Pyotr Leonidovich Kapitsa (Russian Пётр Леонидович Капица) (1894 – April 8, 1984) was a Russian physicist who discovered superfluidity with John F. Allen and Don Misener in 1937.
He was born in the city of Kronstadt. He worked in Cambridge for over 10 years and then went on a professional visit to the Soviet Union and was not allowed to return to Cambridge.
Ernest Rutherford, whom Kapitsa had worked with at Cambridge, sold the Soviets Kapitsa's laboratory equipment. The Soviets then made Kapitsa form the Institute for Physical Problems with his equipment.
Kapitsa won the Nobel Prize in Physics in 1978 for his work in low-temperature physics. He shared the Prize with Arno Allan Penzias and Robert Woodrow Wilson.