Talk:Trouton–Rankine experiment

I like to read that paper, as this article implies that special relativity is wrong. An extraordinary claim! Many such claims have been made in the past, and nearly all, if not all, have either been shown to rest on error or have never been reproduced. harrylin at gmx dot net Harald88 20:08, 4 January 2006 (UTC)

Well, I guess now, after all the discussions you know better that you misread the post. ati3414


 * Which post? Harald88 18:06, 11 January 2006 (UTC)


 * The article claims that the experimental outcome did not match the Lorentz-FitzGerald contraction hypothesis. I agree that that is a extraordinary claim.
 * I will recapitulate why the claim is extraordinary.
 * The Lorentz-Fitzgerald contraction hypothesis is a necessary hypothesis in order to unify the Maxwell equations and the assumption of galilean relativity into a single theory. According to Lorentz Ether theory, the contraction is inherently unobservable. According to Lorentz Ether theory, the Lorentz-FitzGerald contraction is part of the "conspiracy of Nature" to "hide" the luminiferous ether from experimental observation.
 * Lorentz Ether theory matches every prediction of special relativity. Experiments cannot distinguish between the two theories. The difference between Lorentz Ether theory and special relativity is that Lorentz Ether theory requires more auxillary assumptions, and the necessity to keep adding ad hoc hypotheses would have continued if physicists would have continued to use Lorentz Ether theory.


 * It is not clear whether the contributors to the article are aware of these matters. --Cleonis | Talk 17:13, 5 January 2006 (UTC)

Looks like you are retracting most of the above at the bottom of this page, aren't you? ati3414

The Trouton-Noble experiment
Some more information on Troutons experiments is available from the the physicist Michael Jansen, who has expert knowledge on the Trouton-Noble experiment.  Micheal Jansens discussion of theTrouton-Noble experiment (PDF-file 572 KB)

The null result of the Trouton-Noble experiment can only be reconciled with Lorentz Ether theory by abandoning the law of conservation of momentum. Lorentz opted to allow that momentum is not always conserved, the alternative would have been to abandon Lorentz Ether theory.

Both the Trouton-Noble experiment and the Trouton-Rankine experiment address the question of velocity relative to the motionless ether. The special characteristic of the Trouton experiments is that they are not experiments in optics. --Cleonis | Talk 17:54, 5 January 2006 (UTC)


 * Hi Cleon thanks for that link -- I never understood that experiment, and now I understood it from just the first page. But why do you claim that conservation of momentum neeeded to be abandoned? I suppose that you mean that the classical law of momentum needed expansion, as Jannssen described. In fact, Janssen's description is so clear that it is easy to see how Lorentz was drawn into confusion by Fitzgerald; for the total momentum of all matter present in that system obviously remains constant, also according to the theory brought forward by Lorentz himself in 1904. Harald88 20:32, 5 January 2006 (UTC)
 * I may have made a mistake in claiming conservation of momentum must be abandoned, maybe some other auxillary hypothesis would be needed. Newtons third law can be seen as asserting conservation of momentum. Lorentz agreed that "there are grounds for saying that the ether exerts forces on ponderable matter", but the reverse, matter exerting a force on the ether, did not seem to apply. That is: it appeared to Lorentz that the principle: action = -reaction does not always apply. --Cleonis | Talk 20:59, 5 January 2006 (UTC)

Trouton-Rankine expected the Wheatstone bridge to become imbalanced after rotation (see paper). That would have happened if the FitzGerald contraction were as described by FitzGerald, an observable phenomenon, i.e. if the arms of the Wheatstone bridge got shorter in the direction parallel to the "aether". The imbalance of the bridge did not happen, meaning the end of the FitzGerald contraction. The Trouton-Rankine experiment shut the door on FC, the only contraction is the Lorentz contraction as a consequence of the utilization of Lorentz transforms in SR.


