Talk:Relativity priority dispute/Archive 3

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Ives's paper

There is a copy of Ives's paper in a Book called "The Einstein Myth and the Ives papers" (a complete collection of Ive's relativity papers. Licorne said somewhere this book is in every University Library, if that is any help. There is something odd about Ives's criticism. Ives claims that Einstein assumption that the energy = rest energy + kinetic energy (the assumption Planck questioend and de Kludde discusses above) "builds in the relation E = mc^2". If this were so one would think that Einstein would then derive E = mc^2 exactly. However Einstein does not derive it exactly, he has to approximate the term $\left(1-v^{2}/c^{2}\right)^{-1/2}-1$ as $\approx {\frac {1}{2}}v^{2}/c^{2}$, so I am not entirely satisfied with Ives's criticism (why doesn't the results "fall out" exactly if it were "built in". On another point, I don't think anyone has claimed that Planck's rederivation was not correct and in fact better than Einstein's. But Planck never claimed to have priority in suggesting the mass-energy equivalence. E4mmacro 07:59, 28 February 2006 (UTC)

There have been later papers (i think one in the AJP) that showed (IMO, so let's say they claimed) that Ives was mistaken on that point. I have in mind to write myself (one day!) a paper that shows that he was not entirly mistaken, that indeed there was something wrong with that paper of Einstein; but that nevertheless we may say that Einstein derived E=mc2 there. The truth is often subtle! Harald88 12:58, 10 March 2006 (UTC)

Proposal for the "History" section of E=mc².

I would propose a text like the following:

While some people see remarks of Newton in Opticks ("are not gross bodies and light convertible into each other") as a forerunner of E=mc², the history of this equation in the modern sense starts in 1881, when J. J. Thomson studied the movement of a charged spherical conductor moving in a straight line. He found that its inertia increases as if it had an excess mass equal (4/3c²) times the energy of its electrostatic field. This differs from the correct result by the factor 4/3. The mistake in Thomson's deduction was analyzed by Enrico Fermi in 1922, who explained how one can derive the correct result following Thomson's considerations. Results similar to Thomson's, which also differ from the correct result by a factor, were published by Hasenöhrl in 1904/5. --De kludde 11:14, 28 February 2006 (UTC)

I think Thomson's result is a forerunner of Poincare's result. It shows that radiation has inertia, or appears to have inertia because of Maxwell's radiation pressure on the inside of the cavity. What is different about Einstein's result is that it shows that mass can be converted to energy, acoording to Einstein, energy in any form - it could be heat lost by conduction which reduces the mass or inertia of the body. Now of course Einstein, if he knew of it, could have taken Poincare's or Thomson (or Maxwell's) fictitious mass of radiation seriously (in a way Poincare never did) and wondered if the mass was not spontaneously created from nowhere as Poincare (1900) had assumed (btw, this is WHY Poincare did not believe it, and one reason why his 1900 paper was a criticism of Lorentz's theory of electrons). Even if you guess the mass comes from somewhere you have to produce an argument to suggest the mass of a body losing energy is decreasing, don't you think? The missing link is the variation of mass with velocity, the recognition that perhaps all mass is electromagnetic in origin (something said by Poincare a few times). Now Poincare had Lorentz's 1899 paper which had $m=\gamma m_{0}$ yet Poincare never did "connect the dots" and give Einstein's or Planck's or Lewis's derivation of E = mc^2, in the meaning of Einstein. This was not a trivial step, and the mainstream is not outrageously wrong to think it is the biggest step. E4mmacro 21:29, 28 February 2006 (UTC)

Hmmm, sorry. I better check Thomson's paper. Maybe his result come not from radiation pressure but the self-induction effect of the moving charges being equivalent to an electric current. This is what Poincare means by "electromagnetic inertia" as far as I know. E4mmacro 21:39, 28 February 2006 (UTC)

The first author to derive a related result with the correct factor 1 instead of 4/3 was Henri Poincaré in 1900, in a paper devoted to the discussion of Lorentz' theory of electromagnetism. Poincaré pointed out that the electromagnetic field behaved in a certain sense like a fluid possessing mass density equal to its energy density divided by c². He did not apply this to the inertia of macroscopic bodies. Moreover, as Special Relativity was still in development at that time, he treated the movement of charged particles in a classical framework. Another derivation of a formula related to E=mc², also in a non-relativistic setting, was published by Olinto de Pretto in 1903. --De kludde 11:14, 28 February 2006 (UTC)

The subject was taken up by Albert Einstein in 1905, who presented a formal derivation that the mass of a body emitting light is diminished by (1/c²) times the amount of energy lost. His arguments could be formulated the same way for other emission processes as long as certain formal assumptions concerning the conservation of a 4-momentum transforming according to the Lorentz transformation are valid. There appears to be no doubt that this is the first time the formula was presented as a formal consequence of Special Relativity. The correctness of Einstein's derivation has, however, sometimes been questioned. In 1907 Max Planck pointed out that some hidden assumption in Einstein's argument leads to a question of relativistic thermodynamics, and presented a formula where enthalpy rather than energy is related to mc². Another criticism of Einstein's reasoning which is sometimes accepted by serious scholars was published by Herbert Ives in 1952. --De kludde 11:14, 28 February 2006 (UTC)

Modern textbooks rarely present the formal derivation of E=mc² given by Einstein in 1905. Many follow the line of thought of an article published by Gilbert N. Lewis in 1908. --De kludde 11:14, 28 February 2006 (UTC)

Some comments:

• I assume the correctnes of Whittaker's description of the development of E=mc². As far as I can see, this is still justified. I consider e4mmacro's criticism only as valid in the sense that some phrases used by Whittaker can be misunderstood when quoted out of context. --De kludde 11:14, 28 February 2006 (UTC)
• As far as I can see, the derivation which Whittaker attributes to Lewis is the one often presented in modern textbooks. But this may be open to debate.
• I treat de Pretto from hearsay. --De kludde 11:14, 28 February 2006 (UTC)

I may have been mistaken about de Pretto as Bartocci now seems to claim that de Pretto predicted E=mc²/2, one more result with a wrong factor like in the Thomson and Hasenöhrl papers. --De kludde 22:38, 28 February 2006 (UTC)

• Apart from these points, I think that what I am presenting here is mostly covered by WP:NPOV saying that "Facts ... are not Points Of View".
• I may have copied a few consecutive words from Whittaker but think that this OK from the Copyright point of view as it never concerns more than about five consecutive words. As long as we mention his book in the references section, nobody is going to complain. --De kludde 11:14, 28 February 2006 (UTC)
• I think that the Ives criticism should be explained somewhere, as it is sometimes accepted by serious scholars. After this has been done, perhaps in the priority dispute article, that article should be linked to the short remark about Ives in E=mc². --De kludde 11:14, 28 February 2006 (UTC)
• e4mmacro, as you seem to be an expert on the history of special relativity: Which textbook for relativistic thermodynamics you would recommend? The only refernce I could find on Wikipedia is a German book by Neugebauer, which is about a quarter century old but may still be OK for this issue. I don't have this book. We should certainly figure out whether energy or enthalpy is the correct quantity, even for completely non-ideological reasons. If this was a bet about a horse race, my money would be on the correctness of Planck's analysis. --De kludde 11:14, 28 February 2006 (UTC)

re Max Planck and enthalpy: stating e=mc2 in terms of enthalpy, as the term is defined on enthalpy, would require defining the term "pressure" for a number of situations where I see no easy definition of it (photon in free space, for instance) . Planck may have been using another definition of enthalpy. --Alvestrand 12:56, 28 February 2006 (UTC)

No, I don't think so. Planck's definition is the usual one, R=E+pV in the text I was quoting, or H=U+pV using modern notations. Planck also considers situations like a huge body with ideally reflecting walls filled with light. In this situation, the radiation pressure contributes to p. --De kludde 14:00, 28 February 2006 (UTC)

Some might perhaps claim that because pV is so very tiny compared to mc² (unless you are in hell), the difference between Planck's and Einstein's formula is minimal and quite academic in nature. But what Einstein and perhaps Thomson as well (as opposed to Poincaré) considered was the way in which the mass of a body changes if it emits radiation or is given an electrical charge. In this case, the difference between the right hand side of

$\Delta m={\frac {\Delta U}{c^{2}}}$

and

$\Delta m={\frac {\Delta H}{c^{2}}}$

is $\Delta (pV)/c^{2}$, and this is not always so tiny compared to $\Delta (U)/c^{2}.$ --De kludde 14:00, 28 February 2006 (UTC)

