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Difference between Lorentz and Einstein

  1. Mar 26, 2012 #1
    For Dalespam:

    The difference between Lorentz and Einstein is that the transformation is only applicable to one frame and must be fully inverse for the moving frame. Lorentz transform into the moving frame but invert the calculation to arrive back at the stationary one. The transformation is applied the same in both frames for SR, because both frames actually are equivalent. The frames only "appear" equivalent to each observer in LET. In LET you convert from the "truth" of the stationary frame to the "illusion" of the moving frame whereas you convert from "truth" to "truth" in SR. It's not a difference in the math but in the application of it.

    There is absolutely no version of the twins paradox in LET because of this. In LET, the moving frame is length contracted and time dilated, but if you ever attempt to convert from the moving frame to the stationary then the moving frame sees the stationary frame as length dilated and time contracted. If you do not understand what I'm saying then you simply don't understand the genesis of LET which is perfectly understandable because it's a very esoteric subject. Most people don't spend their time learning old incorrect theories in detail. I do.

    Surely you understand that a child can show all their work for a word problem, solve every equation properly, but still solve the word problem improperly. This is the difference between the theories. Einstein showed that Lorentz had the right equations, solved them properly but failed the word problem.

    I'd be glad to help you understand this further if you're willing to learn about this old defunct theory. But your assumption that there is no difference between the theories just comes from the fact that nobody really cares anymore just like they don't care about the exact minutia in corpuscular theory, so some detail about the old theories get lost.

    I, however, enjoy looking into the process of errors that led us to where we are. If you are willing to have some patience, I will explain in detail -when I have a few minutes- why LET would assume that light would arrive at .466 but why SR knows it is .288 The difference is a single preferred frame of ether. The difference is that LET frames are not actually equal even though they appear to be to the observer inside them. In SR the frames are actually equivalent.

    In LET light appears constant in the moving frame because the changes to light's apparent speed (from being retarded by the ether) are balanced by changes to time such that they cannot be detected. (an illusion) In LET light governs time, in SR time governs light.

    As I said, if you wish, I can provide more detail and I believe you will see that what I'm saying makes sense if light traveled like sound does. We now know that it doesn't but it's entertaining to see that the Lorentz transformation will actually work for sound if you apply it as Lorentz initially did. (because he believed light was a mechanical wave in a medium)

    You only see that I'm applying the transformation incorrectly. You can see what Einstein saw about Lorentz, that I'm solving the word problem incorrectly (as Lorentz did), but wouldn't you also like to see what Lorentz saw?
  2. jcsd
  3. Mar 26, 2012 #2
    My OP above was actually was a continuation of, well, somewhat of a thread hijacking but tangentially related. Below was my first post on it. Dale basically commented that it was wrong and that there is no difference between the Lorentz transformations in LET and those in SR. I agree, with the below exception...

    While I do not doubt my understanding of the Lorentz derivation, I do doubt my understanding of how exactly it transitioned into light constancy and a lack of simultaneity (lack of simultaneity does not exist in LET) which leads to my final question below.

    According to Lorentz, a traveller going to a star .5 lightyears away at .5C takes 1 year in the stationary frame but the traveller only records .866 as much time elapsing for a total of .866 years to arrive. Many perspectives were changed for the traveller however: During his travel he believed the point he travelled to was 1.1547 as many units away. He believes light to travel at 1.33 units per second but also still calculates his speed as .5C (because time effects from shortening affect distance inversely leaving only the wind effect visible to in-frame observers).

    According to Einstein, a traveller going to a star .5 lightyears away at .5C takes 1 year according to the stationary frame but the traveller only records .866 as much time elapsing for a total of .866 years to arrive. The traveller believes himself to be stationary and that the distant object is approaching at .5C from a distance of .433 lightyears away.

    So far there is little effective difference, however:

    According to Lorentz, a beam of light travelling to that distant star would take .5 years in the stationary frame and would take .433 years in the moving frame.

    According to Einstein, a beam of light travelling to that distant star would take .5 years in the stationary frame and would take .433 years in the moving frame less the movement of the distant star for a total of .288 years.

