Did Lorentz or Einstein theoretically derive special relativity?

[harrylin]

[...]
Didn't the fact that the speed of light as measured from occluded light sources far out in space all came to the same speed have much more relevance? Did Einstein know about those measurements?

Dear Zentralls, Einstein closely followed the writings of Poincare who discussed that issue in, again:

http://en.wikisource.org/wiki/The_Measure_of_Time (especially section XII)

Enjoy

 

[harrylin]

Of course it's the topic. Lorentz himself used (for good reasons) the expression "preferred", in so far as clocks at rest in this aether indicate the "true" time and an "absolute" simultaneity [..].

Your comment ignores the context of my reply to GreyGhost. "Preferred" was used at that time to designate a frame that is preferred for the description of physical phenomena. I explained that according to the PoR no inertial frame can be preferred in that sense; and consistent with that Lorentz did not (as far as I know, and apparently also as far as you know!) use the expression "preferred" for a PoR-compatible ether. If he did, that would have created a lot of confusion.

Do you still (like the generous Poincaré) want to downplay this issue?

Similarly, do you still (like the generous Lorentz) want to blow that issue out of proportion? This is not a place for dog fights and the question of the OP has been sufficiently answered.

According to this argument, Joseph Larmor would be the inventor of SR, who already in 1897 and 1900 had the complete transformation.

That would certainly be the case if Larmor's transformations were intended to show the complete impossibility of detecting absolute inertial motion; but I doubt that.

[..] You have to explain this to Lorentz, not to me.

Lorentz explained it to you and Einstein.

Look, the problem is that we have to be careful, when we speak about "physical" time when referring to Lorentz's application of this time variable, since Lorentz himself said in 1909, 1913, 1914, 1927 etc.., that time t' was only a mathematical artifice, which includes also the "modified" local time (including time dilation) from 1899 and 1904...

As I showed, Lorentz described the physical slowdown due to motion in 1899; the logical connection between his time dilation and his t' is what I meant with "the penny had not yet dropped". That was a problem for him then but not for Poincare and Langevin in 1904, nor for us now.

The topic's title is "Did Lorentz or Einstein theoretically derive special relativity?". All of the quotes I brought show, that Lorentz did not regard himself as having derived SR. And this is in agreement with the modern interpretation by most reputable Historians of Science (Holton, Pais, Miller, Stachel, Janssen, etc.) Off-topic are your references to Einstein's non-technical aether papers and lectures, which were ignored in any physics-textbooks in the last 70 years, while his initial judgments from 1905-1909 are still valid and accepted.
Regards,

I showed similarly that SR includes Lorentz's work of 1904, as it was Einstein who later named the theory that according to him in 1907 followed from both papers, "SR". Modern interpretation is increasingly aware of the full history of which even Lorentz was only partially aware, as more old documents are made easily available to all.
Thanks to that nowadays Poincare is acknowledged for his contributions to SR, while in the past he was often completely overlooked.
And references to papers that clarify and balance some of your citations that you seemed to misunderstand are certainly appropriate; only a desire to obscure such clarifications can explain an allergic reaction to them.

Regards,
Harald

 

[harrylin]

Perhaps it's useful to present a little timeline for the OP and other onlookers who may have lost track.

A number of people worked in the 19th century on trying to fit theory to experiment, but all or most of them were just adapting after-the-fact; although they made contributions to the development, I will omit them here.

- In 1904 and at the request of Poincare, Lorentz published a new theory that was intended to perfectly comply with the PoR. The Lorentz transformations follow directly from this paper. However he was confused about the meaning of "time" t' and he made a few small errors in the equations for current and charge. As a result it was just not perfect.

- In June 1905 Poincare published a commentary on Lorentz's paper in which he presented the Lorentz transformations in the symmetrical form as we know them today, in order to emphasise the group property. With that he established the perfect invariance of the electromagnetic equations and he corrected some errors of Lorentz's paper which he deemed to be minor.

- In September 1905 Einstein published a paper with a similar title as the former and also with the purpose to obtain a theory that obeys the PoR. He also established the Lorentz transformations and the full invariance of the electromagnetic equations. On top of that he discussed such topics as time dilation and Doppler effect.

Poincare gave the honour to Lorentz (without mention of Einstein), Einstein gave the honour to Lorentz and himself, and Lorentz gave the honour to Poincare and Einstein.

Many more papers were published on the topic, see the list here:
http://en.wikisource.org/wiki/Portal:Relativity

And an overview of the related priority debate with many sources can be found here:
http://en.wikipedia.org/wiki/Relativity_priority_dispute

PS. With that I un-subscribe of thread which isn't really about physics

 

[Histspec]

Perhaps it's useful to present a little timeline for the OP and other onlookers who may have lost track.

