# Did Lorentz or Einstein theoretically derive special relativity?

#### harrylin

Thanx Harrylin. By force-fit, I meant "not by logical deduction, but rather by insertion". IOWs, if you assume you know the required final form of the equations to guarantee the PoR, you "make it happen" during derivation. From what you say, Lorentz obtained his linear coefficients by deduction, as Einstein did. I'll have to read thru his paper more closely.
How can one know what guarantees the PoR without first deriving it? Before 1904 Lorentz kept the unknown factor l in his discussions, leaving the question open if what we now call Lorentz contraction is indeed the right solution.
Wrt the PoR ... Consider a dual pan balance whereby the line joining the pan midpoints are aligned with the balance's propagational path. Assume the pans are separated by a very long beam, and the wonder beam cannot bend. Further assume that "someone who believes himself at rest in Lorentz's master aether frame" records the balance's motion at luminal v thru the aether. Now, LET and SR produce the very same solns, so in either case, observers at rest with the balance should always witness the same result(s) ... ie, it's presumedly not possible to distinguish between SR & LET by experiement. Now, let's say 2 weights of identical mass drop from the sky, always of identical velocity and strike the balance pads AT ONCE "per an observer at rest with the balance". What would each theory predict wrt the balance beam tilting upon impact?

SR says ... the balance beam would not tilt.

LET (I think) would say ... the balance beam tilts, because the 2 weights do NOT strike the pads AT ONCE per an aether frame observer "if they strike the pads AT ONCE per the observer moving with the balance thru the aether". The aether POV is always right.

Wrt LET theory ... How is it that the PoR is upheld by LET theory? It seems to me that ... even though the LT results are the same in either case, they do not mean the same thing. The PoR "only appears to be upheld" (per LET) from a kinematic standpoint, but not with regards to force, and thus not with regards to energy. What is wrong with my reasoning here?

If all the coefficients were logically obtained by deduction, then I would agree. However, it just seems to me that the PoR is upheld kinematically, but not beyond that. How do you explain the scenario I pose above?

GrayGhost
Probably you mean with "LET" Lorentz's 1904 paper, which Einstein summarized in 1907 together with his 1905 paper as the new theory that is based on the PoR (and which he later renamed "SR").
To be frank, I did not carefully read your example as any such discussion or paradox that I know of can be rephrased by replacing "aether" or "aether frame" by "rest frame". For a correct understanding of SR it is essential to realise that according to SR you may assume any inertial frame to be "truly in rest" so that the laws of nature should be valid wrt it, without any frame jumping.
Thus rephrased in interpretation-free SR:

"the 2 weights do NOT strike the pads AT ONCE per a rest frame observer if they strike the pads AT ONCE per the observer who is moving with the balance".

Note:a wonder beam that cannot bend cannot exist in SR

Harald

#### Zentrails

For a correct understanding of SR it is essential to realise that according to SR you may assume any inertial frame to be "truly in rest" so that the laws of nature should be valid wrt it, without any frame jumping.
Thus rephrased in interpretation-free SR:

"the 2 weights do NOT strike the pads AT ONCE per a rest frame observer if they strike the pads AT ONCE per the observer who is moving with the balance".

Note:a wonder beam that cannot bend cannot exist in SR

Harald
A non-accelerating frame of reference is all that is required for SR, which led Einstein to the next logical step and thought experiment - accelerating frames of reference and how the physics in them share many similarities with the physics inside a frame of reference fixed on the solid surface of a planet, or any non-solid surface where buoyancy is at equilibrium.

#### GrayGhost

harrylinn,

When one says "wonder beam", most folks generally accept that the beam does something that cannot happen in relality, or at least in practice to date. No different from discussing a wonder-traveler who attains c, which everyone knows cannot happen. But just for the sake of point, let's assume a wonder beam.

Well, I understand how SR handles my stated scenario. You skipped over that at first, and it remains clear that you are misreading it based on your prior response. I'm questioning the LET interpretation, that's all. As I said, I have not studied LET in any depth. If I may amplify my prior scenario a bit here ...

Assume a clock is attached to each always-inertial balance PAD, and they have been synchronized prior by the Einstein/Poincare synchronisation method.

SR says that the clocks are truely synchronised per those at rest with the balance, whereby the like-readouts are always simultaneous.

LET says that the clocks appear synchronised per those at rest with the balance, but are not truely simultaneous. An observer at rest in the aether frame disagrees that the moving PAD-clocks possess the same time readout (ie they are not synchronised), and so they cannot be simultaneous when the 2 PAD-clocks possess the same time readout, and the aether frame POV is always correct. Simultaneity is always dictated by only the aether POV.​

I know how SR works. Is my understanding of LET incorrect here? If so, it seems to me that "the PoR only appears to be upheld" under LET. That is, the balance beam would tip under LET, and the observer at rest in the aether frame would predict it. That is ... the balance should tip based upon simultaneous events, but not necessarily based upon like PAD-clock-time-readouts.