 * If I understand well, this means that the Fitzgerald ether theory (as anon. sketches here) was disproved. Harald88 19:49, 5 January 2006 (UTC)


 * To my knowledge, there were several ether theories at the time. In some theories the ether is unmoving, in some theories the ether is dragged along by the Earth, with all sorts of varieties of being dragged along.
 * At the time, experiments were set up to test theories, and there were a lot of theories around. As Poincaré commented:"Hypotheses are what we lack the least at the moment."
 * I have no knowledge of Fitzgerald Ether theory, but I suspect it is very similar to Lorentz Ether theory, I don't know. As mentioned earlier, it is my understanding that Lorentz Ether theory can match every prediction of special relativity. --Cleonis | Talk 21:11, 5 January 2006 (UTC)


 * From the article of Janssen that I now read, it appears that Fitzgerald had a particlar idea about momentum transfer that conflicts with the POR, and also Lorentz was brought into confusion by it. Thus, it depends on what you mean with LET: some use that label as a strawman, including the imperfections of 1904 or even earlier while others use it for the perfected theory of which SRT makes up the experimental part. Harald88 00:03, 6 January 2006 (UTC)

Then who keeps editing my posting ?


 * Easy: read the edit history. It also contains comments... For example, copying whole pieces of text from other sources withotu accrediting is "not done" and can cause copyright problems. Harald88 20:35, 5 January 2006 (UTC)

That's BS, I recast the whole thing is my own words. As to Cleonis' "disertation" he's missing a very big point (though he seems to make it later on): yes, FC required "ad-hoc", auxilliary hypothesis in order to explain each particular experiment, this is why it was abandoned. So far we agree, Where the disagreement starts is the fact that the little known Trouton-Rankine experiment is exceptional: there is no auxilliary, ad-hoc explanation for it. So, no mr. Cleonis, the FitzGerald ether theory could not "match every prediction of SR", it died a natural death in 1908. TR is incorrectly considered an "electrical" counterpart to MM. In the case of MM the FC explanation coincided with the experiment, in the TR case it DID NOT. This is why TR had such a huge contribution in spelling the end of FC. SR owes a lot to TR, though for some hard to explain reason, all the credit goes to TN. Though M.Jenssen dedicated a whole thesis to Trouton-Noble, there is no mention of Trouton-Rankine. Maybe someone will do a PhD on it? —Preceding unsigned comment added by 12.36.122.2 (talk • contribs)


 * From http://www.phys.ucl.ac.uk/department/history/BFox1.html:
 * In 1908 with A.O.Rankine, an old student appointed Assistant in 1904, an attempt was made to measure the change of resistance of a wire when parallel and transverse to the ether drift. Four rectangular coils were wound, mounted on a common stand and connected in such a way that they formed a Wheatstone network, the wires forming opposite arms of the bridge being parallel. The bridge was balanced when the wire in two of the coils was at right angles to the resultant drift and then the whole assembly was rotated through 90 degrees and the change of balance tested. Once again every realizable precaution was taken only to lead to a negative result as recorded in Proc. Roy. Soc. 80A, 420-435, 1908.
 * 'Your' text:
 * Together with A.O.Rankine he set up to verify this in 1908 by attempting to measure the change of resistance of a wire when parallel and transverse to the ether drift. Four rectangular coils were wound, mounted on a common stand and connected in such a way that they formed a Wheatstone network. The bridge was balanced when the wire in two of the coils was at right angles to the resultant drift and then the whole assembly was rotated through 90 degrees and the expected change of balance tested. Once again every realizable precaution was taken only to lead to a negative result as recorded in "On the electrical resitance of moving matter"Proc. Roy. Soc. 80A, 420-435, 1908.
 * Sorry, that is not using your own words.
 * As for the experiment, I haven't been able to find much information about it. Could you perhaps explain why it was predicted that the resistance would change if the wires contracted? Your link seems to assume that the electrical resistivity would be constant during length contraction, which does not seem to obvious to me. Rasmus (talk) 22:42, 5 January 2006 (UTC)

...because resistivity is a material constant, i.e. an invariant. Ati3414 16:08, 3 February 2006 (UTC)

What determines the resistance of a material?
I have the same question as Rasmus, with a plausibility argument. Materials shorten and lengthen with temperature variation, and the electrical resistance of materials varies with temperature.

It seems plausible that in determining the resistance of a specific length of wire the amount of atoms counts. Therefore, when a stretch of wire increases in resistance on heating up, the increase of resistance is ascribed entirely to the rise in temperature, none is ascribed to the increased length of the wire.