For the mainstream view (based on Janssen, Stachel, Darrigol, Pais, Holton, Miller etc.), some readers might also be interested in

http://en.wikipedia.org/wiki/History_of_special_relativity"

Anyway, it is interesting, that even with so many direct quotations as given in this thread, no agreement could be achieved. It's quite clear to me (and to most mainstream historians of science as well), that the theory Lorentz created between 1892-1904 is not special relativity (as Lorentz himself clearly said). Of course, this should not be understood as a criticism of Lorentz. He was one of the greatest physicists of all times, and without him, modern physics would probably look very different today.

PS. With that I un-subscribe of thread which isn't really about physics

Thanks for the interesting discussion.

Regards,

 

[Histspec]

I've also read that Einstein learned of the Michaelson-Morley experiment long after he published his SR paper.

Can someone explain to me why that would be important to Einstein? Wouldn't he consider the Earth to be one big inertia frame of reference and expect the speed of light to be the same in both directions for that reason alone?

I've never quite understood why that experiment would have anything to do with SR. (I got my MS at CWRU and have seen their experimental setup - fascinating stuff).

There were many experiments that were important for the development of the Lorentz transformation.

*The aberration of light, which showed that the aether is not completely dragged by matter. This also refutes the idea, that Earth is "one big inertia frame of reference".
*The http://en.wikipedia.org/wiki/Fizeau_experiment" , which gave more details on "aether entrainment". However, it was shown by Lorentz, that no aether entrainment is necessary at all to explain the result.
*The negative aether drift experiments, most importantly Michelson-Morley.
*The http://en.wikipedia.org/wiki/Moving_magnet_and_conductor_problem" , showing that em-processes are only depending on relative motion.
*The success of Lorentz's stationary aether theory (light speed is independent of the source speed).

You will find, that it is hardly possible to explain all of those things without inventing the Lorentz transformation (as it was done by Voigt, Lorentz, Larmor, Poincaré, Einstein).

Didn't the fact that the speed of light as measured from occluded light sources far out in space all came to the same speed have much more relevance? Did Einstein know about those measurements?

To which experiments are you referring to?

For example, the http://en.wikipedia.org/wiki/De_Sitter_double_star_experiment" was not done before 1913.

Regards,

 

[GrayGhost]

Anyway, it is interesting, that even with so many direct quotations as given in this thread, no agreement could be achieved. It's quite clear to me (and to most mainstream historians of science as well), that the theory Lorentz created between 1892-1904 is not special relativity (as Lorentz himself clearly said).

Histspec,

I thank you for your references you provided. I've been trying to blend the fine references from both you and Harrylinn, in search of a single consistent synopsis.

Harrylinn suggests that Poincare's 1905 re-interpretation of Lorentz's 1904 paper made the spacetime transformations equivalent to Einstein's 1905 work (ie SR), except that their foundations differ of course. However Harrylinn also makes the assumption that Lorentz understood time dilation prior to 1904 based on other historical documents. Yet, it would seem by Lorentz's own statements thereafter, that he either did not, or that he disbelieved it even if he was aware. In either case, Poincare should get the credit for the icing on the cake for his 1905 modifications.

If I may ask you, and even considering Lorentz's modifications, do you assume that the transformations "mean the same thing" in SR and LET? Here's the reason I ask ...

Wrt LET, my understanding is that true simultaneity is defined only by those at rest with the aether frame. If this is true, should not the meaning of t' in LET theory have to differ from the meaning of t' per SR, for the LT solns to be mathematically the same? It has always seemed to me that if each theory considers time dilation something "a little different", then the LTs cannot mean the very same thing, even though they are mathematically the same. This is why I've always questioned whether LET supports the PoR wrt force, as opposed to kinematics alone. Scenario ...

If 2 identical falling weights strike the 2 trays of a balanced scale "simultaneously", with trays-centerline colinear with propagational path, then they should not tilt. However, LET requires that synchronised clocks (per the balance) attached to the each scale pad are not simultaneous per the aether frame. Hence, the scale should tip per LET if the weights strike the pads when they display identical clock readouts.​

Is there a flaw in my reasoning here? Please realize that I understand how SR handles this, and that I am asking only in regards to LET here. Or, is my understanding of LET mistaken maybe?

thanx,
GrayGhost

 

[GrayGhost]

Anyway, it is interesting, that even with so many direct quotations as given in this thread, no agreement could be achieved. It's quite clear to me (and to most mainstream historians of science as well), that the theory Lorentz created between 1892-1904 is not special relativity (as Lorentz himself clearly said).

