# Talk:History of special relativity/Archive 1

## Differences and similarities between Newtonian space and special relativity space-time.

(The following discussion is about the history of special relativity, but maybe it would be more fitting in an article about philosophy of relativity)

Newtonian dynamics and special relativity have themes in common, which does not come as a surprise because both theories address the very same questions.

The Principle of Relativity of inertial motion is one of the cornerstones of Newtonian dynamics. Special relativity marked a return to this principle, (but with Lorentz-transformations instead of Galilean transformations) after doubt had been cast on the principle of relativity of inertial motion by the apparent necessity to assume the existence of a luminiferous ether.

The principle of relativity of inertial motion also entails, as Newton had seen better than his contempories, a principle of relativity of inertia. In order to accelerate an object, a force must be exerted, and there there is no such thing as a difference between accelerating and decelerating, it is intrinsically only possible to measure change of velocity.

However, something must be the physical cause of inertia. There is an opposition to change of velocity, like a coil with selfinduction will oppose a change of current strength, while not resisting uniform current. The origin of inertia must be some physical interaction, opposing change of velocity while not interacting with uniform velocity. Therefore Newton had explicitly announced the assumption of absolute space, fully aware of the strangeness of the situation. Why would nature fine-tune everything to ensure that there is always relativity of inertial motion, while space is nonetheless absolute?

There was an aspect of special relativity that Einstein was very dissatisfied with. Even as he worked out special relativity he knew special relativity needed to be followed by a deeper theory. Just as in newtonian dynamics special relativity assumes an absolute background reference that is the cause of inertia. Minkowski space-time does not have absolute time and it does not have absolute space, but as a whole, als space-time, it is just as present and immutable as newtonian absolute space.

Mach's criticism of Newtonian absolute space was just as valid for special relativity as it was for Newtonian absolute space, and Einstein was quite aware of that. Mach had argued that what is seen everywhere in nature is that the laws of physics describe physical entities that act on other entities and that are being acted upon. But newtonian absolute space was immutable, it acts on matter, but it is not being acted upon. Likewise, Minkowski space-time acts on matter, as the physical cause of inertia, but is not being acted upon. It is this immutable, non-reciprocal character that is the focus of Mach's criticism.

Einstein saw special relativity as a transitional theory, it really had to be overthrown.
--Cleon Teunissen | Talk 19:02, 28 July 2005 (UTC)

I now saw the above, and I think it's quite OK although it may be supected of being OR, if no references are given. An alternative title would be Metaphysics of Relativity. And the presentaion can be next continued to the GRT in which physical space affects matter but is also affected by matter. Harald88 19:18, 29 October 2005 (UTC)

## merged and reedited

I merged the History page with the version that was still on the Special relativity page, and reedited it plus made some additions. I some cases I had to make a choice between different renderings; some confusing/erroneous sentences I deleted as well as some non-relevant material that just didn't fit in. In case I stepped on a sore toe by deleting something, just reinsert any lost phrase that you may consider essential. Harald88 13:45, 29 October 2005 (UTC)

## error?

I think in this text:

As the equations referred to propagation with respect to the hypothesised aether, physicists tried to use this idea to measure the speed of light with respect to the aether. It should say "speed of the Earth with respect to the aether".

Huh? Hmmm... You're dead right! No doubt about it. I correct it immediately. Harald88 19:04, 3 December 2005 (UTC)

## The Role of Huygens

Um, I was wondering why there is no mention of Christiaan Huygens's role in discussing relative motion and invariants within Galilian/Newtonian space. If no one has any information on this subject, would you like me to supply it? Let me know. SJCstudent 19:20, 11 April 2006 (UTC)

Sounds interesting! Please add it first here with a reference. Harald88 12:45, 12 April 2006 (UTC)

## Cleanup plez

Fact checking, neutralization, diction. ---CH 23:34, 13 June 2006 (UTC)

I cleaned up the typos. JoJan 13:35, 15 May 2007 (UTC)

## Sentence sense

My contribution to the discussion on need to edit the history page: the first sentence in the 2nd paragraph of the Criticisms of special relativity seems to need clarifying. soj

Done. Harald88 20:01, 20 June 2006 (UTC)

## Galileo did not have Galilean transformation equations?

I think Galileo did not form the Galilean transformation equations; if he did what is the reference?; I think the equations were derived later based upon his physics by others. As to the issue of light speed he was trying to measure it and failed, if he had succeded he might have formed different equations than the so-called Galilean transformation equations.

