Authors of Relativity

  • #26
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Poincare proposed all fundamental laws are Lorentz-invariant? In what paper? If true, that would seem to make Poincare the real originator of what we know today as special relativity, even if Einstein grounded the idea more in physical arguments involving rulers and clocks (and perhaps even if Poincare did come up with Lorentz-invariance, he may not have realized various implications such as differential aging and E=mc^2)
See translations here, and in particular his June 1905 paper:
http://en.wikisource.org/wiki/Author:Henri_Poincaré

Note also his earlier paper on clocks and measurements.
 
  • #28
JesseM
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Thanks guys, both of those are very illuminating. In particular, it's notable that in the June 1905 paper, Poincare actually attributes the idea that all laws of physics could be Lorentz-invariant to Lorentz himself:
But that's not all: Lorentz, in the work quoted, found it necessary to complete his hypothesis by assuming that all forces, whatever their origin, are affected by translation in the same way as electromagnetic forces and, consequently, the effect produced on their components by the Lorentz transformation is still defined by equations (4).
The paper by Lorentz he refers to says the following on p. 819:
In the second place I shall suppose that the forces between uncharged particles, as well as those between such particles and electrons, are influenced by a translation in quite the same way as the electric forces in an electrostatic system.
This does seem to be equivalent to the notion of Lorentz-invariance, although it's interesting that Lorentz invokes this idea as just a sort of lemma in his attempt to derive the more specific phenomenon of Lorentz contraction (if I'm following the paper correctly, I just skimmed it), whereas Einstein made the postulate that all laws of physics transform the same way as electromagnetic laws the basic starting point of his paper. The following section from atyy's link has a good discussion of Lorentz's views and how he remained rather dubious of his own suggestion, and also seemed to have mistakenly thought he had "deduced" it rather than just postulating it:
Also, as Max Born remarked, to the end of Poincare’s life his expositions of relativity “definitely give you the impression that he is recording Lorentz’s work”, and yet “Lorentz never claimed to be the author of the principle of relativity”, but invariably attributed it to Einstein. Indeed Lorentz himself often expressed reservations about the relativistic interpretation.

Regarding Born’s impression that Poincare was just “recording Lorentz’s work”, it should be noted that Poincare habitually wrote in a self-effacing manner. He named many of his discoveries after other people, and expounded many important and original ideas in writings that were ostensibly just reviewing the works of others, with “minor amplifications and corrections”. So, we shouldn’t be misled by Born’s impression. Poincare always gave the impression that he was just recording someone else’s work – in contrast with Einstein, whose style of writing, as Born said, “gives you the impression of quite a new venture”. Of course, Born went on to say, when recalling his first reading of Einstein’s paper in 1907, “Although I was quite familiar with the relativistic idea and the Lorentz transformations, Einstein’s reasoning was a revelation to me… which had a stronger influence on my thinking than any other scientific experience”.

Lorentz’s reluctance to fully embrace the relativity principle (that he himself did so much to uncover) is partly explained by his belief that "Einstein simply postulates what we have deduced... from the equations of the electromagnetic field". If this were true, it would be a valid reason for preferring Lorentz's approach. However, if we closely examine Lorentz's electron theory we find that full agreement with experiment required not only the invocation of Fitzgerald's contraction hypothesis, but also the assumption that mechanical inertia is Lorentz covariant. It's true that, after Poincare complained about the proliferation of hypotheses, Lorentz realized that the contraction could be deduced from more fundamental principles (as discussed in Section 1.5), but this was based on yet another hypothesis, the co-called molecular force hypothesis, which simply asserts that all physical forces and configurations (including the unknown forces that maintain the shape of the electron) transform according to the same laws as do electromagnetic forces. Needless to say, it obviously cannot follow deductively "from the equations of the electromagnetic field" that the necessarily non-electromagnetic forces which hold the electron together must transform according to the same laws. (Both Poincare and Einstein had already realized by 1905 that the mass of the electron cannot be entirely electromagnetic in origin.) Even less can the Lorentz covariance of mechanical inertia be deduced from electromagnetic theory. We still do not know to this day the origin of inertia, so there is no sense in which Lorentz or anyone else can claim to have deduced Lorentz covariance in any constructive sense, let alone from the laws of electromagnetism.