Histspec,

I thank you for your references you provided. I've been trying to blend the fine references from both you and Harrylinn, in search of a single consistent synopsis.

Harrylinn suggests that Poincare's 1905 re-interpretation of Lorentz's 1904 paper made the spacetime transformations equivalent to Einstein's 1905 work (ie SR), except that their foundations differ of course. However Harrylinn also makes the assumption that Lorentz understood time dilation prior to 1904 based on other historical documents. Yet, it would seem by Lorentz's own statements thereafter, that he either did not, or that he disbelieved it even if he was aware. In either case, Poincare should get the credit for the icing on the LET cake for his 1905 modifications. Yet, Einstein's 1905 OEMB became the accepted theory.

If I may ask you, and even considering Lorentz's modifications, do you assume that the transformations "mean the same thing" in SR and LET? Here's the reason I ask ...

Wrt LET, my understanding is that true simultaneity is defined only by those at rest with the aether frame. If this is true, should not the meaning of t' in LET theory have to differ from the meaning of t' per SR, for the LT solns to be mathematically the same? It has always seemed to me that if each theory considers time dilation something "a little different", then the LTs cannot mean the very same thing, even though they are mathematically the same. This is why I've always questioned whether LET supports the PoR wrt force, as opposed to kinematics alone. Scenario ...

If 2 identical falling weights strike the 2 trays of a balanced scale "simultaneously", with trays-centerline colinear with propagational path, then they should not tilt. However, LET requires that synchronised clocks (per the balance) attached to the each scale pad are not simultaneous per the aether frame. Hence, the scale should tip per LET if the weights strike the pads when they display identical clock readouts.​

Is there a flaw in my reasoning here? Please realize that I understand how SR handles this, and that I am asking only in regards to LET here. Or, is my understanding of LET mistaken maybe?

thanx,
GrayGhost

 

[harrylin]

[..]

If I may ask you, and even considering Lorentz's modifications, do you assume that the transformations "mean the same thing" in SR and LET? Here's the reason I ask ...

Wrt LET, my understanding is that true simultaneity is defined only by those at rest with the aether frame. [..] is my understanding of LET mistaken maybe?

thanx,
GrayGhost

Hi GreyGhost I could not resist another look at this thread; evidently I did not give you a satisfying answer, perhaps because I was not inclined to solve again another paradox now.

There is however also a generic answer from a modern perspective; I don't know if that will answer your question, or if it will be helpful. However it may also clarify my earlier remarks about being consistent with how the words "theory" and "interpretation" are used nowadays. So here we go:

In the QM forum we're discussing Bell's Theorem about the question if there can be "hidden variables" that explain the correlation between distant entangled particles. This theorem led to the concept that the "collapse of the wave function" implies "spooky action at a distance" at infinite speed. There are other interpretations, but this is one of the main interpretations (note: I'm still not convinced). See Bell's explanation here (near the end, third option):
http://cdsweb.cern.ch/record/142461?ln=en

As a consequence of this popular interpretation, there would be a "true" inertial frame of reference for this action, relative to which such hidden influence occurs simultaneously at distant places; the simultaneity of frames that are in motion relative to it is then only apparent (although it works just as well for a description of the phenomena).

Such an interpretation of SR sounds very much like "LET", but with a new and unheard of property that allows for influences much faster than light. Some people even call it a "preferred" frame for reasons that escape me, for no deviation of SR is implied at all.

And as I tried to make clear before, it's irrelevant for the description of the phenomena and their prediction if we assume them to be caused by an unobservable hidden reality or not. But it is relevant for the question of this thread if "special relativity" is regarded as a theory in the sense that Newton and Lorentz used that word (incl. what some call "metaphysics"), or in the operational sense in which Einstein and many people nowadays use that word.

For more on this, see Tim Maudlin's book "Quantum Non-Locality and Relativity: Metaphysical Intimations of Modern Physics".
You can browse through it here:
https://www.amazon.com/dp/0631232214/?tag=pfamazon01-20Harald

PS if you like to discuss the puzzle that you presented here: please start it as a new topic so that others who are not interested in history will notice hat topic.

 

[Samshorn]

Hence, the scale should tip per LET if the weights strike the pads when they display identical clock readouts... is my understanding of LET mistaken maybe?

Yes, your understanding of LET is mistaken. The balance beam doesn't rotate (at the fulcrum) according to either SR or [the final version of] LET, because they are empirically equivalent, both kinematically and in terms of forces and dynamics.

LET requires that synchronised clocks (per the balance) attached to the each scale pad are not simultaneous per the aether frame.