Lorentz-FitzGerald contraction implies that the individual atoms must assume an oblate shape, but the number of atoms remains the same, of course. Why did Trouton and Rankine expect the resistance of the wires to change in going from a state of being Lorentz-FitzGerald contracted to a state of no contraction? --Cleonis | Talk 23:59, 5 January 2006 (UTC)


 * Hi Cleonis, your assumption is erroneous: strain gauges operate by the fact that resistance changes with deformation. However, that is true when there is a strain; in this case there is no strain and the fields are distorted. In such complex cases, it is easy to overlook an effect and then end up with such things like perpetuum mobilae. Harald88

Author's Answer
The point that you are both missing is that Trouton-Rankine expected the resistance to change as a result of length contraction. They did their computations under these circumstances (I give out the exact title and publication, much more than many other links do plus a mathematical explanation as an attachment). They predicted a non-null result.

The experiment came back null. They did not continue to speculate on the change of resistivity (I believe this to be a material constant anyway, invariant to any transformations), nor did they speculate about the possible change in the cross-section. This is what sets the TR experiment as an exception, there is no "ad-hoc" addition, there is no attempt to an auxilliary explanation.It's the end of the line. And as such, it spelled the end of the FC hypothesis. This is the gist of the posting. Now, if any of you gentlemen wants to change the words in the posting WITHOUT changing the meaning, be my guests.


 * Well, as we have been trying to explain to you, that gist is wrong: it only ended a particular assumption of Fitzgerald. The Lorentz contraction is for example included in the Kennedy-Thorndike experiment and can't be removed from special relativity. Harald88 09:29, 6 January 2006 (UTC)

My posting says clearly: "spelled the end of the FitzGerald ether hypothesis". So what is your argument with the "Lorentz contraction" and Kennedy-Thorndike? Stay on subject. OK, you are objecting to the second entry, the one that mentions Lorentz, I corrected that.


 * Easy: the contraction hypothesis is part of SRT. Spelling its end also ends SRT. Instead, it disproved Fitzgerald's prediction, based on his particular theory. His error was not the contraction hypothesis, but another one, to do with momentum. Experiments can't do more than to either corraborate or disprove a combination of a great number of hypotheses and calculations. Harald88 02:24, 7 January 2006 (UTC)

I think you are mixing to different things:

1.The Lorentz contraction of STR, which is the APPARENT contraction resulting from the application of the Lorentz transforms WITHIN the framework of STR. This one is produced as we well known by the effect of observing the same object from diffrent reference frames in uniform motion wrt each other

2. The FitzGerald contraction (and its later Lorentz extension) which was considered to be FACTUAL (not reference frame dependent). This hypothesis assumed that atom lattices contracted in the direction of motion, etc. This is the hypothesis rejected by the Trouton-Rankine experiment Do you agree with this?


 * I agree that the concept of length contraction of ether theories entails that the length contraction is not reference frame dependent. In ether theories, the length contraction is deemed on equal footing with say, shortening/lengthening due to temperature variation.


 * As you point out, in Special Relativity the spatial distance that you assign between two points in space-time is reference frame dependent.


 * Generally, in ether theories it is assumed that the physics of all procedures to measure length undergoes proportional contraction. Thus, the length contraction remains unobservable. For example: if the length contraction would induce a strain in the wires, the resistance would change. But in for example Lorentz ether theory you do not expect the material to be strained, for Lorentz ether theory assumes that the individual atoms take on an oblate shape, as a consequence of their velocity with respect to the Lorentzian ether.


 * Possibly FitzGerald thought it likely that individual atoms retain a spherical shape. Then you do expect the material to be strained.


 * Generally speaking, in ether theories you expext that the resistance of the wires used in the Trouton-Rankine experiment will not change. --Cleonis | Talk 12:12, 7 January 2006 (UTC)

Vastly different concepts of length contraction
According to Lorentz ether theory, the length contraction is not frame dependent. According to Lorentz ether theory the contraction occurs anyway, but it's observability is frame dependent; you are prevented from observing it when you are co-moving. According to special relativity the length contraction itself is frame dependent; there is no length contraction of atoms with respect to a co-moving reference frame. The length contraction concept of ether theories is vastly different from the length contraction concept of special relativity, and I am not surprised that Trouton and Rankine hoped to obtain experimental evidence.


