Re: What is LET?


> Thanks for bringing this to the attention of sci.physics.relativity and
> again for the intelligent converstaion. Here is my problem with the
> wikipedia site you linked:
>
> "This lesser known paper demonstrated that FitzGerald's assumptions
> were wrong, and cemented STR's status as the standard theory for
> judging relativity."
>
> The website, and links therin, do not suggest how FitzGerald's
> assumptions would lead to a change of resistance in the wire!

Yes, it does. You need to read the references at the bottom of the
page. There is one that explains what Troutopn-Rankine expected and
why. See under the caption "See also", first reference.


There is
> no discussion of what leads to the measured resistance of the wire, so
> the claims are entirely baseless.

See under "See also" and "External links"


>
> It's likely that I'm just ignorant on the topic, but I think the
> theoretical underpinnings of Ohm's law are complex - the analogy is
> with a terminal velocity of a falling object due to air resistance,
> except that for an electron moving through a metal, the resistance is
> due to momentary bindings with local nuclei. The number of nuclei in
> the wire doesn't change due to its orientation, so I see no reason why
> the resistance would change.

Because the wire length and croossection were expected to change. See
again.....


>
> I assume that the original paper must at least mention something about
> this.. did you find a copy of the 1908 proc. roy. soc. online? I
>
> >
> > I think that we may be hitting on a piece of dogma:
> >
> > 1.It was repeated time and again that LET is perfectly equivalent to
> > SR.
> > 2. In reality the two are not equivalent, what separates them is the
> > so-called length contraction: in SR it is only apparent whereas in LET
> > it is should be measurable.
>
> I agree that they are not "perfectly equivalent", but in my mind a
> bigger difference is that LET postulates the existence of a local rest
> frame of the aether as important while SR says that the aether is
> "superfluous".

We agree here 100%


Time dilation and length contraction in SR are not
> "only apparent" - but are well measured by experiments.

Time dilation : yes (see Ives-Stilwell), length contraction : no. See
another good wiki page on this subject:

http://en.wikipedia.org/wiki/Time_dilation_and_length_contraction#References


>
> AFAIK the LET interpretation doesn't say that the contraction should be
> "measurable" any more than the SR interpretation. A meter stick in
> motion contracts compared to another one not in motion, but it is still
> one meter long - as measured in it's own reference frame. Just
> as with SR. The only difference is in the explanation of the effect.
> Einstein pointed out that in the explanation of the effect the local
> motion of the aether drops out of the equations - the aether is indeed
> "superfluous" with respect to these calculations. A remarkable and
> important conclusion as Lorentz admitted.
>
> > 3.What made it measurable is Lorentz 1904 paper, paragraph 8 where he
> > introduced the electron contraction in order to explain the result of
> > the 1903 Trouton-Noble experiment, which in turn was an attempt to
> > verify experimentally the FitzGerald contraction.
>
> He does suggest electron contraction there, but he doesn't mention
> Trouton-Noble..

Sorry, he does, please read on to paragraph 10 where Lorentz tries to
explain Trouton-Noble based on the electron contraction introduced at
paragraph 8



clearly his simplistic model of the electron doesn't
> take into account important quantum mechanical findings with regards to
> electron wavefunction shapes.
>
> > 4. So Lorentz managed to do away with the disturbing results of the
> > Trouton-Noble experiment but Trouton proved to be a very perseverent
> > person so he set to verify the "new" contraction, the "Lorentz
> > contraction"
> > 5.So, in 1908 he put together another experiment, the Trouton-Rankine.
> > The result is well known, the death of the Lorentz contraction (Lorentz
> > did not come back with any more ad-hoc theories) and with that, the end
> > of LET.
>
> How does that follow? Why would LET predict a different measured
> resistance of the wire?

Please check out the original TR paper plus the references I gave you.
BTW, you may want to check the more modern papers of Chase and Tomashek


>
> > 6. The Troton-Rankine was reprised by Chase and by Tomashek in 1927,
> > same results.
> > By then , Lorentz had already conceded. Time for the newly
> > selfdiscovered "aetherists": to do the same. The wiki page contains the
> > direct references to all 3 experiments, take your complaints up with
> > the respective experimenters.
> >
>
> My pleasure. I'll be at the library on monday to take a look, but I
> doubt they did a very good job then modeling the behavior of valence
> electrons. Electron structure is difficult to probe! I'm doubtful
> that theoretical models of resistance are very accurate - it's hard
> enough to do in a plasma and there it's much simpler.

Great, let us know what you find out.


>
> > Hope this tidbit of history helps in changing the view that "SR and LET
> > are indistinguishable". They aren't, Trouton took care of that.
>
> Trouton took care of measuring that the resistance of a wire doesn't
> depend on its orientation. What does that have to do with SR and LET?
>
>
> Cheers - shevek

.

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