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“Any single one of the following contributions would have marked Oppenheimer out as a pre-eminent scientist: his own research work in physics; his influence as a teacher; his leadership at Los Alamos; the growth of the Institute for Advanced Study to a leading centre of theoretical physics under his directorship; and his efforts to promote a more common understanding of science. When all combined, we honour Oppenheimer as a great leader of science in our time. When all is interwoven with dramatic events that centred around him, we remember Oppenheimer as one of the most remarkable personalities of this century.” Abraham Pais “It is not possible to be a scientist unless you believe that knowledge of the world, and the power which this gives, is a thing which is of intrinsic value to humanity, and that you are using it to help in the spread of knowledge, and are willing to take the consequences.” Robert Oppenheimer | |
Julius Robert Oppenheimer was a first class theoretical physicist, a synthesiser of ideas, an inspiring teacher, an able scientific administrator, a nuclear policy-maker and an advocate of international arm control. However, Oppenheimer is mainly remembered for his association with the Manhattan Project. This project spearheaded by Oppenheimer led to the development of the atomic bomb. This was one of the most controversial scientific enterprises of the 20th century. The story of Oppenheimer or the story of how the atomic weapon was made, is really gripping. Oppenheimer was one of the most brilliant men of the twentieth century. Thus his longtime associate Charles Lauritsen said: “This man was unbelievable. He always gave you the answer before you had the time to formulate the question.” He was one of the most inspiring teachers of his time. The story of Oppenheimer’s life and work make a compelling reading. It is compelling not only because he headed a project that unleashed a terrifying power that changed the world for ever but it also clearly demonstrated what dominating role science would play in the world affairs. Oppenheimer was born on April 22, 1904 to a wealthy family in New York. In those days New York was the scientific and commercial capital of the USA. His father Julius Oppenheimer had come to the USA from Germany at the age of 17 in 1888. At the time of his arrival, Julius had no fortune. He possessed few job skills and he could speak little English. However, he prospered in his adopted country as a successful garment importer. To make a career, Julius was helped by his other family members, who were already in the USA. Two of his older cousins had come to New York about 10 years before Julius’ arrival. Julius Oppenheimer was quite active in many community affairs. He was interested in art and music. In his collection of paintings he had three Van Gogh’s. Oppenheimer’s mother, Ella Oppenheimer (nee Freedman) was a painter, who had studied in Paris. Oppenheimer attended the New York School for Ethical Culture. It is in this school Oppenheimer spent almost the whole period of his pre-college studies. The school, run by Felix Adler, a philosopher and an educator, was one of the best schools in New York. At all levels, the school curriculum stressed the responsibility of the individual to the larger society. In school he was taught language, literature including Greek and French literature, science, art and ethics. He had a true feel for language. He could learn a new language in a period of one or two months. He learnt Sanskrit. He had developed a keen interest in literature. He had even written some philosophical poems. Oppenheimer’s interest in science developed very early. Since his childhood he was always eager to explore the nature around him and to understand its different phenomena. Already at the age of five, Oppenheimer collected mineralogical specimens. It was his grandfather who made him interested in mineralogy. One of his biographers, Jack Rummel, wrote: “When he was five, his parents took him and his brother Frank back to Germany to visit his grandfather, Benjamin, who had remained in Europe after Julius Oppenheimer immigrated to the United States. His grandfather gave Robert a gift of a collection of minerals. The chiseled and glittering stones immediately captivated the boy. After he returned to the United States, he became a devoted amateur mineralogist, often touring the countryside during weekends in search of new samples to add to his collection. His fascination with geology and mineralogy became so strong that by his 11th birthday he had become an elected member of the New York Mineralogical Club. His first scientific paper was a report about minerals that he read to the club when he was 12.” After completing his school education in 1922, Oppenheimer joined the Harvard University. In 1925 he graduated with a major in chemistry. He took just three years for the normal four-year course. In addition to studying the science subjects he learnt Latin and Greek. At Harvard he was very much influenced by Percy Williams Bridgman (1882-1961), an original