Hence Lorentz's molecular force hypothesis and his hypothesis of covariant mechanical inertia together are simply a disguised and piece-meal way of postulating universal Lorentz invariance - which is precisely what Lorentz claims to have deduced rather than postulated. The whole task was to reconcile the Lorentzian covariance of electromagnetism with the Galilean covariance of mechanical dynamics, and Lorentz simply recognized that one way of doing this is to assume that mechanical dynamics (i.e., inertia) is actually Lorentz covariant. This is presented as an explicit postulate (not a deduction) in the final edition of his book on the Electron Theory. In essence, Lorentz’s program consisted of performing a great deal of deductive labor, at the end of which it was still necessary, in order to arrive at results that agreed with experiment, to simply postulate the same principle that forms the basis of special relativity. (To his credit, Lorentz candidly acknowledged that his deductions were "not altogether satisfactory", but this is actually an understatement, because in the end he simply postulated what he claimed to have deduced.)

In contrast, Einstein recognized the necessity of invoking the principle of relativity and Lorentz invariance at the start, and then demonstrated that all the other "constructive" labor involved in Lorentz's approach was superfluous, because once we have adopted these premises, all the experimental results arise naturally from the simple kinematics of the situation, with no need for molecular force hypotheses or any other exotic and dubious conjectures regarding the ultimate constituency of matter. On some level Lorentz grasped the superiority of the purely relativistic approach, as is evident from the words he included in the second edition of his "Theory of Electrons" in 1916:

If I had to write the last chapter now, I should certainly have given a more prominent place to Einstein's theory of relativity by which the theory of electromagnetic phenomena in moving systems gains a simplicity that I had not been able to attain. The chief cause of my failure was my clinging to the idea that the variable t only can be considered as the true time, and that my local time t' must be regarded as no more than an auxiliary mathematical quantity.
Still, it's clear that neither Lorentz nor Poincare ever whole-heartedly embraced special relativity, for reasons that may best be summed up by Lorentz when he wrote

Yet, I think, something may also be claimed in favor of the form in which I have presented the theory. I cannot but regard the aether, which can be the seat of an electromagnetic field with its energy and its vibrations, as endowed with a certain degree of substantiality, however different it may be from all ordinary matter. In this line of thought it seems natural not to assume at starting that it can never make any difference whether a body moves through the aether or not, and to measure distances and lengths of time by means of rods and clocks having a fixed position relatively to the aether.
This passage implies that Lorentz's rationale for retaining a substantial aether and attempting to refer all measurements to the rest frame of this aether (without, of course, specifying how that is to be done) was the belief that it might, after all, make some difference whether a body moves through the aether or not. In other words, we should continue to look for physical effects that violate Lorentz invariance (by which we now mean local Lorentz invariance), both in new physical forces and at higher orders of v/c for the known forces. A century later, our present knowledge of the weak and strong nuclear forces and the precise behavior of particles at 0.99999c has vindicated Einstein's judgment that Lorentz invariance is a fundamental principle whose significance and applicability extends far beyond Maxwell's equations, and apparently expresses a general attribute of space and time, rather than a specific attribute of particular physical entities.
Reading this, I tend to agree with the suggestion in this article that if there had ever been a Nobel Prize awarded for special relativity, it should have gone jointly to Lorentz and Einstein.
 
  • #29
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Thanks guys, both of those are very illuminating. In particular, it's notable that in the June 1905 paper, Poincare actually attributes the idea that all laws of physics could be Lorentz-invariant to Lorentz himself: [..].
You're welcome. :-)
Poincare was overly modest, in contrast to Einstein. And actually, in the first paragraph, you read Poincare making the relativity statement in a definite way - while Lorentz in 1904 simply gave in to pressure from Poincare, as he admitted in his paper. *

And in 1904, after having read Lorentz's paper, Poincare also stressed the PoR at a conference:
"The principle of relativity, according to which the laws of physical phenomena must be the same for a stationary observer as for an observer carried along in a uniform motion of translation; so that we have not and can not have any means of discerning whether or not we are carried along in such a motion. [..] Thus, the principle of relativity has been valiantly defended in these latter times, but the very energy of the defense proves how serious was the attack."
- http://en.wikisource.org/wiki/The_Principles_of_Mathematical_Physics

*[edit:] Note that Poincare already said in 1900, in the paper cited by Lorentz(1904): "I must explain why I do not believe, in spite of Lorentz, that more exact observations will ever make evident anything else but the relative displacements of material bodies."
That shows that only a few years before Einstein published his paper, Poincare whole-heartedly advocated the relativity principle.
And from Pais we know that Einstein was inspired by Poincare, reading all (or most of) his papers.
 