This should be a fairly non-ideological question, which has to be resolved for the sake of the article's quality. Note that I am not giving Planck's or Ives' criticism of Einstein's derivation undue weight, since the major contribution of Einstein's paper as I see it, pointing out the connection with special relativity, is still new and important even if the proof itself collapses. For this reason, Ives' criticism (as opposed to the question of whether energy or enthalpy is the correct quantity), should not be discussed in E=mc² but some other article (perhaps the priority dispute article) should be linked. But neglecting the fact that the equation had a history of almost a quarter century when Einstein published his paper, and that the development of ideas may not have stopped at this point but continued, with Planck and perhaps Lewis making the final steps, is in patent conflict with the facts. In any case, as Licorne has simply added his statement about Poincaré to the history section of this article, it might be worthwhile to point out how a somewhat larger version stating all the relevant facts might look like. I think it is still not too large, since the E=mc² article is quite large. --De kludde 14:00, 28 February 2006 (UTC)

Perhaps "History of special relativity" needs a section on the development of the theory after Einstein's 1905 papers? It doesn't seem to belong on the dispute page.... --Alvestrand 18:26, 28 February 2006 (UTC)

I think E=mc² should have its own history section. The way I understand it, it started when people realized that for bodies containing an electromagnetic field the Maxwell equations predict that an additional amount of force is needed to drag the field along with body. Of course you can analyze this even if you don't know about special relativity. Einstein seems to have been the first one who attempted to derive a intertia type (or, in fact, any type whatsoever) E=mc² result from assumptions of special relativity, and this is certainly a major achievement even if the details of his derivation are flawed. Lorentz invariance and 4-momentum conservation only allow for field equations exhibiting this type of E=mc² behaviour, but if you are familiar with Maxwell's equations you can derive the result for this special case in a classical framework. The fact that the formula had a history of one generation before it was interpreted in the framework of special relativity means, in my opinion, that it is a subject of its own, albeit with close relations to SRT and GRT. It is reasonable to give it its own history section. --De kludde 22:38, 28 February 2006 (UTC)

I think a history of E = mc^2 is a reasonable idea. E4mmacro 00:33, 1 March 2006 (UTC)

I don't know of any relativistic thermodynamics textbook. E4mmacro 00:33, 1 March 2006 (UTC)

Planck's derivation

As an engineer, I see Planck's getting the mass equivalent of enthalpy as more general. I always assume that enthalpy applies only to fluids (it accounts for flow work) - so for a solid Planck's result reduces to E/c^2 (I suppose I have to include enthalpy for solids to account for solid-gas phase changes though). Whittaker, as I remember, says that someone (possibly Lorentz in about 1910?) extended the E term to include potential energy, elastic strain energy, and that some of these missing terms explained why earlier results came out as (3/4)E/c^2 or some other constant. E4mmacro 00:33, 1 March 2006 (UTC)

Yes, for the situation Einstein considered at the end of his paper (a radioactive solid), there is not much of a difference between the two results. --De kludde 07:55, 1 March 2006 (UTC)

As for the correction to Thomson, this is footnote 2 on Whittaker II p. 51, concerning Thomson's result: It was shown long afterwards by E. Fermi, Lincei Rend. xxxi₁ (1922), pp. 184, 306, that the transport of the stress system set up in the material of the sphere should be taken into account, and that when this is done, Thomson's result becomes

Additional mass = ${\frac {1}{c^{2}}}\times$ Energy of field. --De kludde 07:55, 1 March 2006 (UTC)

de Kludde, can you tell us what papers are cited by Planck in his derivation? What does he start from? E4mmacro 00:33, 1 March 2006 (UTC)

He attributes (in the introduction) to Lorentz, Poincaré and Abraham the fact that electromagnetic radiation has momentum ("Bewegungsgröße"), without quoting their papers. Apparently he considers the fact that the energy content of a body influences its (inertial) mass to be a consequence of their considerations, without quoting Einstein at that moment:--De kludde 07:55, 1 March 2006 (UTC)

Denn nach den Untersuchungen von H. A. Lorentz, H. Poincaré und M. Abraham besitzt die innere Wärmestrahlung eines bewegten Körpers, ebenso wie überhaupt jede elektromagnetische Strahlung, eine bestimmte endliche Bewegungsgröße, welche in der gesamten Bewegungsgröße des Körpers mit enthalten ist. Dieselbe hängt aber, ebenso wie die Strahlungsenergie, von der Temperatur ab, und infolgedessen auch die durch sie definierte Masse. --(Vol 2 Planck Coll. Papers, p. 178)

For, according to the investigations of H. A. Lorentz, H. Poincaré and M. Abraham, the internal thermic radiation of a moving body, just like any type of electromagnetic radiation, possesses a certain finite momentum contributing to the total momentum of the body. This [momentum] depends, just like radiation energy, on the temperature of the body, and therefore the same holds for its contribution to mass. --(Vol 2 Planck Coll. Papers, p. 178)

(I find it somewhat difficult to give a literal translation of this). It is clear that by "mass" he means inertial ("träge") mass, as this is what he is saying at the beginning of that paragraph. Interestingly, he then poses the question of whether thermic radiation also possesses a gravitational ("ponderable") mass, and seems to deny this: "Wenn diese Frage zu verneinen ist, was wohl das Nächstliegende sein dürfte ..." - "If this question is to be answered negatively, which perhaps is the most plausible assumption". --De kludde 07:55, 1 March 2006 (UTC)

The papers which he quotes in his derivation are Lorentz (1904), Einstein (1905) and Michelson/Morley(1887) for the relativity principle, Mosengeil and Abraham for some radiation pressure considerations, Helmholtz for the principle of least action, some paper of Byk(1906) for the Equation of state, again Einstein(1905) for the transformation of Maxwell's equations, his own Lectures on Thermic Radiation for the Planck constant (which is not used later on, however), Abraham's textbook for the notion of transversal mass, and finally the Einstein 1905 mc² paper for comparing his own result with Einstein's. I only listed the literature up to that point, and did not list a reference a second time when I got the impression that it is used in the same way as before. --De kludde 07:55, 1 March 2006 (UTC)

So, my impression of it is that Planck is unwilling to credit the fact that inertial mass depends on energy to any specific person, as he only quotes from the older papers in the introduction, but he does quote Einstein for the precise law, which he then improved. --De kludde 07:55, 1 March 2006 (UTC)

I am not terribly clear on these definitions. But to me, it seems that what Planck was saying above is that the inertial mass of a hot body is larger than the inertial mass of a cold body, and that the relation is our good old E=mc2. From the way it is described, and from the pattern of quoting you mention, it looks to me as if Planck was deriving the formula for one specific case, but (NOTE: PERSONAL OPINION) that Planck did not want to believe Einstein's leap-of-faith that E=mc2 applies to ALL mass, so he did not quote that specific part of Einstein's paper. Same formula, different context. --Alvestrand 08:45, 1 March 2006 (UTC)

The Einstein 1905 article simply says that a body emitting light suffers a weight loss. The reasoning (whether right or wrong) could be formulated in the same for all type of energy emissions satisfying certains rules. Planck does not doubt this but makes it a bit more precise by pointing out that enthalpy and not energy is the quantity to consider (so it is not the same formula after all). What he DOES seem to doubt in the introduction is that all energy has a gravitational mass, which is just the OPPOSITE of what Whittaker claims about this paper in his chapter on gravity, p. 152. So e4mmacro may have his case against Whittaker after all, although I still think Whittaker's description of Poincaré's 1900 mc² result is correct. --De kludde 00:48, 2 March 2006 (UTC)

He's a bit more forceful in [Ein05d] [1] - he says "The fact that the energy withdrawn from the body becomes energy of radiation evidently makes no difference, so that we are led to the more general conclusion that: The mass of a body is a measure of its energy-content; if the energy changes by L, the mass changes in the same sense by L/9 × 10^20" --Alvestrand 06:55, 2 March 2006 (UTC)

See Kevin Brown's review of Whittaker. He concludes that Whittaker is not anti-Einstein, but just pro-aether. He just wants to show that relativity can be construed as an aether theory. Your quote from Planck 1907 about ponderable mass rang a faint bell, and I see now Brown in his reveiw mentions it - it certainly seems the most blatant distortion of Whittaker's. E4mmacro 18:14, 2 March 2006 (UTC)

The arguments against Poincaré

I hope my claims that Poincare did not do everything in special relativity are not construed as anti-Poincare. I had also to argue strongly to Licorne that Poincare's gravity theories were a failure, and perhaps I express it too forcefully. In my view, it is clear that Poncare did not consider relativity to be his theory and I assume he wouldn't turn in his grave if I say others (such as Whittaker) have exaggerated what he did. E4mmacro 18:56, 2 March 2006 (UTC)

I have looked at your (e4mmacro's) quotes of Poincaré's 1900 paper, and I am still not sure that your criticism is valid. You seem to insist that he did not really believe this result. But what he states in the introduction to his paper was his lack of confidence in the 1900 version of Lorentz' theory, which was of course justified. He never said, as far as I understand the intro of his paper, that he downright rejects the Lorentz theory. Therefore, disbelief in the 1900 version of Lorentz' theory does not necessarily mean that Poincaré did not trust this particular consequence.

