PRINCETON, N. J., Feb. 18--Dr. J. Robert Oppenheimer, the nuclear physicist, died here tonight at the age of 62. A spokesman for the family said Dr. Oppenheimer died at 8 o'clock in his home on the grounds of the Institute for Advanced Study. He had been ailing since early last year with cancer of the throat. The physicist took part in the development of the first atomic bomb. In 1954 he was stripped of security clearance by the Atomic Energy Commission because of alleged association with Communists. The same agency nine years later awarded Dr. Oppenheimer the $50,000 Fermi award for "his outstanding contributions to theoretical physics and his scientific and administrative leadership." Starting precisely at 5:30 A.M., Mountain War Time, July 16, 1945, J. (for nothing) Robert Oppenheimer lived the remainder of his life in the blinding light and the crepusculine shadow of the world's first manmade atomic explosion, an event for which he was largely responsible. That sunlike flash illuminated him as a scientific genius, the technocrat of a new age for mankind. At the same time it led to his public disgrace when, in 1954, he was officially described as a security risk to his country and a man with "fundamental defects in his character." Publicly rehabilitated in 1963 by a singular Government honor, this bafflingly complex man nonetheless never fully succeeded in dispelling doubts about his conduct during a crucial period of his life. The perplexities centered on a story of attempted atomic espionage that he told Army Counter- Intelligence officers in 1943 and that he later repudiated as a fabrication. His sole explanation for what he called "a cock-and-bull story" was that he had been "an idiot." Misgivings also sprang from the manner in which he implicated a close friend in his asserted concoction. A brilliant nuclear physicist, with a comprehensive grasp of his field, Dr. Oppenheimer was also a cultivated scholar, a humanist, a linguist of eight tongues and a brooding searcher for ultimate spiritual values. And, from the moment that the test bomb exploded at Alamogordo, N.M., he was haunted by the implications for man in the unleashing of the basic forces of the universe. As he clung to one of the uprights in the desert control room that July morning and saw the mushroom clouds rising in the explosion, a passage from the Bhagavad-Gita, the Hindu sacred epic, flashed through his mind. He related it later as: "If the radiance of a thousand suns were to burst into the sky, that would be like the splendor of the Mighty One." And as the black, then gray, atomic cloud pushed higher above Point Zero, another line--"I am become Death, the shatterer of worlds"--came to him from the same scripture. Two years later, he was still beset by the moral consequences of the bomb, which, he told fellow physicists, had "dramatized so mercilessly the inhumanity and evil of modern war." "In some sort of crude sense which no vulgarity, no humor, no overstatements can quite extinguish," he went on, "the physicists have known sin; and this is a knowledge which they cannot lose." In later years, he seemed to indicated that "sin" was not to be taken personally. "I carry no weight on my conscience," he said in 1961 in reference to the atomic bombing of Hiroshima and Nagasaki. "Scientists are not delinquents," he added. "Our work has changed the conditions in which men live, but the use made of these changes is the problem of governments, not of scientists." With the detonation of the first three atomic bombs and the immediate Allied victory in World War II, Dr. Oppenheimer, at the age of 41, reached the apogee of his career. Acclaimed as "the father of the atomic bomb," he was officially credited by the War Department "with achieving the implementation of atomic energy for military purposes." Secretary of War Henry L. Stimson led a chorus of national praise when he said of the scientist: "The development of the bomb itself has been largely due to his genius and the inspiration and leadership he has given to his colleagues." Shortly thereafter, in 1946, Dr. Oppenheimer received a Presidential Citation and a Medal of Merit for his direction of the Los Alamos Laboratory, where the bomb had been developed. In the years from 1945 to 1952, Dr. Oppenheimer was one of the foremost Government advisers on key phases of United States atomic policy. He was the dominant author of the Acheson- Lilienthal Report [named for Secretary of State Dean Acheson and David Lilienthal, first chairman of the Atomic Energy Commission], which offered a plan for international control of atomic energy. He was also the virtual author of the Baruch Plan, which was based on the Acheson-Lilienthal Report, calling for United Nations supervision of nuclear power. He was consultant to Bernard M. Baruch at the United Nations and to Frederick H. Osborn, his successor, in futile United Nations negotiations over the