86, you're right that we bneed a reference. I know that they are on the web; hopefully one of us will add it when he/she stumbles on it again. Harald88 20:32, 11 July 2006 (UTC)
The above editor apparently added the following phrase: to the article in-between the introduction to classical relativity and the discussion of it: The relativity issue was further taken up by the Kant-Boscovich theory.
As it didn't seem to fit there (and I don't know where it would fit), I park it here for discussion where to put it, if at all. Harald88 20:18, 11 July 2006 (UTC)

## Need for Leibniz and Riemann

more important than Galileo is Leibniz who presented a general theory of reletivity that may prove supperior to Einstein's in Leibniz's letters with Clarke. Also it is hard to bleive this article does not get into Riemann's discoveries about the relativity of space. For example in Riemann's ON THE HYPOTHESES WHICH LIE AT THE FOUNDATIONS OF GEOMETRY, he destroys the Euclidean axioms which reletivity later was given credit for destroying. Einstein later gave much credit to Gauss and Riemann for making the discovery before himself.

I don't have time to add these two important historical figures, perhaps someone else can do the scholarly work? —The preceding unsigned comment was added by 76.166.224.229 (talk) 07:13, 6 March 2007 (UTC).

Please, learn how to spell, and list your reliable sources that state what you have said in your above comment.

## Connection with set theory?

Recently here and at General relativity and Relativity of simultaneity long sections about connections with set theory were added[1]. These additions are now reverted and sources should be given and discussed befored adding it again. --Pjacobi 16:26, 23 April 2007 (UTC)

## Einstein's Own View of Relativity

Poincare, in SCIENCE AND HYPOTHESIS (1902), formulated the idea of natural mathematics: that mathematics inevitably led to paradoxes and to avoid or solve these, a statement had to be inserted into arguments that mathematics is an inherent human faculty. This polemical position was developed in response to the supposed set-paradoxes. The statement itself has always begged the question of the internal consistency of the arguments into which the statement is inserted. See Penelope Maddy's NATURALISM IN MATHEMATICS for a statement of the position of natural mathematics.

Recently the reason for developing the position itself has been called into question by historians of mathematics, on the grounds that the set-theoretic paradoxes are not paradoxes, and are devoid of logical content. See A. Garciadiego, BERTRAND RUSSELL AND THE ORIGINS OF THE SET-THEORETIC 'PARADOXES' (1902). Poincare's own understanding of the what was at stake in the set theory discussions around the turn of the century, has recently come under scathing attack by I. Grattan-Guinness in THE SEARCH FOR MATHEMATICAL ROOTS. According to Grattan-Guinness, Poincare had a “contempt for logic (and also ignorance of it)….” Poincaré understood mathematical logic “not very deeply….” (129,356) Einstein was never aware of this.

Einstein never looked into the set theory background of SCIENCE AND HYPOTHESIS--he never at any time questioned Poincare's formulation of the issues. Indeed, as D. Howard and J. Stachel point out in their recent EINSTEIN'S FORMATIVE YEARS, Einstein made a “careful reading” of the book (6) and he and his circle of friends, adopted its view enthusiastically. In that book, Einstein read Poincare's formulation of natural mathematics, that “the mind has a direct intuition of this power [“proof by recurrence” or “mathematical induction”], and experiment can only be for [the mind] an opportunity of using it, and thereby of becoming conscious of it.” In geometry “we are brought to [the concept of space] solely by studying the laws by which…[muscular] sensations succeed one another.” (1952 edition, 13, 58)

