Andrei Dmitrievich Sakharov (; 21 May 192114 December 1989) was a Soviet physicist and a Nobel Peace Prize laureate, which he was awarded in 1975 for emphasizing human rights around the world.
Although he spent his career in physics in the Soviet program of nuclear weapons, overseeing the development of thermonuclear weapons, Sakharov also did fundamental work in understanding particle physics, magnetism, and physical cosmology. Sakharov is mostly known for his political activism for individual freedom, human rights, civil liberties and reforms in the Soviet Union, for which he was deemed a dissident and faced persecution from the Soviet establishment.
In his memory, the Sakharov Prize was established and is awarded annually by the European Parliament for people and organizations dedicated to human rights and freedoms.
Life and career Family background and early life
Andrei Dmitrievich Sakharov was born in Moscow on 21 May 1921, to a Russian family. His father, Dmitri Ivanovich Sakharov, was a physics professor at the Second Moscow State University and an amateur pianist.Sidney David Drell, Sergeǐ Petrovich Kapitsa, Sakharov Remembered: a tribute by friends and colleagues (1991), p. 4 His grandfather, Ivan, was a lawyer in the former Russian Empire who had displayed respect for social awareness and humanitarian principles (including advocating the abolition of capital punishment). Sakharov's mother, Yekaterina Alekseevna Sofiano, was a daughter of Aleksey Semenovich Sofiano, a general in the Tsarist Russian Army with Greek heritage.
Sakharov's parents and paternal grandmother, Maria Petrovna, largely shaped his personality; his mother and grandmother were members of the Russian Orthodox Church, although his father was a non-believer. When Andrei was about thirteen, he realized that he did not believe in God. However, despite being an atheist, he did believe in a "guiding principle" that transcends physical laws.
After schooling, Sakharov studied physics at the Moscow State University in 1938 and, following evacuation in 1941 from fighting on the Eastern Front with Germany, he graduated in Ashgabat in the Turkmen Soviet Socialist Republic. In 1942 he moved to Ulyanovsk, working in the Voldarsky munitions plant. Whilst there, he invented a successful process to test for flaws in armour piercing shells.Sakharov patent. In 1943, he married Klavdia Alekseyevna Vikhireva, with whom he raised two daughters and a son. They were married until Klavdia's death in 1969. In 1945, he joined the Theoretical Department of Physical Institute of the Russian Academy of Sciences under Igor Tamm in Moscow. In 1947, Sakharov successfully defended his thesis for the Doctor of Sciences (lit. Doktor Nauk), which covered the topic of nuclear transmutation.
Soviet program of nuclear weapons
After World War II, he researched cosmic rays. In mid-1948 he participated in the Soviet atomic bomb project under Igor Kurchatov and Igor Tamm. Sakharov's study group at FIAN in 1948 came up with a second concept in August–September 1948.Zaloga, Steve (17 February 2002). The Kremlin's Nuclear Sword: The Rise and Fall of Russia's Strategic Nuclear Forces 1945–2000. Smithsonian Books. . Adding a shell of natural, unenriched uranium around the deuterium would increase the deuterium concentration at the uranium-deuterium boundary and the overall yield of the device, because the natural uranium would capture neutrons and itself fission as part of the thermonuclear reaction. This idea of a layered fission-fusion-fission bomb led Sakharov to call it the sloika, or layered cake. The first Soviet atomic device was tested on August 29, 1949. After moving to Sarov in 1950, Sakharov played a key role in the development of the first megaton-range Soviet hydrogen bomb using a design known as Sakharov's Third Idea in Russia and the Teller–Ulam design in the United States. Before his Third Idea, Sakharov tried a "layer cake" of alternating layers of fission and fusion fuel. The results were disappointing, yielding no more than a typical fission bomb. However the design was seen to be worth pursuing because deuterium is abundant and uranium is scarce, and he had no idea how powerful the US design was. Sakharov realised that in order to cause the explosion of one side of the fuel to symmetrically compress the fusion fuel, a mirror could be used to reflect the radiation. The details had not been officially declassified in Russia when Sakharov was writing his memoirs, but in the Teller–Ulam design, soft X-rays emitted by the fission bomb were focused onto a cylinder of lithium deuteride to compress it symmetrically. This is called radiation implosion. The Teller–Ulam design also had a secondary fission device inside the fusion cylinder to assist with the compression of the fusion fuel and generate neutrons to convert some of the lithium to tritium, producing a mixture of deuterium and tritium. Sakharov's idea was first tested as RDS-37 in 1955. A larger variation of the same design which Sakharov worked on was the 50 Mt Tsar Bomba of October 1961, which was the most powerful nuclear device ever detonated.
Sakharov saw "striking parallels" between his fate and those of J. Robert Oppenheimer and Edward Teller in the US. Sakharov believed that in this "tragic confrontation of two outstanding people", both deserved respect, because "each of them was certain he had right on his side and was morally obligated to go to the end in the name of truth." While Sakharov strongly disagreed with Teller over nuclear testing in the atmosphere and the Strategic Defense Initiative, he believed that American academics had been unfair to Teller's resolve to get the H-bomb for the United States since "all steps by the Americans of a temporary or permanent rejection of developing thermonuclear weapons would have been seen either as a clever feint, or as the manifestation of stupidity. In both cases, the reaction would have been the same – avoid the trap and immediately take advantage of the enemy's stupidity."