True, but SR likewise entails that the clocks are not synchronized per the frame that you are calling the aether frame. Nevertheless, the beam doesn't rotate at the fulcrum. You said you understand how SR handles this, so you must also understand how LET handles it, because they handle it the same way. The only difference is purely a metaphysical one.

...do you assume that the transformations "mean the same thing" in SR and LET?

It isn't an assumption, they mean the same thing, physically, by definition. Take special relativity, and declare that one of the infinitely many systems of inertial coordinates is named "Fred", although you are unable to say which one it is, and you are unable to identify any physical consequences of being named "Fred". This is LET (if you replace the word "Fred" with the word "True").

By the way, be wary of anyone trying to tell you that this has something to do with quantum entanglement and/or hidden variables. It doesn't. Relativistic quantum mechanics is, well, relativistic. Some people focus on the early non-relativistic version of quantum mechanics, and they point out that it is (gasp) non-relativistic. Needless to say, that kind of "reasoning" is misguided. Also, be wary of anyone trying to tell you that the difference between SR and (the final version of) LET is something other than metaphysical, even though they concede that the two are empirically indistinguishable.

 

[PhilDSP]

Also, be wary of anyone trying to tell you that the difference between SR and (the final version of) LET is something other than metaphysical, even though they concede that the two are empirically indistinguishable.

Let's not overlook the fundamental mathematical difference between SR and LET. I believe someone might have already posted Einstein's derivation of the Lorentz transformation. Lorentz wrote a detailed description of it himself in a later edition of his monograph.

The essentials of the Lorentz derivation are very different (https://www.physicsforums.com/showpost.php?p=3328134&postcount=6) Lorentz made no assumptions or postulates. He merely used (already by then) previously used techniques for solving differential equations to arrive at new coordinates that could simplify the analysis of EM and optical problems. Only the transformation of variables is the same between SR and LET. Lorentz employed the transformed differential equations, including those for media, to arrive at optical and other solutions.

Einstein and Minkowski used tensor equations very different from the differential equations Lorentz employed. Their use of equations for media was minimal and not a centrally important consideration as was the case for Lorentz. In fact, no exact solutions for media were possibly to find by Minkowski. He needed to do some averaging of certain parameters while Lorentz's solutions were exact.

It's the operations around the transformation that are most important and those operations are not the same between the 2 theories, at least they were performed in very different ways and are not subject to the same limitations.

 

[Histspec]

If I may ask you, and even considering Lorentz's modifications, do you assume that the transformations "mean the same thing" in SR and LET? Here's the reason I ask ...

As Samshorn (and Lorentz in the quoted passages) already explained -
Observationally: The same.
Metaphysically: Not the same.
(Of course, this applies to Poincaré's version, not to Lorentz's 1904-theory).

If 2 identical falling weights strike the 2 trays of a balanced scale "simultaneously", with trays-centerline colinear with propagational path, then they should not tilt. However, LET requires that synchronised clocks (per the balance) attached to the each scale pad are not simultaneous per the aether frame. Hence, the scale should tip per LET if the weights strike the pads when they display identical clock readouts.

Simply replace LET with SR, and "aether frame" with "non-co-moving frame". Then you will understand, that if your proposal is correct, not only LET, but also SR would be violated. Since this isn't the case, your thought experiment is wrong.

Regards,

 

[GrayGhost]

As Samshorn (and Lorentz in the quoted passages) already explained -
Observationally: The same.
Metaphysically: Not the same.
(Of course, this applies to Poincaré's version, not to Lorentz's 1904-theory).

Just curious though, was Poincare's re-interpretation published before Einstein's 1905 OEMB?

Simply replace LET with SR, and "aether frame" with "non-co-moving frame". Then you will understand, that if your proposal is correct, not only LET, but also SR would be violated. Since this isn't the case, your thought experiment is wrong.

OK, so per LET, if the clocks attached to the balance-trays are synchronised per the balance POV, then identical weights impacting the trays at identical clock readouts must arrive simultaneously per the balance and the scale does not tip per all ... as in SR.

So a 2-way speed of light of c as measured by contracted moving rulers in LET is not different from a 2-way speed of light of c as measured by uncontracted inertial rulers in SR, yes? You are saying that this is a metaphysical difference alone?

It still seems to me that a test that measures the 1-way speed of light w/o using a 2-way trip should validate which foundation is the correct one, SR vs LET, yes? Or, will you suggest that the choice of clock synchronisation convention dictates the 1-way speed, and so no real 1-way speed of light is determinable in theory?

GrayGhost

 

[PAllen]

It still seems to me that a test that measures the 1-way speed of light w/o using a 2-way trip should validate which foundation is the correct one, SR vs LET, yes? Or, will you suggest that the choice of clock synchronisation convention dictates the 1-way speed, and so no real 1-way speed of light is determinable in theory?