There is no question that Einstein adopted this idea of mathematics. He expressed it in SIDELIGHTS ON RELATIVITY:

"It is clear that the system of concepts of axiomatic geometry alone cannot make any assertions as to the relations of real objects of this kind, which we will call practically-rigid bodies. To be able to make such assertions, geometry must be stripped of its merely logical-formal character by the co-ordination of real objects of experience with the empty conceptual frame-work of axiomatic geometry. To accomplish this, we need only add the proposition:--solid bodies are related, with respect to their possible dispositions, as are bodies in Euclidean geometry of three dimensions. Then the propositions of Euclid contain affirmations as to the relations of practically-rigid bodies." (31-32)

Although self-confessedly internally inconsistent, natural mathematics was never considered a problem for the relativity of simultaneity because it was not clear where it played any specific role in the formulation of the relativity of simultaneity. However, it does. Here is Einstein's formulation of the relativity of simultaneity in RELATIVITY:

"Are two events (e.g. the two strokes of lightning A and B) which are simultaneous with reference to the railway embankment also simultaneous relatively to the train? We shall show directly that the answer must be in the negative. When we say that the lightning strokes A and B are simultaneous with respect to be embankment, we mean: the rays of light emitted at the places A and B, where the lightning occurs, meet each other at the mid-point M of the length AB of the embankment. But the events A and B also correspond to positions A and B on the train. Let M1 be the mid-point of the distance AB on the traveling train. Just when the flashes (as judged from the embankment) of lightning occur, this point M1 naturally coincides with the point M but it moves…with the velocity…of the train." (5th edition, 19-20)

The logical problem is that the term "naturally coincides" is unjustified--and it is a specific use of natural mathematics. The term is not among the definitions or postulates of the formulation; neither is it a deduction. Logically, then, it plays no role in the argument. If, however, on that basis it is dropped, and M and M' are said to coincide, then we run into a situation in which Einstein has told us to assume two Cartesian coordinate systems, but now leaves us with one, since, following from the definition of the coincidence of two points, if two parallel coordinate systems coincide at one point, they coincide at all points and are one coordinate system, not two. We have been led to a contradiction.

In formulating the relativity of simultaneity, Einstein dutifully followed Poincare's instructions. The idea that one point "naturally coincides" with another is not supposed to be among the postulates or definitions of the relativity of simultaneity. Following the natural mathematics protocol, its role is to float free of all context, serving as a facilitator of the argument. This is why the term occurs where it occurs: it “allows” one point to “succeed” another, in conformity with the demands of natural mathematics. However, its anomalous role means that the relativity of simultaneity no longer seems not to be a scientific argument.

Nor is the relativity of simultaneity the only formulation in which Einstein employed natural mathematics, or where it caused problems. As Sahotra Sarkar points out in the Stachel and Howard book, in his discussion of Einstein's 1905 paper on Brownian motion: “Einstein begins with an assumption whose status is still problematic and troubled his contemporaries: that there exists ‘a time interval ô, which shall be very small compared with observable time intervals but still so large that all motions performed by a particle during two consecutive time intervals ô may be considered as mutually independent events….'” Sarkar notes: “[t]his is essentially a very strong Markov postulate. Einstein makes no attempt to justify it….[W]here mathematics ends and physics begins is far from clear….” This is another example of the clear use of natual mathematics. (211, 220-221)

It is important to note, then, that Einstein did not intend that relativity be an internally consistent argument: he intended it to have a logical flaw, because that is what he felt natural mathematics required.