experimental physicist. It was Bridgman, who attracted Oppenheimer to the world of physics. In Oppenheimer’s own words Bridgman was “wonderful teacher because he never really was quite reconciled to things being the way they were and he always thought them out; his exercises were a good way to learn where the bones were in …physics…He was a man to whom one wanted to appreciate.” At Harvard Oppenheimer did not miss any chance to gain knowledge. Later he said: “I had a real chance to learn. I loved it. I almost came alive. I took more courses than I was supposed to, lived in the library stacks, just raided the place intellectually.” In the last year of his graduation, Oppenheimer had made up his mind to plunge into the world of physics. The decision was not easy. He knew that his degree majoring in chemistry would not be welcomed by the renowned physicists at the leading European universities, with whom Oppenheimer would like to work for his graduate study in physics. He also knew that he had only a beginner’s knowledge in physics. With a letter of recommendation from Percy Bridgman, Oppenheimer left USA for England in September 1925. This was the beginning of his four-year tour to the great centres of physics in Europe. The year 1925, in which Oppenheimer decided to enter physics, was very important in the history of physics. In this year the modern quantum mechanics came into being. He spent the year 1925-26 at the Cavendish Laboratory of the Cambridge University, where he came in contact with Lord Ernest Rutherford (1871-1937), one of the finest research physicists of the twentieth century. Initially Rutherford was not very willing to admit Oppenheimer as a student at the Cavendish Laboratory. However, relentless pleading for admittance by Oppenheimer persuaded Rutherford to change his mind. Oppenheimer was placed under the charge of Joseph John Thomson (1856-1940), who had discovered electron in 1897. The stay at Cambridge was not much enjoyable for Oppenheimer. He had to consult a psychiatrist for treatment for his emotional problems. He did not like the work at Thomson’s laboratory. He wrote to one of his Harvard friends, Francis Fergusson: “I am having a pretty bad time. The lab work is a terrible bore, and I am so bad at it that it is impossible to feel that I am learning anything.” At Cambridge he read physics with all seriousness. He became familiar with the new ideas in physics. He mastered quantum mechanics. At Cavendish Laboratory Oppenheimer also met Niels Bohr, who had come there to meet his old teacher Rutherford. Oppenheimer realized that his aptitude was more suited to theoretical physics and not experimental physics. Eventually he overcame his emotional insecurities. After completing one year at Cambridge he went to Germany to work with the German-born British theoretical physicist Max Born (1882-1970) at the University of Gottingen for his PhD. He completed his PhD within two years after his graduation. With Born, Oppenheimer wrote a very important paper on the “Quantum Theory of Molecules.” After obtaining his PhD in 1927, he returned to the USA for the academic year 1927-28 and became a Fellow of the National Research Council, first at Harvard University and then at the California Institute of Technology. As a Fellow of the International Education Board (1928-29), Oppenheimer visited Leiden and Zurich. During this period he worked with the Austrian-born American physicist Wolfgang Pauli (1900-58), who influenced his scientific work to a great extent. During his stay at Europe, Oppenheimer also interacted with the German physicist Werner Heisenberg (1901-76), and the Italian-born American physicist Enrico Fermi (1901-54). Heisenberg formulated the principle of nuclear indeterminancy and he was awarded Nobel Prize in physics in 1932. It was Fermi who directed the construction of the first atomic pile. Fermi was awarded the Nobel Prize in physics in 1938. Commenting on the work done by Oppenheimer during his stay at Europe, Rummel wrote: “Between 1926 and 1929, his last year in Europe, Oppenheimer published 16 papers on the physics of quantum mechanics. His papers, which were densely mathematical and difficult for a non-physicist to understand, used the concept of quantum theory to focus on different aspects of the atom, such as electron spin, or the idea that the electron itself spins on its own axis as it moves around the nucleus in the same way the Earth spins as it moves around the Sun. The concept of electron spin helped physicists resolve questions about how the atom binds together.” The sixteen papers published by Oppenheimer marked him as a rising theoretical physicist. After returning from Europe, Oppenheimer accepted joint appointments at the California Institute of Technology at Pasadena and the University of California at Berkeley. The areas in which he worked included quantum electrodynamics, cosmic rays, nuclear physics and astrophysics including the first theoretical suggestion of black holes. It was at Berkeley, that Oppenheimer created his great school of theoretical physics. Most of the best theoretical physicists who