Lorentz derivation of length contraction in electrodynamics

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The discussion centers on the Lorentz derivation of length contraction in electrodynamics, which was initially proposed by George FitzGerald and H.A. Lorentz in 1892 to explain the Michelson-Morley experiment's negative results. Lorentz modeled matter as a collection of electric charges, showing that motion leads to a contraction in the direction of movement, thus eliminating the need for a stationary aether. Albert Einstein's 1905 theory of special relativity further validated this concept, removing its ad hoc nature and establishing that length contraction is a fundamental consequence of relativistic physics. Modern textbooks incorporate Lorentz Transformations and the special theory of relativity, affirming the soundness of Lorentz's derivation.

PREREQUISITES
  • Understanding of Maxwell's theory of electromagnetism
  • Familiarity with Lorentz Transformations
  • Knowledge of special relativity principles
  • Basic grasp of the Michelson-Morley experiment
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  • Study the derivation of Lorentz Transformations in detail
  • Explore the implications of special relativity on time and simultaneity
  • Investigate the historical context of the Michelson-Morley experiment
  • Examine modern interpretations of length contraction in physics textbooks
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Physicists, students of theoretical physics, and educators seeking a deeper understanding of the historical and conceptual foundations of length contraction and special relativity.

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What Lorentz was able to show was that Maxwell's theory of electromagnetism predicted precisely this much longitudinal contraction.To get this result, Lorentz modeled matter composing a body as a large collection of electric charges, all held together in equilibrium by electric and magnetic forces.
lattice_at_rest.png

The equilibrium was disturbed if the entire object was set in motion. Moving electric charges create magnetic fields that in turn act back of electric charges. All these changes settle out into a new equilibrium configuration. What Lorentz could show was that new configuration consists in a contraction of the body in the direction of motion in just the amount needed to eradicate a possible result from the Michelson Morley experiment.

lattice_moving.png

My question is: is this derivation of length contraction considered to be sound and correct today? Are they treated in modern textbooks?
 
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Length contraction was postulated by George FitzGerald and H.A Lorentz (1892) to explain the negative outcome of the Michelson–Morley experiment and to rescue the hypothesis of the stationary aether .

It was considered an ad hoc hypothesis, because at this time there was no sufficient reason to assume that intermolecular forces behave the same way as electromagnetic ones.

Eventually, Albert Einstein (1905) was the first to completely remove the ad hoc character from the contraction hypothesis, by demonstrating that this contraction did not require motion through a supposed aether, but could be explained using special relativity, which changed our notions of space, time, and simultaneity.

Now a days the special theory of relativity and Lorentz Transformations are used to derive contraction as a consequence of STR.
one can see details of historical development in <https://en.wikipedia.org/wiki/Length_contraction>
 
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drvrm said:
Length contraction was postulated by George FitzGerald and H.A Lorentz (1892) to explain the negative outcome of the Michelson–Morley experiment and to rescue the hypothesis of the stationary aether .

It was considered an ad hoc hypothesis, because at this time there was no sufficient reason to assume that intermolecular forces behave the same way as electromagnetic ones.

Eventually, Albert Einstein (1905) was the first to completely remove the ad hoc character from the contraction hypothesis, by demonstrating that this contraction did not require motion through a supposed aether, but could be explained using special relativity, which changed our notions of space, time, and simultaneity.

Now a days the special theory of relativity and Lorentz Transformations are used to derive contraction as a consequence of STR.
one can see details of historical development in <https://en.wikipedia.org/wiki/Length_contraction>

Thank you very much for your reply.
If I understand well what happened I would say the objections of "ad hoc" hypothesis addressed to Lorentz actually vanished not just because of Einstein's revolution but also because Loretnz's hypothesis that intermolecular forces are electromagnetic turned out to be true. Is this right? So it makes sense to consider the possibility that Lorentz derivation was indeed sound/correct and if it is so maybe it would be remarkable enough to deserve to be treated in textbook today. Is this the case?
 
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The question that Lorentz left open but Einstein answered is what happens to matter that is not held together by electromagnetic forces. Michelson and Morley's interferometer was built on a solid base. But what would happen to an interferometer with mirrors floating freely in vacuum? Einstein says that it will behave the same way as the one with the solid base. But the argument you laid out above gives no reason to expect the distance between free-floating unconnected mirrors to change. That makes it a detailed application of Einstein's more general argument to the case of solid matter, I think.
 

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