GrayGhost

A worthwhile exercise is to examine the limiting behavior of so called 'slow moving clock synchronization'. To measure one way speed of light you need two clocks synchronized at a distance, in some frame. To synchronize them without light, imagine synchronizing at one location, and moving one away *very* slowly. Then, it seems, you have one way measurement independent of the Lorentz transform. However, this would be wrong. If you examine limiting behavior of Lorentz transform (using the slow velocity), the fact that the slower the speed, the longer it takes to move the clocks, means that moving clocks apart slowly is exactly equivalent to synchronizing them with light. As a result, any version of LET which uses Lorentz transform for all interactions is, in principle, indistinguishable from SR.

 

[GrayGhost]

A worthwhile exercise is to examine the limiting behavior of so called 'slow moving clock synchronization'. To measure one way speed of light you need two clocks synchronized at a distance, in some frame. To synchronize them without light, imagine synchronizing at one location, and moving one away *very* slowly. Then, it seems, you have one way measurement independent of the Lorentz transform. However, this would be wrong. If you examine limiting behavior of Lorentz transform (using the slow velocity), the fact that the slower the speed, the longer it takes to move the clocks, means that moving clocks apart slowly is exactly equivalent to synchronizing them with light. As a result, any version of LET which uses Lorentz transform for all interactions is, in principle, indistinguishable from SR.

Well, let's see ...

t' = gamma(t-vx/c²)​

where gamma = 1/(1-v²/c²)^1/2

Slow clock transport ... Ignoring gravity, with clocks originally in sync, let's say a space shuttle traveled from the ISS at 25,000 mi/hr for 7.44 hr, then decelerates to rest with the ISS. His speed is 3.73357x10^-5 ls/sec. On arrival, the shuttle is ~1 light sec away from the ISS. Gamma = 1.0000000007, so virtually unity. So after 7.44 hr, the shuttle clock is desynchronised from the ISS clock by 0.0000000007 sec ... so virtually in sync. If the 1-way seed of light was in fact not c (as per LET), and the ISS/shuttle velocity wrt the aether frame "somewhat luminal", it seems to make sense that the light speed measured from ISS to shuttle could be notably different from a light speed measured from shuttle to ISS. No?

GrayGhost

 

[PAllen]

Well, let's see ...

t' = gamma(t-vx/c²)​

where gamma = 1/(1-v²/c²)^1/2

Slow clock transport ... Ignoring gravity, with clocks originally in sync, let's say a space shuttle traveled from the ISS at 25,000 mi/hr for 7.44 hr, then decelerates to rest with the ISS. His speed is 3.73357x10^-5 ls/sec. On arrival, the shuttle is ~1 light sec away from the ISS. Gamma = 1.0000000007, so virtually unity. So after 7.44 hr, the shuttle clock is desynchronised from the ISS clock by 0.0000000007 sec ... so virtually in sync. If the 1-way seed of light was in fact not c (as per LET), and the ISS/shuttle velocity wrt the aether frame "somewhat luminal", it seems to make sense that the light speed measured from ISS to shuttle could be notably different from a light speed measured from shuttle to ISS. No?

GrayGhost

I think I wasn't clear enough what I meant. Imagine you believe in a either frame. The problem is to determing the one way spee of light in the aether frame versus the one way sped of light in a fast train, each using slow clock synchronization to try to avoid a circular definition of one way speed of light.

LET posits actual length contractions and time dilation for motion relative to aether. Let's derive the time difference, from the aether frame, for two clocks at the opposite ends of a train, synchronized with slow clock transport.

If the train, in its own frame is L, its length in the aether frame is L/gamma(v). A clock at (say) the back end of the train is going at a rate of t/gamma(v) compared to aether. Suppose slow transport speed is delta, that is, aether frame perceives clock being moved at v+delta. So now transport time is L/(delta*gamma(v)). For this time, the slow clock is moving at t/(gamma(v+delta)) rather than t/gamma(v). So, the accumulated time difference (in the aeither frame) when the slow clock reaches the ed of the train is:

(L/(gamma(v)) * (1/delta) * (1/gamma(v+delta) - 1/gamma(v))

Taking limit as delta->0 is just:

(L/gamma(v)) Dv (1/gamma(v))

where Dv is derivative with respect to v. This is seen to be exactly:

-Lv/c^2

This is time difference in aether frame. Time synch difference in train frame (as seen from aether frame) is -gamma*L*v/c^2.

Note two things. For v=0 (aether frame), difference is zero. That is, you can make slow clock transport have no effect, in the limit of zero transport speed. For any v relative to aether, you get a simultaneity deviation exactly as in the Lorentz transform. Thus slow transport with one way measure of c, produces the same result as Lorentz transform predicts. Thus no way to disinguish moving frame using one way light measurement with slow transport.