    So the point is that in LET, the motion relative to the universal reference frame is already accounted for in the calculation, whereas in SR, even after the calculation, motion must still be accounted for. (or so I understand)

    My question is this: SR leads to two different arrival times for light in the stationary frame: .5 years and (.288 * 1.1547 =) .332 years for the beam of light. Is this part of the lack of simultaneity?

    It seems like that since I should only have to apply gamma once after calculating distances:
    IE the traveler says he arrives in .866 years, therefore (.866 * 1.1547=)1 year is the simultaneous calculation for my frame.

    Yet this somehow seems to not work for light. What did I do wrong and what did I misunderstand?

    Looking back on this I suppose it's because you can't keep going back and forth between the frames with the transformation because you'll end up in an ever-growing or ever-diminishing loop. This seems to be the cardinal difference between relativity and all other mathematical theories before it.

    We learn in grade school to work our problems backwards by inverting the sign to check them and in this way we can just go back and forth at will. This simply isn't true about relativity which is really quite revolutionary.

    I suppose this is only true frames that have never experienced acceleration though, since the two frames in the twins paradox are not actually equivalent. We solve the twins paradox by simply assigning the true stationary frame to the one who dos not experience acceleration.

    Interestingly, this leads to a very LET-like situation. Now that we have established that the planetary twin is truly the one experiencing more time, we find that from the perspective of the travelling twin, the stationary twin is length dilated and time contracted. IE he sees the stationary twin as longer and his time seems to elapse more quickly. IE the Lorentz transformation must be inverted to properly model the solved twins paradox if one is converting from the moving twin's frame to the stationary twins frame.

    And with this Lorentz-like model we go back to the elementary method of working equations backwards and can switch frames infinitely without an ever-growing or ever diminishing answer.

    So I guess my question is better stated as, what is it that led to the "non-reversible", or non-looping version of the theory. Does it have something to do with non-simultaneity?
  4. Mar 27, 2012 #3


    Staff: Mentor

    Hi NotAName, sorry it took me a while to respond. I felt that it would be rude to not respond, but I have no interest in the subject so my response is a little rude also. In the end, I figured it was better to be open about my lack of interest.

    This is wrong, as I already explained in the locked thread. Because I firmly believe you have a misunderstanding I am not terribly interested in your opinions on LET.

    However suppose that we discussed for several pages and you managed to convince me that you are correct. That would mean that LET produces different experimental predictions than SR; in which case LET has already been experimentally falsified and I would have even less interest in the topic. So, all you could possibly accomplish would be to convince me that I am even less interested than my current level of dis-interest.

    If you are interested in learning SR I will be glad to participate. If you are interested in promoting or explaining LET then I am not going to be the best contact.
  5. Mar 27, 2012 #4
    Lol... yeah, I didn't think you would be terribly interested in LET in particular. Some people study history and some people study other subjects. I happen to like both physics and history.

    The thing is, while I want to learn about SR I want to learn it in the context of its predecessors. I am now at the point of transition which is why I asked the questions above.

    Perhaps I should re-state my question? Here, lets try this:

    Why is it that when we solve the twins paradox, there is an inverse relationship between the two frames. (The shorter sees the other as longer and the slower sees the other as faster - and vice versa) yet this relationship does not exist in fully inertial frames?

    IE: In fully inertial frames, the slower sees the other as slower and the shorter sees the other as shorter.

    What is the cause of this difference? This is the essence of Einstein's revelation. The one difference between the theories so understanding it seems crucial to me.
  6. Mar 27, 2012 #5


    Staff: Mentor

    What are you talking about here? I have read this several times and can't seem to parse it.
  7. Mar 28, 2012 #6
    There are three frames in twin paradox. One frame is for rest observer and two frames is for moving observer (outgoing and incoming). Yes, in SR one frame sees other as slower and shorter. The rest sees outgoing is slower and shorter, same the outgoing sees for rest, and this applies to rest and incoming too. The age difference is cause of gap between lines of simultaneity of outgoing and incoming frame to rest frame. The observer jumping from outgoing to incoming sees time jumping in rest.
  8. Mar 28, 2012 #7
    A few general comments: I don't believe Lorentz employed the concept of "inertial frame" very heavily (and possibly not at all). But we should check his book again. Granted even in SR it's a bit of an idealization because an inertial frame implies that no outside forces are acting on the frame and that effectively occurs only for temporally non-interacting particles such as neutrinos.