Sakharov never felt that by creating nuclear weapons he had "known sin", in Oppenheimer's expression. He later wrote:
Support for peaceful use of nuclear technology
In 1950 he proposed an idea for a controlled nuclear fusion reactor, the tokamak, based on Oleg Lavrentiev's idea. Sakharov, in association with Tamm, proposed confining extremely hot ionized plasma by torus shaped magnetic fields for controlling thermonuclear fusion that led to the development of the tokamak device.
Magneto-implosive generators
In 1951 he invented and tested the first explosively pumped flux compression generators, Translated as: Republished as: Translated as: compressing magnetic fields by explosives. He called these devices MK (for MagnetoKumulative) generators. The radial MK-1 produced a pulsed magnetic field of 25 megagauss (2500 teslas). The resulting helical MK-2 generated 1000 million amperes in 1953.
Sakharov then tested a MK-driven "plasma cannon" where a small aluminum ring was vaporized by huge eddy currents into a stable, self-confined toroidal plasmoid and was accelerated to 100 km/s. Sakharov later suggested replacing the copper coil in MK generators with a large superconductor solenoid to magnetically compress and focus underground nuclear explosions into a shaped charge effect. He theorized this could focus 1023 protons per second on a 1 mm2 surface.
Particle physics and cosmology After 1965 Sakharov returned to fundamental science and began working on particle physics and physical cosmology. Translated as: Translated as: Dokl. Akad. Nauk SSSR 177, 70 (1967) [trans. Sov. Phys.-Dokl. 12, 1040 (1968)] Dedicated to the 30th anniversary of N. N. Bogolyubov.Paper at seminar, Phys. Inst. Acad. Sci., June 1970
He tried to explain the baryon asymmetry of the universe; in that regard, he was the first to give a theoretical motivation for proton decay. Proton decay was suggested by Eugene Wigner in 1949 and 1952.E. P. Wigner, Proc. Am. Philos. Soc. 93, 521 (1949); Proc. Natl.Ac'ad. Sci. (U. S.) 38, 449 (1952) Proton decay experiments had been performed since 1954 already.F. Reines, C.L. Cowan, M. Goldhaber, Phys.Rev. 96 (1954) 1157. Sakharov was the first to consider CPT-symmetric events occurring before the Big Bang:We can visualize that neutral spinless maximons (or photons) are produced at ''t'' < 0 from contracting matter having an excess of antiquarks, that they pass "one through the other" at the instant ''t'' = 0 when the density is infinite, and decay with an excess of quarks when ''t'' > 0, realizing total CPT symmetry of the universe. All the phenomena at t < 0 are assumed in this hypothesis to be CPT reflections of the phenomena at t > 0. Translated as: Republished as His legacy in this domain are the famous conditions named after him: Baryon number violation, C-symmetry and CP-symmetry violation, and interactions out of thermal equilibrium.
Sakharov was also interested in explaining why the curvature of the universe is so small. This led him to consider cyclic models, where the universe oscillates between contraction and expansion phases. Translated as: Translated as: In those models, after a certain number of cycles the curvature naturally becomes infinite even if it had not started this way: Sakharov considered three starting points, a flat universe with a slightly negative cosmological constant, a universe with a positive curvature and a zero cosmological constant, and a universe with a negative curvature and a slightly negative cosmological constant. Those last two models feature what Sakharov calls a reversal of the time arrow, which can be summarized as follows: He considers times t > 0 after the initial Big Bang singularity at t = 0 (which he calls "Friedman singularity" and denotes Φ) as well as times t < 0 before that singularity. He then assumes that entropy increases when time increases for t > 0 as well as when time decreases for t < 0, which constitutes his reversal of time. Then he considers the case when the universe at t < 0 is the image of the universe at t > 0 under CPT symmetry but also the case when it is not so: the universe has a non-zero CPT charge at t = 0 in this case. Sakharov considers a variant of this model where the reversal of the time arrow occurs at a point of maximum entropy instead of happening at the singularity. In those models there is no dynamic interaction between the universe at t < 0 and t > 0.
In his first model the two universes did not interact, except via local matter accumulation whose density and pressure become high enough to connect the two sheets through a bridge without spacetime between them, but with a continuity of geodesics beyond the Schwarzschild radius with no singularity, allowing an exchange of matter between the two conjugated sheets, based on an idea after Igor Dmitriyevich Novikov. Novikov called such singularities a collapse and an anticollapse, which are an alternative to the couple black hole and white hole in the wormhole model. Sakharov also proposed the idea of induced gravity as an alternative theory of quantum gravity. Translated as:
Turn to activism
Since the late 1950s Sakharov had become concerned about the moral and political implications of his work. Politically active during the 1960s, Sakharov was against nuclear proliferation. Pushing for the end of atmospheric tests, he played a role in the 1963 Partial Test Ban Treaty, signed in Moscow.