Henry Holt, 2002. Describes rivalries and cooperation among physicists.

Pais, Abraham, with supplemental material by Robert P. Crease. J. Robert Oppenheimer: A Life. New York: Oxford University Press, 2006. By a physicist who was also Oppenheimer’s neighbor.

Schweber, S. S. In the Shadow of the Bomb: Bethe, Oppenheimer, and the Moral Responsibility of the Scientist. Princeton, NJ: Princeton University Press, 2000. Describes the role of Bethe and Oppenheimer in their roles as advisers to the government and emphasizes the moral dilemmas faced by these scientists.

Thorpe, Charles. Oppenheimer: The Tragic Intellect. Chicago: University of Chicago Press, 2006. Covers Oppenheimer’s activities at Los Alamos and as a public intellectual after World War II.

Directorship of Los Alamos

Rhodes, Richard. The Making of the Atomic Bomb. New York: Simon and Schuster, 1986.

AEC Inquiry into Security Clearance

Polenberg, Richard, ed. In the Matter of J. Robert Oppenheimer: The Security Clearance Hearing. Ithaca, NY: Cornell University Press, 2002.

U.S. Atomic Energy Commission. In the Matter of J. Robert Oppenheimer: Transcript of Hearing before Personnel Security Board and Texts of Principal Documents and Letters. Cambridge, MA: MIT Press. 1971. Covers the 1954 AEC inquiry into Oppenheimer’’’s security clearance.

Miscellaneous

Adams, John, and Peter Sellars. Doctor Atomic. An opera by the contemporary minimalist American composer John Adams, with libretto by Peter Sellars. It premiered at the San Francisco Opera on 1 October 2005.

Else, Jon, and KTEH-TV (San Jose, California). The Day after Trinity: J. Robert Oppenheimer and the Atomic Bomb. A film by Jon Else. Santa Monica, CA: Pyramid Films, 1981.

Kipphardt, Heinar. In the Matter of J. Robert Oppenheimer: A Play Freely Adapted on the Basis of the Documents by Heinar Kipphardt. New York: Hill and Wang, 1968.

Silvan Schweber

Cite this article Pick a style below, and copy the text for your bibliography.

Citation styles

Encyclopedia.com gives you the ability to cite reference entries and articles according to common styles from the Modern Language Association (MLA), The Chicago Manual of Style, and the American Psychological Association (APA).

Within the “Cite this article” tool, pick a style to see how all available information looks when formatted according to that style. Then, copy and paste the text into your bibliography or works cited list.

Because each style has its own formatting nuances that evolve over time and not all information is available for every reference entry or article, Encyclopedia.com cannot guarantee each citation it generates. Therefore, it’s best to use Encyclopedia.com citations as a starting point before checking the style against your school or publication’s requirements and the most-recent information available at these sites:

Modern Language Association

The Chicago Manual of Style

American Psychological Association

Notes:

Most online reference entries and articles do not have page numbers. Therefore, that information is unavailable for most Encyclopedia.com content. However, the date of retrieval is often important. Refer to each style’s convention regarding the best way to format page numbers and retrieval dates.

In addition to the MLA, Chicago, and APA styles, your school, university, publication, or institution may have its own requirements for citations. Therefore, be sure to refer to those guidelines when editing your bibliography or works cited list.

J. Robert Oppenheimer

J. Robert Oppenheimer

The American physicist J. Robert Oppenheimer (1904-1967) made fundamental contributions to theoretical physics and was director of the atomic energy research project at Los Alamos, N.Mex.

On April 22, 1904, J. Robert Oppenheimer, whose father was a German immigrant and wealthy textile importer, was born in New York City. After attending the Ethical Culture School in New York, where his lifelong devotion to literature, the arts, and science was nurtured, he entered Harvard University in 1922 and completed his bachelor's degree in 3 years. He required only 2 additional years of study at Cambridge University and the University of Göttingen to complete his doctoral degree in 1927.

Following 2 years of postdoctoral study at home and abroad on fellowships, Oppenheimer became associate professor of physics at the California Institute of Technology in Pasadena. Almost immediately, however, he began spending part of each academic year at the University of California at Berkeley, and he simultaneously rose through the academic ranks at both institutions. His teaching and research abilities were so exceptional and his personal magnetism was so great that many of his students followed him in his annual Berkeley-Pasadena pilgrimages, often willingly repeating the courses he offered. In general, by attracting and training an unusually large number of highly competent physicists, Oppenheimer, more than any other individual, was responsible for moving theoretical physics in America from a position of obscurity into one of preeminence in the world.

