Voigt (1887)
Woldemar Voigt (1887) developed a transformation in connection with the Doppler effect and an incompressible medium, being in modern notation:
- .
If the right-hand sides of his equations are multiplied by they are the modern Lorentz transformation. In Voigt's theory the speed of light is invariant, but his transformations mix up a relativistic boost together with a rescaling of space-time. Maxwell's electrodynamics is scale, conformal, and Lorentz invariant, so the combination is invariant too. But scale transformations are not a symmetry of all the laws of nature, only of electromagnetism, so these transformations cannot be used to formulate a principle of relativity in general. Lorentz acknowledged Voigt's work in 1909 by saying:
| “ | In a paper "Über das Doppler'sche Princip", published in 1887 ... and which to my regret has escaped my notice all these years, Voigt has applied to equations of the form (6) ... a transformation equivalent to the formulae (287) and (288). The idea of the transformations used above ... might therefore have been borrowed from Voigt and the proof that it does not alter the form of the equations for the free ether is contained in his paper. | ” |
Also Hermann Minkowski said in 1908 that the transformations which play the main role in the principle of relativity were first examined by Voigt in 1887. Voigt responded in the same paper by saying, that his theory was based on an elastic theory of light, not an electromagnetic one. However, he concluded that some results were actually the same.
Read more about this topic: History Of Lorentz Transformations