 * Cleon, I can't make sense of that, sorry. Likely this is due to a lack of definitions. There is no operational difference between SRT with one explanation and SRT with another explanation. However, Firzgerald had apparently another theory, even after 1905/1906. Harald88 03:56, 8 January 2006 (UTC)

Let an ionized atoms be circling around in a particle accelerator, at a velocity very close to the speed of light. What will happen to them? According to Lorentz ether theory the atoms should be drastically flattened in those circumstances. Given a sufficiently high velocity the atoms must be physically flatter than the diameter of the nucleus of uncontracted matter. Can atoms be that flattened, without any special tension arising because of that? In ether theories it seems plausible that at extremely high velocities you do get deviation from normal behavior, due to the extreme flattening. I am not aware of any such deviations


 * This serves to illustrate my point: you just described the behaviour according to SRT - but no mecahnical tensions: we are dealing with equilibria, as you yourself explained above. Harald88 03:56, 8 January 2006 (UTC)

So it can be argued that the behavior of atoms in particle accelerators indicates that special relativity is correct, and ether theories are wrong. I think Trouton-Rankine is unhelpful in ruling out ether theories, but it may be possible nonetheless. --Cleonis | Talk 21:31, 7 January 2006 (UTC)

Trouton-Rankine has little to do with aether (if anything). It simply refutes the ad-hoc FitzGerald contraction.It proves that it does not exist. What is so difficult to understand?


 * Nonsense - it only disproves the set of particular assumptions that the test was set out to test for. but I already explained that experiments usually test an accumulation of hypotheses, and this is a good example. Nothing more to add. Harald88 19:12, 10 January 2006 (UTC)

The myth of the crisis
In the article it is stated:
 * The famous Michelson-Morley experiment of 1887 had plunged the physics world in general and the then existing "aether" theory in particular into a deep crisis.

That statement is incorrect. At the time, there was no perception in the physics community that a crisis was on. There was general confidence that the anomalies would be resolved. When Einstein was awarded the 1921 Nobel Price for Physics, the Nobel committee did not mention Einstein's work in relativistic physics. The Nobel prize committee cited other work, presumably the committee felt that the status of relativity theory was still unclear.

The idea of the Michelson-Morley experiment plunging the physics world in a crisis just a fairy-tale.

There was no perception of a crisis, but over the years the scientific community's preference did shift to relativistic physics, because it was recognized that relativistic physics is superior. --Cleonis | Talk 20:43, 10 January 2006 (UTC)


 * I agree that it is exaggerated; nevertheless according to Poincare, physics was in a crisis but I don't remember what words he used exactly. For the moment I'll just remove "deep". Harald88 00:20, 11 January 2006 (UTC)

LET vs SR
Cleonis, let's try settling a few things. I am going to list a few questions, I would like your educated answers.

1. LET (Lorentz ether theory) states that the speed of light follows the "c+v" and "c-v" speed composition rules. YES or NO?

2. LET cannot be distinguished through any experiment from SR. YES or NO?

3. LET predicts the same outcome as SR for the Michelson-Morley, Kennedy-Thorndike and Ives-Stilwell experiments. YES or NO?

1. I am unfamiliar with the notation that you use here. I don't know what you have in mind in writing the "c+v speed composition rules"

I thought it is pretty clear, the question was if you agree that LET uses the Galilean speed composition rule. If an emitter moves towards an observer with speed v, the light arrives to the observer with speed "c+v". YES or NO?

2. Initially I said 'cannot be distinguished through experiment', but I now think that was too bold. Particle accelerator experiments put pressure on LET: particle circling in the accelerator very close to lightspeed would have to be extremely contracted, that makes me suspicious. 

Well, you were quick to reprimand me, now that you are thinking a little about the gaffe you are retracting. So is it YES or NO?

