Kapitza , Pyotr Leonidovich

(1894–1984) Russian physicist

Pyotr (or Peter) Kapitza was born in Kronstadt, Russia, and educated (1918–21) at the Polytechnic Institute and the Physical and Technical Institute in Petrograd (now St. Petersburg). He lectured at the Polytechnic Institute from 1919 to 1921. From 1921 to 1924 he was involved in magnetic research at the Cavendish Laboratory of Cambridge University under Ernest Rutherford and gained his PhD there in 1923. He was made director of the Royal Society Mond Laboratory at Cambridge in 1930. In 1934 he paid a visit to his homeland but was detained by the Soviet authorities. The next year Kapitza was made director of a newly founded research institute in Moscow – the Institute for Physical Problems – and was able to continue the line of his Cambridge research through the purchase of his original equipment. He worked there until 1946 when, apparently, he fell into disfavor with Stalin for declining to work on nuclear weapons. He was held under house arrest until 1955, when he was able to resume his work at the Institute. Kapitza had shown similar courage earlier in 1938 when he had intervened on behalf of his colleague Lev Landau who had been arrested as a supposed German spy. Without Landau, Kapitza insisted, he would be unable to complete work considered to be important by the authorities. Soon after, Landau was released.

Kapitza's most significant work in low-temperature physics was on the viscosity of the form of liquid helium known as He–II. This he (and, independently, J.F. Allen and A.D. Misener) found to exist in a ‘superfluid’ state – escaping from tightly sealed vessels and exhibiting unusual flow behavior. Kapitza found that He–II is in a macroscopic quantum state with perfect atomic order. In a series of experiments, he found also that a novel form of internal convection occurs in this form of helium.

Besides work on the unusual properties of helium, Kapitza also devised a liquefaction technique for the gas, which is the basis of present-day helium liquefiers, and was able to produce large quantities of liquid hydrogen, helium, and oxygen. The availability of liquid helium has led to the production of electric superconductors and enabled much other work at extremely low temperatures to proceed. Kapitza also created very high magnetic fields for his experiments, and his record of 500 kilogauss in 1924 was not surpassed until 1956. Kapitza's low-temperature work was honored after almost forty years by the award of the 1978 Nobel Prize for physics.

From 1955, Kapitza headed the Soviet Committee for Interplanetary Flight and played an important part in the preparations for the first Soviet satellite launchings. In his career, Kapitza collected many awards from scientific institutions of both East and West, including the Order of Lenin on six occasions. In 1965 he was finally allowed to travel outside the Soviet Union. He first visited Copenhagen and in 1966 he spent some time in Cambridge, England, with his colleagues of the 1930s, John Cockroft and Paul Dirac.