GrayGhost

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#### harrylin

harrylinn,

When one says "wonder beam", most folks generally accept that the beam does something that cannot happen in relality, or at least in practice to date. No different from discussing a wonder-traveler who attains c, which everyone knows cannot happen. But just for the sake of point, let's assume a wonder beam.
A wonder beam creates a paradox in SR - just as a wonder signal at infinite speed. If you do want to discuss your paradox, please start a separate thread on that.
Well, I understand how SR handles my stated scenario. You skipped over that at first, and it remains clear that you are misreading it based on your prior response. [..]
GrayGhost
Sorry but evidently you did not understand my reply to you: According to the PoR the same laws of physics must be valid in any inertial frame, "ether" frame or not. Consequently, any problem that you imagine for "LET" is identical for standard SR, in which "ether frame" merely serves as a lable for a certain "rest frame". The laws of physics - even for moving balances (but not for wonder beams which break those laws) - must be valid wrt such a frame, as otherwise absolute inertial motion could be detected. The balance beam cannot tip according to the PoR, and both POV's must agree that the beam does not tip; that was the purpose of both Lorentz-1904 and Einstein-1905.

Note that in his 1904 paper Lorentz made one or two little errors, which made him unsure that the new theory perfectly obeyed the PoR; but that was soon straightened out by Poincare (and perhaps he answers your question clearer than I do!):
- http://en.wikisource.org/wiki/On_the_Dynamics_of_the_Electron_(June)

And for a primer to the light postulate and relativity of simultaneity, see (again!) a paper by Poincare (in XII and XIII, near the end):
http://en.wikisource.org/wiki/The_Measure_of_Time

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#### GrayGhost

Harrylinn,

I never suggested any paradox exists. Far as the wonder beam simplication is concerned, if you prefer, you can simply assume it bends but does not break, and that there's nothing wonderful about it. I also never suggested that observers of differing frames would disagree as to whether the beam tips. I'm not sure where you get all this stuff, but you should really read posts more carefully before responding, because it just muddies the thread. What I was asking about was (1) did Lorentz force-fit his LT derivation to accomodate the PoR (you say no), and (2) does the PoR truely apply to the all-of-physics under LET, or does it apply only kinematically? From your last post, it seems that it applies period.

LET an SR are not the same theory. Some folks here claim that the theories are identical, except that any aether frame is superfluous per SR, and that it's impossible to detect the truely existent aether frame per LET. Light speed is defined differently per each theory. One theory says that what you measure matches what is real, while the other says length-contractions prevent your contracted ruler from measuring the true-contractions. It seems to me that there is more a difference between the 2 theories than these alone. Lorentz disagrees that 2 inertial clocks synchrionised-with-each-other moving thru the aether are "truely simultaneous" per themselves. Is this correct, or not?

GrayGhost

#### Sybren

As far as I know, Lorentz invented his transformations to account for the result of the Michelson-Morley interferometer experiment, in case of a luminiferous ether. The experimental setup was moving through the ether, he said, and it may possibly be a yet unknown property of electrons that they contract in the direction they are moving in through the ether. This would deform the interferometer setup in the right way to produce the observation. What he did here was come up with the necessary mathematical relation if you accept the experimental outcome, and accept the ether concept.

Einstein knew nothing about this experiment, and was studying Maxwell's equations, when he was considering the problem of a moving magnet and a conductor (moving magnet and conductor problem). When using Galilean transformations between the magnet frame and the conductor frame, the normal procedure at that moment, the calculated Lorentz force an an electron was identical in both cases. However, the electromagnetic fields producing the force were different. Although the Galilean transformation conserved the Lorentz force in this case, it did not conserve the Maxwells equations (as seen by substituting the Galilean-transformed fields into the Maxwell equations). At this point, it can be shown (I yet have to complete this part of the derivation) that there exists a transformation (non-Galilean) that conserves Maxwell's equations as well as the Lorentz force in both frames. This transformation equation is, in fact, the Lorentz transformation equation.

#### PhilDSP

LET an SR are not the same theory. Some folks here claim that the theories are identical, except that any aether frame is superfluous per SR, and that it's impossible to detect the truely existent aether frame per LET.
I think I agree with you on those points. If you don't delve into either the mathematics or the rationale of development deeply enough it seems reasonable to view the observables as equivalent, but that may be deceptive. Lorentz's theory is built around the concept of the invariance of the wave operator and the spatial deformation of an extended electron charge. It doesn't make any ad hoc postulates that force a redefinition of the metric relationships between space and time. It isn't necessarily limited to inertial frames and is therefore potentially more encompassing from a mathematical point of view, even to the point of potentially making an absolute frame of reference observable.

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#### Histspec

What I was asking about was (1) did Lorentz force-fit his LT derivation to accomodate the PoR (you say no), and (2) does the PoR truely apply to the all-of-physics under LET, or does it apply only kinematically?
Maybe one has to look at the predictions of various kinematic and dynamic test theories of SR:

http://en.wikipedia.org/wiki/Test_theories_of_special_relativity" [Broken]

For example, the Robertson-Mansouri-Sexl theory is a kinematic framework. Giving to the test-parameters their relativistic values, then (and only then) this "preferred frame theory" is experimentally indistinguishable from SR.
It becomes a little more complicated, when one uses more extensive test theories like the

http://en.wikipedia.org/wiki/Standard-Model_Extension" [Broken].

This model includes a bunch of parameters, which also apply to dynamics. Of course, also in this model, a suitable combination of the parameters leads to a "preferred frame theory" experimentally indistinguishable from SR, but the probability of such a theory is extremely small due to the large number of ad hoc hypotheses required.

So, in summary: I think it's always possible to modify "LET" so that it is experimentally equivalent to SR. However, the increasing number of effects that must be explained, decreases the probability of such a theory.