    One essential difference between Lorentz's work and SR is that SR addresses only 2 frames at a time (with the exception of a possible third frame whose relative velocity is linked according to the rule of velocity addition). Lorentz (and his predecessors such as Hertz, Cohn and Ritz) considered a universal or invariant perspective important where 2 particles not only have a relationship between themselves but a relationship to the rest of the universe as well. SR provides a covariant perspective in comparison.
    Last edited: Mar 28, 2012
  9. Mar 29, 2012 #8
    Well said PhilDSP...

    This concept seems hard to grasp for people who work in Relativity a lot...

    If I were to shrink you, what would the world look like to you? Think of "Honey I shrank the kids" When you are smaller, everything else looks bigger but you seem normal sized to yourself.

    When you are slowed, you seem normal speed to yourself but everything else seems sped up.

    Once we determine for certain that one twin is actually shortened and actually slowed we also then determine that his viewpoint will be skewed in an inverse way. This is a truth of reality and is reflected in the simple basics of math. When you "look through" a problem from reverse, the sign changes. IE if I parse an equation backwards it's like seeing it from the opposite perspective. From the end...

    Therefore, in the solution of the twins paradox, we have established that one of the frames is accelerating and therefore is the one that undergoes and change while the other does not.

    This means that the travelling twin looks through the equation backwards, just like the kids in "Honey, I shrank the kids" The traveling slowed and shortened twin, looks at his other twin through a telescope back to earth and sees his twin running about very quickly and also notices that he is lengthened.

    This is the normal way math is done. This is not how you do the math in SR when both frames are inertial. Ergo a very fundamental change to the way we do math and the way we see reality. This is Einstein's contribution quite specifically.

    It is the reason we even think there is a twin's paradox in the first place. The expectation of inverse viewpoints. Unfortunately, the resolution of the twins paradox tells us nothing with regard to Einstein's special revelation since we reduce it to an invert-able intuitive problem to solve it.

    In SR, nobody experiences the lengthening and speeding up that would be required of classical physics and any intuitive view of the situation....

    So, as I said before I'm just trying to understand this specific difference between the two because the solution of the twins paradox just reduces the situation to a classical one and isn't useful for this purpose.
  10. Mar 30, 2012 #9


    Staff: Mentor

    This is completely wrong. Einstein used the same math that everyone else uses. There is no change whatsoever about how you use math. All he did is expand the set of quantities which are frame variant.

    In Newtonian physics it is possible that [itex]v_A>v_B[/itex] and [itex]v'_A<v'_B[/itex], so Einstein didn't change math and what you are attributing to him is simply a standard property of frame variant quantities that has been part of physics from the beginning.
    Last edited: Mar 30, 2012
  11. Mar 30, 2012 #10
    You are linking two unrelated things above: Yes of course coordinate systems in motion wrt each other will measure the same object differently... this truth is utterly off topic.

    Let me make this abundantly clear: I understand that the addition of a an additional dimension we call time simply changes the relationship of the two frames as though they are at an angle to each other.

    Let me say the same thing in terms a little more agreeable. Never before in math has it been thought of to simply add an additional subscript on an array to make a paradoxical answer no longer paradoxical. You see it in particular terms you are used to but I'm attempting to tell you that I'm looking for the justification to go from three dimensions to four. That is the big leap. Perhaps this is more agreeable nomenclature?

    Furthermore I'm pointing out that the same transformation were used with only three dimensions and that when you reduce the twins paradox to one twin actually being larger and the other twin actually being shorter, the fourth dimension gets eliminated in the process. You've simply reduced it to a neo-classical explanation that Lorentz might give if he ever shifted perspective into the moving frame to view a stationary one. (Not all frames were equal in LET because the ether defined them. There was only one universal frame by which all others were judged)

    The twins no longer see each other equally shortened and slowed. One sees the other as lengthened and sped up.

