Pyotr Nikolayevich LebedevDied 1 Apr 1912 at age 46 (born 8 Mar 1866).Russian physicist who, in experiments with William Crookes' radiometer, proved (1910) that light exerts a minute pressure on bodies (as predicted by James Clerk Maxwell's theory of electromagnetism), and furthermore that this effect is twice as great for reflecting surfaces than for absorbent surfaces. He had proposed that light pressure on small particles of cosmic dust could be greater than gravitational attraction, thus explaining why a comet's tail points away from the Sun (though it is now understood the solar wind has a greater influence). He built an extremely small vibrator source capable of generating 4-6 mm waves, which he used to demonstrate the first observation of douible refraction of electromagnetic waves in crystals of rhombic sulphur.«[DSB gives dates 8 Mar 1866 - 1 Apr 1912. EB gives Old Style 24 Feb 1866 - 1 Mar 1912 (New Style 8 Mar 1866 - 14 Mar 1912).] |