Regards,

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#### harrylin

Harrylinn,
I never suggested any paradox exists.
[..] I also never suggested that observers of differing frames would disagree as to whether the beam tips.
Indeed it was not you but me who suggested that your example is a paradox (=apparent contradiction): I actually understood that according to you, "the observer at rest in the aether frame would predict" that "the balance beam would tip", while according to "observers at rest with the balance" "the balance beam would not tilt". Sorry that I misunderstood you.

That would be perfectly incompatible with Poincare's 1905 summary to which I gave a link:
Lorentz [managed to] bring [his hypothesis] into accord with the postulate of the complete impossibility of determining absolute motion [..] in his article entitled Electromagnetic phenomena in a system moving with any velocity smaller than that of Light (Proceedings de l’Académie d’Amsterdam, May 27, 1904).
[...] LET an SR are not the same theory.
Some folks here claim that the theories are identical, except that any aether frame is superfluous per SR, and that it's impossible to detect the truely existent aether frame per LET. Light speed is defined differently per each theory. One theory says that what you measure matches what is real, while the other says length-contractions prevent your contracted ruler from measuring the true-contractions. It seems to me that there is more a difference between the 2 theories than these alone. Lorentz disagrees that 2 inertial clocks synchrionised-with-each-other moving thru the aether are "truely simultaneous" per themselves. Is this correct, or not?
GrayGhost
As I already mentioned, according to Einstein a new theory emerged with the writings of Lorentz in 1904 and his own in 1905; I agree with that. However there is a subtle difference between the two interpretations of the theory: whereas Lorentz found it useful to distinguish between what appears to happen and what "really" happens from an unknown perspective that cannot be detected, Einstein found it better to only discuss the phenomena (=appearances, not what "truly" happens!).

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#### GrayGhost

Indeed it was not you but me who suggested that your example is a paradox (=apparent contradiction): I actually understood that according to you, "the observer at rest in the aether frame would predict" that "the balance beam would tip", while according to "observers at rest with the balance" "the balance beam would not tilt". Sorry that I misunderstood you.
No problem. I thank you for doubling back for reread.

As I already mentioned, according to Einstein a new theory emerged with the writings of Lorentz in 1904 and his own in 1905; I agree with that. However there is a subtle difference between the two interpretations of the theory:

whereas Lorentz found it useful to distinguish between what appears to happen and what "really" happens from an unknown perspective that cannot be detected, Einstein found it better to only discuss the phenomena (=appearances, not what "truly" happens!).
Well, sounds about right. Now please understand that I am not just trying to argue here, but two points that I feel are debatable ...

(1) as to whether Lorentz and Einstein have 2 interpretations of a same theory. I've always considered the theories to differ, so 2 differing theories that happen to possess the same solutions.

(2) as to whether Einstein's comments as-to-what "appears to be" means "possibly untrue". From my studies of OEMB, my impression is that Einstein discusses what is measurable/recordable by observers using light itself as part of the measuring apparatus. In Einstein's theory, an extension of rigid coordinate system axes would be consistent with relativistic measurements using light signals. In this sense, what is measured matches what is real, per any inertial measurer. The fact that OEMB requires a moving observer contract and his moving clock slow down, while yet said moving-observer never measures/discerns any change in his own length or clock rate, does not necessarily lead that Einstein assumed relativistic effects are "not true".​

I'm just trying to get to the core of "the differences in meaning" between SR and LET, and as to whether the PoR is upheld (for the all of physics) in LET as well as it is upheld in SR. I've never fully understood the full meaning of LET, mainly because "folks who understand LET well" often tend to make differing statements about its deeper meaning. By "deeper meaning", I refer to those concepts upon which the theory is constructed, and as to how they impact the meaning of the final LT solns (the LTs being the same in both theories).

Just a couple related points on this, per http://en.wikipedia.org/wiki/Lorentz_ether_theory" [Broken] ...

In 1904 he (Poincare) illustrated the same procedure in the following way: A sends a signal at the time 0 to B, which arrives at the time t. B also sends a signal at the time 0 to A, which arrives at the time t. If in both cases t has the same value the clocks are synchronous, but only in the system in which the clocks are at rest in the ether. So according to Darrigol Poincaré understood local time as a physical effect just like length contraction - in contrast to Lorentz, who used the same interpretation not before 1906. However, contrary to Einstein, who later used a similar synchronisation procedure which was called Einstein synchronisation, he still was the opinion that only clocks resting in the ether are showing the "true" time.

In 1907 Einstein criticized the "ad hoc" character of Lorentz's contraction hypothesis in his theory of electrons, because according to him it was only invented to rescue the hypothesis of an immobile ether. Einstein thought it necessary to replace Lorentz's theory of electrons by assuming that Lorentz's "local time" can simply be called "time", and he stated that the immobile ether as the theoretical fundament of electrodynamics was unsatisfactory.​

So Einstein saw Lorentz's "local time" as "time", which suggests to me "true time". This is no different from saying that the readout of a distant moving clock is the true time of said moving clock, per the observer. IOWs, it's not some kind of luminal effect that produces a moving time readout that is less-than-real.

