Editing Radiation pressure (section)

== Discovery ==
[[File:125-річчя з дня народження П. Н. Лебедєва.jpg|thumb|[[Soviet ruble]] coin commemorating Lebedev's discovery]]
[[Johannes Kepler]] put forward the concept of radiation pressure in 1619 to explain the observation that a tail of a [[comet]] always points away from the Sun.<ref>{{cite book|author=Johannes Kepler|author-link=Johannes Kepler|title=De Cometis Libelli Tres|date=1619|title-link=De Cometis Libelli Tres}}</ref>

The assertion that light, as [[electromagnetic radiation]], has the property of [[momentum]] and thus exerts a [[pressure]] upon any surface that is exposed to it was published by [[James Clerk Maxwell]] in 1862, and proven experimentally by Russian physicist [[Pyotr Nikolaevich Lebedev|Pyotr Lebedev]] in 1900<ref>P. Lebedew, 1901, "Untersuchungen über die Druckkräfte des Lichtes", ''Annalen der Physik'', 1901 Series 4 6, 433-458.</ref> and by [[Ernest Fox Nichols]] and [[Gordon Ferrie Hull]] in 1901.<ref>Nichols, E. F & Hull, G. F. (1903) [https://books.google.com/books?id=8n8OAAAAIAAJ&pg=RA5-PA327 The Pressure due to Radiation], ''The Astrophysical Journal'', Vol.17 No.5, p.315-351</ref> The pressure is very small, but can be detected by allowing the radiation to fall upon a delicately poised vane of reflective metal in a [[Nichols radiometer]] (this should not be confused with the [[Crookes radiometer]], whose characteristic motion is ''not'' caused by radiation pressure but by air flow caused by temperature differentials.)