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Sakharov, Andrei Dmitriyevich

universe protons asymmetry soviet

[ sa karof] (1921–89) Russian nuclear physicist and political activist.

The son of a physics teacher, Sakharov was born and educated in Moscow, where he graduated in 1942. From that time he worked in the Lebedev Institute of Physics, and from 1948 he was the key figure in developing the Soviet hydrogen bomb, which was exploded in 1962, when he received the highest honours from the state for this work. But he had long been concerned about the pollution effects of nuclear weapon testing, and after he had published his underground essay Thoughts on Progress, Peaceful Co-existence and Intellectual Freedom (1968) he was seen by the state as a possibly subversive critic and was excluded from secret work.

From 1965 Sakarov became interested in cosmology, and especially in the problem of ‘what was before the “Big Bang”?’ In a major paper of 1967 he attempted to explain why the universe is built of protons, neutrons and electrons while the corresponding anti-particles are rare. To explain this ‘baryon asymmetry of the universe’ he proposed that the original universe was neutral and had no such asymmetry; the asymmetry built up following the ‘Big Bang’, as a result of non-stationary processes in the expansion of the early universe, together with his idea that protons are inherently unstable (with a lifetime perhaps of 10 50 years) and the fact that particle–antiparticle symmetry can be violated. This last fact had been shown experimentally by others in 1964, but confirmation of the ultimate instability of protons (whose decay would involve disposing of three quarks) has yet to be observed, perhaps because it is too rare an event: the proposed proton lifetime is 10 20 times the present age of the universe.

During the 1970s the Soviet state became more repressive, while Sakharov became increasingly active as a human rights supporter, especially after his marriage to his Jewish second wife in 1971. He was awarded the Nobel Peace Prize in 1975 but not permitted to collect it, and his outright condemnation of Soviet aggression in Afghanistan in 1979 led to his arrest in 1980 and exile in the ‘closed city’ of Gorky. In 1986 the new leader of the USSR, Gorbachev, recalled him to Moscow and to relative freedom, but by then he was exhausted and ill, and in his remaining years his role as an advocate for change in his country to a democratic multi-party state with a free-market economy was mainly symbolic. There is no doubt that for many years he had been a moral leader of the opposition to the communist regime in Russia, but he was never a direct and fully effective political figure and he was elected to the Congress of People’s Deputies only shortly before his death.

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