plan, which was balked by the Soviet Union. Furthermore, from 1947 to 1952, Dr. Oppenheimer headed the Atomic Energy Commission's General Advisory Committee of top nuclear scientists, and for the following two years he was its consultant. He also served on the atomic committee of the Research and Development Board to advise the military, the science advisory committee of the Office of Defense Mobilization and study groups by the dozen. He had a desk in the President's Executive Offices, across the street from the White House. This eminence ended abruptly in December, 1953, when President Dwight D. Eisenhower ordered that a "blank wall be placed between Dr. Oppenheimer and any secret data" pending a security hearing. The following June he was stripped of his security clearance by the Atomic Energy Commission. It was never restored to him. Up to 1954 Dr. Oppenheimer's big-brimmed brown porkpie hat, size 6 7/8, was a frequent (and telltale) sight in Washington and the capitals of Western Europe, where he traveled to lecture or consult. (The trademark hat was also in evidence at Princeton, N. J., where he headed the Institute for Advanced Study from 1947 to 1966.) He was Oppy, Oppie or Opje to hundreds of persons who were captivated by his charm, eloquence and sharp, subtle humor and who were awed by the scope of his erudition, the incisiveness of his mind, the chill of his sarcasm and his arrogance toward those he thought were slow or shoddy thinkers. Six feet tall and a bit stooped, he is as thin as the wisps from his chain-smoked cigarettes or pipes. Blue-eyed, with close-cropped hair (it was dark in 1943, gray by 1954 and white a few years later), he had a mobile, expressive face that became lined and haggard after his security hearings. He was extremely fidgety when he sat, and he constantly shifted himself in his chair, bit his knuckles, scratched his head and crossed and uncrossed his legs. When he spoke on his feet, he paced and stalked, smoking incessantly and jerking a cigarette or pipe out of his mouth almost violently when he wanted to emphasize a word or phrase with a gesture. He was an energetic man at parties, where he was usually the center of attention. He was gracious as a host and the maker of fine and potent martinis. He was full of droll stories. What impressed people first about Dr. Oppenheimer was his intellect. "Robert is the only authentic genius I know," Mr. Lilienthal said of him. Echoing this appraisal, Charles Lauritsen, a former colleague at the California Institute of Technology, once remarked: "The man was unbelievable! He always gave you the right answer before you formulated the question." Knowledge came easily to Dr. Oppenheimer. As a young man he learned enough Dutch in six weeks to deliver a technical lecture while on a visit to the Netherlands. At the age of 30 he learned Sanskrit, and he used to enjoy passing notes to other savants in that language. On a train trip from San Francisco to the East Coast he read Edward Gibbon's seven-volume "The History of the Decline and Fall of the Roman Empire." On another such trip he read the four volumes of Karl Marx's "Das Kapital" in German. On a short summer holiday in Corsica he read in French Marcel Proust's massive "A La Recherche du Temps Perdu," which he later said was one of the great experiences of his life. This almost compulsive avidity for learning was not sterile, for he invariably made some use of what he read. He was, moreover, an authority, if not an expert, in baroque and classical music, to which he liked to listen. In the words of a friend, Dr. Oppenheimer was a "culture hound." Even as a child, J. Robert Oppenheimer was made much of for his ability to absorb knowledge. He was born in New York on April 22, 1904, the son of Julius and Ella Freedman (or Friedman) Oppenheimer. Julius Oppenheimer was a prosperous textile importer who had emigrated from Germany and his wife was a Baltimore artist, who died when her elder son was 10. (The younger son, Frank Friedman Oppenheimer, also became a physicist.) The family lived in comfort, with a private art collection that included three Van Goghs. Robert was encouraged to delve into rocks after starting a collection at the age of 5, and he was admitted to the Mineralogical Club of New York when he was 11. He was a shy, delicate boy (he was once thought to have tuberculosis), who was more concerned with his homework and with poetry and architecture than with mixing with other youngsters. After attending the Ethical Culture School ("It is characteristic that I don't remember any of my classmates, he said) he entered Harvard College in 1922, intending to become a chemist. He was a solitary student with an astonishing appetite for work. "I had a real chance to learn," he said later. "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." Typical of his absorption was this note that he wrote about himself: "It was so hot