20 August marks the 125th anniversary of the birth of a famous theoretical physicist, one of the JINR founders Leopold Infeld (1898 – 1968). He was an Academician of the Polish Academy of Sciences and some foreign academies, creator of the school of theoretical physics in Poland. He seemed to have made his own phrase as his motto “Nothing in the world should remain hidden from humanity”. At JINR, he was a member of the Scientific Council.

He was born in Krakow in 1898 and graduated from the University of Krakow in 1921. Until 1930, he taught physics in schools, after which he became an assistant at the Department of Theoretical Physics at the University of Lviv. In 1832, he worked in Leipzig, in 1933 – 1935 at Cambridge, in 1936 – 1938 at Princeton, in 1939 – 1950 he was a professor at the University of Toronto.

In 1950, Infeld returned to his homeland, where he began to play a leading role in the development of theoretical physics. He was the head of the Department of the University of Warsaw, founded and headed the Institute of Theoretical Physics at this university. Teaching was one of the scientist’s favourite activities. He fostered critical thinking in his students and developed the habit of scientific discussions.

In 1952, he was elected an Academician of the Polish Academy of Sciences, in 1952 – 1962, he was a member of the PAS Presidium. In 1953, he began working at the Institute of Physics of PAS. He was President of the Polish Physical Society from 1955 to 1957. Leopold Infeld made great efforts to develop international scientific cooperation in Poland. In 1962, he organized a conference on gravity, which many outstanding physicists, including Paul Dirac, Richard Feynman, and others attended.

Infeld’s main interests laid in the theory of relativity, equations of motion, unified field theory, and quantum mechanics. He wrote more than a hundred scientific papers on general relativity, classical, relativistic, and quantum field theory, the interpretation of the uncertainty relation, the electron wave equation in general relativity (together with Bartel van der Waerden, 1933). Jointly with Max Born, he developed a phenomenological model of classical electrodynamics (Born-Infeld theory, 1934 – 1935).

In 1936, at Princeton University in the USA, he started cooperation with Albert Einstein, who became his friend and mentor. In 1938, together with Einstein and Banesh Hoffmann, he derived equations of motion in the gravitational field of a system of bodies with a velocity significantly lower than the speed of light. “These works marked the beginning of a line of research that has been continued all over the world and which is now used in astrophysics to describe the movement and stellar evolution,” one of Infeld’s students, professor Andrzej Trautman recalled.

Einstein and Infeld co-authored a popular-science book The Evolution of Physics, which was very successful and was reprinted in numerous editions. In addition, Infeld also wrote a biographical book about Evariste Galois, the founder of modern higher algebra.

He was one of the founders of the Pugwash Conferences on Science and World Affairs, a member of the World Peace Council, and one of 11 famous scientists who signed the Russell–Einstein Manifesto, i.e. a document that emphasised the dangers posed by nuclear weapons and called on world leaders to strive for a peaceful resolution of international conflicts. In 1964, he was among the Polish intellectuals who opposed censorship (the so-called “Letter of 34”).

He was awarded the highest state awards of Poland. The educational programme of the JINR University Centre titled Bogoliubov – Infeld devoted to the development of cooperation between theoreticians from Poland and Dubna bore the name of Leopold Infeld.