GrayGhost

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#### harrylin

[..]two points that I feel are debatable ...
(1) as to whether Lorentz and Einstein have 2 interpretations of a same theory. I've always considered the theories to differ, so 2 differing theories that happen to possess the same solutions.​

As I and Pallen discussed early in this thread, it's a bit funny that people treat such questions regarding QM differently. I still don't fully understand why. Would you argue that there are different theories* of QM? Or is this all just word games perhaps? :uhh:
(2) as to whether Einstein's comments as-to-what "appears to be" means "possibly untrue". From my studies of OEMB, my impression is that Einstein discusses what is measurable/recordable by observers using light itself as part of the measuring apparatus. In Einstein's theory, an extension of rigid coordinate system axes would be consistent with relativistic measurements using light signals. In this sense, what is measured matches what is real, per any inertial measurer. The fact that OEMB requires a moving observer contract and his moving clock slow down, while yet said moving-observer never measures/discerns any change in his own length or clock rate, does not necessarily lead that Einstein assumed relativistic effects are "not true".
I don't know what you mean with "OEMB", but it sounds as if you mean with "real" something else than what for example Newton meant with "real" or "true". In any case, you can easily verify that Einstein's 1905 paper avoids those words altogether; and I am sure that was on purpose. Definitely such non-measurables are not part of SR.
I'm just trying to get to the core of "the differences in meaning" between SR and LET, and as to whether the PoR is upheld (for the all of physics) in LET as well as it is upheld in SR. I've never fully understood the full meaning of LET, mainly because "folks who understand LET well" often tend to make differing statements about its deeper meaning.
The funny thing is that Lorentz himself probably did not know about this "LET" that you discuss here; a long time ago when I tried to find its origin, I found that it almost certainly originated from a confusion by Minkowski - a confusion that has lived on until today, as so often happens.
By "deeper meaning", I refer to those concepts upon which the theory is constructed, and as to how they impact the meaning of the final LT solns (the LTs being the same in both theories). [..Wikipedia..]
Let's not discuss the mix of accuracies and inaccuracies of Wikipedia on this forum; please stick with the original (mostly peer-reviewed) papers!
So Einstein saw Lorentz's "local time" as "time", which suggests to me "true time". This is no different from saying that the readout of a distant moving clock is the true time of said moving clock, per the observer. IOWs, it's not some kind of luminal effect that produces a moving time readout that is less-than-real.
GrayGhost
I'm sorry but I can't make sense of what you mean with "true": you appear to have no problem with contradictory truth, so that your definition of "true" is close to my definition of "untrue"; and I think that we had that same problem in an earlier thread, and that we could not solve it. So I won't try again. In any case, "true" is not defined in SR. SR is about predictions and observations.

Regards,
Harald

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#### Doc C PhDo

Appears that as Lorentz was striving to present his 'electrical theory of matter'. He developed
his transform: x' = x - [ vt/SquareRoot( 1 - (v^2/c^2))], c the velocity of light. ----- Because of the enigma of 'length contraction' and the Michelson-Morley 'failure' (no aether detected).
Lorentz suggested, regarding relative motion; that if you 'hold' c as the/a constant and arbitrarily make space and time variables; his equation accounts for 'length contraction'.

#### GrayGhost

As I and Pallen discussed early in this thread, it's a bit funny that people treat such questions regarding QM differently. I still don't fully understand why. Would you argue that there are different theories* of QM? Or is this all just word games perhaps?
Well, I would say that there is one QM theory, but that there exists various interpretations of the theory. The varying interpretations come from trying to explain the meaning of things such as (say) the wave function collapse.

Here though, we've been talking about 2 different theories, LET and SR, which just happens to have the same LT solns. Their foundations differ.

I don't know what you mean with "OEMB", but it sounds as if you mean with "real" something else than what for example Newton meant with "real" or "true". In any case, you can easily verify that Einstein's 1905 paper avoids those words altogether; and I am sure that was on purpose. Definitely such non-measurables are not part of SR.
I suppose it best to replace "real" with the word "measured/measurable", for otherwise folks often tend to use that to send the discussion off track and out into left field. In LET though, it's not so easy. We have (in LET) the issue of a moving contracted ruler not able to measure itself as contracted because it too length-contracts by the same amount, which seems a "less than real" measurement. It's contracted, but it cannot tell. In SR, inertial rulers cannot measure themselves contracted because they aren't, because no contractions exist when stationary, and so different story altogether.

The funny thing is that Lorentz himself probably did not know about this "LET" that you discuss here; a long time ago when I tried to find its origin, I found that it almost certainly originated from a confusion by Minkowski - a confusion that has lived on until today, as so often happens. Let's not discuss the mix of accuracies and inaccuracies of Wikipedia on this forum; please stick with the original (mostly peer-reviewed) papers!
Well, maybe so. I am not sure as yet, myself. I now see your position on this matter, but I've read much over the years that contends otherwise. I'll have to look online for some verification. It reminds me of the democrat who says FOX news has unreputable sources, and the republican who says CNN has unreputable sources :) I'd like to see some statements made by Lorentz himself, between 1904 and (say) 1908, and after.

I'm sorry but I can't make sense of what you mean with "true": you appear to have no problem with contradictory truth, so that your definition of "true" is close to my definition of "untrue"; and I think that we had that same problem in an earlier thread, and that we could not solve it. So I won't try again. In any case, "true" is not defined in SR. SR is about predictions and observations.
In the context of SR, my definition of true is "measured". I'm not so sure that this definition apply as well to LET though, as I stated prior here.

