Editing Hendrik Lorentz (section)

===Electrodynamics and relativity===
{{Main|Lorentz ether theory|History of special relativity|History of Lorentz transformations#Lorentz1|History of Lorentz transformations#Lorentz2}}

In 1892 and 1895, Lorentz worked on describing electromagnetic phenomena (the propagation of light) in reference frames that move relative to the postulated [[luminiferous aether]].<ref>{{Citation
|author=Lorentz, Hendrik Antoon
|year=1892
|title=La Théorie electromagnétique de Maxwell et son application aux corps mouvants
|url = https://archive.org/details/lathorielectrom00loregoog
|journal=Archives Néerlandaises des Sciences Exactes et Naturelles
|volume=25
|pages=363–552}}</ref><ref>{{Citation
|author=Lorentz, Hendrik Antoon
|year=1895
|title=Versuch einer Theorie der electrischen und optischen Erscheinungen in bewegten Körpern
|location=Leiden
|publisher=E.J. Brill|title-link=s:de:Versuch einer Theorie der electrischen und optischen Erscheinungen in bewegten Körpern
}}
*English Wikisource translation: [[s:Translation:Attempt of a Theory of Electrical and Optical Phenomena in Moving Bodies|Attempt of a Theory of Electrical and Optical Phenomena in Moving Bodies]]</ref> He discovered that the transition from one to another reference frame could be simplified by using a new time variable that he called ''local time'' and which depended on universal time and the location under consideration. Although Lorentz did not give a detailed interpretation of the physical significance of local time, with it, he could explain the [[aberration of light]] and the result of the [[Fizeau experiment]]. In 1900 and 1904, [[Henri Poincaré]] called local time Lorentz's "most ingenious idea" and illustrated it by showing that clocks in moving frames are synchronized by exchanging light signals that are assumed to travel at the same speed against and with the motion of the frame<ref>{{Citation
|author=Poincaré, Henri
|year=1900
|title=La théorie de Lorentz et le principe de réaction
|journal=Archives Néerlandaises des Sciences Exactes et Naturelles
|volume=5
|pages=252–278|title-link=s:fr:La théorie de Lorentz et le principe de réaction
}}. See also the [http://www.physicsinsights.org/poincare-1900.pdf English translation].</ref><ref>{{Citation
|author=Poincaré, Henri
|year=1904
|chapter=[[s:The Principles of Mathematical Physics|The Principles of Mathematical Physics]]
|title=Congress of arts and science, universal exposition, St. Louis, 1904
|volume=1
|pages=604–622
|publisher=Houghton, Mifflin and Company
|location=Boston and New York}}</ref> (see [[Einstein synchronisation]] and [[Relativity of simultaneity]]). In 1892, with the attempt to explain the [[Michelson–Morley experiment]], Lorentz also proposed that moving bodies contract in the direction of motion (see [[length contraction]]; [[George Francis FitzGerald|George FitzGerald]] had already arrived at this conclusion in 1889).<ref>{{Citation
|last=Lorentz
|first=Hendrik Antoon
|year=1892b
|title=The Relative Motion of the Earth and the Aether
|journal=Zittingsverlag Akad. V. Wet.
|pages=74–79
|volume=1|title-link=s:Translation:The Relative Motion of the Earth and the Aether
}}</ref>

In 1899 and again in 1904, Lorentz added [[time dilation]] to his transformations and published what Poincaré in 1905 named [[Lorentz transformations]].<ref>{{Citation
|author=Lorentz, Hendrik Antoon
|year=1899
|title=Simplified Theory of Electrical and Optical Phenomena in Moving Systems
|journal=Proceedings of the Royal Netherlands Academy of Arts and Sciences
|volume=1
|pages=427–442|title-link=s:Simplified Theory of Electrical and Optical Phenomena in Moving Systems
|bibcode=1898KNAB....1..427L
}}</ref><ref>{{Citation
|author=Lorentz, Hendrik Antoon
|year=1904
|title=Electromagnetic phenomena in a system moving with any velocity smaller than that of light
|journal=Proceedings of the Royal Netherlands Academy of Arts and Sciences
|volume=6
|pages=809–831|title-link=s:Electromagnetic phenomena
|bibcode=1903KNAB....6..809L
}}</ref>{{electromagnetism|Scientists}}
It was apparently unknown to Lorentz that [[Joseph Larmor]] had used identical transformations to describe orbiting electrons in 1897. Larmor's and Lorentz's equations look somewhat dissimilar, but they are algebraically equivalent to those presented by Poincaré and Einstein in 1905.<ref name=Macrossan/> Lorentz's 1904 paper includes the covariant formulation of electrodynamics, in which electrodynamic phenomena in different reference frames are described by identical equations with well defined transformation properties. The paper clearly recognizes the significance of this formulation, namely that the outcomes of electrodynamic experiments do not depend on the relative motion of the reference frame. The 1904 paper includes a detailed discussion of the increase of the inertial mass of rapidly moving objects in a useless attempt to make momentum look exactly like Newtonian momentum; it was also an attempt to explain the length contraction as the accumulation of "stuff" onto mass making it slow and contract.