 

[PAllen]

-Lv/c^2

This is time difference in aether frame. Time synch difference in train frame (as seen from aether frame) is -gamma*L*v/c^2.

This part of the argument is incorrect in justification (result is right). Carefully reviewing the derivation, I see the de-synchronization of -Lv/c^2 is as perceived in the aether frame, but measured in units of train time. To express in aether time, multiply by gamma.

 

[GrayGhost]

This part of the argument is incorrect in justification (result is right). Carefully reviewing the derivation, I see the de-synchronization of -Lv/c^2 is as perceived in the aether frame, but measured in units of train time. To express in aether time, multiply by gamma.

You lost me at your derivative, however no matter. I will look into that further, afterwards.

Thanx for your response Pallen. I agree that the clocks are observed by the aether to be desynchronised by gamma*(-Lv/c²), and the train records them in sync. One thing though ... I am not quite sure how any of this demands that light's 1-way speed is indeterminable.

GrayGhost

 

[PAllen]

You lost me at your derivative, however no matter. I will look into that further, afterwards.

Thanx for your response Pallen. I agree that the clocks are observed by the aether to be desynchronised by gamma*(-Lv/c²), and the train records them in sync. One thing though ... I am not quite sure how any of this demands that light's 1-way speed is indeterminable.

GrayGhost

The derivative just comes from its definition. We had something of the form:

limit as delta->0 : (f(v+delta)-f(v))/delta

That is the definition of the derivative of f(v) by v.

 

[PAllen]

You lost me at your derivative, however no matter. I will look into that further, afterwards.

Thanx for your response Pallen. I agree that the clocks are observed by the aether to be desynchronised by gamma*(-Lv/c²), and the train records them in sync. One thing though ... I am not quite sure how any of this demands that light's 1-way speed is indeterminable.

GrayGhost

I don't think the one way speed of light is indeterminate. There are different ways of synchronizing clocks and measuring distance without involving light. What *is* true is that these fail to distinguish SR from the final form of LET, even though LET has speed light constant only in the aether frame. In the sense of comparing these two particular models, you fail to establish the one way speed of light. However, you rule out essentially all alternatives to SR except LET.

I will show how LET explain how the moving train measures one way speed of light the same as the aether frame, even though LET says this is really true only in the aether frame.

For train going at +v, rest length L, its measurement of one way speed from - to + end of train is as follows:

[ (L/gamma)/(c-v) - L*v*gamma/c^2)] (1/gamma)

The /(c-v) term is contracted length over slower light speed (giving time pereceived for this measurement in the aether frame). The next term is the clock synchronization difference (as I derived for slow transport) in the aether frame. Finally, we multiply by (1/gamma) to express what is seen on the train clocks. Work this out and you get L/c.

Similarly, for measuring one way speed the other way, you get:

[ (L/gamma)/(c+v) + L*v*gamma/c^2)] (1/gamma)

which again works out to L/c.

It really is thoroughly established the the LET interpretation is indistinguishable by experiment from the standard SR interpretation.

 

[atyy]

http://books.google.com/books?id=4DunN-eD3VIC&vq=one+way&source=gbs_navlinks_s

Ohanian's irritating and fun book discusses how to measure the one way speed of light (p98-100). He does list PAllen's slow clock transport. But I think the funnest one he gives is to send a signal one way, then wait half a day, and send it back. The Earth's rotation means that sending it back is sending it in the same direction. The clocks don't have to be synchronized, they just need to be capable of timing half a day. He then says that GPS has been tested with so many arbitrary delays that the constancy of the one way speed of light is effectively measured.

 

[GrayGhost]

EDIT 1: I just realized your prior response here, after I had already posted this. I'll leave this post up for now, while I go back and anxiously read thru your post there. Thanx.
**********************************

PAllen,

Thanx for the derivative clarification.

SR assumes isotropic light speed in any and all inertial frames, so the 1-way = 2-way = c. The LTs are designed such that space and time possesses a symmetry that allows for this, ie Lorentz symmetry. A spacetime interval is observed by moving others as dilated, by gamma. If in the proper frame light travels 1 ls in 1 sec, in the frame that moves relatively the light travels across 2 ls in 2 sec, so still speed c.

LET assumes isotropic light speed in only the aether frame, so the 1-way = 2-way = c. Per anyone moving thru the aether, the 1-way speed of light is not really c. Yet, the theory determines that the 2-way speed of light must always be measured at c. Moving contracted rulers and slower ticking clocks do not realize they are contracted, and so bodies moving thru the aether never realize they are contracted from their proper values.