Oppenheimer's own researches between 1926 and 1942 took root in his extremely insightful exploitation of the recently discovered quantum mechanics of Werner Heisenberg, Erwin Schrödinger, Paul Dirac, Max Born, and others. With Born he developed a now-standard quantum theoretical understanding of molecules and their spectra. He undertook extensive investigations on processes involving transitions to the continuous spectrum, showing, for example, how to understand the photoelectric effect quantum-mechanically. He explored electron capture and exchange processes, as well as electron-atom collision processes. In 1930 he presented a cogent symmetry argument that was later recognized to be tantamount to the prediction of the positive electron, or positron. He studied the production of cosmic-ray showers. He explored various problems in quantum electrodynamics, as well as the properties and role of the meson in nuclear forces. He helped develop the so-called Oppenheimer-Phillips interpretation of deuteronnuclear reactions, which eventually led to great insight into the structure of the nucleus. In all of these theoretical investigations—and many more could be cited— Oppenheimer displayed his genius in implementing Wolfgang Pauli's conviction that a physicist should concern himself first and foremost with those problems on the very frontiers of current knowledge.

To the general public, Oppenheimer, as a scientist, is best known for his role in directing the development of the atomic bomb at Los Alamos, the laboratory high on a New Mexican mesa at a site he chose. Many of America's foremost physicists were persuaded to come with their families to this isolated laboratory to beat the Germans in the development of the most awesome weapon of destruction in human history. When all of the huge and unique problems were solved, and the test bomb was exploded on July 16, 1945, in the desert near Alamogordo, N. Mex., Oppenheimer was deeply shaken. He thought of the words from the Bhagavad-Gita: "If the radiance of a thousands suns/ Were to burst into the sky/That would be like/The splendor of the Mighty One…./Iam become Death, the shatterer of worlds." Not much later Hiroshima and Nagasaki were obliterated.

Oppenheimer was a complex man, one who could inspire distrust as well as utter devotion, and one who could commit indiscretions as well as be a scientist of faultless integrity. After the war, his early left-wing sympathies, inflated by Senator Joseph McCarthy and his coterie of witch-hunters, made Oppenheimer the defendant in perhaps the most celebrated trial since the time of Galileo. In spite of the fact that Oppenheimer's past associations had aroused no undue concern earlier—he had received the coveted Presidential Medal of Merit in 1946 and had been serving on the highest policy-making committees—his security clearance was revoked, deeply shocking the vast majority of his fellow scientists. Not until 1961, when President John F. Kennedy made the decision to give the Fermi Award to Oppenheimer (it was actually presented in 1963 by President Lyndon B. Johnson), was a significant attempt made to publicly clear Oppenheimer's name. In the interim, Oppenheimer had been serving as the director of the Institute for Advanced Study in Princeton, giving his splendid administrative and technical talents to the young group of highly gifted physicists who had gathered there.

Oppenheimer will remain a subject of study, discussion, controversy, and admiration for years to come. His profound concern for uniting the intellectual community, and humanity in general, is evident from the vast number of lectures and articles he devoted to the subject. He died of cancer in Princeton on Feb. 18, 1967.

Further Reading

The most complete obituary notice of Oppenheimer is by H. A. Bethe in the Royal Society of London, Biographical Memoirs of Fellows of the Royal Society, vol. 14 (1968). Considerable biographical information, along with selected writings of Oppenheimer included as an addendum, is in a study of his scientific contributions to atomic theory: Michel Rouze, Robert Oppenheimer: The Man and His Theories, translated by Patrick Evans (1964). See also Peter Michelmore, The Swift Years: The Robert Oppenheimer Story (1969).

A number of works deal with the dramatic and controversial investigation of Oppenheimer's security status. The reports of the U.S. Atomic Energy Commission in 1954-1955, published as In the Matter of J. Robert Oppenheimer, constitute the official record of his trial. Haakon Chevalier, Oppenheimer: The Story of a Friendship (1965), is a personal account of the still obscure events of the 1940s. Other books on this aspect of Oppenheimer's life are Joseph and Stewart Alsop, We Accuse! (1954); Cushing Strout, ed., Conscience, Science and Security: The Case of Dr. J. Robert Oppenheimer (1963); and Philip M. Stern and Harold P. Green, The Oppenheimer Case: Security on Trial (1969).

For Oppenheimer's work on atomic energy see J. Alvin Kugelmass, J. Robert Oppenheimer and the Atomic Story (1953); Richard G. Hewlett and Oscar E. Anderson, Jr., A History of the United States Atomic Energy Commission (2 vols., 1962-1969); and Nuel Pharr Davis, Lawrence and Oppenheimer (1968). □

Cite this article Pick a style below, and copy the text for your bibliography.