GrayGhost

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#### GrayGhost

So, in summary: I think it's always possible to modify "LET" so that it is experimentally equivalent to SR. However, the increasing number of effects that must be explained, decreases the probability of such a theory. Regards,
Sounds rather reasonable to me. However the fact that these "increased number of effects" need be explained in LET, suggests to me that the meaning of the LTs likely differs for SR vs LET ... even though the solns are the same. no?

GrayGhost

#### Histspec

Let's not discuss the mix of accuracies and inaccuracies of Wikipedia on this forum; please stick with the original (mostly peer-reviewed) papers!

I'm sorry but I can't make sense of what you mean with "true": you appear to have no problem with contradictory truth, so that your definition of "true" is close to my definition of "untrue"; and I think that we had that same problem in an earlier thread, and that we could not solve it. So I won't try again. In any case, "true" is not defined in SR. SR is about predictions and observations.
The Wikipedia article is correct. It was Lorentz himself, who used the word "true time" to distinguish his own views from that of Einstein and Minkowski (and Poincaré). For example in 1914: http://en.wikisource.org/wiki/Two_Papers_of_Henri_Poincaré_on_Mathematical_Physics, p. 252, emphasis by me:
Lorentz1914 said:
The formulas (4) and (7) are not in my memoir of 1904. Because I had not thought of the direct way which led there, and because I had the idea that there is an essential difference between systems x, y, z, t and x',y',z',t'. In one we use - such was my thought - coordinate axes which have a fixed position in the aether and which we can call "true" time; in the other system, on the contrary, we would deal with simple auxiliary quantities whose introduction is only a mathematical artifice. In particular, the variable t' could not be called "time" in the same way as the variable t.....Poincaré, on the contrary, obtained a perfect invariance of the equations of electrodynamics, and he formulated the "postulate of relativity".
So Lorentz clearly wrote, that the shortcomings of his 1904-paper are the consequence of his distinction between "true" time in the aether; and "local" time which is only a "mathematical artifice".

Or in 1910: http://de.wikisource.org/wiki/Das_Relativitätsprinzip_und_seine_Anwendung, p. 75, (translation and emphasis by me):
Lorentz1910 said:
Provided that there would exist an aether: then one of all systems x, y, z, t, would be preferred by the fact that the coordinate axes as well as the clocks are resting in the aether. If one connects with this the idea (which I only reluctantly would abandon) that space and time be completely different things, and that there be a "true time" (simultaneity thus would be existing independently, corresponding to the fact, that it is possible for us to imagine infinitely great speeds), then one can easily see, the this true time shall be indicated by clocks at rest in the aether. Now, if the relativity principle had general validity in nature, however, one would consequently be unable to find out whether the reference system momentarily employed is that preferred one. Thus one arrives at the same results, as when one denies the existence of the aether and of true time, and to view all reference systems as equally valid, following Einstein and Minkowski. To which of both ways of thinking one adheres to, we can leave to the judgment of each individual.
So on one hand, we have Lorentz's view that there is a "preferred frame", "absolute simultaneity" and "true time", but all of them are unobservable. And we have Einstein and Minkowski, according to which all of those concepts are meaningless.

And the same in 1913: http://de.wikisource.org/wiki/Das_Relativitätsprinzip_(Lorentz)), p. 23, (translation and emphasis by me):
Lorentz1913 said:
If the observers would like to view the concept of time as something primary, something completely separated from the concept of space, then they would surely recognize, that absolute simultaneity exists; however, they would leave it undecided again, whether this simultaneity is indicated by equal values of t, or by equal values of t', or maybe neither by one nor the other.
Einstein says in short, that all questions mentioned before, have no meaning. Thus he arrives at the abolishment of the aether. The latter is, by the way, to some extent a quarrel about words: it makes no great difference, whether one speaks of vacuum or aether. Anyway, according to Einstein it has no meaning to speak about a motion relative to the aether. He also denies the existence of absolute simultaneity.
It is certainly remarkable, that those relativity concepts, even with respect to time, have been adopted so fast.
The evaluations of those concepts mostly belong to epistemology, and one can leave it to its judgment, trusting that it considers the questions discussed with the thoroughness required. However, it is for sure, that for a large part it will depend on the way of thinking to which one is accustomed, whether one is mostly attracted to one or the other view. Regarding the lecturer himself, he finds a certain satisfaction in the elder views, that the aether at least possesses some substance, that space and time can sharply be separated, and that one can speak of simultaneity without closer specification. Regarding the latter, one can maybe rely on our ability, to (at least) imagine arbitrary great speeds. By that, one comes very near to the concept of absolute simultaneity.
Regards,

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#### harrylin

Well, I would say that there is one QM theory, but that there exists various interpretations of the theory. The varying interpretations come from trying to explain the meaning of things such as (say) the wave function collapse.

Here though, we've been talking about 2 different theories, LET and SR, which just happens to have the same LT solns. Their foundations differ.
QM had multiple philosophical foundations relating to differing philosophies as locality, no locality, particles, waves and wave-particles; differing interpretations have been there right from the beginning. The "solution" of modern theories of physics such as SR and QM is to formulate them in such a way that they discuss only observables.

I refer you again to Einstein's overview of 1907 of what he later named SR: its foundation is the construction of a theory in which Maxwell's equations are invariant for a change of inertial reference system, so that the PoR is valid for all laws of physics. The unification of Lorentz's Theory of Electrons with the principle of relativity was the common basis for Lorentz-1904 and Einstein-1905.

