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Pyotr Nikolaiyevich Lebedev (1866-1912), Russian physicist. Lebedev was born in Moscow, and educated both there and at Strasbourg. Lebedev's major work was in the effect of light upon small bodies. Maxwell's theory of electromagnetism predicted that light would exert a small pressure on matter. Lebedev succeeded in detecting this minute effect, and later even measured it. Light pressure (or radiation pressure) was an important confirmation of Maxwell's theory. By 1902, Lebedev had risen to the rank of professor at Moscow University. In 1911, however, he resigned in protest against the actions of the Minister of Education, and died soon after. (KEYSTONE/SCIENCE PHOTO LIBRARY/SCIENCE PHOTO LIBRARY)