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  • #30
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I would like to know if there is any credit given to Einstein that he does not deserve. For instance, apparently he cited no references in his 1905 paper on SR, but clearly before that, others had contributed to relativity, for instance, I believe Poincare introduced length contraction, and apparently Nikola Tesla thought Ruđer Bošković was the inventor of relativity. Is there any validity to this? I am skeptical of these accusations. It seems far-fetched that Einstein stole SR but not GR, Brownian motion, and the photoelectric effect, or that he stole all of them. Please , if you can, give me any information about the foundations of relativity, or any credible sources I can read on the topic.

Thank you, Rich
Well, there were a number of other physicists that were working in similar directions, since the later 1800s. Indeed, Einstein did not give them any credit in his 1905 OEMB. Yet Einstein developed his theory on a unique foundation, never before done. He obtained Lorentz's transformations and the Fitzgerald's contraction without any need of their own formulations whatsoever. In essense, Einstein's paper validated their formulae, except with a new meaning altogether. It's the meaning that made Einstein's work special, and accepted. Einstein formulated his theory from the relation between 2 arbitrary inertial POVs, whereas everyone else began with an aether frame and then considered POVs that move thru it.

That said, I don't figure Einstein needed to give credit to anyone else. Also, my understanding was that Einstein was unaware of Lorentz's similar 1904 paper, when he published his 1905 OEMB.

GrayGhost
 
  • #31
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Well, there were a number of other physicists that were working in similar directions, since the later 1800s. Indeed, Einstein did not give them any credit in his 1905 OEMB. Yet Einstein developed his theory on a unique foundation, never before done. He obtained Lorentz's transformations and the Fitzgerald's contraction without any need of their own formulations whatsoever. In essense, Einstein's paper validated their formulae, except with a new meaning altogether. It's the meaning that made Einstein's work special, and accepted. Einstein formulated his theory from the relation between 2 arbitrary inertial POVs, whereas everyone else began with an aether frame and then considered POVs that move thru it.

That said, I don't figure Einstein needed to give credit to anyone else. Also, my understanding was that Einstein was unaware of Lorentz's similar 1904 paper, when he published his 1905 OEMB.

GrayGhost
Einstein may very well have seen Poincare's 1905 paper before he submitted his paper. And Einstein's Lorentz transformations have the same operational meaning as those of Poincare.
 
  • #32
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would the crew of a lightspeed approaching spacecraft "see" the universe's gamma factor increasing and what is to stop that interpretation from being real? if the crew saw the universe as slowing down wouldn't they have violated einstein's rule of nothing exceeding the lightspeed barrier? if the crew saw the the distance to their destination contracting due to its movement relative to lightspeed wouldn't they again be violating the lightspeed restriction? if we see it in the crews point of view the ship is not moving the universe is. what stops that from happening?
 
  • #33
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6
Reading this, I tend to agree with the suggestion in this article that if there had ever been a Nobel Prize awarded for special relativity, it should have gone jointly to Lorentz and Einstein.
We shall also look what Lorentz had to say about Poincaré:

http://en.wikisource.org/wiki/Two_Papers_of_Henri_Poincaré_on_Mathematical_Physics

On the other hand, in many other papers after 1905, Lorentz didn't mention Poincaré's contribution to relativity, but only referred to Einstein as the founder of the "principle of relativity".

  • So we have Lorentz, who attributed relativity to Einstein (and a single time to Poincaré).
  • Poincaré, who attributed relativity to Lorentz (while ignoring Einstein).
  • Einstein, who attributed relativity to himself and sometimes to Lorentz (while ignoring Poincaré).
  • Planck, who attributed relativity to Lorentz and Einstein (while ignoring Poincaré).
  • Minkowski, who (on different occasions) attributed relativity to Lorentz, Einstein, Poincaré, Planck - and mostly himself.

http://en.wikipedia.org/wiki/History_of_special_relativity
http://en.wikisource.org/wiki/Portal:Relativity