    Do you understand that the Lorentz transformation will work for a physical wave in a medium with all the same results? Let me explain in a separate post to follow...

    What Lorentz thought was an illusion, Einstein discovered was a reality...
  12. Mar 30, 2012 #11
    Before going further, it is important to understand:
    1) That Lorentz believed a substance flowed across atoms causing their electromagnetic bonds to increase in strength thus physically shortening objects.
    2) There is a neo-classical understanding of time effects that is a "given" in LET and prior ether theories. It is inferred that light having to travel "upstream" and "downstream" between atoms would cause all electromagnetic interactions to happen slower, thus slowing time for a traveler.

    Below is a description of an experiment analogous to the Michelson Morely that, very surprisingly, will actually work. Please use the image below for visual aid:

    In this experiment we are studying sound and echo. We have a material that is very well suited for reflecting sound. In our discussion of the experiment we will use a simplified model that disregards finite details such as turbulence temperature etc.

    For the sake of simplicity we will assume there is some elevation and temperature at which sound travels one foot in one millisecond and use this as a convenient dual unit of measurement.

    We will mount a speaker as an origin point at the back of an open flat-bed trailer and conveniently also use it as a microphone. We will then mount a reflective surface exactly ten feet closer to the front of the trailer. We will also mount a second reflective surface at a ninety degree angle off the left side of the trailer.

    When the trailer is parked and a chirp is emitted from the speaker/microphone, it will record an echo from both reflective surfaces at precisely the same moment 20 milliseconds later.

    In the process of putting the experiment in motion we found that the echos from the reflective surfaces no longer arrive simultaneously and to study the echo properly we wanted them both to arrive at the same time. We wanted an experiment in motion to have the same experience as a stationary experiment.

    An associate of mine we call “Fitz” suggested we simply move the upwind mirror a bit closer. Henry, the math wiz kid of our group, then went about figuring out how far we'd need to move the mirror for any given experimental speed.

    It turns out that we'd have to move the mirror back to 8.66 feet if the truck was moving at half the speed of sound and instead of taking 20 milliseconds to hear the echo, it would take 23.094 milliseconds so the experiment is a little slower overall. We wanted it to be the same experience as stationary but it turns out a stationary experiment could elapse 1.1547 times in the period it took the moving experiment to only occur once.

    A very astute listener might recognize those numbers as the change factor from Special Relativity and Lorentz Ether Theory. That listener should be intrigued that it works perfectly for a conventional mechanical wave propagating at differing angles through a moving medium. For if he is not intrigued by these results, he lacks a very fundamental understanding of the concept of light speed constancy...

    Sound's "constancy" could be erroneously inferred from these observations but these observations obviously do not require sound to be "constant" like light is constant.

    IE: If we simply assume that air flow will always shorten this experiment the right amount just like Lorentz assumed ether shortened objects just the right amount then sound waves can replace light waves and we can use all the conventions of synchronizing clocks etc found in OEMB to infer that the speed of sound is constant in the same way light is inferred to be constant.

    This begs the question: Did Einstien know something else he didn't tell us that led to his discovery of the special properties of light, or (quite unlikely) did he come up with the right answer for the wrong reason?

    Attached Files:

  13. Mar 31, 2012 #12


    Staff: Mentor

    It doesn't seem like a big leap to me. A couple of years before I learned about relativity I did a similar thing in a completely different context simply because I wanted to use the matrix exponent to solve my system. Also, physicists had been working with higher dimensional phase spaces for quite some time The math justifies it, and it makes things easier to calculate. What is the big leap?

    You keep describing things as though Einstein completely rewrote all of math and physics, he didn't. He took the already existing equations at face value, and came up with an exceptionally simple derivation of them with a small number of powerful postulates. That was his genius.