today the only thing I could do was lie on my bed and read Jeans's 'Dynamical Theory of Gases.'" In addition to studying physics and other sciences, he learned Latin and Greek and was graduated summa cum laude in 1925, having completed four years' work in three. From Harvard, Robert Oppenheimer went to the University of Cambridge, in England, where he worked in atomics under Lord Rutherford, the eminent physicist. Thence he went to the Georg- August-Universitat in Gottingen, Germany, at the invitation of Dr. Max Born, also a celebrated scientist interested in the quantum theory of atomic systems. He received his doctorate there in 1927, along with a reputation for being pushy. In 1927-28 he was a National Research Fellow at Harvard and Caltech, and the following year he was an International Education Board Fellow at the University of Leyden, in the Netherlands, and the Technische Hochschule in Zurich, Switzerland. Returning to the United States in 1929, Dr. Oppenheimer joined the faculties of Caltech at Pasadena, Calif., and the University of California at Berkeley. He was attached to both schools until 1947 and rose to the rank of professor. He proved an outstanding teacher. Magnetic, lucid, always accessible, he developed hundreds of young physicists, some of whom were so devoted to him that they migrated with him back and forth from Berkeley to Pasadena and even copied his mannerisms. Describing to his security hearings his ivory-tower life up to late 1936, he said: "I was not interested in and did not read about economics or politics. I was almost wholly divorced from the contemporary scene in this country. I never read a newspaper or a current magazine like Time or Harper's; I had no radio, no telephone; I learned of the stockmarket crash in the fall of 1929 only long after the event; the first time I ever voted was in the Presidential election of 1936." In this period and subsequently, Dr. Oppenheimer was noted more for his inspirational teaching and his over-all grasp of nuclear physics than for any major discoveries or theories. However, in the nineteen-thirties Dr. Oppenheimer greatly influenced American physics as leader of a dynamic school of theoreticians in California. His influence continued in his recent years at the Institute for Advanced Study. In the words of one Nobel laureate in physics: "No one in his age group has been as familiar with all aspects of current developments in theoretical physics." One of his earliest contributions was in 1926-27 while he was working with Dr. Born, then a professor at Gottingen. Together they helped lay the foundations of modern theory for the quantum behavior of molecules. In 1935 he and Melba Phillips made another basic contribution to quantum theory, discovering what is known as the Oppenheimer-Phillips process. It involves the break-up of deuterons in collisions that had been thought far too weak for such an effect. The deuteron consists of a proton and neutron bound into a single particle. The two physicists found that, when a deuteron is fired into an atom even weakly, the neutron be stripped off the proton and penetrate the nucleus of the atom. It had been assumed that, since the deuteron and nucleus are both positively charged, each would repel the other except in high-energy collisions. Another theoretical study by Dr. Oppenheimer has figured prominently in recent efforts to explain the astronomical objects, known as quasars, that radiate light and radio waves of extraordinary intensity. One possibility is that the quasar is a cloud of material being drawn together by its own gravity. In 1938-39 Dr. Oppenheimer, with Dr. George M. Volkoff and others, had analyzed such a "gravitational collapse" in terms of the general theory of relativity. Their calculations are now cited in efforts to explain the quasars. Beginning in late 1936, Dr. Oppenheimer's life underwent a change of direction that involved him in numerous Communist, trade union and liberal causes to which he devoted time and money and that added to his circle of acquaintances many Communist and liberals, some of whom became intimate friends. These commitments and associations, which were to be recalled with sinister overtones at his security hearings, ended about 1940, according to the scientist or, in the version of some others, they persisted until the end of 1942, when he was about to go to Los Alamos. One precipitating factor in Dr. Oppenheimer's awakening to the world about him was a love affair, starting in 1936, with a woman Communist, now dead. (In 1940 he married the former Miss Katherine Puening, who had been a Communist during her marriage to Joseph Dallet, a Communist who died fighting for the Spanish Republican Government.) Apart from the influence exerted by his fiancee in 1936 there were other compelling elements in Dr. Oppenheimer's transformation from cloistered academician to social activist. He described them