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Russian physicist Ilya M. Frank won the Nobel Prize in physics in 1958. Frank advanced nuclear physics and the study of cosmic rays.

Ilya M. Frank (1908-1990), Russian physicist and cowinner of the 1958 Nobel Prize in physics for his interpretation of the Cherenkov effect. This phenomenon occurs when high-energy, charged particles travel through a medium, such as water or plastic, at a speed greater than the speed of light in the same medium. The result is the emission of bluish light. His research greatly advanced nuclear physics and the study of cosmic rays (protons and atomic nuclei from outer space). Frank shared the 1958 Nobel Prize with Soviet physicists Pavel Cherenkov and Igor Tamm.

Born in Saint Petersburg (formerly Leningrad), Russia, Frank attended Moscow State University, graduating in 1930 with a degree in physics. He earned his doctorate in physical and mathematical sciences in 1935 from the State Optical Institute in Saint Petersburg. Frank served as a professor at the State Optical Institute from 1931 to 1934. He accepted a position at the Lebedev Institute of Physics of the Academy of Sciences in Moscow in 1934, and joined the faculty at Moscow State University in 1944. He held both positions until his retirement.

In 1934 Cherenkov first observed that water emitted an unusual blue light when bombarded by gamma rays (high energy photons—see Radioactivity), but he could not explain his observations theoretically. In 1937 Frank and fellow scientist Tamm used a simple mathematical formula to calculate the angle between the gamma ray's travel path and the direction of the particle's wave of emitted energy (the blue light). This angle helped explain the nature of the Cherenkov radiation. The team also helped construct the Cherenkov detector (see Particle Detectors), which assisted them in observing the Cherenkov effect with other high-energy particles.

Frank expanded his research on Cherenkov radiation by studying how the phenomenon was affected by the optical properties of different media. He also performed significant research on neutrons, uncharged atomic particles that are one of the fundamental particles of matter.