    FYI, I didn't respond to the rest because, as I wrote above, I am uninterested in LET. My apologies, I know it is irritating to write so much and have it be ignored.
    Last edited: Mar 31, 2012
  14. Apr 1, 2012 #13
    Math does not justify reality, reality justifies math. Of course additional dimensions were already part of math. Not, however, part of reality.

    You're just not following what I'm saying. I put it in different terms than usual because the question I'm asking is poorly represented in other terms. I'll attempt -in a moment- to represent it in those poor other terms which seem to be required, but first let me continue down a little more metaphorical track.

    If you ask a student to describe the motion of two trains on the same track moving towards each other in terms of their relation to each other mathematically and that student describes the experience of each train in such a way that the two descriptions taken together cause a paradox but the student simply adds an additional dimension you give him an F.

    IE: If I say two trains on an East-West rail are approaching each other. The eastbound train is moving 25 miles per hour and the westbound train is moving 75. You can change coordinate systems around such that one believes it is travelling 33 1/3 and the other is travelling 66 2/3 or any number of other descriptions which add up to 100.

    If however, any of your answers add up to 120 miles per hour or only a total of 80, you get an F...

    Even if you create a knifty coordinate system, in which you arbitrarily add the additional "dimension of smell" where both trains see the other "at an angle" (for lack of a better description), which causes them to seem slower such that each believes itself and the other to be travelling 40 miles per hour and therefore have a total closing speed of 80 -and I'm sure you are personally capable of doing this-, you still get an F...

    Why? Because, your math can be correct and your application be an invalid description of reality. (or at least defy all proof up to this point in history)

    If you could, however, prove the dimension of smell was real, then every grade-schooler from now on would be even more confused by trains and tunnels but that is not my interest. My interest is how you figured out there was a dimension of smell in the first place with the current set of proof.

    Now, the question is muddled but the essence of it in the poorer terms you're looking for is back to: why did he decide another dimension is proper to add? Not what proof vindicated him after the fact.. what led up to that decision.

    No, not at all, don't sweat it. I'm quite used to seeing that. ;) It wasn't written for you in the first place, anyway. I'm writing for those with more interest in the proofs that lead up to their beliefs. History isn't everyone's favorite subject. This is just for a history project I'm working on.

    Some people look back and others just focus forward. Forge ahead my good man, I wont stop you.
  15. Apr 1, 2012 #14
    Truthfully, I suppose the answer to the question of "why additional dimensions" is likely because of Lorentz and others already considering classical effects on time caused by "additional distance" required for electromagnetic interactions in moving objects.

    So the better question, I suppose, is why to deviate from Lorentz's idea of an illusion (caused by shortening, ether, and time effects on the observer) in which both observers see the same light? Why deviate from Lorentz's two systems in which events are simultaneous, to create a system in which events are not simultaneous? (Lorentz's frames disagreed on times and lengths but under transformation, events are, while perceived differently actually simultaneous)

    And I suppose we can refer to OEMB in which Einstein shows that light constancy in each frame makes each frame disagree on the simultaneous location of a single beam of light. This constancy would explain why light, while the same within a frame, is different when frames are compared... because neither can be identified as truly universal.

    But why light constancy as a reality instead of as an illusion? Why break Lorentz's simultaneous model? Why remove a single universal frame and treat each perspective as having its own universal frame?

    Why make time govern light instead of light govern time?
  16. Apr 1, 2012 #15
    SR didn't try to explain why c is invariant,,, it turned around that valid observation and considered it as a preposition then jumped to LT,,, so SR is not a fundamental theory of light. Einstein didn't bother to explain facts, instead, he skiped that and turned to other problem of how coordinates correlated for different observers

    Therefor, if light propagation has to be thought, SR should not be considered at all. C is invariant in one FOR -> x & t transformed between FORs given that c is invariant there too -> new sets of x & t -> c is invariant again in that new FOR,,,, circular motion!
    Last edited: Apr 1, 2012
  17. Apr 1, 2012 #16


    Staff: Mentor

    This is a very strange comment in the context of this thread. Are you saying that you have some great insight into reality that allows you to know that Einstein is wrong and reality is not 4 dimensional? Or are you saying that reality used to not be 4 dimensional until Einstein had his idea and then because of his idea reality changed and is now 4 dimensional?

