Pyotr Leonidovich Kapitsa (Russian Пётр Леонидович Капица) (July 9, 1894 – April 8, 1984) was an innovative Soviet/Russian physicist and Nobel laureate, who made important discoveries in a number of different areas.
Kapitsa was born in the city of Kronstadt, and graduated from the Petrograd Polytechnical Institute in 1918. He worked in the Cavendish Laboratory in Cambridge with Ernest Rutherford for over 10 years, was made a Fellow of the Royal Society in 1929, and was the first director of the Mond Laboratory in Cambridge from 1930 to 1934. During the 1920s he originated techniques for creating ultrastrong magnetic fields by injecting high currents into specially constructed air-core electromagnets for brief periods of time. In 1928 he discovered the linear dependence of resistivity on magnetic field for various metals placed in very strong magnetic fields.
In the 1930s he turned to low temperature research. He began with a critical analysis of the methods that existed at the time for obtaining low temperatures. In 1934 he developed a new and original apparatus for producing significant quantities of liquid helium, based on the adiabatic principle.
In 1934 he was on a professional visit to the Soviet Union when his passport was detained and he was not permitted to leave the country. Kapitsa was required to form the Institute for Physical Problems, with equipment purchased by the Soviet Government from the Mond Laboratory in Cambridge with the assistance of Rutherford, once it was clear that Kapitsa would not be permitted to return to England.
In Russia Kapitsa began a series of experiments to study the properties of liquid helium that led to discovery of the superfluidity of helium in 1937, and in a series of papers he reported the properties of this new state of matter. For these reports Kapitsa was later awarded the Nobel Prize in Physics "for basic inventions and discoveries in the area of low-temperature physics". (Superfluidity is not to be confused with superconductivity). In 1939 he developed a new method for liquefaction of air with a lowpressure cycle using a special high-efficiency expansion turbine. Consequently during World War II he was assigned to head the Department of Oxygen Industry attached to the USSR Council of Ministers, where he developed his lowpressure expansion techniques for industrial purposes. In the years after the war he turned his attention to a totally new range of physical problems: he invented high power microwave generators (1950-1955) and discovered a new kind of continuous high pressure plasma discharge with electron temperatures over a million K.
Immediately after the War, a group of prominent Soviet scientists, including Kapitsa in particular, lobbied the government for the creation of a brand new technical university, the Moscow Institute of Physics and Technology. It has become one of the leading Russian universities. Kapitsa was a longtime teacher there. From 1957 onward Kapitsa was also a member of the presidium of the Soviet Academy of Sciences and at his death in 1984 he was the only presidium member who was not a member of the Communist Party.
Belatedly in 1978 Kapitsa won the Nobel Prize in Physics for the work in low temperature physics that he did around 1937. He shared the prize with Arno Allan Penzias and Robert Woodrow Wilson, who won for entirely unrelated work.
Kapitsa resistance is a resistance to the flow of heat across the interface between liquid helium and a solid that produces a temperature discontinuity.