I suppose based on this, that you are saying that Einstein's relativity of simultaneity is false because it naturally leads to a contradiction within the mathematical contex which he uses?71.251.178.128 17:07, 26 July 2007 (UTC)

## Failure To Discuss and Reference All Of Einstein's Special Relativity Papers

This article does not reference Einstein's most important paper published in 1907. Because of this fact, people have a wrong understanding of his theory. Other important papers followed in 1910 and 1911, but they are not mentioned. In fact The Theory Of Relativity is not defined until the paper of 1911, which has this name for its title. As a minimum, these papers should be referenced, and it is my belief that the 1907 paper has been published on the web, so an external link could be provided for it. There were other papers after 1911, and they should be referenced as well.71.251.178.128 16:59, 26 July 2007 (UTC)

I know of no relativity priority dispute in connection with papers published after 1906 and before the inception of GRT. Harald88 17:04, 11 November 2007 (UTC)
Here are my suggestions, anonymous:
(1) Sign up for an account so I don't have to call you anonymous
(2) Be bold, and make the corrective edits you believe are necessary - make sure to include authoritative references, please!
(3) Important: Make sure to read and absorb the following warning which is printed below the edit box:
If you don't want your writing to be edited mercilessly or redistributed by others, do not submit it.
(4) Also Important: Make sure to read and absorb this: Wikipedia is not a soapbox
Regards, Alfred Centauri 23:32, 26 July 2007 (UTC)

## Update necessary

This article doesn't match its goal. It looks more than a sequel to a priority dispute between Poincaré and Einstein, and not like a "history of special relativity". Also the important work between 1905-1912 by Planck, Mosengeil, Laue, Minkowski, Laub, Born, Sommerfeld, Frank etc., is not even mentioned in the article. I will try to correct this in time, if nobody disagrees. --D.H (talk) 10:32, 16 March 2008 (UTC)

Based on the German version, I've rewritten the article. It now contains a new section from 1906-1915, and a much larger section from 1880-1905. However, now it's time that I quit my writings on Wikipedia for some time. Good bye! --D.H (talk) 17:16, 21 March 2008 (UTC)
The extreme edit by D.H. included removal of a paragraph long called "Looking back on special relativity". This was a mathematical piece remarking on the parallel development of linear algebra and the spacetime science. It asked if the founders needed new mathematics. One can say they did as linear algebra was an infant. But the idea of the tessarine multiplication that Cockle displayed in 1848 had been a toy of W.K. Clifford, so the mathematics was on the shelf to be used. The current article includes too much mystique on the nature of Lorentz' magical transformations; but that is where linear algebra has its source, in useful applications of transformations like the squeeze mapping.Rgdboer (talk) 02:52, 1 April 2008 (UTC)

Your are right, therefore I reinserted the mathematical section. See "Mathematical background". --D.H (talk) 09:22, 1 April 2008 (UTC)

Thank you.Rgdboer (talk) 21:15, 1 April 2008 (UTC)

## Rewriting the article

So, after some months of rewriting and copyediting the article, it contains 2 major sections: The Prehistory with Michelson, Lorentz, and Poincaré. And the final theory of special relativity, from Einstein and Minkowski until the development of general relativity. --D.H (talk) 21:37, 3 October 2008 (UTC)

OK, after I've divided the prehistory in 4 parts (Ether, Electrodynamics, Electrons, constancy of light), some headlines should be included into the section "further development" as well. Some suggestions? --D.H (talk) 09:55, 9 November 2008 (UTC)

## Concerns regarding philosophical prejudice

Here's a quote from Michael Polanyi.

The usual textbook account of relativity as a theoretical response to the Michelson-Morley experiment is an invention. It is the product of a philosophical prejudice. When Einstein discovered rationality in nature, unaided by any observation that had not been available for at least fifty years before, our positivistic textbooks promptly covered up the scandal by an apppropriately embellished account of his discovery.