    I don't know how you could justify either statement, and I cannot think of another way that you could intend this comment. Please clarify.
    Last edited: Apr 1, 2012
  18. Apr 2, 2012 #17
    While I know no such theory, coincidentally the very first discussion of the "twins paradox" (although not yet twins) was based on the ether concept - and it's the opposite of what you claim, there was nothing paradoxical to it.
    Thus it may be interesting for you, notably p.47-53. You can find it here: http://en.wikisource.org/wiki/The_Evolution_of_Space_and_Time
    Last edited: Apr 2, 2012
  19. Apr 2, 2012 #18
    Hmm it's hard to be more wrong: Lorentz believed that all matter is manifestations in the ether (he rejected a material ether such as that of Stokes), and that the equilibrium position is affected by speed. The electromagnetic bonds do not increase in strength!
  20. Apr 2, 2012 #19


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    1911 was not the very first discussion of the "twins paradox". It was first introduced by Einstein in his 1905 paper, near the end of section 4, and it was not based on the ether concept, but you're right about it not being paradoxical.
  21. Apr 2, 2012 #20


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    Maybe that's because prior to Einstein, there was no version of LET that allowed LET believers to recognize the issue that the twins paradox reveals.

    Which version of LET do you keep referring to?
  22. Apr 2, 2012 #21
    Although not for space travel but for clocks on Earth, indeed Einstein calculated a similar clock retardation there - however it was from a single perspective. It's essential for a possible paradox to describe the situation from the perspective of each twin.

    And of course, that's besides the point. The point was here that a reading of Langevin's paper (which presents special relativity from the combined viewpoints of Minkowski and Lorentz) should show the OP that there is no difference in calculation, contrary to what he/she claims.

    But when I wrote "based on" I was not clear enough, sorry. The calculation is simply based on the Lorentz transformations and interpretation cannot change this. However the metaphysical interpretation may be absent (as in Einstein's paper), or based on a physical model (as in Langevin's paper).
    Last edited: Apr 2, 2012
  23. Apr 2, 2012 #22


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    You're right, Einstein didn't go into the details of the Doppler shifts that each clock would see of the other ones clock like the 1911 paper did, but that also is not what is meant by the paradoxical nature of the "twins paradox". The "paradox" in the "twins paradox" is what happens when you assign a Frame of Reference to both inertial portions of the traveling twin's trip during which his clock ticks normally while the home twin's clock ticks slower while in the home twin's FoR, his clock is ticking normally while the traveling twin's clock is ticking slower.

    But if you use just one FoR for the entire scenario, there is no paradox, which is what Einstein did.

    So as you said, the 1911 paper also does not treat the "twins paradox" as a paradox, so I don't know why you want to give credit to it for first discussion of the "twins paradox" when it was Einstein who was first.
  24. Apr 2, 2012 #23


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    I see you edited your post while I was composing my comment.

    First off, Einstein's clocks were not limited to Earth. He merely made a prediction that could possibly be carried out long before space travel became feasible.

    The problem with the OP's ideas is that he hasn't nailed down which version of LET he is talking about. He expressed an interest in the historical development of SR and how Einstein came up with his ideas but he seems unaware that LET was truly an evolving theory prior to 1905 and it wasn't until Einstein's single presentation of SR in 1905 that LET could then adopt all of his results and claim them as their own in what is now discussed as LET or neo-Lorentzian Theory which is nothing more than SR stripped of it second postulate and inserted with the postulate that light travels at c in only one fixed absolute frame.
  25. Apr 3, 2012 #24
    Neither. Einstein seemed to have some great insight into reality and I am just trying to find his "in-road" to that insight. At the time, there was no motivation (experimental evidence) to come to that idea and a great big pile of motivations not to. I mean for god's sake, nothing in the history of mankind or science has ever behaved that way! So it's unbelievably revolutionary.