(Comparison: if the temperature of a quantity of matter is lowered further and further, then the material will shrink more and more. In a particular range the relation between temperature and length of a specimen will be a linear relation. At some point the graph will start to deviate from a linear graph; when alle the molecules are snugly together the material cannot shrink further. So there is a law of shrinking with temperature, but at some point that law breaks down. My expectation is that the law of length contraction as postulated by LET breaks down at a velocity that is accessable to experiment. SR does not have that problem, for SR boldly assumes that for the co-moving observer the length contraction does not occur at all.

That sounds very weird, it illustrates how totally different SR is from LET) 

Is SR "weird"? Is LET "normal" then?

3. YES, I expect that for experiments that do not push very close to lightspeed, LET predictions matches all SR predictions. --Cleonis | Talk 22:21, 10 January 2006 (UTC)

Is v=0.3c too close to c for you? YES or NO?


 * As I'm familiar with the topic, I'll give my comments too.
 * First of all, it depends what you mean with "LET" and "SR". Assuming that you mean with "LET" and "SR" the different concepts of Lorentz and Einstein since 1906 about "relativity":


 * 1. YES/NO: your question lacks precision. Depending on how you ask it, Lorentz and Einstein would answer the same. Lorentz accepted Poincare's 1905 velocity composition rules which were identical to those of Einstein.

LET as in Lorentz ether theory PRIOR to Einstein 1905 paper. Very precise. YES or NO? (remember the math used by Lorentz in explaining the MM experiment)


 * AFAIK nobody had worked the equation out before 1905. However, even without a crystal ball it is easy to see with the used math that the Galilean rule (which assumes that the units transform as 1:1) is invalid, and Poincare based himself fully on Lorentz 1904; and your example is simply about obeying the PoR.
 * Thus, assuming that you ask about the composition of velocities in different frames: definitely NO.


 * 2. YES, ignoring Einstein's stellar aberration equation (Lorentz apparently did not spot it at the time, and the error only popped up with De Sitter). Also, some interpretations of QM that are definitely incompatible with SR could be compatible with LET.
 * BTW, according to Einstein, For v=c all moving objects --viewed from the "stationary" system-- shrivel up into plane figures.

Well, this is taken out of context, Einstein made it clear that only photons in vacuo can attain c. Besides, he died before he had a chance to read the Terrell paper.

YES or NO ? Your answer reads like a "YES but..."
 * NO, by again almost using a crystal ball: Einstein's theory was erroneous on a point that almost certainly Lorentz's wouldn't have been if he had made that calculation, due to their different way of reasoning. But that doesn't invalidate your "SR", it was just a mistake that has been corrected later.


 * 3. YES, ignoring that M-M was one of the boundary conditions for the new theory (and thus not a prediction). Both KT's and Ives-Stillwell's predictions and conclusions were based on LET-like reasoning.
 * Cheers, Harald88 23:12, 10 January 2006 (UTC)

again, YES or NO ? Your answer reads like a "YES but..." . No bet hedging.


 * YES.

Harald, just for you, since I am not an expert in "ether" theories I have a suplimentary question:

4. Does LET, (pre 1905) have the notion of transverse Doppler effect? YES or NO?


 * NO: AFAIK that effect was not discussed prior to 1905. However, frequency change with speed was mentioned.

Thank you, this is all. ati3414


 * You're welcome. Please note that your questions are partly about predictions, and partly about differences in the level of development between the theories with one year interval. Freezing Lorentz to his ideas of 1904 and Einstein to his ideas of 1905 is artificial, and not surprisingly the latter was further developed. Moreover, neither was free of error. Mixing such different issues easily leads to twisted reasoning. Harald88 00:17, 11 January 2006 (UTC)

corrections to make
From sci.physics.relativity (posting not by me):


 * "> And now for the literature search results. Following the paper trail from Chase's 1927 paper "The Trouton-Noble Ether Drift Experiment", he references his own paper from 1926 "A repetition of the Trouton-Noble Ether Drift Experiment", which then references:


 * > "Fitzgerald & Loretz, Scientific papers, p. 556"


 * >Any idea where that could be found? His experimental setup seems somewhat different from the Trouton and Rankine experiment, as he measures a torque and not a resistance..