this way: "I had had a continuing smoldering fury about the treatment of Jews in Germany. I had relatives there, and was later to help in extricating them and bringing them to this country. I saw what the Depression was doing to my students. Often they could get no jobs, or jobs which were wholly inadequate. And through them, I began to understand how deeply political and economic events could affect men's lives. I began to feel the need to participate more fully in the life of the community." Dr. Oppenheimer's activism was far-ranging, but he consistently denied that he was ever a member of the Communist party ("I never accepted Communist dogma or theory") and no substantial evidence was ever adduced to refute him. Dr. Arthur H. Compton, the Nobel Prize-wining scientist, brought Dr. Oppenheimer informally into the atomic project in 1941. Within a year he had convinced Dr. Compton and military authorities that, to build a bomb, it was essential to concentrate qualified scientists and their equipment in a single community under a unified command. He also impressed Maj. Gen. Leslie R. Groves, in charge of the $2-billion Manhattan Engineer District, as the bomb project was code-named, who selected him for the post of director and who ordered him cleared for the job despite Army Counter-Intelligence qualms over his past associations. With General Groves, Dr. Oppenheimer selected the Los Alamos site for the laboratory. "To recruit staff," he said later, "I traveled all over the country talking with people who had been working on one or another aspect of the atomic-energy enterprise, and people in radar work, for example, and underwater sound, telling them about the job, the place that we are going to, and enlisting their enthusiasm." Dr. Oppenheimer's persuasiveness and his new-found qualities of leadership were such that he gathered a top-notch scientific staff that numbered nearly 4,000 by 1945 and that lived, often amid frustrations and under quasi-military rule, in the hastily built houses of Los Alamos. Among the staff were Dr. Enrico Fermi and Dr. Niels Bohr, two physicists of immense world standing. In the two tension-filled years it took to construct the bombs, Dr. Oppenheimer displayed a special genius for administration, for handling the sensitive prima-donna scientific staff (often he spent as much time on personal as on professional problems) and for coordinating its work. He drove himself at breakneck speed, and at one time his weight dropped under the whiplash of the war to 115 pounds. But he always managed to surmount whatever problem arose, and it was for this enormous all-around task that he was acclaimed as "the father of the atomic bomb." Dr. Oppenheimer's security troubles had their genesis while he was director at Los Alamos. Because a security-risk potential was imputed to him on account of past associations, Dr. Oppenheimer was dogged by Army agents, his phone calls were monitored, his mail was opened and his every footstep was watched. In these circumstances his overnight visit with his former fiancee--by then no longer a Communist--on a trip to San Francisco in June 1943, aroused the Counter-Intelligence Corps. The following August, for reasons that still remain obscure, Dr. Oppenheimer volunteered to a C.I.C. agent that the Russians had tried to get information about the Los Alamos project. George Eltenton a Briton and a slight acquaintance of Dr. Oppenheimer, had asked a third party to get in touch with some project scientists. In three subsequent interrogations Dr. Oppenheimer embroidered this story, but he declined to name the third party who had approached him or to identify the scientists. (In one interrogation, however, he gave the C.I.C., a long list of persons he said were Communists or Communist sympathizers in the San Francisco area, and he offered to dig up information as to former Communists at Los Alamos.) Finally, in December, 1943, Dr. Oppenheimer, at General Groves's direct order, vouchsafed the third party's name as Prof. Haakon Chevalier, a French teacher at Berkeley and a longtime close and devoted friend of the Oppenheimer family. At the security hearings in 1954, the scientist recanted his espionage account as a "cock-and-bull story," saying only that he was "an idiot" to have told it. Dr. Oppenheimer never gave a further explanation. There was some basis for Oppenheimer's original story, according to him and Professor Chevalier. The professor said that Mr. Eltenton had indeed approached him in late 1942 or early 1943 with a nebulous notion about getting scientific information and had been quickly rebuffed. Professor Chevalier said that he had recounted the episode to Dr. Oppenheimer and that both had dismissed the matter. This part of the incident was corroborated by Dr. Oppenheimer in his testimony at his security hearings. (Just how much of Dr. Oppenheimer's spy-attempt story the C.I.C. believed is