Citation styles

Encyclopedia.com gives you the ability to cite reference entries and articles according to common styles from the Modern Language Association (MLA), The Chicago Manual of Style, and the American Psychological Association (APA).

Within the “Cite this article” tool, pick a style to see how all available information looks when formatted according to that style. Then, copy and paste the text into your bibliography or works cited list.

Because each style has its own formatting nuances that evolve over time and not all information is available for every reference entry or article, Encyclopedia.com cannot guarantee each citation it generates. Therefore, it’s best to use Encyclopedia.com citations as a starting point before checking the style against your school or publication’s requirements and the most-recent information available at these sites:

Modern Language Association

The Chicago Manual of Style

American Psychological Association

Notes:

Most online reference entries and articles do not have page numbers. Therefore, that information is unavailable for most Encyclopedia.com content. However, the date of retrieval is often important. Refer to each style’s convention regarding the best way to format page numbers and retrieval dates.

In addition to the MLA, Chicago, and APA styles, your school, university, publication, or institution may have its own requirements for citations. Therefore, be sure to refer to those guidelines when editing your bibliography or works cited list.

Oppenheimer, Robert

Oppenheimer, Robert

AMERICAN PHYSICIST1904–1967

The son of a wealthy New York City textile importer (Julius) and a painter (Elle Friedman), Julius Robert Oppenheimer enjoyed an affluent childhood. He graduated from the Ethical Culture School of New York at the top of his class in 1921 and summa cum laude from Harvard in 1925. He then studied at the Cavendish Laboratory in Cambridge, England, and with Max Born at the University of Göttingen, in Germany, where he earned a doctorate in 1927. Although a rising star, he often was plagued by deep self-doubts and dark moods.

In 1929 Oppenheimer moved to California and for many years taught at both the California Institute of Technology (Caltech) and the University of California, Berkeley. He made several contributions to subatomic physics, including (with his former mentor) the Born–Oppenheimer approximation, which posited that the spin and vibration of protons could be ignored in theoretical calculations. Thin, wiry, enigmatic, and charismatic, Oppenheimer was associated with several leftist groups, which he helped fund. In 1940 he married biologist Katherine Harrison, a former member of the Communist Party.

Oppenheimer declared his leftist ties severed soon after he joined a secret group of elite scientists working with Ernest O. Lawrence at Berkeley's radiation laboratory to develop an atomic bomb. In spite of continuing suspicions about his loyalty, the U.S. Army appointed him director of the bomb design unit in October 1942. Oppenheimer's team of hundreds of gifted young scientists was secluded at a facility in Los Alamos, New Mexico. One of the brightest, Edward Teller, became a disaffected rival of Oppenheimer, but most found him a brilliant and inspiring leader.

Pushing the boundaries of theoretical physics , Oppenheimer's Los Alamos scientists followed two technological paths simultaneously. One was a "gun assembly" designed to fire two masses of uranium at each other to initiate a chain reaction. But because fissionable uranium was exceedingly difficult to refine, other scientists worked on a design using more readily available but less stable plutonium, imploding a hollow sphere of the fuel with high explosives. Both designs worked, and they were used against Japan—a uranium bomb was dropped over Hiroshima, a plutonium one over Nagasaki—in early August 1945 to end World War II.

Initially, Oppenheimer was elated over these technical achievements, but he quickly be came regretful and despondent about a nuclear future. As director of the prestigious Center for Advanced Study at Princeton (1947–1952) and chair of the General Advisory Committee of the Atomic Energy Commission (AEC), he was an outspoken advocate for the international sharing of nuclear technology and for international arms control, and he opposed further development of the hydrogen bomb. After a 1954 hearing, the AEC security board affirmed his loyalty but revoked his security clearance. Although there is little hard evidence that Oppenheimer ever passed atomic secrets to the former Soviet Union, the controversy surrounding this claim continues. Oppenheimer spent his final years sailing in the Virgin Islands and writing about science and Western culture. He died in Princeton, New Jersey, on February 18, 1967.

EDWARD TELLER (1908–2003)

Edward Teller was a physical chemist and an important, if controversial, voice in the politics of nuclear science. His work contributed to an understanding of both fusion and fission bombs. Regarded as the "father of the H-bomb," he was an ardent anticommunist and cold war warrior and he staunchly advocated the development and stockpiling of nuclear weapons. He opposed treaties limiting nuclear arsenals and testing, and he supported the development of space-based weapons.

—Valerie Borek

see also Lawrence, Ernest; Manhattan Project.

