Lebedev, Peter Nikolaievich (1866-1912)

Russian physicist. He proved by experiment that light exerts a minute pressure upon a physical body, thereby confirming James Maxwell's theoretic prediction. Lebedev was born in Moscow and studied in Germany at Strasbourg. He was professor at Moscow University 1892-1911, resigning on political grounds. Lebedev began studying light pressure (now called radiation pressure) in the late 1890s but did not complete his investigations until 1910. Working first with solid bodies and later with gases, he not only observed the minute physical effects caused by the infinitesimal pressure exerted by light on matter but also measured this pressure using extremely lightweight apparatus in an evacuated chamber. Lebedev also investigated the effects of electromagnetic, acoustic, and hydrodynamic waves on resonators; demonstrated the behavioural similarities between light and (as they are now known to be) other electromagnetic radiations; detected electromagnetic waves of higher frequency than had previously been studied; and researched into the Earth's magnetic field.