What I find interesting though, is this ... SR assumes the 1-way = c, and the LTs are the result of this assumption. LET possesses the very same LTs, and so it seems that its 1-way way light speed should also be assumed at c ... even though it cannot really be as such. This all suggests that measurement errors cause LET to appear as SR ... errors being due to measurements made with contracted rulers and slower ticking clocks (that don't recognize they are as such). Wrt LET upholding the PoR, I can understand why Minkowski called it "a gift from above". However, it seems to me that length contraction and time dilation alone cannot explain how LET allows for a reflection event to bisect the 2-way roundtrip interval ... because this requires the 1-way speed of light be c. Seems to me that something extra is required ... that after a Poincare synchronisation procedure is executed, although train clocks believe themselves to be simultaneous when in sync, that they in fact are not. If this mis-assumption in simultaneity is just right, then light can appear to travel at c out and c back even though it does not, because a misassumption in simultaneity can cause light's 1-way speed to "appear" invariant while it is not in reality. No?

I will have to study Lorentz's 1904 paper, and Poincare's 1905 corrections to get to the bottom of this. IOWs, to see LET as you guys do. I realize it is mathematically equivalent to SR, but I questions whether the meaning is the same. It seems to me they must mean the same for LET to uphold the PoR.

GrayGhost

 

[PAllen]

I will have to study Lorentz's 1904 paper, and Poincare's 1905 corrections to get to the bottom of this. IOWs, to see LET as you guys do. I realize it is mathematically equivalent to SR, but I questions whether the meaning is the same. It seems to me they must mean the same for LET to uphold the PoR.

GrayGhost

I don't think the meaning is the same. Just the predictions are the same. Bohm and many worlds interpretations of QM have radically different meanings, but purport to make identical predictions, in principle. LET and SR are similar - interpretations with very different meanings, but identical predictions.

As harrylin keeps pointing out, there is a simple conceptual proof that the predictions must be the same. SR says any inertial frame is as good as any other. Pick one, call it Bob, and declare Bob's measurements are real, by convention (anyone else transforms to Bob using LTs if they want). Clearly, there cannot be any difference in prediction. Now rename Bob to aether, and call the convention 'reality' and you have LET.

 

[atyy]

I will have to study Lorentz's 1904 paper, and Poincare's 1905 corrections to get to the bottom of this. IOWs, to see LET as you guys do. I realize it is mathematically equivalent to SR, but I questions whether the meaning is the same. It seems to me they must mean the same for LET to uphold the PoR.

As harrylin keeps pointing out, there is a simple conceptual proof that the predictions must be the same. SR says any inertial frame is as good as any other. Pick one, call it Bob, and declare Bob's measurements are real, by convention (anyone else transforms to Bob using LTs if they want). Clearly, there cannot be any difference in prediction. Now rename Bob to aether, and call the convention 'reality' and you have LET.

Is the LET defined by Lorentz's 1904 paper the same as the "modern" LET which is equivalent to SR?

 

[GrayGhost]

Is the LET defined by Lorentz's 1904 paper the same as the "modern" LET which is equivalent to SR?

Atyy,

Depends on who you ask, it seems. Poincare made a small correction and re-interpreted the meaning of "the 1904 paper" in 1905. It is documented that Poincare's 1905 work made LET fully Lorentz covariant, because time dilation was finally given a physical meaning (required to do so) by Poincare. Some contend that Lorentz understood this prior, but various documents suggest Lorentz either did not consider his t' as time dilation (prior to 1906), or that he simply didn't except it ... one or the other. I'm not well versed in LET myself, modern or old, so I'm not sure what changes may have been made to the theory since the 1905 Poincare mods. One of the other fellows here can tell us, I'm sure.

GrayGhost

 

[GrayGhost]

I don't think the meaning is the same. Just the predictions are the same. Bohm and many worlds interpretations of QM have radically different meanings, but purport to make identical predictions, in principle. LET and SR are similar - interpretations with very different meanings, but identical predictions.

Understood. I do understand the foundations differ. It's just that I find it difficult to believe that the solns would be identical and have the same meaning even though the foundations differ. I mean, the LTs transform frame-to-frame, and thus require no knowledge of the master aether frame's whereabouts. I must say, I have to give LET much more respect if that's all true. Need to bone up a bit.

As harrylin keeps pointing out, there is a simple conceptual proof that the predictions must be the same. SR says any inertial frame is as good as any other. Pick one, call it Bob, and declare Bob's measurements are real, by convention (anyone else transforms to Bob using LTs if they want). Clearly, there cannot be any difference in prediction. Now rename Bob to aether, and call the convention 'reality' and you have LET.