David B. Sicilia

Bibliography

Herken, Gregg (2002). Brotherhood of the Bomb: The Tangled Lives and Loyalties of Robert Oppenheimer, Ernest Lawrence, and Edward Teller. New York: Henry Holt and Co.

Rhodes, Richard (1986). The Making of the Atomic Bomb. New York: Simon & Schuster.

Rhodes, Richard (1995). Dark Sun: The Making of the Hydrogen Bomb. New York: Simon & Schuster.

Cite this article Pick a style below, and copy the text for your bibliography.

Citation styles

Encyclopedia.com gives you the ability to cite reference entries and articles according to common styles from the Modern Language Association (MLA), The Chicago Manual of Style, and the American Psychological Association (APA).

Within the “Cite this article” tool, pick a style to see how all available information looks when formatted according to that style. Then, copy and paste the text into your bibliography or works cited list.

Because each style has its own formatting nuances that evolve over time and not all information is available for every reference entry or article, Encyclopedia.com cannot guarantee each citation it generates. Therefore, it’s best to use Encyclopedia.com citations as a starting point before checking the style against your school or publication’s requirements and the most-recent information available at these sites:

Modern Language Association

The Chicago Manual of Style

American Psychological Association

Notes:

Most online reference entries and articles do not have page numbers. Therefore, that information is unavailable for most Encyclopedia.com content. However, the date of retrieval is often important. Refer to each style’s convention regarding the best way to format page numbers and retrieval dates.

In addition to the MLA, Chicago, and APA styles, your school, university, publication, or institution may have its own requirements for citations. Therefore, be sure to refer to those guidelines when editing your bibliography or works cited list.

Oppenheimer, J. Robert

Oppenheimer, J. Robert (1904–1967), physicist.Perhaps the most controversial scientist of this century, J. Robert Oppenheimer was awarded kudos in the 1940s for his contributions to the war effort and censure for allegedly betraying the country of his birth. Born in New York City and educated at Harvard and Görringen, Oppenheimer earned his Ph.D. in 1927 and quickly became recognized as a leader in theoretical physics, simultaneously rising through the academic ranks at the California Institute of Technology and the University of California at Berkeley, and gathering large numbers of the best scientific minds in the United States to his seminars and laboratories. In so doing, he became the catalyst for the emergence of American theoretical physics as preeminent in the world.

At the National Academy of Scientists in 1941, Oppenheimer led a group of scientists in theoretical discussions of nuclear bombs. Although intensely ambivalent about the creation of such weapons of mass destruction, he was concerned that the Nazis might produce one first, so he accepted an offer from Gen. Leslie Groves to serve as director of a highly classified U.S.‐led effort to build an atomic bomb. This effort, the Manhattan Project, was headquartered at Los Alamos, New Mexico. Many atomic scientists gathered there between 1942 and the first detonation of an atomic bomb on 16 July 1945.

Even though the dropping of atomic bombs on Hiroshima and Nagasaki ended World War II and kept the Russians from invading Japan, Oppenheimer was overwhelmed by the devastation he had wrought. He called for a cessation of atomic research or for international guidelines on the use of atomic weaponry. Both during the war and later he became associated with Communist Party members and others with strong leftist political positions. Although no clear violations of security were ever proven, there had been instances of negligence and indiscretion. During the McCarthy investigations and purges of alleged Communists in the U.S. government in the 1950s, Oppenheimer lost his security clearance and was forced to resign from the seven atomic committees he chaired. He became director of the Institute for Advanced Study in Princeton and was later at least partially vindicated when President Lyndon B. Johnson presented him with the Enrico Fermi Award in 1963.[See also Cold War: Domestic Course.]

Citation styles

Encyclopedia.com gives you the ability to cite reference entries and articles according to common styles from the Modern Language Association (MLA), The Chicago Manual of Style, and the American Psychological Association (APA).

Within the “Cite this article” tool, pick a style to see how all available information looks when formatted according to that style. Then, copy and paste the text into your bibliography or works cited list.

Because each style has its own formatting nuances that evolve over time and not all information is available for every reference entry or article, Encyclopedia.com cannot guarantee each citation it generates. Therefore, it’s best to use Encyclopedia.com citations as a starting point before checking the style against your school or publication’s requirements and the most-recent information available at these sites:

Modern Language Association

The Chicago Manual of Style

American Psychological Association

Notes:

Most online reference entries and articles do not have page numbers. Therefore, that information is unavailable for most Encyclopedia.com content. However, the date of retrieval is often important. Refer to each style’s convention regarding the best way to format page numbers and retrieval dates.

In addition to the MLA, Chicago, and APA styles, your school, university, publication, or institution may have its own requirements for citations. Therefore, be sure to refer to those guidelines when editing your bibliography or works cited list.