[..] In SR, inertial rulers cannot measure themselves contracted because they aren't, because no contractions exist when stationary [..]
Those rulers are contracted according to any observer who is moving wrt to them while you say that "they arent"... if you want to suggest with that that the POV of that observer is "wrong" - that is at odds with the PoR. The whole point of the PoR is that such claims can not be made. But I'm sure that we have been here before, it's perhaps a difference of how are brains are wired.
I'd like to see some statements made by Lorentz himself, between 1904 and (say) 1908, and after.
Mere statements won't suffice as they should be understood in context; a whole section is more reliable than a sound bite. You can find increasingly more original papers of that time in Wikisources to which I already gave links:
http://en.wikisource.org/wiki/Portal:Relativity
In the context of SR, my definition of true is "measured". I'm not so sure that this definition apply as well to LET though, as I stated prior here.
GrayGhost
Certainly Lorentz meant with "true" not what is measured but invisible reality, like Newton.

#### harrylin

Sounds rather reasonable to me. However the fact that these "increased number of effects" need be explained in LET, suggests to me that the meaning of the LTs likely differs for SR vs LET ... even though the solns are the same. no?

GrayGhost
It depends on what you mean with "LET", and with "the LTs". They don't exist in that form in the 1904 paper by Lorentz, and he had not thought enough about the meaning in practice of his "local time". However, in the 1905 paper by Poincare the meaning of the equations is the same as it is today.

#### harrylin

The Wikipedia article is correct. [..]
Nothing is perfect and certainly not Wikipedia! I referred to suggestions of that article (not related to your citations) that were cited here.

Anyway, thanks for the many citations.

I note that you forgot to include citations of Einstein's 1918 and 1920 replies in which he abandoned his earlier interpretation; but all that has little to do with the topic.

Regards,
Harald

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#### GrayGhost

It depends on what you mean with "LET", and with "the LTs". They don't exist in that form in the 1904 paper by Lorentz, and he had not thought enough about the meaning in practice of his "local time". However, in the 1905 paper by Poincare the meaning of the equations is the same as it is today.
OK harrylin. So Lorentz derived the correct LT solns first in 1904, although he did not understand the meaning of time t', ie time dilation. Poincare made a correction to the 2004 LET in 2005 (wrt electric charge), and also re-interpreted Lorentz's LET in a way that allowed it finally become Lorentz covariant ... whereby Lorent'z provided a physical meaning for Lorentz's "local time", versus some mathematical artifact during derivation. So in the same year, 2005, we have Poincare's re-interpretation of LET and Einstein's OEMB published. Lorentz finally began accepting Poincare's re-interpretation in 2006. Einstein's theory was accepted over LET because of simplicity, the result of an invariant light speed ... ie, a choice of convention that makes everything more convenient. Sound about right?

I must say, it remains strange to me that we have one theory that begins from a preferred aether frame, and another theory that assumes no preferred frame exists, and the solns are identical with both supporting the PoR. If so, would this not be true ... Wouldn't any arbitrary inertial frame be able to be defined as the preferred aether frame, and if so, would not the very same LTs arise during the same Lorentz derivation? I mean if no experiment can determine the aether frame (or distinguish LET from SR), then I suppose it matters not which frame you begin with "as the aether frame". Yes? I mean the end results are the very same. And if it doesn't matter, then one has to wonder whether there really is an aether frame at all (even if an aether exists). So I still seem to be missing something about LET here, but I don't yet know what it is :)

GrayGhost

#### harrylin

OK harrylin. So Lorentz derived the correct LT solns first in 1904, although he did not understand the meaning of time t', ie time dilation. Poincare made a correction to the 2004 LET in 2005 (wrt electric charge), and also re-interpreted Lorentz's LET in a way that allowed it finally become Lorentz covariant ... whereby Lorent'z provided a physical meaning for Lorentz's "local time", versus some mathematical artifact during derivation. So in the same year, 2005, we have Poincare's re-interpretation of LET and Einstein's OEMB published. Lorentz finally began accepting Poincare's re-interpretation in 2006. Einstein's theory was accepted over LET because of simplicity, the result of an invariant light speed ... ie, a choice of convention that makes everything more convenient. Sound about right?
That sounds almost right to me.
However:
- You placed the events it in the wrong century.
- Poincare as well as Langevin were not mistaken or cheating when they claimed that Lorentz managed to create what you here call a "Lorentz covariant" theory: the Lorentz transformations follow directly from Lorentz's 1904 paper without any correction and with the modern operational meaning.
- Lorentz had already mentioned the physical meaning of time dilation in an earlier paper and he certainly understood the fact that the PoR of classical mechanics implies that the corresponding transformations hold just as well between moving systems; thus there was no need for him to "begin accepting" Poincare's interpretation. It was simply that by 1904, in his head "all the pennies had not yet dropped".

Note that the phrase "they form a group" is very mathematical and Poincare was also a mathematician. However it was not a common thing to say for physicists at that time. I think that Lorentz did not use that expression. Consequently the fact that Einstein put that phrase in his paper has been advanced as evidence for the hypothesis that he had seen Poincare's paper. However, that's irrelevant for the priority of the 1904 and 1905 papers of Lorentz and Poincare.

