Pavel Cherenkov, at the Lebedev Physical Institute in Moscow, observes in 1934 a faint blue glow emitted by transparent liquids irradiated with radioactive sources, distinct from known fluorescence. Ilya Frank and Igor Tamm provide the complete theoretical explanation in 1937: a charged particle traveling through a transparent medium faster than light travels in that medium generates an electromagnetic shock wave analogous to a sonic boom. This radiation, today known as Cherenkov radiation, becomes a fundamental tool for detecting high-energy subatomic particles: it explains the characteristic blue glow in nuclear reactor pools, and detectors based on the phenomenon — such as Super-Kamiokande in Japan or IceCube in Antarctica — detect neutrinos and other weakly interacting particles.