Oppenheimer, J. Robert

The Columbia Encyclopedia, 6th ed.

Copyright The Columbia University Press

J. Robert Oppenheimer (ŏp´ənhī´mər), 1904–67, American physicist, b. New York City, grad. Harvard (B.A., 1925), Ph.D. Univ. of Göttingen, 1927. He taught at the Univ. of California and the California Institute of Technology from 1929 (as professor from 1936) until his appointment in 1947 as director of the Institute for Advanced Study at Princeton, N.J. His early work was concerned with the quantum theory and nuclear physics. With Max Born he contributed to the quantum theory of molecules, and later (1930) he published an important paper on the nature of antiparticles, which had been predicted but not yet detected.

As director of the atomic-energy research project at Los Alamos, N.Mex., from 1942 to 1945, Oppenheimer made important contributions to the development of atomic energy for military purposes. After the atomic bomb was used against Japan, Oppenheimer became one of the foremost proponents of civilian and international control of atomic energy; he was chairman of the general advisory committee of the U.S. Atomic Energy Commission from 1946 to 1952 and consultant to the American delegate to the UN Atomic Energy Committee. He opposed the development of the hydrogen bomb in 1949 on technical, financial, and moral grounds. In 1953, Oppenheimer was suspended by the Atomic Energy Commission as an alleged security risk, in part due to criticism from Edward Teller, who was instrumental in the hydrogen bomb's development. Oppenheimer's case stirred wide controversy. Declassified in 2014, transcripts of the secret hearings tend to exonerate him of any disloyality. In Oct., 1954, he was unanimously reelected director of the Institute for Advanced Study. In addition to his contributions as a theoretical physicist and an administrator, Oppenheimer achieved a reputation as one of the outstanding teachers of his generation; he left a lasting influence both at California and at Princeton. His book Science and the Common Understanding was published in 1954.

Citation styles

Encyclopedia.com gives you the ability to cite reference entries and articles according to common styles from the Modern Language Association (MLA), The Chicago Manual of Style, and the American Psychological Association (APA).

Within the “Cite this article” tool, pick a style to see how all available information looks when formatted according to that style. Then, copy and paste the text into your bibliography or works cited list.

Because each style has its own formatting nuances that evolve over time and not all information is available for every reference entry or article, Encyclopedia.com cannot guarantee each citation it generates. Therefore, it’s best to use Encyclopedia.com citations as a starting point before checking the style against your school or publication’s requirements and the most-recent information available at these sites:

Modern Language Association

The Chicago Manual of Style

American Psychological Association

Notes:

Most online reference entries and articles do not have page numbers. Therefore, that information is unavailable for most Encyclopedia.com content. However, the date of retrieval is often important. Refer to each style’s convention regarding the best way to format page numbers and retrieval dates.

In addition to the MLA, Chicago, and APA styles, your school, university, publication, or institution may have its own requirements for citations. Therefore, be sure to refer to those guidelines when editing your bibliography or works cited list.

Oppenheimer, (Julius) Robert

Oppenheimer, (Julius) Robert (1904–67) US physicist. He was appointed director (1943–45) of the Los Alamos laboratory in New Mexico, where he headed the Manhattan Project to develop the atomic bomb. In 1949, Oppenheimer opposed the construction of the hydrogen bomb. In 1953, following investigations by Senator Joseph McCarthy, Oppenheimer was suspended by the Atomic Energy Commission. In 1963, he was reinstated.

Cite this article Pick a style below, and copy the text for your bibliography.

Citation styles

Encyclopedia.com gives you the ability to cite reference entries and articles according to common styles from the Modern Language Association (MLA), The Chicago Manual of Style, and the American Psychological Association (APA).

Within the “Cite this article” tool, pick a style to see how all available information looks when formatted according to that style. Then, copy and paste the text into your bibliography or works cited list.

Because each style has its own formatting nuances that evolve over time and not all information is available for every reference entry or article, Encyclopedia.com cannot guarantee each citation it generates. Therefore, it’s best to use Encyclopedia.com citations as a starting point before checking the style against your school or publication’s requirements and the most-recent information available at these sites:

Modern Language Association

The Chicago Manual of Style

American Psychological Association

Notes:

Most online reference entries and articles do not have page numbers. Therefore, that information is unavailable for most Encyclopedia.com content. However, the date of retrieval is often important. Refer to each style’s convention regarding the best way to format page numbers and retrieval dates.

In addition to the MLA, Chicago, and APA styles, your school, university, publication, or institution may have its own requirements for citations. Therefore, be sure to refer to those guidelines when editing your bibliography or works cited list.