difficult to judge in the light of the fact that neither Professor Chevalier nor Mr. Eltenton was interrogated until May, 1946. Neither was prosecuted. Indeed, Professor Chevalier was an interpreter on the United States staff at the Nuremberg war crimes trial in 1945. Twenty years later he wrote "Oppenheimer: The Story of a Friendship," in which he charged that Dr. Oppenheimer had betrayed him out of ambition for fame and to stay in C.I.C.'s good graces. (A C.I.C. operative who had questioned Dr. Oppenheimer in 1943 suggested to his Army superiors that an unimpeachable assistant be assigned to the scientist. The operative's memo included this sentence: ("It is the opinion of this office that subject's [Dr. Oppenheimer's] personal inclinations would be to protect his own future and reputation and the high degree of honor which would be his if his present work is successful, and, consequently, it is felt that he would lend every effort to cooperation with the Government in any plan which would leave him in charge.") With the end of World War II and Dr. Oppenheimer's return to full civilian life, he caused some disquiet in the scientific community by supporting the May-Johnson bill for military control of further atomic experiments. This was countered, however, when he later supported the McMahon bill, which created the Atomic Energy Commission, a civilian agency. Another of the charges pressed against Dr. Oppenheimer in 1954 also had its origin at Los Alamos, and it involved the hydrogen, or fusion, bomb and his relations with Dr. Edward Teller over that superweapon, of which the Hungarian scientist was a vociferous proponent. At Los Alamos Dr. Teller was passed over for Dr. Hans Bethe as head of the important Theoretical Physics Division. Dr. Teller, meantime, worked on problems of fusion. At the war's end, when most of the Los Alamos scientists returned to their campuses, hydrogen bomb work was generally suspended. In 1949, however, when the Soviet Union exploded its first fission bomb, the United States considered pressing forward immediately with building and testing a fusion device. The matter came to the Atomic Energy Commission's General Advisory Committee, headed by Dr. Oppenheimer. On the ground that manufacturing a hydrogen bomb was not technically feasible at the moment, the committee unanimously recommended that thermonuclear research be maintained at a theoretical level only. Dr. Oppenheimer, who also thought a hydrogen bomb morally dubious, played a leading role in this proposal, and it did not endear him to Dr. Teller. In 1950 President Harry S. Truman overruled Dr. Oppenheimer's committee and ordered work pushed on the fusion bomb. Dr. Teller was given his own laboratory and within a few months the hydrogen bomb was perfected with the aid of a technical (and still secret) devise suggested by Dr. Teller. It was charged at the security hearings that Dr. Oppenheimer was not sufficiently diligent himself in furthering the hydrogen bomb and that he influenced other scientists against participating in work on it. Dr. Teller testified that, apart from giving him a list of names, Dr. Oppenheimer had not assisted him "in the slightest" in recruiting scientists for the project. Dr. Teller, moreover, went on record as being opposed to restoring Dr. Oppenheimer's security clearance, saying: "In a great number of cases I have seen Dr. Oppenheimer act--I understood that Dr. Oppenheimer acted--in a way which for me was exceedingly hard to understand. I thoroughly disagreed with him in numerous issues and his actions frankly appeared to me confused and complicated. To this extent I feel that I would like to see the vital interests of this country in hands which I understand better, and therefore trust more. "In this very limited sense I would like to express a feeling that I would personally feel more secure if public matters would rest in other hands." Dr. Oppenheimer, for his part, vigorously denied that he had been dilatory or neglectful in supporting the hydrogen bomb, once President Truman had acted. "I never urged anyone not to work on the hydrogen bomb project," he declared. He insisted, too, that his board had materially assisted Dr. Teller's work. If Dr. Oppenheimer had stirred Dr. Teller's displeasure in 1949, he had also aroused strong feelings in Dr. Edward U. Condon of the National Bureau of Standards for different reasons. In an appearance before an executive session of the House Un-American Activities Committee, Dr. Oppenheimer described a fellow atomic scientist as a former German Communist. When quotations from the testimony were printed in the newspapers, Dr. Condon and a number of other scientists were shocked on the ground that Dr. Oppenheimer had acted as an informer. "It appears that he [Dr. Oppenheimer] is trying to buy personal immunity from attack by turning informer," Dr. Condon wrote. Subsequently, Dr. Oppenheimer wrote a