 * > I was also able to download the 1908 paper from the JSTOR.ORG archive (Proc. Roy. Soc. 80A, 420-435, 1908)


 * > From that paper, page 421:


 * > "Now suppose that the wire AR is turned tlirough a right angle, so that its length is perpendicular to the velocity v. According to the Fitzgerald-Lorentz shrinkage hypothesis, the length of the wire will be thus increased by a srnall amount [\delta l], such that [\delta l /l = 1/2 (v/V)^2], where V is the velocity of light, and all powers of v/V higher than the second have been neglected, v being supposed very small compared with V."


 * > Trouton and Rankine fail to say here that this Lorentz-Fitzgerald change of length occurs in the ether frame and not in the laboratory frame! Why should the resistance of a wire as measured in the laboratory depend on the length of the wire as measured in some other frame of reference?


 * > Also interesting to note is that Trouton & Rankine's conclusion is nowhere near the same as the statements attributed them on the wikipedia website, rather (p.434):


 * > "... the specific resistance of a material is dependent upon the direction of flow of the current, being greater to a current flowing parallel to the velocity of the material through space than to a current in a perpendicular direction.  The magnitude of this change of specific resistance is shown by the experiments to be certainly within 2 per cent. of being sufficient to compensate the change of length.


 * >  Note.- In view of the very general acceptance of the Fitzgerald-Lorentz shrinkage theory, the negative results of these experiments will probably be attributed to a dependence of specific resistance on direction of current flow.  In this connection it is worthy of note that certain independent considerations point to the same conclusion..."


 * > Conclusion: The wikipedia Trouton-Rankine page misrepresents the authors of that paper, as well as failing to point out the shortcomings of the analysis in the paper. "

Harald88 23:21, 1 February 2006 (UTC)

Trouton comes up with one more ad-hoc hypothesis, the change of resistivity ("specific resistance" ). The year is 1908, Trouton was a well known antirelativist, he desperately wanted to prove Lorentz's ad-hoc contraction right. But,Trouton is honest, he says : "the negative results of these experiments WILL PROBABLY be attributed to a dependence of specific resistance on direction of current flow", i.e. he comes up with one last gasp ad-hoc hypothesis but he admits it, he admits that he's making up something. Therefore the "WILL PROBABLY". Remember : resistivity or specific resistance is a material constant, pretty much like permeability, so it is an invariant.

Wrong. Trouton was a much better physicist than you are making him to be here. I recommend for you as a refresher to read the definition of the Lorentz contraction, paragraph 8 of his famous 1904 paper.(hint BOTH the resistence and the wire length are taken in the same frame, the lab frame IN MOTION with speed "v" wrt "aether").

No, the correct statement is that you are failing to understand things and try to distort facts in order to make them agree with your own personal anachronistic antirelativistic views. Ati3414 18:56, 2 February 2006 (UTC)


 * Who are you talking to? The writer of the above message is a certain "Shevek", but I don't know if he is watching. If you want, you can email him; apparently you already discussed with him. I included this because it contains citations of he paper as well as a link to it (and why didn't you include this information yourself?). However, I have no access to that link; If there are errors in those quotations, please tell. Harald88 12:46, 2 February 2006 (UTC)

Is it or isn't it?
This doesn't make sense, as it contradicts itself:

"Lorentz ether theory and in Special Relativity, the Lorentz-FitzGerald contraction is not measurable in a co-moving frame. Based on the Lorentz 1904 version of the Lorentz ether theory the Lorentz-FitzGerald contraction should have been measurable in a co-moving frame."

Can someone who knows the material please correct it?

Długosz 23-Aug-2007 —The preceding  signed but undated.

I've corrected the passage. It was meant that based on an older version of Lorentz ether theory (before 1905), it was thought that the Lorentz-FitzGerald contraction should have been measurable in a co-moving frame. --D.H 09:40, 25 October 2007 (UTC)


 * Who thought so? Lorentz? Reference please! Others such as Langevin and Poincare concluded the contrary. Harald88 21:46, 10 November 2007 (UTC)

Who thought so? Well, obviously Trouton thought that the contraction is measurable, that's the reason why he was performing his experiments. And yes, Lorentz and Poincare believed in 1908 that it is not measurable. But we are not talking about Lorentz and Poincare's believes, but we are talking about Trouton and his interpretation of the Fitzgerald-contraction. What about the following phrase:

"However, Trouton thought that the Lorentz-FitzGerald contraction should have been measurable in a co-moving frame, while others like Poincaré didn't believed that any violation of the relativity principle is possible."