— Michael Polanyi, Personal Knowledge (University of Chicago, 1958)], page 11

In the book there are also citations and quotes from Einstien himself (with whom Polayni had direct and indirect contact in the confirmation of issues related to these concerns [e.g., page 10 of Personal Knowledge: "There is no mention here of the Michelson-Morley experiment. Its findings were, on the basis of pure speculation, rationally intuited by Einstein before he had ever heard about it. To make sure of this, I addressed an enquiry to the late Professor Einstein, who confirmed the fact that 'the Michelson-Morley experiment had a negligible effect on the discovery of relativity." —Preceding unsigned comment added by Firefly322 (talkcontribs)

We must distinguish between the works of Lorentz and Poincare (which was very influenced by the MM experiment) and Einstein, who denied any direct influence of that experiment on his thinking. Also most physicists after 1905 considered the experiment as extremely important of the developmet of that theory. For more recent papers on that topic, see:
--D.H (talk) 17:46, 15 October 2008 (UTC)
Actually, not sure where this material fits or if has been covered somewhere else (I haven't seen it if it has). But Michael Polanyi above and Stachel are both bringing up philosophy as a concern in regards to Einstein and Michelsen. And whatever investigation Einstein actually performed prior to 1905 would also be relevant to section on the relevance or irrelevance of philosophy to Einstein's discovery(ies). --Firefly322 (talk) 03:58, 16 October 2008 (UTC)
The article already appears to do all this. What exactly do you (FF) want to change? William M. Connolley (talk) 18:43, 16 October 2008 (UTC)
Not thinking of changing anything really. Just adding a section on some notably similar material/set of ideas. The famed physicistFreeman Dyson has written that science is usually tool-driven (usually agreeing with Peter Galison's thesis in various books of his) and not idea-driven (usually not agreeing with Kuhnians, though being open to Thomas Kuhn himself who jokingly denied that he was a Kuhnian). He states that Einstein's work is the rare exception, actually being idea-driven. The Scientist as Rebel By Freeman J. Dyson (2006, pages 201-212). --Firefly322 (talk) 15:43, 17 October 2008 (UTC)

## Tessarines?

The section entitled "Mathematical Background" seems to be "novel narrative" at best. This is supposed to be an article on the actual history of the development of special relativity, not a speculative re-construction of how special relativity might have been developed. As far as I know, the concept of "tessarines" has no effect on the actual historical development of special relativity. There is no evidence that Poincare, Lorentz, Einstein, Minkowski, Planck or any of the other contributors to special relativity had ever even heard of tessarines, let alone made use of the concept. The fact that a Lorentz boost corresponds to a hyperbolic rotation seems much more relevant and meaningful. Granted this can be represented in two dimensions by multiplication by a 2x2 matrix with equal diagonal and equal off-diagonal terms, but surely this is better motivated as a rotation. One could trace this back to Hariot and Wallis, or even earlier. I think it's a stretch to credit Cockle as the originator of the idea of hyperbolic rotations. It surely is not historically relevant. It is novel narrative, and doesn't belong in the article on the history of special relativity. Does anyone disagree?130.76.32.16 (talk) 19:40, 28 October 2008 (UTC)

I also don't think that this section is necesarry for the understanding of the actual history - at least concering the contributions of Lorentz, Einstein &c.. As far as I know, it was User:Rgdboer who defended the inclusion of that section, so I will ask him on his talk page. --D.H (talk) 21:14, 28 October 2008 (UTC)
On further thought, there may be a valid point about the introduction of non-positive-definite metrics (i.e., pseudo-metrics), but historically for Minkowski this came about by introducing "imaginary time" in 3+1 dimensional spacetime, not by considering "tessarines". Also, tessarines seem limited to two dimensions, so at best they could only be cited as an early example of an algebra with non-positive-definite modulous. But this rudimentary idea (along with rotation through imaginary angles) could be traced back even earlier, and I still have the impression that this is novel narrative and not very historical.130.76.32.144 (talk) 14:59, 30 October 2008 (UTC)