From the two quotes you have given, I still do not see why they imply that Poincaré does not believe in his own result. The one from p. 256 (which p. 468 vol IX of his collected works) only says that the liquid is ficticious. For me, this simply says that it lacks some of the properties of normal liquids, in other words the analogy with normal liquids breaks down somewhere. It does not necessarily mean that Poincaré believed that the mass of this "liquid" is also fictitious. This is a long paper, and it is easy to overlook things. Could you give an example where Poincaré says that he considers the mass of this liquid also as fictitious? Also, what you quote from p. 258 is p. 470 in the collected works and there is a gap of 1/2 page between "èlectromagnétique" and "Pour definir". I assume you also have that gap in the version from which you were quoting. I don't know why either part of your quote should imply that Poincaré did not believe the result. Could you perhaps translate? I am not always sure whether I interpret Poincaré's French well when he tries to convey his intuition about things (as opposed to clear-cut statements like "Il n'y a pas de temps absolu". For me, his conclusion "L'énergie électromagnetique se comportant donc au point de vue qui nous occupe comme une fluide doué d'inertie", which I interpret that as saying that the inertia of electromagnetic radiation must be accepted once one accepts Lorentz' theory, which Poincaré eventually did after the difficulties of the 1900 version had been resolved. The considerations at the beginning of Poincaré's paper could easily be modified to work with the correct theory.

Before I go any further, may I ask have you read the chapter in the Value of Science which I claim makes clear what Poincare thought? I think that has to be read in conjuction with Poincare 1900. I will check if I have misquoted Poincare 1900 (do not have the original at hand). One quote from The Value of Science 1904: "the apparatus recoils ... and that is contrary to the principle of Newton since our projectile here has no mass, it is not matter, it is energy". E4mmacro 19:11, 2 March 2006 (UTC)

Yes I left out about 4 paragraphs starting "Mais il faut convenir ..." and ending " ... 3. aux forces d'inertie du fluide fictif renferme dans ce volume". E4mmacro 23:19, 2 March 2006 (UTC)

Also, why did you add the remark "but did not specify any particular convention." to "Poincaré claimed that simultaneity of distant events would have to be established by convention". Why should he specify one? He did not believe in absolute time, after all.

Well, I add the remark because it is true and might be relevant. You think I have drawn some negative conclusion from it? Maybe I could, but I tried to state facts not conclusions. What I was thinking of is something I stated elsewhere. I think when Poincare saw Lorentz's 1895 introduction of local time (I am guessing Poincare saw this after his 1898) Poincare went "Aha! That is the convention I was looking for! And it does make a big difference". Both Poincare and Lorentz had previously used the idea of retarded potentials (i.e. for effects that propogate at the speed of light) but Lorentz's local time is more than that. You will notice that Poincare mentions it over and over again from 1900 to 1904 - I think he was impressed by it. The fact that Poincare mentioned no particular convention is significant for another reason. It is sometime suggested as part of a Einstein-plagiarism charge that Einstein got the definition of simultaneity from Poincare 1898, which cannot be true since it wasn't in it, or at least in the reprint in the popular book that Einstein might have read. I have assumed the reprint is the same as the original. E4mmacro 18:46, 2 March 2006 (UTC)

E4, what do you mean? I found not long ago (I copy-paste it here from a newsgroup) that there, Poincare stated about measurements in inertial frames:

" [...] admit that light has a constant speed, and specifically that its speed is the same in all directions. Now that's a postulate without which no measurement of that speed could be attempted." (translation mine)

He next elaborated on the definition of simultaneity. Did you not read that part? Harald88 21:33, 4 March 2006 (UTC)

No I didn't read that part. What definition did he propose? As I said, I was working from a reprint (or probably rewrite) of "The measure of Time" which appeared in his book of 1901 (Science and Hypothesis). If you can tell us the definition he used and the date, then clearly we should delete my statement that Poincare did not give any specfic definition or procedure (before 1900). I think "Science and Hypothesis" is relevant because it is the book usually mentioned in Einstein-plagiarism arguments ("we know Einstein read it"). E4mmacro 20:38, 7 March 2006 (UTC)

I don't see what you are getting at with "He didn't believe in absolute time". Why does that mean he wouldn't give a convention, if he said a convention was necessary? E4mmacro 19:28, 2 March 2006 (UTC)

Next, for your remark He said the "ensemble of these transformations together with all rotations of space" form a group (but did not give details of the proof). Note that Einstein never states (with or without proof) anything like this. The group theoretic picture enters his discussion only in a remark where he considers the 1-parameter group of Lorentz transforms in a given direction. It is Poincaré and not Einstein who really considered the symmetry group of x²-t². What you seem to try to insinuate looks like a revival of the old Pais claim that Einstein introduced the Poincaré group before Poincaré, which is completely wrong.

No I wasn't trying to say anything like that at all. I was thinking that Poincare had already written the (1-parameter) proof to Lorentz in a letter in 1905, and perhaps thought it was trivial by the time he published. But that sentennce was a pre-emptive anti-Licorne move intended to show that Einstein could not have copied a proof of the group property from Poincare 1905, even if he had seen Poincare 1905, which I very much doubt. (At some stage Licorne was hovering round a claim that because Poincare had the proof of the group property before Einstein - as proved by Poincare's letter to Lorentz in May 1904 - that Einstein must have plagiarised it). I am sure Poincare was a better mathetician than Einstein! E4mmacro 18:23, 2 March 2006 (UTC)

I made no claims about Einstein in the "history of pre-relativity" section, and I am not saying Poincare had no proof. I thought I was merely stating the facts (all directed to showing what facts have to be taken into account in any plagiarism claims). E4mmacro 18:23, 2 March 2006 (UTC)

And proving Poincaré's claim is fairly easy. One only has to prove that G=PK=KP holds, where G is the connected component of the group of isometries of x²-t², and K is the group of rotations of x-space, and P the set of Lorentz transformations. Let I(x,t)=(x,-t), and let ^T denote the adjoint operator wrto the Euclidean scalar product xy+st. Let G' be the group of all isometries of x²-t², then a linear automorphism A belongs to G' iff IAI=(A^T)^-1. Now, it is a well-known fact that every automorphism g of the (x,t)-space has a unique representation as g=kp, where k is an isometry of the Euclidean scalar product xy+st and p>0 is self-adjoint. In a situation where g belongs to G, we have

IkIIpI=IgI=(g^T)^-1=kp^-1,

from which it follows that IkI=k and IpI=p^-1 by the above mentioned uniqueness of the kp decomposition of matrices. Hence k and p belong to G', and it follows that p is an element of P. If g is in G, it also follows that k is in K, and the Cartan decomposition in this special case is proven. Poincaré was almost certainly familiar with this as the same group, and the same situation, also occurs in non-Euclidean geometry (where K is the group of rotations around a point and P is the set of translations along lines passing through this point). All this is standard stuff and would not occupy more than a few lines in a research paper. Poincaré was certainly justified in not devoting much space to this.

[all the above apparently by De kludde, 2 March 2006]

See above. I agree Poincare thought it was trivial. I was not blaming Poincare for not publishing it in his short note of his talk to the Academy. I hope my anti-Licorneness has not made me anti-Poincare (though it has made me more pro-Einstein that I was!). E4mmacro 18:33, 2 March 2006 (UTC)

Just a hidey-hole for some history stuff

1905: The mathematics professors of Göttingen-- Hilbert and his protege Minkowski-- were fascinated by the physics of the time. They studied the work of Fitzgerald contraction, Lorentz "local-time", Michaelson and Morley interference experiment (Reid p. 105).