--D.H 08:51, 11 November 2007 (UTC)


 * Actually, I think we're both not phrasing this well. Based on Lorentz 1904, Langevin and Poincare concluded in 1905 that absolute motion is not measurable in any way. Whatever Trouton thought should be accredited to him. However, relativistic effects are measurable, at least in principle - physics is first of all about measurables. I'll check the text again and modify if needed. Harald88 09:40, 11 November 2007 (UTC)

suspect phrase
I moved the following phrase about "Lorentz Ether Theory" here:

"which was completed by Lorentz and Poincaré after 1905".

No theory of such name was known at the time and Lorentz's theory was corrected and completed by Poincaré in 1905. It is questionable that after the emergence of what became known as "relativity" since 1905, anything "else" (but in fact the same) was "completed". At the very least, a quality reference should be stated that expressed that opinion. Moreover, it doesn't seem relevant here. Harald88 21:43, 10 November 2007 (UTC)


 * Ok. --D.H 08:56, 11 November 2007 (UTC)

Useless first paragraph, start with second paragraph?
The first paragraph after the lead appears useless to me, it's not about the topic and anyway there are links to related topics. I propose to eliminate that paragraph and to start, after the lead, the text of the description as follows:


 * In Lorentz ether theory and in Special Relativity, the Lorentz-FitzGerald contraction is not measurable in a co-moving frame. However, based on an older version of Lorentz electron theory (before 1904), Trouton thought that effects of the Lorentz-FitzGerald contraction should be measurable in a co-moving frame. In order to set up their experiment, Trouton and Rankine had the idea that length contraction may yield a measurable change in electrical resistance in the object's rest frame. It was this effect that the experiment sought to measure. Chase and Tomascheck set up similar experiments with identical results.

Harald88 10:26, 11 November 2007 (UTC)

Much better, thanks! --D.H 19:12, 11 November 2007 (UTC)


 * OK for good order I park the deleted paragraph here; perhaps some of it can be recycled somewhere.
 * The famous Michelson-Morley experiment of 1887 showed that the then accepted aether theory was not correct. FitzGerald and Lorentz, independent of each other proposed a contraction that would explain the null result of the Michelson Morley experiment.  Lorentz showed that this contraction hypothesis along with what he referred to as "local time" made the Maxwell equations and Lorentz force law invariant to second order in a moving frame (he later expounded upon this to make Maxwell's equations perfectly invariant in a moving frame in agreement with special relativity).
 * Harald88 23:03, 11 November 2007 (UTC)

The point of this experiment was to try to measure the effects of length contraction in the co-moving frame. The history of what they were looking for and why they were looking for it is important and is a good idea for a lead in to a discussion of the actual experiment. The current wording attributes this effect to Lorentz's ideas, which I do not feel is correct. He advocated an immovable prevading aether which he felt was the correct frame to work out Maxwell's equations in. Reading the paper, Trouton instead calculates the length contraction using the velocity with respect to the aether, but then proceeds to do the electrodynamic calculations in the lab frame instead of the aether frame. I don't feel Lorentz would have supported this at all. If he had done all the calculations in some arbitrary "aether frame" he would of course got the correct answer.

So I agree with D.H who commented "But we are not talking about Lorentz and Poincare's believes, but we are talking about Trouton and his interpretation of the Fitzgerald-contraction." Mentioning the historical atmosphere is essential in understanding this experiment and its impact, so I see no problem with mentioning how this fit in with the current theories, but ultimately this interpretation of length contraction was Trouton's.

I'll try to change the paragraph accordingly. -- GrapeSmuckers (talk) 21:21, 16 November 2007 (UTC)

Chase, Tomaschek
I deleted the references to Chase and Tomaschek, and moved them to the article on Trouton–Noble experiment, since the authors themselves call their experiments a variation of the Trouton-Noble experiment to measure some sort of torque, while the Trouton-Rankine paper or length contraction are not mentioned at all. --D.H (talk) 17:15, 16 April 2011 (UTC)