Editing Interferometry (section)

==History==
The law of interference of light was described by [[Thomas Young (scientist)|Thomas Young]] in his 1803 Bakerian Lecture to the Royal Society of London.<ref> T.Young, “The Bakerian Lecture:Experiments and Calculations Relative to Physical Optics,” Philosophical Transactions of the Royal Society of London 94 (1804): 1–16.</ref>   In preparation for the lecture, Young performed a double-aperture experiment that demonstrated interference fringes.  His interpretation in terms of the interference of waves was rejected by most scientists at the time because of the dominance of Isaac Newton's corpuscular theory of light proposed a century before.<ref>{{Cite book|last=Kipnis|first=Nahum|date=1991|title=History of the Principle of Interference of Light|url=https://link.springer.com/book/10.1007/978-3-0348-8652-9|language=en-gb|doi=10.1007/978-3-0348-8652-9|isbn=978-3-0348-9717-4 }}</ref>

The French engineer [[Augustin-Jean Fresnel]], unaware of Young's results, began working on a wave theory of light and interference and was introduced to [[François Arago]].  Between 1816 and 1818, Fresnel and Arago performed interference experiments at the Paris Observatory.  During this time, Arago designed and built the first interferometer, using it to measure the refractive index of moist air relative to dry air, which posed a potential problem for astronomical observations of star positions.<ref> J. Lequeux, François Arago A 19th Century French Humanist and Pioneer in Astrophysics (Springer International Publishing: Imprint: Springer, 2015).</ref>  The success of Fresnel's wave theory of light was established in his prize-winning memoire of 1819 that predicted and measured diffraction patterns.  The Arago interferometer was later employed in 1850 by [[Léon Foucault |Leon Foucault]] to measure the speed of light in air relative to water, and it was used again in 1851 by [[Hippolyte Fizeau]] to measure the effect of Fresnel drag on the speed of light in moving water.<ref>{{Cite book|last=Nolte|first=David D.|date=2023|title=Interference: The History of Optical Interferometry and the Scientists Who Tamed Light (Oxford University Press, 2023)|publisher=Oxford University Press |url=https://global.oup.com/academic/product/interference-9780192869760  |isbn=978-0192869760}}pp. 99-108</ref>

[[Jules Jamin]] developed the first single-beam interferometer (not requiring a splitting aperture as the Arago interferometer did) in 1856.  In 1881, the American physicist [[Albert A. Michelson]], while visiting [[Hermann von Helmholtz]] in Berlin, invented the interferometer that is named after him, the [[Michelson Interferometer]], to search for effects of the motion of the Earth on the speed of light.  Michelson's null results performed in the basement of the Potsdam Observatory outside of Berlin (the horse traffic in the center of Berlin created too many vibrations), and his later more-accurate null results observed with [[Edward W. Morley]] at [[Case Western Reserve University|Case College]] in Cleveland, Ohio, contributed to the growing crisis of the luminiferous ether.  Einstein stated that it was Fizeau's measurement of the speed of light in moving water using the Arago interferometer that inspired his theory of the relativistic addition of velocities.<ref>Nolte, Interference,pg.111</ref>