Then Einstein had difficulties with the math behind the General Theory. Hilbert solved the matrix equations that had stumped Einstein (Einstein was no Einstein when it came to tensor calculus...) (Funny quote from Minkowski here, re the lousy inattentive student Einstein was... that he could develop what he did seemed an outright miracle.

• "(Oh that Einstein, always missing lectures -- I really would not have believed him capable of it!) (Reid p. 105) But... hey Einstein's papers were there for all to read.

1908-1909 -- Minkowski describes "space-time" at the Society of German Scientists and Physicians in Cologne.(Reid p. 112). Hilbert is working on Waring's Problem. Minkowski dies suddenly of acute appendicitis.

1909 -- Born reconstructs Minkowski's notes them re the electromagnetic self-energy of the electron

1910 -- Hilbert works on "kinetic gas theory" and "elementary radiation theory"

1911 -- Einstein publishes a paper on the equivalence principle, with a rudimentary GRT Harald88 22:18, 4 March 2006 (UTC)

1913 -- Neils Bohr puts forth his theory of the atom

1914 -- "The work of Einstein as he pressed forward toward a general theory of relativity was followd with great interest... while Einstein was attempting in a rather roundabout way to develop the binding laws for the 10 coefficients of the differential form which determines gravitation, Hilbert independently solved the problem in a different, more direct way.

"Both men arrivd at almost the same time at the goal....

"It was a remarkable coincidence...but even more remarkable was the fact that it led, not to a controversy over priority, but to a series of freindly encounters and letters.

"Hilbert freely admitted, and frequencly stated in lectures, that the great idea was Einstein's." (Reid, p. 141)

More funny quotes here from Hilbert re Einstein.

1915 --

"To Hilbert, the beauty of Einstein's theory lay in its great geometrical abstraction; and when the time arrived for the awarding of the third Bolyai Prize in 1915, he recommended that it go to Einsten..." (Reid, p. 142)

References

• Constance Reid, Hilbert, Copernicus: Springer-Verlag, 1966. First published 1970.

wvbaileyWvbailey 17:48, 1 March 2006 (UTC)

Hilbert quotes crediting Einstein - Should we add these?

Both Phillip Frank and Constance Reid (perhaps relying on Frank?) quote Hilbert giving credit to Einstein.

• Every boy in the streets of our mathematical Gottingen understands more about four-dimensional geometry than Einstein. Yet, despite that, Einstein did the work and not the mathematicians.
• Do you know why Einstein said the most original and profound things about space and time that have been said in our generation? Because he had learnt nothing about all the philosophy and mathematics of time and space."

Should these quotes be included in the article?

Paul August ☎ 18:18, 2 March 2006 (UTC)

You can of course put them in if you want to, but I think they should be interpreted with giving Einstein credit for starting the theory (something which no one in a sane state of mind has ever doubted), not for getting the field equations first or independently. Also, you should not forget that one could easily "prove" Woldemar Voigt's priority for the Lorentz transformations by quoting Lorentz. This shows that quotes of this kind are rather worthless, as theses scientists acted in a rather gentlemanly way and were always willing to give credit to their colleagues as long as this was not utterly unreasonable, and sometimes even then. --De kludde 08:39, 3 March 2006 (UTC)

If you insert the [Phillip Frank] quote, am I allowed to insert the following [Max Born] quote:

Von Einstein und Freundlich hörte ich jetzt, daß Sie die Gravitation in Ordnung gebracht haben; ... Einstein selbst sagt, er habe das Problem ebenfalls gelöst, doch scheint mir seine Betrachtung ein Spezialfall der Ihrigen.

I have now learned from Einstein and Freundlich that you have tackled gravitation; ... Einstein himself told me that he has also solved the problem, however his consideration looks to me like a special case of yours.

Note that Born wrote this in 1915. Did Frank quote someone else or did he quote Hilbert from memory, several decades after the event? --De kludde 08:39, 3 March 2006 (UTC)

I agree that the Hilbert quotes above don't "prove" anything. But even though I take your point about these guys being "gentlemanly", they still don't sound to me like the kind of thing Hilbert would be likely to say, if he thought Einstein was getting more credit than was his due. As regards to your opinion that Hilbert is crediting Einstein for formulating the theory, rather than finding the field equations, you may be correct. Nevertheless, the "priority dispute" regarding GR, is broader than just the dispute over the field equations. Unfortunately Frank gives no source for the Hilbert quotes. I don't intend to add the quotes. I will let others decide that. As for the Born quote I have no objection to it. Paul August ☎ 22:19, 3 March 2006 (UTC)

References

• Phillip Frank, Einstein, His Life and Times, Da Capo Press; Rev edition (May 1, 1989), ISBN 0306803585, p. 206
• Constance Reid, Hilbert, Springer; 1st edition (April 19, 1996) ISBN 0387946748, p. 142

Believing Stachel or Bjerknes

A discussion came up on Wikipedia talk:Requests for arbitration/Licorne/Evidence on how much weight one shoudl put on Bjerknes vs Stachel as sources. Since I think that's a good question, but not relevant to Licorne's RfA case, I'll make a comment here.

My opinion is somewhat simple: In the case of Stachel, I know from [2] that he did his doctoral thesis on Einstein - and that presumably, a commission accepted his doctoral thesis. Furthermore, a group of people with budgetary responsibilities considered his qualifications seriously enough that they made him director of the Boston University Center for Einstein Studies.

In the case of Bjerknes, I know that he's published a book, and I've heard the claim (which I can't verify) that it's a "vanity" publisher - one that will publish anything people ask to have published.

So I know that a number of people have evaluated Stachel's work specifically about Einstein and found it good. I don't have any such reassurance about Bjerknes. So in a conflict, where neither party's arguments are convincing on their own, I tend to believe Stachel more.

(I also am much more turned off by the way Bjerknes presents things. So there are more things than just background that tend to make me doubt Bjerknes as a serious source. But I attach less weight to that.)

That's my reason. Other people need to make up their own minds. --Alvestrand 21:38, 3 March 2006 (UTC)

Since they are both obviously biased, I take both their opinons with some grains of salt. Anyway: nearly all the relevant information is available to everyone, so that neither of them needs to be used as source for anything (except for the subject of the debate itself). Harald88 00:59, 4 March 2006 (UTC)

--

Being new wikipedia, I would like to ask a question about citation style related to this Bjerknes discussion. Some say it is ok reference a quote to a primary source directly, even if you got it from a secondary source. I strongly disagree. The authors I respect most follow a practice of distinguishing 'from source x as quoted in source y', in such a case, as distinct from 'from source x', the latter being reserved for the case when the author obtained or fully validated the quote against the primary source x. Even such an explicitly opinionated writer as Chomsky follows this convention. This is not trivial, in my view - you are relying not only on y's accuracy, but on y's judgement of quote being consistent with it's overall context. Dershowitz was, in my opinion, rightly criticized for not doing this, with the possible interpretation that listing the particular secondary source would reduce the credibility of the quotes (on the other hand, I find Finkelstein's characterization of this as plagiarism absurd). The connection to the matter at hand, is that, irrespective of one's view about Bjerkne's reliability in giving quotes consistent with their overall context, a quote obtained from Bjerknes without actually reviewing the primary source, should be credited as "from x as quoted by Bjerknes". Like it or not, this immediately reduces the credibility of the reference. Thus, I have no issue at all with someone using Bjerkne's ideas and information on a talk page, to be compared with other sources, but would generally oppose using it any way at all as a source on page whose general credibility is important - like Einstein or Poincare. Of course, he is a very relevant source for the dispute article. --Pallen 23:39, 3 March 2006 (UTC)

I agree, as I stated before: secondary sources have use for putting our attention to primary sources; and in some cases, if we can't access the primary ones. However, often we have access to primary sources, after which the secondary sources become superfluous for the discussion. Harald88 00:59, 4 March 2006 (UTC)

Having dabbled in Bible scholarship on occasion, I feel that I have to insert a word of warning... when reading primary sources without a background in the period from which it arises, it is easy to misunderstand what is being said. Secondary sources by reputable scholars have a value in interpreting the context for us who know it less well. That said, 1905 is only a hundred years ago - two years after the Wright brothers, I'd hesitate to interpret a sentence mentioning flight, but other aspects of the culture of the time are far less distant. --Alvestrand 08:51, 4 March 2006 (UTC)