I must say, it remains strange to me that we have one theory that begins from a preferred aether frame, and another theory that assumes no preferred frame exists, and the solns are identical with both supporting the PoR.
Ehm, not exactly. It's similar to classical mechanics vs. Newton's mechanics. Both Lorentz-1904 and Einstein-1905 begin from the PoR, which implies that no frame is preferred for the phenomena. Lorentz's derivation starts from a "true" (or "absolute") rest frame which cannot be determined, while Einstein's derivation omits that assumption because it is "superfluous" for the derivations: it plays no role in the predictions that are based on the postulates. However, the light postulate corresponds to the Maxwell-Lorentz wave theory of light, as opposed to ballistic light theories (see further).

If so, would this not be true ... Wouldn't any arbitrary inertial frame be able to be defined as the preferred aether frame, and if so, would not the very same LTs arise during the same Lorentz derivation? I mean if no experiment can determine the aether frame (or distinguish LET from SR), then I suppose it matters not which frame you begin with "as the aether frame". Yes? I mean the end results are the very same. And if it doesn't matter, then one has to wonder whether there really is an aether frame at all (even if an aether exists). So I still seem to be missing something about LET here, but I don't yet know what it is :)

GrayGhost
Exactly - such a "frame" is not "preferred" in that sense.
What you may have missed, is the wish of many physicists to come up with a physical model of light propagation (even if just a sketchy concept like the atom for the ancient Greeks), so as to be able to ascribe a physical cause for such things as a limit speed, electromagnetic fields, etc*. It's similar to Einstein's later wish for a "local-realistic" physical explanation of the apparent "spooky action at a distance" of QM.

*Einstein motivated the light postulate as follows in 1907:
[this] "principle of the constancy of the velocity of light," is at least for a coordinate system in a certain state of motion [..] made plausible by the confirmation through experiment of the Lorentz theory [of 1895], which is based on the assumption of an ether that is absolutely at rest.
- German original: http://www.soso.ch/wissen/hist/SRT/E-1907.pdf

Regards,
Harald

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#### Histspec

- Poincare as well as Langevin were not mistaken or cheating when they claimed that Lorentz managed to create what you here call a "Lorentz covariant" theory: the Lorentz transformations follow directly from Lorentz's 1904 paper without any correction and with the modern operational meaning.
Unfortunately, Lorentz himself said that he didn't arrive at a fully Lorentz covariant theory, due to his assumption, that there is a fundamental difference between "true" and "local" time. (see his Poincaré-paper above). So it's quite clear that Langevin and Poincaré were very generous in his assessment. See also Lorentz's remark: http://en.wikisource.org/wiki/Two_Papers_of_Henri_Poincaré_on_Mathematical_Physics
Lorentz1914 said:
Poincaré, on the contrary, obtained a perfect invariance of the equations of electrodynamics, and he formulated the "postulate of relativity", terms which he was the first to employ. Indeed, stating from the point of view that I had missed, he found the formulas (4) and (7). Let us add that by correcting the imperfections of my work he never reproached me for them.
Here is another statement of Lorentz from 1928, p. 350: http://adsabs.harvard.edu/abs/1928ApJ%E2%80%A6.68..341M [Broken]
Lorentz1928 said:
A transformation of time was also necessary. So I introduced the conception of a local time which is different for different systems of reference which are in motion relative to each other. But I never thought that this had anything to do with the real time. This real time for me was still represented by the old classical motion of an absolute time, which is independently of any reference to special frames of co-ordinates. There existed for me only this one true time. I considered my time transformation only as a heuristic working hypothesis. So the theory of relativity is really solely Einstein's work. And there can be no doubt that he would have conceived it even if the work of all his predecessors in the theory of this field had not been done at all. His work is in this respect independent of the previous theories.
However, one may wonder that in one text he referred to Einstein, and in another to Poincaré...
harrylin said:
Lorentz had already mentioned the physical meaning of time dilation in an earlier paper and he certainly understood the fact that the PoR of classical mechanics implies that the corresponding transformations hold just as well between moving systems; thus there was no need for him to "begin accepting" Poincare's interpretation. It was simply that by 1904, in his head "all the pennies had not yet dropped".
Not according to Lorentz's own opinion. He had the local time formula in 1892, and the time-dilation formula in 1899, but as he himself noticed, this was only a "mathematical artifice" (see his Poincaré-paper or the quote given above). It was not before 1906, when he first spoke about a physical interpretation of both "local time" and "time dilation" by using clocks.
In fact, the light-signal interpretation of local time was first given by Poincaré in 1900, and the transported-clock interpretation of time-dilation was first given by Larmor and Cohn in 1904.
Einstein motivated the light postulate as follows in 1907:
- German original: http://www.soso.ch/wissen/hist/SRT/E-1907.pdf
[this] "principle of the constancy of the velocity of light," is at least for a coordinate system in a certain state of motion [..] made plausible by the confirmation through experiment of the Lorentz theory [of 1895], which is based on the assumption of an ether that is absolutely at rest.
Yes, Lorentz's aether theory influenced Einstein's thinking on the light postulate – but he didn't used the aether concept itself. See p. 413. (translation and emphasis by me)
Einstein1907 said:
However, it was demonstrated surprisingly, that it was only necessary to define the concept of time sufficiently precise, to overcome the difficulty discussed before. Only the idea was necessary, that an auxiliary quantity introduced by H. A. Lorentz, which was denoted by him as "local time", can be defined as "time" per se. If one continues to adhere to the sketched definition of time, then the fundamental equations of Lorentz's theory correspond to the relativity principle, when one replaces the transformation equations above, by such ones corresponding to the new concept of time. The hypothesis of H. A. Lorentz and Fitzgerald then appears to be as a necessary consequence of the theory. Only the idea of a luminiferous aether as the carrier of electric and magnetic forces does not fit into the theory laid out here; namely, electromagnetic fields doesn't appear here as states of some sort of matter, but as independently existing things, that are equally valid to ponderable matter and share with it the property of inertia.
Regards,

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#### GrayGhost

Histspec,

Well, you do seem to have your sources. Thanx for the references.