    More specifically, in that quote, I was saying that you cannot justify a completely new way of solving a problem that does not fit with the rest of reality if you do not have some link(experimental data) that supports that idea.(and he didn't have it at that point) Math alone cannot justify a completely new version of the way reality works. It seems some string theorists believe that if the math works out then that's all you need and unfortunately I think we're starting to see that as a laughable, or sad, mistake. I guess they are all hoping to be the next Einstein...

    I'm saying that there is a much greater distance between Einstein and Lorentz than it seems at first glance, and I suppose I'm also saying "I'm no Einstein" because try as I might, I just can't see how he got there unless it truly was just a leap of faith and serendipity that he didn't get laughed out of physics before they found evidence of this new view of reality.

    ...though I suspect there might be some small piece of the puzzle I've missed that leads to light constancy.

    His "logical derivation" (the words that justify the math) for light constancy in the first few sections of OEMB, unfortunately would work for LET and even for clocks synchronized by sound waves so he didn't convey his insight at that point.

    I've been attacking it from every angle to try to find where the idea came from and hoping others might be able to use some of the info I have to help me nail down where this moment in history came from.
  26. Apr 3, 2012 #25
    My ideas agree with what you are saying. I'm not sure what you're saying the disagreement is. First off, how do you pick a single version if it is a work in progress? Secondly, yes Lorentz was still basing his idea of ether theory upon Maxwell's version of the ether which was the dominant explanation of the time. (That doesn't invalidate anything I've said) To Maxwell, all atoms were simply vortices of ether which is where most crackpots get their idea of "ether vortices." He referred to the ether as a "wheels and pulleys" (It's actually kind of intriguing) But there was an initial idea used in the derivation of Lorentz Ether Theory that atoms were drawn together because of the motion of the ether and this was developed in coordination with George FitzGerald who was the first to come up with the idea of shortening. They also believe that perhaps atoms were repelled along the other axis at the same time but later discarded that idea.

    So sure, equilibrium position is a good way of saying the same thing. If he had a model based upon ether pressure like most of the people dawdling around with it today then equilibrium can be described as pulling or pushing just like buoyancy can. One may be a little more accurate but let's not split terminology hairs... I suppose I might have missed that subtle shift in the theory though so thanks for the heads up. (I may still explain it in more modern friendly terms though)

    Are you saying he didn't believe specifically in "atomic" theory? Even those who didn't believe in atomic theory believed in things made of parts so perhaps I substituted the word atoms for molecules?

    However, one thing I must vehemently disagree with, you must must understand LET enough to see that it isn't "just SR stripped of the second postulate." There is an entirely different "logical derivation" for it. It can be derived with simple Pythagorean theorem and a tad of trig. Look at the experiment description posted above for a moment and I'm sure you can see it. Though if you'd like an explanation of the steps perhaps it just seems easier to me because I've read a lot on it...

    And as I was saying about the twins paradox, when you make one frame be dominant there is no twins paradox but that isn't a solution, that's a deferral. Reducing it to one frame infers a universal frame and you eliminate any need for the one thing that Einstein added: Light constancy.

    It's easier to understand the difference when you look at the solved twins paradox and realize that when one twin sees the other as shortened, the opposite sees the other as lengthened. When one sees the other as as slower, the opposite sees the other as faster. This is still explicable via classical ether based physics because of Lorentz.

    In LET shortening causes a speed-up of time but the motion causes a much larger slowing of time. The theory gets really boggling with shorter measuring sticks leading to larger distances and then slower time somehow making up the difference... blah blah... I don't want to get into all the gory details here unless you really want me to. That part is a confusing pain but it does lead to a theory which does not have the twins paradox (of course) but still has light seeming to travel the same speed in all frames without breaking simultaneity.

    If you'd like more information on how the simple derivation works though I've already got parts of a presentation created that I can post here and this is my hobby so I'm glad to help. It's really fun and entertaining to see the first workings of relativity... And that's why I'm frustrated because coming up with the transformations from the michelson-morely is really quite trivial (well after you've read all about it), but the next leap to constancy has completely stumped me.
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