That's a good point, except of course when the secondary sources are almost as old. Indeed secondary sources that point out differences in meaning of concepts can be very relevant; there are a few concepts that one could misunderstand, for example the definition of "mass" that Lorentz and Einstein used at the time, and some people mistakenly think that the modern American distinction between speed and velocity also existed at the time. But it's certainly more difficult to read and correctly understand translations of Newton's works (but then, in part, such translations are already secondary sources by themselves, just as in Bible scholarship). Cheers, Harald88 10:42, 4 March 2006 (UTC)

I would point out that relying only on primary sources risks straying into original research, which of course is not our job. Ours is to simply report what the historians have concluded. Paul August ☎ 15:54, 4 March 2006 (UTC)

IWikipedia first of all aims to simply report on the facts; conclusions of historians are certainly interesting and useful (as any conclusions should be quoted from them), but open for change. Wikipedia is not a religion. Many Wikipedia readers are sufficiently intelligent to be able to draw their own conclusions from the available facts (which tend to change much less!). Harald88 17:24, 4 March 2006 (UTC)

Harald, nobody is saying Wikipedia is a religion. But take a look at WP:NOR -- it explicitly demands that secondary sources be used wherever possible. You can disagree with this but it is a deliberate stance taken in regards to what constitutes a "fact" on Wikipedia. --Fastfission 03:04, 7 March 2006 (UTC)

If it states what you seem to claim, then I think that WP:NOR is in conflict with Jimbo's demands for NOR as well as making a quality encyclopedia. In particular, it would imply that we should not refer to, for example, Einstein's 1905 publications, but only to opinions of others about his works. I'll have a look at that. Harald88 11:12, 7 March 2006 (UTC)

OK, that was quickly done, and I see no confirmation of your claim, instead it states clearly:

"research that consists of collecting and organizing information from existing primary and/or secondary sources is, of course, strongly encouraged".

And searching for "secondary", I found no such remark as you stated. Perhaps you refer to an older version, and the wording has been improved since? Harald88 11:18, 7 March 2006 (UTC)

Well perhaps I expressed the idea simplistically. I didn't mean to imply, nor does WP:OR say, that we should only use secondary sources. But it does say that using only primary sources, should be exceptional:

In some cases, where an article (1) makes descriptive claims the accuracy of which is easily verifiable by any reasonable adult without specialist knowledge, and (2) makes no analytic, synthetic, interpretive, or evaluative claims, a Wikipedia article may be based entirely on primary sources (examples would include apple pie or current events), but these are exceptions.

My point is just that we should be careful not to stray into doing original research here. It is fine to use primary sources, but when it comes to analyzing, synthesizing, interpreting or evaluating those primary sources, we should leave that to secondary sources. Paul August ☎ 21:35, 7 March 2006 (UTC)

Related to this subject, all scientific sources ("primary sources"?) that I know of, analyze, interpret, and make evaluations - that's what good articles do. Thus, perhaps what you understand to be "primary" sources (raw data?) don't really exist in this context, and virtually all sources are, in that sense, both "primary" as well as "secondary" ... Harald88 21:45, 7 March 2006 (UTC)

Yes a good research paper should, for example, do those things (analyze etc.) but not an encyclopedia article. Paul August ☎ 22:04, 7 March 2006 (UTC)

Very right: an encyclopedia article should simply give an overview of the information (data + conclusions and opinions) that is contained in such sources. Harald88 22:16, 7 March 2006 (UTC)

The case against Stachel

Stachel:

• has at least one case of mistranslating sources to fit his case, as Bjerknes points out on p. 202 of his "Incorrigible Plagiarist" book, he translates

... wenn wir beide zusammen unsere Arbeit über die Relativbewegung siegreich zu Ende geführt haben.

... when we two together have victoriously led our work on relative motion to an end.

from a letter of Albert to Mileva as

... when we are together and can bring our work on relative motion to a successful conclusion.

Which is way of a difference and certainly fits Stachel's case better than the aforementioned, better translation. As Stachel has not responded to this assertion in his response to Bjerknes, I assume it is correct.

Yes, any kid who knows German will confirm that that is correct. It can be safely stated as fact. Harald88 17:24, 4 March 2006 (UTC)

sorry for belaboring this sentence, but does anyone have the literature reference for the place where this quote comes from? I tried to google for the German phrase, but the best I could come up with was this one from [3]: Wie stolz und glücklich werde ich sein, wenn wir beide zusammen unsere Arbeit über die Relativbewegung siegreich zu Ende geführt haben. Wenn ich so andre Leute sehe, da kommt mirs so recht, was an Dir ist! Ref there is (Einstein an Maric, Dok. 94, 27. März 1901) - don't know how to resolve "Dok. 94", but the date was four years before Einstein published SR.

(Stachel's review wasn't in any way written as a response to Bjerknes' attack on him personally, so I wouldn't expect to see a response to that specific point there.) --Alvestrand 19:32, 6 March 2006 (UTC)

Bjerknes mentions another case, in which it is not so clear however why Stachel profits from the mistranslation.

• accuses Bjerknes of citing Johannes Stark, which is not true.
• in the CRS article, fails to mention the missing piece of the printer proof.
• in the same paper, claims that Hilberts modification of his paper in December 1915 explains Einstein's outburst to Zangger from November 25, 1915, whereas in fact this outburst would be difficult to explain unless Einstein felt he had been anticipated by Hilbert. --De kludde 12:23, 4 March 2006 (UTC)

A valid difference of opinion?? E4mmacro 20:18, 4 March 2006 (UTC)

The case against Bjerknes

Bjerknes

• on P. 19 of "Incorrigible Plagiarist", mistranslates Thirring

Die Klärung des Zeitproblemes war schon mehrere Jahre vor dem Erscheinen von Einsteins grundlegender Arbeit (1905) durch H. Poincaré weitgehend vorbereitet worden.

The solution of the problem of time had already been mostly prepared by Poincaré, several years before Einsteins ground-breaking paper appeared.

as

H. Poincaré had already completely solved the problem of time several years before the appearence of Einstein's first work (1905).

• He does the same thing on p. 85 of his second book.
• The discussion in chapter 2.4 of his second book is not convincing. He misquotes Einstein's November 11 field equations as

$R_{i}^{k}={\frac {8\pi G}{c^{4}}}T_{i}^{k}$

whereas Einstein simply called his coupling constant κ and never considered the Newtonian limit or otherwise explained the relation between his coupling constant and Newton's.

• His way of presenting things is unreasonable: Not mentioning Poincaré, Lorentz or Hilbert while (possibly) knowing about their work is plagiarism. Not mentioning Gerber in the Mercury paper is imo inappropriate (as is not mentioning Poincaré in that paper), but not plagiarism. Other things pointed out by Bjerknes of course are not plagiarism at all, for instance would have been unreasonable for Einstein to quote all the authors mentioned on pages 231-233 of his first book. --De kludde 12:23, 4 March 2006 (UTC)

De kludde: Congratulations! you are one of those rare editors who is sufficiently unbiased to not defend a camp but instead read (and comment on) everything critically. Because of your obvious expertise and NPOV, I look forward to see more of your contributions to Wikipedia. Harald88 17:30, 4 March 2006 (UTC)

Poincaré's considerations of synchronisation procedures (revisited from archives)

About the synchronisation procedure that was examined by Poincaré: to my knowledge, Poincaré's discussion is in the context of the theories of Lorentz. Poincaré describes for example synchronisation of clocks that are hundreds of kilometers apart. (It is known at that time that the transmission is not instantaneous, but the time is too short to be measurable with the instruments available around 1900)

From Poincaré's discussion I infer that without the Lorentz theories he expects the following: if sufficiently accurate measurement is possible, then a difference in the two-way transit time would be measurable in signals exchanged from, say, Paris to Berlin. Measurements 6 hour apart would be compared (in 6 hours the line paris-berlin rotates over 90 degrees of angle, as the Earth rotates.)

But Poincaré is aware of the Michelson-Morley experiment and the Lorentz theory to account for that. Fundamentally, the Michelson-Morley experiment is a time-dissemination procedure, using light. If the transit time of the light is direction dependent then a shift of interference fringes should be detected, depending on direction of motion of the experimental setup. (Instead of having a 6 hour interval between measurements that are to be compared, Michelson and Morley had a setup that could swivel; a huge circular slab of stone floating on mercury.)

Poincaré recognized the significance of the Lorentz theory for synchronisation procedures. If the Lorentz theory for accounting for the null result of the Michelson-Morley experiment is good, then a synchronisation procedure between clocks in Paris and Berlin will be similarly affected.

