Editing Michelson interferometer (section)

{{Short description|Common configuration for optical interferometry}}
{{For|the astronomical interferometer|Michelson stellar interferometer}}
[[Image:Michelson Interferometer.jpg|thumb|right|300px|Figure 1. A basic Michelson interferometer, not including the optical source and detector.]]
[[File:Michelson interferometer.png|thumb|This image demonstrates a simple but typical Michelson interferometer. The bright yellow line indicates the path of light.]]

The '''Michelson interferometer''' is a common configuration for optical [[interferometry]] and was invented by the American physicist [[Albert Abraham Michelson]] in 1887. Using a [[beam splitter]], a [[light]] source is split into two arms. Each of those [[light beam]]s is reflected back toward the beamsplitter which then combines their amplitudes using the [[superposition principle]]. The resulting [[interference pattern]] that is not directed back toward the source is typically directed to some type of [[Photodetector|photoelectric detector]] or [[camera]]. For different applications of the interferometer, the two light paths can be with different lengths or incorporate optical elements or even materials under test.

The Michelson interferometer is employed in many scientific experiments and became well known for its use by Michelson and [[Edward Morley]] in the famous [[Michelson–Morley experiment]] (1887)<ref name=Michelson1887>{{cite journal|author=Albert Michelson |author2=Edward Morley|date=1887|title=On the Relative Motion of the Earth and the Luminiferous Ether|journal=American Journal of Science|volume=34|issue=203|pages=333–345|url=https://en.wikisource.org/wiki/Index:On_the_Relative_Motion_of_the_Earth_and_the_Luminiferous_Ether.djvu|doi=10.2475/ajs.s3-34.203.333|bibcode=1887AmJS...34..333M|s2cid=124333204}}</ref> in a configuration which would have detected the Earth's motion through the supposed [[luminiferous aether]] that most physicists at the time believed was the medium in which light waves [[Wave propagation|propagated]]. The null result of that experiment essentially disproved the existence of such an aether, leading eventually to the [[special theory of relativity]] and the [[Annus Mirabilis papers|revolution in physics]] at the beginning of the twentieth century. In 2015, another application of the Michelson interferometer, [[LIGO]], made the [[First observation of gravitational waves|first direct observation]] of [[gravitational wave]]s.<ref>{{Cite journal|collaboration=LIGO Scientific Collaboration and Virgo Collaboration|last=Abbott|first=B. P.|date=15 June 2016|title=GW151226: Observation of Gravitational Waves from a 22-Solar-Mass Binary Black Hole Coalescence|journal=[[Physical Review Letters]]|volume=116|issue=24|pages=241103|doi=10.1103/PhysRevLett.116.241103|pmid=27367379|arxiv=1606.04855|bibcode=2016PhRvL.116x1103A|s2cid=118651851 }}</ref> That observation confirmed an important prediction of [[general relativity]], validating the theory's prediction of space-time distortion in the context of large scale cosmic events (known as [[Tests of general relativity|strong field tests]]).