My understanding was that Einstein continued working as a patent clerk from 1904 thru 1908, so for 4 more years, before being approached by colleagues of Max Planck. I'm just curious, at what year did Lorentz (and/or Poincare) first become aware of Einstein's 1905 paper? Any idea?

GrayGhost

#### harrylin

Unfortunately, Lorentz himself said that he didn't arrive at a fully Lorentz covariant theory, due to his assumption, that there is a fundamental difference between "true" and "local" time. (see his Poincaré-paper above). So it's quite clear that Langevin and Poincaré were very generous in his assessment. See also Lorentz's remark: http://en.wikisource.org/wiki/Two_Papers_of_Henri_Poincaré_on_Mathematical_Physics
Generous perhaps, but basically correct since the Lorentz transformations follow directly from Lorentz-1904. It appears that people who more openly proclaim their mistakes and weaknesses are punished for their honesty. Due to lack of rigour (instead of "proceeding more systematically") Lorentz's electromagnetic formulas "remained encumbered with certain terms which should have disappeared".
Note that similarly, there's an error in the transverse mass equation of Einstein-1904: a square root is lacking there (http://www.fourmilab.ch/etexts/einstein/specrel/www/, it's the same in the German original; for a discussion see E. Cullwick, The British Journal for the Philosophy of Science Vol. 32, No. 2, Jun., 1981, http://www.jstor.org/stable/687198?seq=6).

Usually one does not trash a theory because of a few glitches in the original papers; but of course that's a matter of opinion.

Here is another statement of Lorentz from 1928, p. 350: http://adsabs.harvard.edu/abs/1928ApJ%E2%80%A6.68..341M [Broken]

However, one may wonder that in one text he referred to Einstein, and in another to Poincaré...
Indeed - although by then "theory of relativity" commonly referred to GR, it appears that with "theory of relativity" he there referred to special relativity, in which case his accreditation was simply faulty. It could be amnesia due to old age (it was shortly before his death and these are conversation notes); or perhaps it was due to an editing error. Although Lorentz supposedly reviewed those shorthand notes, he may have overlooked the error.
harrylin wrote: "Lorentz had already mentioned the physical meaning of time dilation in an earlier paper and he certainly understood the fact that the PoR of classical mechanics implies that the corresponding transformations hold just as well between moving systems; thus there was no need for him to "begin accepting" Poincare's interpretation. It was simply that by 1904, in his head "all the pennies had not yet dropped"."

Not according to Lorentz's own opinion. [...]
Lorentz never stated that he did not understand that the Galilean transformations conform to the classical PoR so that they are valid between inertially moving systems; indeed that would be rather incredible.

And with the "physical meaning" of time dilation I had his 1899 paper in mind:
Michelson's experiment should always give a negative result, whatever transparent media wore placed on the path of the rays of light, [..] provided however that in S the time of vibration be kε times as great as in S0.
- http://en.wikisource.org/wiki/Simplified_Theory_of_Electrical_and_Optical_Phenomena_in_Moving_Systems

A mere calculation aid cannot affect such a physical vibration time. :tongue2:
Yes, Lorentz's aether theory influenced Einstein's thinking on the light postulate – but he didn't used the aether concept itself. See p. 413. (translation and emphasis by me)
Regards,
Yes, and I wondered what he meant with "an ether as carrier of electric and magnetic forces does not fit in that model"; but happily in 1920 Einstein clarified his 1907 claim as follows:
H. A. Lorentz [..] brought theory into harmony with experience by means of a wonderful simplification of theoretical principles. He achieved this [..] by taking from ether its mechanical [..] qualities. [...] According to Lorentz the elementary particles of matter alone are capable of carrying out movements; their electromagnetic activity is entirely confined to the carrying of electric charges.
Note: I'm afraid that this discussion has drifted rather far from the topic; and I think that the questions of the OP have been more than sufficiently answered. Thus I'll abstain from further commenting on aspects that are not perfectly on topic.

Regards,
Harald

PS more references for the question "who first derived SR" can be found here:
http://en.wikipedia.org/wiki/Relativity_priority_dispute

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#### GrayGhost

harrylin,

Indeed, it helps to get the century right :) Thanx for the correction.

It seems clear as to why SR was accepted over LET. LET assumes an immovable aether that can never be found, a preferred frame, a non-invariant light speed that cannot be recorded, and physically contracted rulers that can never measure their own contraction. SR has none of these issues. Yet, I suppose there is always the possibility that an aether frame does exist, as assumed per the LET model. It seems more intuitive to me that if an aether frame does exist, it be an unpreferred inertial frame of Einstein's model as opposed to Lorentz's undeterminable preferred one. BTW, would not the determination of the 1-way speed of light reveal which theory is the correct one?

GrayGhost

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