That, is my understanding, was the perception of Poincaré. --Cleonis | Talk 10:16, 13 February 2006 (UTC)

I'd appreciate it could you could succinctly state Poincaré's clock synchronization method. It's still not clear exactly was it is. Same for Einstein's method and how it differs from Poincaré's, if at all. I will then be in a better position to understand your other remarks. Thanks. green 65.88.65.217 15:53, 13 February 2006 (UTC)

Let there be two cities A and B, at such a distance apart that a signal transmitted by wireless telegraph takes 10 units of time to complete a two-way transit. Let the master clock be in city A. City B sends a signal, on reception city A immediately sends a return signal. Encoded in A's signal is the exact moment in A's time keeping that the return signal is sent. The operators in city B then subtract half of the two-way transit time, and use that for the official time-keeping.

Poincaré points out that the operators have no way of knowing whether both legs of the transit took the same amount of time.

I've tried to illustrate something like that in the following two images (I've used three clocks that are to be synchronized instead of two but that does not affect the logic) Clocksync01 and clocksync02 --Cleonis | Talk 16:56, 13 February 2006 (UTC)

Thanks. I really must scan Einstein's 1905 paper to ascertain his clock synchronization method, but can I assume that neither Poincaré nor Einstein synchronized two stationary clocks by using a light source equidistant? I cannot recall where I got this idea from. It might be nonsense. green 65.88.65.217 06:08, 14 February 2006 (UTC)

I don't think it matters. The synchronisation procedure is just a tool to illustrate some things. The synchronisation procedure does not matter for the content of the theory, the content of the theory being the two postulates of the 1905 paper. --Cleonis | Talk 13:22, 14 February 2006 (UTC)

I believe you are mistaken. I looked at Einstein (June) 1905 paper and his method of synchronization expressly assumes that the SoL is the same in each direction for a round-trip path (as distinguished from Poincaré btw). See the Kinematical Part, Section 1, Definition of Simultaneity. In fact, he states that without this assumption it’s impossible to define synchronization. I think this answers the question as to whether he denied the ether in 1905. This is a contentious issue and opinions vary, but if I am reading his paper correctly, it would seem that he surely did deny the ether, implicitly, since if the ether exists, the one-way SoL can only be the same in each direction of a round-trip path for the unique frame at rest wrt the ether. In all other inertial frames this would not be so. Do you concur?

Another point worth mentioning is that his definition of simultaneity seems very important for his theory, along with the postulates of course, since it is used in his argument for length contraction and time dilation. Afaict, it is not just a tool to illustrate some things, but crucial in the development of the theory.

Finally, although my limited scan of his 1905 paper did not find any method for synchronizing clocks with a light source equidistant between two stationary clocks, it would be a viable method under Einstein’s assumption that the SoL is invariant on each leg of a round-trip path. This method is used in texts to demonstrate the relativity of simultaneity by synchronizing stationary clocks on a moving train. If this method (and the one used by Einstein in his paper) depends on the no-ether assumption, as I believe is the case, then the argument for the relativity of simultaneity likewise depends on this assumption. Comments appreciated. green 193.108.45.248 19:14, 6 March 2006 (UTC)

I copy-paste here my comment to E4 of yesterday, which disproves one of your claims:

I found not long ago (I copy-paste it here from a newsgroup) that there [Poincare 1898], Poincare stated about measurements in inertial frames:

" [...] admit that light has a constant speed, and specifically that its speed is the same in all directions. Now that's a postulate without which no measurement of that speed could be attempted." (translation mine; he was discussing one-way speed). He next elaborated on the definition of simultaneity.

Indeed, it was (again!) Poincare who stated that this assumption is required to define synchronization. (Obviously this an operational definition, similar to that current flows from + to -, even if it's not so!).

Cheers,

Harald88 20:49, 6 March 2006 (UTC)

I haven’t studied Poincaré’s works even casually, so I shouldn’t have added the parenthetical comment you object to. I inferred, perhaps incorrectly from Cleonis’s remark above (“Poincaré points out that the operators have no way of knowing whether both legs of the transit took the same amount of time.”) that Poincare’s view concerning the SoL on each leg of a round-trip path differed from Einstein’s. That said, it nonetheless seems straightforward and indisputable that Einstein’s definition of simultaneity (that is crucial for obtaining various results in his June 1905 paper) denies the ether. For if an ether exists, there is no way to synchronize clocks in any inertial frame that is not a rest wrt it. Do you concur? If so, I wonder how Builder handles this issue. From private email, I had the impression you thought that Builder successfully argued that Einstein’s version of relativity is consistent with the ether’s existence. Maybe Einstein’s results are consistent with an ether, but I don’t see how his arguments would work if an ether exists. green 193.108.45.129 09:32, 7 March 2006 (UTC)

I already emphasized that one can define what one doesn't know by convention, as was done with current (in fact, the convention was chosen the wrong way round), with potential (the "earth" "is" "zero" volt, but is it?) as well as with light speed - Poincare explained that astronomers had no other option than to simply assume lightspeed to be homogenous, as working hypothesis. In 1905 he showed that the Lorentz transformations form a group, from which follows that there is no practical alternative to that convention.

OK, but my point stands. Einstein's theory or model defacto denies the ether. He assumes that lightspeed is the same on each leg of the round trip path. It is a defacto additional postulate, no different from his two primary postulates, and as such functions as a "law" of physics.

Not really: it was called a postulate by Poincare in 1898, while he at that point in time apparently didn't deny the stationary ether. Einstein repeated that. Moreover, Einstein didn't deny the existence of an ether either(see further).

About Builder:it always depends if one discusses physics (the laws) or also metaphysics (the models). There is no doubt about Einstein's model being different from that of Lorentz, and I understand that to be meant with "Einstein’s version of relativity".

OK, then Einstein's "model" denies the ether. But as I see it, the denial of the ether directly implicit in his concept of simultaneity, is defacto a postulate, aka, a "law".

Such a by definition unverifiable definition is (also by definition) not a law of physics - thus on that point I concur with Cleon. Einstein's model is obscure; in fact, there were jokes about that nobody but Einstein understood what he had in mind. I now simply assume that he had no model - it was in fact his argument that no model was needed to derive the laws. Harald88 20:10, 7 March 2006 (UTC)

I don't see what distinguishes the "laws" (of physics) from the "model". What exactly is the "model" in Einstein's version of relativity that you distinguish from the "laws" (aka postulates, aka assumptions)? I find the distinction unclear.

What is the model of QM? The Copenhagen interpretation? Not everyone agreed (or even agrees). Modern physical theories exist independent of explanations. A modern theory of physics is about verifiability. What can't be verified, isn't considered part of the physics theory proper. Harald88 20:10, 7 March 2006 (UTC)

Builder, as most physicists, understands a theory of physics such as SRT to only address the physics (that is, the observations); and he rediscovered that Lorentz's ether model is compatible with that. Harald88 11:03, 7 March 2006 (UTC)

I don't see how this is possible. One cannot get from Einstein's theory (or model or metaphysics) to Lorentz's without an ether and Einstein denied it. All one can do is show that Einstein's results are the same as Lorentz's, but we knew this without Builder. So I am unclear what Builder accomplished. green 193.108.45.150 14:46, 7 March 2006 (UTC)

Actually (and I'm sure we discussed this before), in 1905 Einstein didn't deny it, while in 1920 he denied the stationary ether, but proposed another kind of ether whcih I can't "copy", and which model nowadays often is labelled "the vacuum". What Einstein denied or not has nothing to do with physics, except those points that are part of physics - that is, that can be supported or disproved with experiments.

I have the impression that Builder, as so many (myself included) did not know that Einstein's results, following a certain logic, yield the denial of his GRT interpretation (Builder 1957, generally accepted) as well as the necessity of a physical reference frame (Builder 1958, largely unknown and not generally accepted). Builder's papers didn't add much to Langevin 1911, although they may be seen as useful elaborations; and likely he didn't know about Langevin's paper (I only discovered it recently, thanks to Wikipedia).

But also these things we have discussed before; thus I primarily reply to it on this page because some others may be interested in this info. You surely understand that I won't go into this with you again, since we have a history of misunderstanding each other, climaxing in irritation.

