Light bending by mass between source and observer
A light source passes behind a gravitational lens (invisible point mass placed in the center of the image). The aqua circle is the light source as it would be seen if there were no lens, while white spots are the multiple images of the source (see Einstein ring ).
A gravitational lens is matter, such as a cluster of galaxies or a point particle , that bends light from a distant source as it travels toward an observer. The amount of gravitational lensing is described by Albert Einstein 's general theory of relativity .[ 1] [ 2] If light is treated as corpuscles travelling at the speed of light , Newtonian physics also predicts the bending of light, but only half of that predicted by general relativity.[ 3] [ 4] [ 5] [ 6]
Orest Khvolson (1924)[ 7] and Frantisek Link (1936)[ 8] are generally credited with being the first to discuss the effect in print, but it is more commonly associated with Einstein, who made unpublished calculations on it in 1912[ 9] and published an article on the subject in 1936.[ 10]
In 1937, Fritz Zwicky posited that galaxy clusters could act as gravitational lenses, a claim confirmed in 1979 by observation of the Twin QSO SBS 0957+561.
^ Drakeford, Jason; Corum, Jonathan; Overbye, Dennis (March 5, 2015). "Einstein's Telescope - video (02:32)" . New York Times . Retrieved December 27, 2015 .
^ Overbye, Dennis (March 5, 2015). "Astronomers Observe Supernova and Find They're Watching Reruns" . New York Times . Retrieved March 5, 2015 .
^ Bernard F. Schutz (1985). A First Course in General Relativity (illustrated, herdruk ed.). Cambridge University Press. p. 295. ISBN 978-0-521-27703-7 .
^ Wolfgang Rindler (2006). Relativity: Special, General, and Cosmological (2nd ed.). OUP Oxford. p. 21. ISBN 978-0-19-152433-2 . Extract of page 21
^ Gabor Kunstatter; Jeffrey G Williams; D E Vincent (1992). General Relativity And Relativistic Astrophysics - Proceedings Of The 4th Canadian Conference . World Scientific. p. 100. ISBN 978-981-4554-87-9 . Extract of page 100
^ Pekka Teerikorpi; Mauri Valtonen; K. Lehto; Harry Lehto; Gene Byrd; Arthur Chernin (2008). The Evolving Universe and the Origin of Life: The Search for Our Cosmic Roots (illustrated ed.). Springer Science & Business Media. p. 165. ISBN 978-0-387-09534-9 . Extract of page 165
^ Turner, Christina (February 14, 2006). "The Early History of Gravitational Lensing" (PDF) . Archived from the original (PDF) on July 25, 2008.
^ Bičák, Jiří; Ledvinka, Tomáš (2014). General Relativity, Cosmology and Astrophysics: Perspectives 100 years after Einstein's stay in Prague (illustrated ed.). Springer. pp. 49–50. ISBN 9783319063492 .
^ Tilman Sauer (2008). "Nova Geminorum 1912 and the Origin of the Idea of Gravitational Lensing". Archive for History of Exact Sciences . 62 (1): 1–22. arXiv :0704.0963 . Bibcode :2008AHES...62....1S . doi :10.1007/s00407-007-0008-4 . S2CID 17384823 .
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