grew up in 1930s or 1940s were trained by Oppenheimer at one stage or other. Hans Albert Bethe (1906- ), who worked with Oppenheimer at Los Alamos, wrote: “…Oppenheimer created the greatest school of theoretical physics that the United States has ever known. Before him, theoretical physics in America was a fairly modest enterprise, although there were a few representatives. Probably the most important ingredient he brought to his teaching was his exquisite taste. He always knew what were the important problems, as shown by his choice of subjects. He truly lived with these problems, struggling for a solution, and he communicated his concern to his group. In its heyday, there were about eight or ten graduate students in his group and about six Post-doctoral Fellows. He met this group once a day in his office, and discussed with one another the status of the student’s research problem. He was interested in everything, and in one afternoon they might discuss quantum electrodynamics, cosmic rays, electron pair production and nuclear physics.” In California, Oppenheimer actively participated in radical politics. Besides joining the radical Teachers’ Union, Oppenheimer was associated with a number of other organizations secretly controlled by Communist Party activists. To quote Oppenheimer: “I became a real left-winger…joined the teachers’ Union, had lots of Communist friends. It was what most people do in college or late high school…but I’m not ashamed of it. I’m more ashamed of its lateness. Most of what I believed then, now seems complete nonsense, but it was an essential part of becoming a whole man.” It is not known whether Oppenheimer was actually a Communist Party member or not. However, his association with left politics became major concerns for the authorities when Oppenheimer was working at Los Alamos for developing the atomic weapon. In May 1942 General Leslie R. Groves appointed Oppenheimer as Director of the Central Laboratory for Bomb Design and Development in Los Alamos, New Mexico. This was the beginning of the Manhattan Project, which led to the development of the atomic bomb. The choice of Oppenheimer was rather surprising. He was not a Nobel Laureate and so his stature was not equal to those of some others who would be expected to join the group. Oppenheimer was a theorist but he was expected to lead a largely experimental programme. The Manhattan Project was work of massive scale and significance. He succeeded in gathering a group of gifted scientists and generating an atmosphere of urgency. He skillfully handled the interface between his military superior General Groves and the unorthodox research scientists under him. It was a very difficult task. They had only some theoretical ideas about how to proceed. Victor Weisskopf, a colleague of Oppenheimer at Los Alamos, said: “The task facing Oppenheimer and his collaborators was stupendous. When the work started at Los Alamos not much more was known than the fundamental ideas of a chain reaction. What happens in a nuclear explosion had to be theoretically predicted in all details for the design of the bomb since there was no time to wait for experiments; no fashionable material was available yet. The details of the fission process had to be understood. The slowing down of neutrons in matter and the theory of explosions and implosions under completely novel conditions had to be investigated. Nuclear physicists had to become experts in fields of technology unknown to them such as shock waves and hydrodynamics. 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 head office. He was intellectually and even physically present at each decisive step. He was present in the laboratory or in 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.” It was Oppenheimer’s intelligence, his unique capacity for assimilating different ideas and his administrative and leadership qualities which made the Manhattan Project successful. Edward Teller, who worked with Oppenheimer and who later worked for the development of the hydrogen bomb, wrote: “Oppie (Oppenheimer) knew in detail what was going in every part of the laboratory. He was incredibly quick and perceptive in analyzing human as well as technical problems…Oppie knew [what the staff’s] relationships with one another were and what made them tick. He knew how to organize, cazole, humor, soothe feelings—how to lead powerfully without seeming to do so. He was an exemplar of dedication, a hero who never lost his humanness. Disappointing him somehow carried with it a sense of wrongdoing.” After four years’ of hard work the team headed by Oppenheimer at Los Alamos designed and built two types of atomic bombs. The first type was a uranium bomb that was triggered by U-235 “bullet” that was impelled into a U-235 sphere by an explosive. It was called ‘Little Boy”. The other was a plutonium implosion-type bomb consisting of a plutonium core, surrounded by an initiator of polonium and beryllium and a circle of explosive. This type was called “Fat Man”. By July 1945, four bombs were built—two bombs of plutonium-assembly type, one bomb for test and another for