Regards, Harald88 20:10, 7 March 2006 (UTC)

Harold: In his June 1905 paper, Einstein did not flat-out state that he denied the ether. However, his expressly stated assumption that lightspeed is the same on each leg of a round-trip path is tantamount (equivalent) to such a denial. There is simply no logical way to circumvent this conclusion. If Poincare anticipated Einstein without expressly denying the ether, it shows that either he did not realize, or chose not to express, the consequences of his conclusion. If an ether exists, lightspeed can only be identical in both directions of a round trip path in the unique frame at rest wrt the ether. Unless you can give a persuasive (or indeed any) counter-argument, you should acknowledge the validity of my conclusion; namely, that Einstein’s theory of relativity as stated in his June 1905 paper defacto denies the ether. Later, in his 1920 Leiden speech, he affirms an immovable ether. He can wax philosophic one way or the other, but his arguments in his June 1905 paper require that an ether that effects lightspeed is nonexistent.

I also take issue with your definition of what constitutes a “law of physics”. Your stated criterion is “verifiability”. If so, Ptolomy's epicycles can be interpreted as bonafide laws of physics. Is this your position?

Imo, you are confusing “theories” with “laws”. There is a general consensus that theories – which include the predictions of the laws -- must be verifiable by empirical means. However, the “laws” of physics are the postulates upon which physical theories are based. Defacto, they are assumptions about the nature of physical reality and are starting points or foundations for theories. In some cases they might be independently verifiable, either empirically or by thought experiments, but there is no necessity for postulates to be verifiable. In the case of Einstein in 1905, his laws (or postulates or assumptions) are the two familiar ones, plus at least a third in the form of invariant lightspeed on each leg of a round trip path; or if you prefer, that an ether that effects lightspeed does not exist. In your conceptualization of these issues, unverifiable postulates do not constitute physics. Imo, this is an error. Although postulates are usually not independently verifiable, they are defacto verified by verifying what they imply.

Concerning models, I strongly disagree that Einstein’s 1905 theory (which he referred to as ‘Special Relativity’ in 1916 to distinguish it from General Relativity) has no model. Every theory requires a model, either explicitly defined, or if not, then implicit. In the case of SR, the “model” consists of the set of interrelated concepts in which the theory is constructed and presented; namely, frames of reference (inertial only), observers with measuring rods and clocks, synchronized clocks, how measurements are performed, etc., etc. One cannot have a theory without a model, but strictly speaking neither the theory nor the model within which the theory is constructed, constitute “laws of physics”. E.g., the bending of light is not a law of physics in GR, but a consequence or prediction of the laws or postulates upon which GR is based; namely, the equivalence principle, etc.

At this point I don’t want to confuse these issues by discussing QM. Suffice it to say that QM has postulates that are empirically verifiable via their consequences, and a model. But unlike relativity, the postulates are closer to Ptolomy’s “philosophy” of science than Einstein’s; that is, the postulates of QM are essentially curve fits that do not explain anything; they merely allows us to correctly predict probabilities. green 193.108.45.233 11:07, 8 March 2006 (UTC)

Harald: This discussion has been useful in clarifying your views. As I see it, your conceptual framework is flawed. E.g., your analysis implies that the postulates of a theory are not part of the theory itself and therefore should not be considered “physics" because they are not, or might not be verifiable. This is an extremely artificial distinction. According to this view, what Einstein assumed about the ether in 1905, implicitly or otherwise, has absolutely nothing to do with his “physics”. (“A modern theory of physics is about verifiability. What can't be verified, isn't considered part of the physics theory proper.”). As a factual matter, one cannot construct a theory without postulates, and the postulates are defacto verified by verifying their implications as expressed by the theory. Your claim that the postulates of SR do not constitute “physics” because they are not directly verifiable seems to miss the point of having a theory, or participating in the science enterprise. The point of physics is to discover the nature of physical reality as expressed by the laws of physics. To divorce the laws from the theories that issue from them, and to then relegate the laws themselves to the status of “metaphysics”, is to emasculate the objective of science. green 193.108.45.153 11:53, 8 March 2006 (UTC)

I disagree with your use of the term "law of physics"; most specifially, laws of physics make no claims about the nature of physical reality. That's philosophy and not physics, and what you call physics is what was called "natural philosophy". Many (most?) scientists have abandoned the old objective of science to understand nature. But I'm not here for a dispute about the scope of physics! We all know that the current in the wire flows from - to +, despite the convention (postulate) that it flows from + to -. Similarly the speed of light is defined by all with an operational definition, and not as a claim about reality. Scientists such as Newton and Poincare understood the difference very well - and without understanding their approach, their arguments can't be understood. I now guess that that's something that one understands immediately, or never; thus I abstain from further discussion about physics or Poincare's approach to it. Both SRT postulates were published by Poincare before 1905; for priority issues one's philosophy doesn't matter. Harald88 12:24, 8 March 2006 (UTC)

If you equate “convention” with “postulate” when discussing physics, it's questionable whether you will ever really understand the subject. It’s a “convention” that the electron’s charge is “negative”; it could just as well have been defined as “positive”. Such conventions simply do not have the same status as, e.g., the symmetry postulate of SR, aka the Principle of Relativity. Further, the SoL has real physical content notwithstanding the modern operational definition (wrt frequency cycles of some atom or whatever, located in Geneva or wherever). If you’re stopped by a cop who clocks you traveling at .5c, will you tell the judge that the SoL has no objective content? Will this be a plausible defense? Like many modern physicists, particularly those who have been seduced by QM, you seem to have lost your common sense. This is why, in part, you simply cannot admit that Einstein’s clock synchronization method constitutes a defacto denial of an ether that effects lightspeed.

I now have stopped trying to explain. But again: it is essentially Poincare's clock synchronization method, and he didn't abandon the stationary ether concept; which disproves your claim that that method constitutes a defacto denial of an ether that affects lighspeed, and establishes your continuing lack of understanding.

Forget about Poincare, and forget about Einstein. Instead try some independent thinking. If the SoL is the same on both legs of a round-trip path, it surely does contradict the existence of a stationary ether that effects lightspeed. green 193.108.45.248 18:15, 8 March 2006 (UTC)

Consider the MMX. The SoL is assumed as c - v and c + v along the non-transverse paths because of the assumed ether flow. If lightspeed is c in both directions, this is tantamount to assuming no ether effect on the SoL, or else no ether. Einstein assumes this for every inertial frame. Ergo, he assumes either that the ether doesn't exist, or that it has no effect on lightspeed. green 193.108.45.232 20:46, 8 March 2006 (UTC)

Green, doing that brings us completely out of the scope of this Talk page, and I'm sure we have discussed this in private. But just in case a last repeat of this could "click", here is my thinking which agrees with that of others: The (one-way) SoL is and was defined as the time difference as measured between two distant clocks, while a light or radio signal passes by. In practice clocks have already since 1898 been synchronized by means of such signals, and according to the theory (Lorentz 1904, Poincare 1905, Einstein 1905) there is no means to "absolutely" synchronize these clocks. No claim about true isotropy is implied nor can be implied, in view of the theoretical impossibility to determine true or absolute simultaneity. Harald88 20:08, 8 March 2006 (UTC)

Why don't you read Einstein's comments in his June 1905 paper in the section I previously cited? He states that he assumes the SoL is the same in both directions for otherwise it is impossible to synchronize clocks. Defacto, this is a postulate in his theory. It assumes that space is isotropic. Of course it can't be proven "absolutely". Generally, postulates are not provable or testable, but they do have testable implications (predictions of the theory). Then, in the next section he uses his synchronization assumption to deal with length contraction and time dilation. Btw, we have not discussed these issues before and they may be important wrt priority issues to understand what Einstein's theory actually is. green 193.108.45.232 20:57, 8 March 2006 (UTC)

Btw, I agree that we can't measure the one-way SoL without having synchronized clocks, but Einstein starts with the assumption that the one-way SoL is the same in both directions so as to make synchronization possible. It's an hypothesis. He expressly states that without this hypothesis, it is impossible to synchronize clocks. Read his words. green 193.108.45.228 21:19, 8 March 2006 (UTC)

Similarly, Lorentz agreed with Einstein's 1905 relativity paper, suggesting that it contained nothing really new (but see below). Harald88 17:46, 8 March 2006 (UTC)

Anyway, as far as priority disputes go, imo it is much more important what Einstein did with the two postulates, then whether Poincare stated them first. I could be mistaken, but I don’t believe Poincare used the implications of synchronizing clocks (using a defacto no-ether assumption), to derive the generally known results of relativity, as well as the LT’s. If not, then he never really developed relativity theory in full, which is why Einstein’s “version” has prevailed. green 193.108.45.244 14:49, 8 March 2006 (UTC)