public letter in which he attested the atomic scientist's patriotism, but the incident perplexed a number of Dr. Oppenheimer's friends. The security hearings for Dr. Oppenheimer were triggered late in 1953, when William L. Borden, former executive director of the Joint Congressional Committee on Atomic Energy, wrote an unsolicited letter to J. Edgar Hoover, director of the Federal Bureau of Investigation. Mr. Borden gave it as his opinion that the scientist had been "a hardened Communist" and that "more probably than not he has since been functioning as an espionage agent." Mr. Hoover wasted little time in sending the letter and an F.B.I. report to the White House and other agencies. It was then that President Eisenhower cut Dr. Oppenheimer off from access to secret material. Lewis L. Strauss (pronounced straws), then chairman of the Atomic Energy Commission, gave Dr. Oppenheimer the option of resigning his consultantship with the commission or asking for a hearing. He chose a hearing. The action against Dr. Oppenheimer dismayed the scientific community and many other Americans. He was widely pictured as a victim of McCarthyism who was being penalized for holding honest, if unpopular, opinions. The A.E.C., Mr. Strauss and the Eisenhower Administration were accused of carrying out a witch hunt in an attempt to account for Soviet atomic successes and to feed a public hysteria about Communists. The Personnel Security Board of the A.E.C., consisting of Gordon Gray, an educator, chairman; Thomas A. Morgan, a businessman, and Dr. Ward V. Evans, a chemist, held hearings in Washington from April 12 to May 6, 1954. They considered a long list of specific charges, one batch dealing with Dr. Oppenheimer's past associations, another with the Haakon Chevalier incident and another with the hydrogen bomb. Dr. Oppenheimer testified in his own behalf, and 40 great names in American science and education offered evidence of his loyalty. However, by a vote of 2 to 1 (Dr. Evans dissented), the board declined to reinstate its consultant's security clearance. After asserting as "a clear conclusion" that Dr. Oppenheimer was "a loyal citizen," the majority report said it had "been unable to arrive at the conclusion that it would be clearly consistent with the security interests of the United States to reinstate Dr. Oppenheimer's clearance. . . ." The report listed the following as controlling its decision.: "1. We find that Dr. Oppenheimer's continuing conduct and associations have reflected a serious disregard for the requirements of the security system. "2. We have found a susceptibility to influence which could have serious implications for the security interests of the country. "3. We find his conduct in the hydrogen-bomb program sufficiently disturbing as to raise a doubt as to whether his future participation, if characterized by the same attitudes in a Government program relating to the national defense, would be clearly consistent with the best interests of security. "4. We have regretfully concluded that Dr. Oppenheimer has been less than candid in several instances in his testimony before this board." On appeal to the commission, Dr. Oppenheimer lost by a vote of 4 to 1. After declaring that Dr. Oppenheimer had "fundamental defects in his character," the majority said that "his associations with persons known to him to be Communists have extended far beyond the limits of prudence and self-restraint." With the commission ruling, Dr. Oppenheimer returned to Princeton and the institute he headed. There he lived in quiet obscurity until April 1962, when President John F. Kennedy invited him to a White House dinner of Nobel Prize winners. In December 1963, as a further evidence of a rapprochement, President Johnson handed Dr. Oppenheimer the highest award of the Atomic Energy Commission, the $50,000 tax-free Fermi Award, which is named for Dr. Enrico Fermi, the late distinguished nuclear pioneer. In his acceptance remarks Dr. Oppenheimer adverted to his security hearings, saying: "I think it is just possible, Mr. President, that it has taken some charity and some courage for you to make this award today." Dr. Oppenheimer was the author of several books: "Science and the Common Understanding" (1954), "The Open Mind" (1955), "Some Reflections on Science and Culture" (1960). Ailing, he retired as director of the institute, a research facility for some 200 postdoctoral fellows in many fields, in early 1966. He was succeeded by Dr. Carl Kaysen of Harvard. In addition to the Medal of Merit for his work in Los Alamos and an assortment of honorary doctorates, Dr. Oppenheimer was a fellow of the National Academy of Arts and Sciences, the American Physical Society and Britain's Royal Society. He was also a member of the National Academy of Sciences, the American Philosophical Society and several foreign academies. Dr. and Mrs. Oppenheimer had two children, Peter and Katherine.