Regards,
 
  • #34
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We shall also look what Lorentz had to say about Poincaré:

http://en.wikisource.org/wiki/Two_Papers_of_Henri_Poincaré_on_Mathematical_Physics

On the other hand, in many other papers after 1905, Lorentz didn't mention Poincaré's contribution to relativity, but only referred to Einstein as the founder of the "principle of relativity".
And as we know, that was not true. His memory problems must have started early. :biggrin:
  • So we have Lorentz, who attributed relativity to Einstein (and a single time to Poincaré).
  • Poincaré, who attributed relativity to Lorentz (while ignoring Einstein).
  • Einstein, who attributed relativity to himself and sometimes to Lorentz (while ignoring Poincaré).
  • Planck, who attributed relativity to Lorentz and Einstein (while ignoring Poincaré).
  • Minkowski, who (on different occasions) attributed relativity to Lorentz, Einstein, Poincaré, Planck - and mostly himself.
Yes, that sums it up nicely. It's really like a detective...
I have been thinking for some time that someone should make a movie out of it!
 
  • #35
JesseM
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*[edit:] Note that Poincare already said in 1900, in the paper cited by Lorentz(1904): "I must explain why I do not believe, in spite of Lorentz, that more exact observations will ever make evident anything else but the relative displacements of material bodies."
That shows that only a few years before Einstein published his paper, Poincare whole-heartedly advocated the relativity principle.
And from Pais we know that Einstein was inspired by Poincare, reading all (or most of) his papers.
But Poincare never wrote down the transformation equation that he expected the laws of physics to be invariant under prior to Lorentz, right? It seems like both Poincare and Einstein were taking Lorentz's work and drawing out certain physical implications that Lorentz himself didn't fully understand or realize the central importance of...I suppose Einstein's approach of starting with the two postulates and deriving everything from that was more clear and compelling to the audience of physicists reading these papers at the time.
 
  • #36
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But Poincare never wrote down the transformation equation that he expected the laws of physics to be invariant under prior to Lorentz, right? It seems like both Poincare and Einstein were taking Lorentz's work and drawing out certain physical implications that Lorentz himself didn't fully understand or realize the central importance of...I suppose Einstein's approach of starting with the two postulates and deriving everything from that was more clear and compelling to the audience of physicists reading these papers at the time.
I think so too. Poincare was an overly modest mathematician who already died in 1912. There also appears to have been some manipulation against Poincare, for political aims. And Einstein's 1905 paper gives a full overview, it reads a bit like a textbook with a good introduction.

Nevertheless, relativity before GR was regarded as the theory of Einstein and Lorentz. If I understand it correctly, it changed when Eddington's mission brought Einstein fame. From then on people started to talk about "relativity" as meaning GR, and SR was simply perceived as part of Einstein's GR. And Lorentz died in 1928.
 
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  • #37
PAllen
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I think so too. Poincare was an overly modest mathematician who already died in 1912. There also appears to have been some manipulation against Poincare, for political aims. And Einstein's 1905 paper gives a full overview, it reads a bit like a textbook with a good introduction.

Nevertheless, relativity before GR was regarded as the theory of Einstein and Lorentz. If I understand it correctly, it changed when Eddington's mission brought Einstein fame. From then on people started to talk about "relativity" as meaning GR, and SR was simply perceived as part of Einstein's GR. And Lorentz died in 1928.
An abiding mystery for me is that Poincare was, by 1900, a long established world famous mathemetician and mathematical physicist, with groundbreaking physical contributions (e.g. his approach to orbital computations are, I believe, still used today for spacecraft). He was nominated numerous times for the Nobel (however, in the early 1900s, the Nobel committee had a strong experimental bias; the very delayed prize for Max Planck was the beginning of the end of this excessive bias. I believe Poincare has the record for nominations without receiving the prize.). Einstein was a nobody in 1905.

I don't have a fully satisfying explanation, but a few parts seem to be:

Poincare published his ideas in fragmentary form, in journals not read by most physicists. Some key ideas were in letters, not formally published. Einstein published in the leading physics journal of the day, with very physical motivations (rather than mathematical). Finally, he was noticed by Planck, who was top of the field.

One thing I've also noticed is that the complexity of credit has never been a mystery among those really expert. For example, I've noticed in papers by Professor Carlip, he scrupulously credits Poincare for any result achieved before Einstein.
 

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