Contrary to what you seem to think, synchronization methods have no importance for a theory of physics; but indeed (and contrary to some claims), according to the records Einstein was the first to publish a derivation of the LT straight from the PoR and the SoL - Lorentz later did express appreciation for that simpler approach to present the theory, and he adopted it in his teaching. Harald88 17:46, 8 March 2006 (UTC)

Take a look at Einstein's June 1905 paper. To measure the length of a moving rod, one needs to know the spacetime positions of the end points simultaneously! Einstein applied simultaneity in deriving some of the major results of relativity. green 193.108.45.248 18:15, 8 March 2006 (UTC)

Sigh... Poincare obtained the LT without linking operational simultaneity to reality; and Ives later -as well as some others such as Selleri [4]- did similar without imposing such operational simultaneity (and in such case the transformations take a more complex form, whereby only two-way SoL equals c locally). There is nothing physical about your decision of how you want to set your' clock, it's just practical and mathematically simplest... Sorry, I can't be bothered anymore with such obvious stuff.Harald88 21:31, 8 March 2006 (UTC)

Please keep your presumptuous laments to yourself. I don't trust your "analysis". I didn't claim that Einstein used simultaneity to derive the LT's. I just stated that he said clocks could not synchronized without assuming the same one-way speed for light on round-trip paths (and I agree), and without simultaneity of clocks within frames, his model and analysis breaks down. How one sets clocks is not "physical" wrt the actual positions of the hands. Any initial setting of any clock is fine. But unless one has a method to sync them, Einstein's theory collapses. The need for having an unambigious method for synching is not trivial and Einstein needed to introduce the additional defacto postulate about isotropy of space to make his theory work. Try reading the section I referenced before posturing as an Einstein expert. Does he not state that the method of using the round-trip circuit would be invalid for synching unless lightspeed is the same on each leg? Is this not tantamount to the assumption of isotropy of space? Is this not a physical assumption, similar in nature to his primary two postulates? green 193.108.45.157 07:54, 9 March 2006 (UTC)

Btw, I am not claiming that another, to some extent similar theory could not be developed using the two way SoL for clock synching. But this is not what Einstein did. He definitely assumes isotropy of space. As you state above, the transformations that Selleri derived are different than the LT's. green 193.108.45.157 07:36, 9 March 2006 (UTC)

The dispute about Lorentz and Poincare's assumptions about isotropy of space (and what they mean with it) vs. that of Einstein isn't the subject of this article nor of this section. You just stated that Einstein "said clocks could not synchronized without assuming the same one-way speed for light on round-trip paths (and I agree), and without simultaneity of clocks within frames, his model and analysis breaks down". I already emphasized that Poincare "said clocks could not synchronized without assuming the same one-way speed for light on round-trip paths" (and I agree also!), but this operational simultaneity of clocks within frames, is independent of Lorentz's (and his) model and analysis.

It may be worth noticing, as a last remark on this subject, that in SRT clocks that have been synchronized "are" still nearly synchronous in the original frame after acceleration, and not at all synchronous in the new one, if they were at different x coordinates (as also hinted at in the above paper by Selleri). Harald88 07:54, 9 March 2006 (UTC)

Harold: THE BOTTOM LINE: I started this discussion to respond to Cleonis’s statement near the top: “The synchronisation procedure does not matter for the content of the theory, the content of the theory being the two postulates of the 1905 paper.” As I have stated repeatedly, in Einstein’s analysis of the synchronization issue he defacto assumes isotropy of space – which is a physical assumption although not directly testable. I reject extreme positivism that claims what is untestable is not part of “physics”. Imo, it is not arguable (that is, is common knowledge) that postulates in physics are assumptions about physical reality that need not be testable and usually are not. Postulates are indirectly verified by the predictions of theories that issue from them. Morevover, isotropy of space is equivalent to a denial of an ether that effects lightspeed. Consider again the MMX. If c – v and c + v are the assumed lightspeeds in the non-tranverse directions in the laboratory frame (which here stands for any inertial frame), and they are assumed equal in both directions, then v = 0. This means that either the ether has no effect on lightspeed, or else it doesn’t exist. I agree that the (implicit) denial of the ether in Einstein’s theory is not a priority dispute issue. But since this has been a contentious, ambiguous, and important issue in relativity, clarifying it is a worthwhile endeavor. Finally, if Poincare never explicitly denied the ether, it clearly suggests he didn’t realize the implication of his conclusion of invariant lightspeed on each leg of a round-trip path. If you disagree, then please address the following question directly: How can the SoL can be the same in both directions in the MMX consistent with an ether that effects lightspeed? green 193.108.45.140 10:45, 9 March 2006 (UTC)

Green, I think the light source equi-distant between two clocks comes from one of Einstein's popular expositions of relativity. Or maybe just what seems the same to me: the two lights at each end of a moving railway carriage which are triggered when each end of the carriage coincides (in the rest frame/platform frame) with the ends of the platform. The pulses of light meet in the middle of the platform (rest frame) but not in the middle of the carriage (which has moved during the ligh transit). Hence the triggering events are not simultaneous in the carriage moving frame. (Incidentally those in the carriage can conclude the carriage is NOT the same length as the platform, whereas those on the platform conclude the moving carriage is as long as the platform). E4mmacro 00:12, 8 March 2006 (UTC)

E4: I find your example confusing and perhaps incorrect. If the carriage at rest is the same length as the platform, then the carriage in motion, from the pov of the rest frame of the platform, will be shorter than the platform. In this case, I don’t see how lights situated on the ends of the carriage can be triggered simultaneously by signals on the platform, when passing the ends of the platform. green 193.108.45.144 19:14, 8 March 2006 (UTC)

E4: Maybe you mean this: when the rear end of the forward-moving carriage coincides with the extremity of the platform when approaching the platform, the lights at either end of the carriages are triggered simultaneously from the pov of the platform frame. But it is unclear how would this be accomplished. green 193.108.45.156 19:40, 8 March 2006 (UTC)

Triggered by this discussion, I now added more on Poincaré's considerations of synchronisation procedures in the article relativity of simultaneity. Harald88 22:32, 9 March 2006 (UTC)

Harold: I went to the link above and read the section entitled “Poincaré's (1900) Calculation of Local Time for Moving Clocks” (which I presume you wrote). How can Poincare believe (your claim on this Talkpage) that the SoL is the same on each leg of a round-trip path and also assume that it is c-v and c+v due to the earth’s velocity v wrt the luminiferous ether? This makes no sense and relates to my comments and question above (in paragraph starting wth “The BOTTOM LINE”). green 193.108.45.237 10:17, 10 March 2006 (UTC)

Harald: You may be suffering from a case of denial (of reality). The c+v and c-v speeds of light in those equations are not closing velocities. They are the speeds of light in the rest frame of the lab (or any inertial frame), different in each direction like the assumptions of the MMX. If Poincare eventually took the pov that the Sol is the same on each leg of a round-trip path, then something is awry with the presentation in the article you cite. He must have finally come to the (defacto) view, like Einstein, that the ether doesn't exist. green 193.108.45.227 08:57, 11 March 2006 (UTC)

That section was written by someone else (E4 probably) and it suffices to remark that "the SoL" in the rest frame of the lab depends on one's definition; I added the information from Poincare's 1898 paper. And contrary to your claims, Poincare continued to refer to the ether, and so did Lorentz; while they both adhered to the (symmetrical!) LT - it was even Poincare who wrote them down in that form, to stress observational symmetry. There is no problem as long as one realises that they understood that physics language is not about reality, but about pragmatic models of reality. Harald88 09:41, 11 March 2006 (UTC)

You don't seem to want to do your own thinking on this issue. The SoL in the rest frame is c - v or c + v, where c is the SoL in the frame of the ether, and v is the assumed velocity of the ether wind along the x axis. The clocks are assumed at rest wrt each other. I don't see how some esoteric velocity convention can save the ether if one assumes the SoL is the same on both legs, but I am open to hearing the argument. In the good ole days, I believe they used the normal meaning of velocity; distance divided by time using (assumed) synchronized clocks. Also, I never claimed, as you state above, that Poincare or Lorentz ceased to refer to the ether. I simply stated that Poincare's belief that the SoL is the same on both legs of a round-trip path is inherently contradictory to the ether's existence. Further, in the good ole days, physicists were not seduced with extreme positivism and had the common sense understanding that the laws of physics refer to the behavior of nature. I'd be grateful if you would define the velocity or SoL convention that is consistent with the ether's existence and the assumption that the SoL is the same on each leg of a round-trip path. green 193.108.45.150 12:41, 11 March 2006 (UTC)