keeping in reserve, two bombs, one of each type, for possible use. Oppenheimer named the site for the first-ever site for atomic explosion Trinity after a sonnet by the English poet John Donne. This is because Oppenheimer thought Donne’s sonnet set the proper tone for the experiment at Trinity. The test of the first atomic bomb called the Fat Man at the Trinity Site on July 16, 1945 was a step into the unknown. No one including the scientist who actually built the bomb knew exactly what would happen when the bomb exploded. The test, though there were several hours of delays because of bad weather and dangerous winds, went exactly as planned. Finally the first atomic bomb exploded over the desert. It changed the world for ever. Enrico Fermi who viewed the explosion from an elevated desert floor called Compania Hill, thirty kilometres away from the actual site said: “ Although I did not look directly toward the object. I had the impression that suddenly the countryside became brighter than in full daylight…After a few seconds the rising flames lost their brightness and appeared as a huge mushroom that rose rapidly beyond the clouds.” After seeing the all-illuminating flash of the explosion of the atomic weapon, Oppenheimer recited a Sanskrit verse from the Bhagvad Gita. “If the radiance of a thousand suns I am become Death Oppenheimer, like any other scientist associated with the project, was elated at the success of the project. They were working with a patriotic zeal to ensure the defeat of Germany and its allies, to wipe out war for ever from the face of the Earth. However, Oppenheimer was deeply concerned with the ominous implications of the atomic weapon. At Los Alamos, Oppenheimer had discussed his concerns with Niels Bohr. In his later life Oppenheimer was a strong advocate of the international control of the atomic weapon. At the time of acquiring atomic weapons the Second World War was not yet over. Japanese forces continued to fight bloody battles. It has been reported that Japan was given an warning to surrender or face inevitable complete destruction of Japanese armed forces and the utter devastation of Japanese homeland. Japan ignored the warning and resolved to fight for successful conclusion of the war. The first atomic weapon was dropped on Hiroshima on August 06, 1945. The bomb was “Little Boy” type and the aircraft, which carried the bomb was called Enola Gay. The destruction was complete. One member of the crew of Enola Gay later recalled: “I don’t believe anyone ever expected to look at a sight quite like that. Where we had seen a clear city two minutes before, we could no longer see the city.” Japanese did not surrender. So on August 09, 1945 another atomic bomb, the “Fat Man” type was dropped on the southern city of Nagasaki. On August 14, 1945, Emperor Hirohito (1901-89) announced Japan’s surrender. The terms of the surrender were signed on September 02, 1945 aboard the battleship USS Missouri and the Second World War was ended officially. Oppenheimer served as the Chairman of the Atomic Energy Commission’s General Advisory Committee. It was very important and time-consuming responsibility. The Committee included Fermi, Rabi, Conant, Dubridge, Smythe and Seaborg and two industrialists, Worthington and Rowe. The Committee used to have six sessions a year. It advised the Commission on both scientific matters as well as matters of general policy. Seaborg wrote: “At the conclusion of each session, when the AEC Commissioners came in to review our work, Oppie presented a masterful summary of the proceedings. I know that my fellow members of the GAC remember with me that this was pure Oppenheimer at his very best. I regret that tape-recordings were not made of these eloquent summations of our deliberations, for I believe that these would provide fascinating historical material.” As a Chairman of the General Advisory Committee of the Atomic Energy Commission, Oppenheimer played an important role in strengthening and expanding research in physics particularly in nuclear physics. Oppenheimer led the General Advisory Committee’s opposition to the development of the hydrogen bomb. The opposition to the hydrogen bomb was not entirely on moral ground but also because fusion did not appear technically feasible. Further the Committee thought that a crash programme would divert scarce resources from newly developed fission weapons. President Harry Truman did not heed to the Committee’s opposition and approved a crash programme for the hydrogen-bomb. Oppenheimer wanted to resign from the Chairmanship of the Committee but his resignation was not accepted. After the war ended, Oppenheimer decided to return to academic life again. General Groves, though reluctantly, accepted Oppenheimer’s resignation. Before leaving the Los Alamos, Oppenheimer accepted the certificate of appreciation from the Army to the Los Alamos Laboratory. On this occasion Oppenheimer said: “If atomic bombs are to be added to the arsenals of the world, or the arsenals of the nations preparing for war, then the time will come when mankind will curse the name of Los Alamos and