April 7, 2002 By LOREN GRAHAM The story of science in the Soviet Union is one of baffling paradoxes that challenge preconceptions and make us uncomfortable. Contrary to the common Western assumption that creativity needs freedom, Russian science seemed to do best when political conditions were worst. Six Nobel Prizes were awarded to Soviet physicists for work done in the 1930's and 40's, a period of tyranny and terror. For one of those physicists, Lev Landau, 1937, when Stalin's horrific purges peaked, was his most productive year in terms of scientific publications. The next year Landau was arrested by the secret police but was released with a warning. Another Nobelist, Pyotr Kapitsa, did his most significant research shortly after he had been detained on Stalin's orders. The designer of the Soviet Union's finest airplanes, Andrei Tupolev, and the rocket scientist who sent the world's first artificial satellites into space, Sergei Korolev, both spent time in prison before they did the work for which they are most remembered. Seeking heroes and villains whose work and achievements fit more felicitously into our beliefs, Western observers point to the pseudogeneticist and charlatan Trofim Lysenko as a more representative product of Stalinism, and to the great human rights advocate Andrei D. Sakharov as an exemplary scientist-rebel against political controls. Lysenko and his doctrines were indeed fruits of Stalinism, but as Richard Lourie's new, subtle and revealing biography of Sakharov demonstrates, the impulses to Sakharov's scientific creativity and his later rise to political heroism were not simple. Throwing off Stalinism was extremely difficult for Sakharov, and like many of his colleagues he did his best scientific work while still in its thrall. In 1948, the same year that Lysenko, with Stalin's backing, squelched all resistance to his teachings, Sakharov was commanded to work on the hydrogen bomb project, which was directed by a particularly loathsome man -- personally and politically -- Lavrenti Beria, head of the secret police. Sakharov threw himself into the effort wholeheartedly. He was soon sent to the center of Soviet nuclear research, a secret laboratory named Arzamas 16, where scientists took over a famous monastery near the town of Sarov. Sakharov was told by a colleague that political prisoners forced to build the scientific plant had rebelled two years earlier; Beria's troops surrounded the mutineers and killed every one. Sakharov later described in his memoirs how in 1950-53, as he worked on scientific projects, he frequently saw columns of prisoners marching by under armed guard. In these years Sakharov was strikingly productive scientifically, perhaps as a subconscious means of avoiding facing the political repression around him; certainly a link between freedom and creativity was completely absent. He designed the Soviet hydrogen bomb in a way that, Western historians now agree, was original and independent of the American one (the Soviet atomic bomb had been built to specifications supplied through espionage). In addition, Sakharov and Igor Tamm worked out a brilliant toroidal approach to controlled thermonuclear reactions that still dominates the field of fusion research everywhere today. Although surrounded by tyranny, Sakharov and his associates gave their outstanding talents to the service of their country. He even found the environment pleasant in some ways. On his 29th birthday in 1950, he later observed, ''we listened to music and had a wonderful conversation about the meaning of life and the future of mankind.'' This combination of scientific creativity, political oppression and utopian dreaming encapsulates the flaws and the virtues of the Soviet intelligentsia. When Stalin died three years later, Sakharov in sadness remarked: ''I am under the influence of a great man's death. I am thinking of his humanity.'' Yet he broke out of his intellectual prison and his illusions and became one of the bravest defenders of human rights of the last century. He ranks with Nelson Mandela as a person who helped guide his country to democracy, changing himself in the process. One of the strengths of Lourie's biography is his description and analysis of how this transition occurred. Sakharov's first impulse to liberation was not revulsion against the political system (''I still believed that the Soviet state represented a breakthrough into the future'') but his sense of guilt about the deaths caused by radioactive fallout from the nuclear tests he directed. When he advised cutting back on the tests, he encountered the unyielding, repressive Soviet system that he had seen applied only to others. The more he attempted to express his opinions, the more he was threatened. Nikita Khrushchev accused him of ''poking his nose where it doesn't belong.'' When Yuri Andropov became head of the K.G.B. he declared Sakharov ''Public Enemy No. 1'' and placed him under constant surveillance. Stripped of his security clearance and dismissed from weapons research, Sakharov turned to research in fundamental science. Lourie describes what then happened not as the emergence of the inner Sakharov under pressure, but as an interaction between his truth-seeking and his shifting political consciousness. For the first time he began to ask questions about politics the same way he had always asked them about physical nature: testing hypotheses, looking for reliable evidence. He quickly found that this approach automatically made him a dissident, and he came to sympathize with other dissidents. As a member of the elite, holding all the highest awards the Soviet state could bestow, he found that his opinions automatically attracted attention. Einstein once said the accident of acquiring authority through science gave him responsibility in the social realm, since it gave him power to help rectify evils and relieve suffering. When Sakharov took on this same responsibility, he did it in a truly inspiring way; he had obviously moved far from the position of his circle at Arzamas 16, whose members could have deep conversations about ''the meaning of life'' but at the same time feel no personal responsibility for the injustices around them. In the late 60's Sakharov began a campaign to make his society more humane. He attended trials of political prisoners and publicized the plight of persecuted religious believers and oppressed nationalities. He called on the government to allow citizens to exercise freedoms guaranteed by the Soviet Constitution but denied in practice. He helped organize a Committee on Human Rights. He protested the Soviet military intervention in Afghanistan in 1979. The action on Afghanistan enraged the Soviet leaders; Sakharov was seized by the secret police and illegally removed to Gorky, a city closed to foreigners, and told he could not leave. He remained with his wife, Yelena Bonner, under forced exile for six years. When he resisted with hunger strikes he was bound and forcibly fed. He was constantly reviled in the Soviet press, and many of his scientific colleagues in the Academy of Sciences, including some from Arzamas 16 (although happily not quite all) signed letters condemning him. After Mikhail Gorbachev came to power, the first hint that Sakharov's situation would change came when a work crew arrived at his apartment and installed a telephone. The reason became clear the next day when the phone rang and Sakharov found himself talking to Gorbachev, who invited him to return to Moscow. Sakharov promptly accepted and, back in the political fray, soon won a position in Gorbachev's new national assembly. When the assembly met, Gorbachev called on Sakharov as the first speaker. It was a stunning turnaround. Yet his position remained uncertain, as shown by Gorbachev's rebuke of him for criticizing the war in Afghanistan. Undeterred, Sakharov went on to become the leader of the democratic forces in the Soviet Union and was preparing a draft for a new constitution at the time of his death in 1989 from a heart attack. Lourie -- an American novelist, translator and critic of Russian literature -- gives a fascinating account of Sakharov; he makes many of his most poignant points through understatement. While his treatment of Sakharov's work in science is a bit weak, his analysis of the man's complicated political journey seems authentic and immensely revealing. Sakharov emerges not as a saint but as a powerful and inspiring human being who came to understand belatedly the society in which he lived. As he approached that understanding he transformed himself. And the new understanding brought grave responsibilities and risks, which Sakharov readily assumed at a time when few others dared to do so. Loren Graham's most recent book is ''What Have We Learned About Science and Technology From the Russian Experience?'' Copyright 2002 The New York Times Company