Yes, Harrylinn has said such. The problem I have is this ... LET theory assumes apriori that light is isotropic per the aether POV and "per measurement", because it's assumed real, and since the rulers & clock rates used to measure are not contracted. The derivation leads to the LTs, which require that inertial observers moving thru the aether also "measure" light as isotropic (using contracted rulers and contracted clock rate). Is it true that LET assumes isotropy of light within the aether frame "as real", and isotropy of light within moving frames "as measured" but something "less than real"? Or, is that a misconception?

GrayGhost

 

[atyy]

Understood. I do understand the foundations differ. It's just that I find it difficult to believe that the solns would be identical and have the same meaning even though the foundations differ. I mean, the LTs transform frame-to-frame, and thus require no knowledge of the master aether frame's whereabouts. I must say, I have to give LET much more respect if that's all true. Need to bone up a bit.

Let me define modern LET as Maxwell's equations plus the modified Newton's law. While SR is Maxwell's equations plus the principle of relativity.

Thus in modern LET, everything is defined using one canonical frame. However, the form of the equations is covariant under the Lorentz transforms, so modern LET implies SR.

OTOH, SR implies the modified Newton's law, so it implies modern LET.

So in LET, the modified Newton's law must come from a match to an experiment that isn't the Michelson-Morley experiment. I'm not sure how close Lorentz got to the modified Newton's law before Einstein, but John Bell does say that Lorentz did propose a modified Newton's law which looks pretty close. http://books.google.com/books?id=qou0iiLPjyoC&source=gbs_navlinks_s, p64, Eq 5.

 

[PAllen]

Is it true that LET assumes isotropy of light within the aether frame "as real", and isotropy of light within moving frames "as measured" but something "less than real"? Or, is that a misconception?

GrayGhost

Yes, exactly.

 

[GrayGhost]

Yes, exactly.

Well, all very interesting indeed. It becomes rather clear to me now why SR became the accepted theory. There is something that seems very desirable of the notion that nothing contracts in-and-of-itself, and that all measurements are just as real as the next. So it seems that the entire difference between the 2 theories is ...

LET assumes an aether frame exists in which light travels isotropically at c. This leads to the effect that moving bodies length-contract and moving clocks slow down. Contracted rulers and slower clocks cannot know they are as such. Measurements made by moving observers are something less than real, yet assumed correct.

SR is indifferent to whether an aether frame exists, and light is isotropic in all inertial frames. If it does, it is neither preferred or special in any way far as spacetime solns are concerned. Bodies, rulers, and clocks never change in-and-of-themselves, and remain always of their proper configuration. Any measurement is just as real as the next, and assumed correct.​

So where LET observers obtain LT results using unbeknownst contracted rulers and clocks, SR observers obtain the same LT results using uncontracted rulers and clocks ... and if any aether frame really does exist, both theories declare light isotropic in that frame. It makes much sense as to why the community accepted SR over LET, even though they have identical solns. I must say though, it still amazes me that Lorentz could have attained the correct solns, given his starting point. So, I'll need to study the LET to determine how he did so, determine what derivational assumptions allowed it to happen. That's what I'm most interested in at this point.

Thanx for all your inputs. Highly appreciated.

GrayGhost

 

[atyy]

So where LET observers obtain LT results using unbeknownst contracted rulers and clocks, SR observers obtain the same LT results using uncontracted rulers and clocks ... and if any aether frame really does exist, both theories declare light isotropic in that frame. It makes much sense as to why the community accepted SR over LET, even though they have identical solns. I must say though, it still amazes me that Lorentz could have attained the correct solns, given his starting point. So, I'll need to study the LET to determine how he did so, determine what derivational assumptions allowed it to happen. That's what I'm most interested in at this point.

Lorentz did try to derive length contraction from electrodynamics. He needed one assumption which is not true in classical electrodynamics - that the ground state configuration of a system of atoms is unique. Lorentz knew he was making this assumption and stated it clearly in his paper. Some have argued that since this is true in many quantum mechanical systems, this gap in Lorentz's derivation of length contraction has been filled in some cases.

An outline of Lorentz's attempt to derive length contraction is given in Bell's http://books.google.com/books?id=qou0iiLPjyoC&source=gbs_navlinks_s, p63-64.

 

[GrayGhost]

Atyy,

Thanx for the fine reference. I'm looking thru it. BTW, in an attempt to put it in a nutshell:

would you agree that any derivation (no matter what the foundation) that ...

(1) allows for contractions given invariant light in at least 1 frame, and
(2) requires all POVs to agree with the proper frame of the lightclock ...​

must end up Lorentz covariant and uphold the PoR?

GrayGhost