Hiroshima. The peoples of the world must unite or perish. This war, that has ravaged so much of the earth, has written these words. The atomic bomb has spelled them out for all men to understand. Other men have spoken them, in other times, in other wars, or other weapons. They have not prevailed. There are some, misled by a false sense of human history, who hold that they will not prevail today. It is not for us to believe that. By our works we are committed, committed to a world united, before the common peril, in law and in humanity.” In 1947, Oppenheimer was appointed as Director of the Institute for Advanced Study in Princeton. At that time the most important member of the Institute was Albert Einstein. At Princeton Oppenheimer himself did not do much research but he certainly inspired his collaborators. He made the Institute a centre of young physicists. Bethe wrote: “…on Oppenheimer’s arrival, the physics department of the Institute changed. While its emphasis had been on well-established professors before, it now became a centre for young physicists. Five research associates from Berkeley came with him in 1947. Thereafter the Institute was open to dozens of post-doctoral fellows, from the United States and abroad. Even more than Berkeley in the 1930’s, the Princeton Institute became the centre of physics. Nearly everybody who was anybody passed its stimulating atmosphere.” In 1953, his political background and his support for making the hydrogen bomb was questioned. In fact Oppenheimer was under investigation since 1942, first as a matter of routine and then more rigorously when reports critical of his loyalty to the interest of the State, began to arrive at the office of Colonel Pash, the in-charge of security at Los Alamos. He came under suspicion because some of his friends had been members of the Communist Party and also because he moved freely in left-wing circles. Joseph McCarthy, one of the most conservative Senators in the US Congress started investigating Oppenheimer’s communist links. The Joint Congressional Committee on Atomic Energy also started an investigation into Oppenheimer’s past. The Joint Committee brought out a series of damaging charges against Oppenheimer. Alarmed by the charges brought out by the Joint Committee against Oppenheimer, the Atomic Energy Commission began investigating against Oppenheimer. He was asked to resign from the post of Chairman of the General Advisory Committee but when Oppenheimer refused to do so, the Commission ordered the proceedings of the trial against Oppenheimer. The hearings ran from April 5 until May 6, 1954. On June 28, 1954, the US Atomic Energy Commission stripped Robert Oppenheimer of his security clearance. Though Oppenheimer was not found guilty of espionage but the Commission judged that Oppenheimer possessed “substantial defects of character and imprudent dangerous associations (with) known subversive” and so he could not be trusted anymore with military/government secrets. After this Oppenheimer found himself cut off from inside circles of nuclear policy. Oppenheimer accepted his downfall with grace. The Atomic Energy Commission trial had its effect on the personal life of Oppenheimer. His brother Franck was dismissed from his teaching job at the University of Minnesota because of his former ties to the Communist Party. A number of friendships and personal associations were either severed or strained. But there were people who lent him their emotional support. Among them were Hans Bethe, Niels Bohr and one of his former colleagues at Caltech and Los Alamos. In 1963, the General Advisory Committee elected Oppenheimer for its Enrico Fermi Award for excellence in the field of nuclear research. The award was to be presented by President John Fitzgeral Kennedy (1917-63). But two weeks before the award ceremony, President Kennedy was assassinated on November 22, 1963. Finally, the President Lyndon Baines Johnson (1908-73) presented the award on December 02, 1963. Not long after this award ceremony he returned to California to join the Faculty of the California Institute of Technology in Pasadena. The success of the atomic bomb had made Oppenheimer a well-known and highly respected public figure. He was no more a simple theoretical physicist. At California he again started doing research in theoretical physics. He succeeded in publishing a few research papers. There are two books by Oppenheimer. The first book, Science and the Common Understanding (1954) offers a firsthand look at physics, quantum mechanics and the role of scientist in modern society. The second book The Open Mind, (1955) is based on lectures given by Oppenheimer during 1946 and 1954. In these lectures Oppenheimer addressed the problems of atomic weapons and the relationship between science and society. Oppenheimer died on February 18, 1967 at his home in Princeton. He was 62 years old. References 1. Chevalier, Haakon. Oppenheimer: The Story of a Friendship. New York: Braziller, 1965. | |
Sunday, January 3, 2010
Julius Robert Oppenheimer - A Great Synthesiser of Ideas
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