In the late 19th century a paradigm shift occured in mathematics with the Erlangen program and transformation theory. The pressure for knowledge pushed out linear algebra and abstract algebra. Certain relations with time and space study are apparent with these tools. For instance, the Galilean relativity corresponded to a use of shear mapping in a space-time plane. The geometry of special relativity was anticipated in the works of Cockle, Cayley, Clifford, and MacFarlane cited. Such is the mathematical context; slowness of physical writers to acknowledge previous science is not a justification for continuing to obscure the mathematical concepts. As for the tessarines, the first instance of split-complex numbers, the parent is entitled to claim the child. As for consciousness of the anticipitory mathematics, reconstruction is challenging but we have the 1912 International congress of mathematicians where MacFarlane must have crossed paths with Ludwik Silberstein. Not all of the early students were ignorant of the hyperbolic rotation concept at root of the Lorentz transformation boost.Rgdboer (talk) 21:21, 30 October 2008 (UTC)

Maybe my comment wasn't clear. I wasn't saying all the originators of special relativity were ignorant of hyperbolic rotation. Quite the contrary. I was saying they were well aware of it, and that this concept pre-dates and subsumes "tessarines". I don't think the attendence of MacFarlane and Silberstein at the same mathematical congress in 1912 establishes that tessarines had any part in the development of special relativity. Both Poincare and Minkowski introduced the idea of an "imaginary" unit for time, and the "four-vector" formulation of special relativity, with non-positive-definite modulous, but as far as I know this was not the "child" of two-dimensional tessarines. I agree that mathematicians and physicists in the 19th century studied some structures (e.g., complex numbers, quaternions, matrices, vectors) that resembled in some ways the mathematical forms that were developed to represent special relativity, but I question whether tessarines actually represent the Lorentz transformation (other than in the 1+1 dimensional case). I think it would be fine for the article to note that the elegant formalism developed by Minkowski had its roots in earlier algebraic (and geometric) abstractions, but I think the current article gives too much weight to tessarines and Cockle.130.76.32.144 (talk) 14:35, 31 October 2008 (UTC)

For those interested in this symbiotic development of linear algebra and spacetime theory it is useful to identify the concept of hyperbolic versor. This operator on a plane was put to paper by James Cockle in 1848. It was MacFarlane 43 years later that fused hyperbolic versors into quaternions obtaining hyperbolic quaternions. The Great Vector Debate that followed has been recounted by Crowe in A History of Vector Analysis and by others elsewhere. One of the positive outcomes was the Quaternion Society. The section on mathematical background in this article balances the well-developed literature of physical-science historians that have not delved to the level of the core mathematical concept, nor have gotten the zeitgeist surrounding the quaternion society. Even Crowe is ignorant of versors (of both types) and turns MacFarlane’s bibliography into bar graphs. Since MacFarlane cites Cockle, and since hyperbolic quaternions anticipated Minkowski space, the influence of tessarines on relativity is transparent.Rgdboer (talk) 23:49, 1 November 2008 (UTC)

I would say rather that the influence of tessarines on relativity is non-existent. Nothing you've said provides any support of your claim. The theory of special relativity was developed by Lorentz, Poincare, Einstein, and Minkowski, not by MacFarlane, Cockle, Hamilton, etc. Again, I think it would be fine for the article to discuss the origins of the ideas that the mathematicians Poincare and Minkowski used in giving special relativity it's most elegant formulation, but to the best of my knowledge this owed nothing to Cockle or MacFarlane. I'll try to trace Poincare's and Minkowski's sources for the mathematical formalism, and make some suitable edits to the article.63.24.124.170 (talk) 08:00, 2 November 2008 (UTC)
I found an interesting article on the history of Lorentz group by Felix Klein, who referred to Arthur Cayley as the most important predecessor of Minkowski. I will try to include that in the article. --D.H (talk) 09:46, 9 November 2008 (UTC)

## Emission theories of light

Should this section mention the criticisms of de Sitter's experiment due to optical extinction and the subsequent confirmation of the conclusion by Brecher and by laboratory experiments such as those by Alvager et al? Martin Hogbin (talk) 17:08, 30 November 2008 (UTC)

Ok, I've included some infos, --D.H (talk) 10:19, 1 December 2008 (UTC)

## Bucherer

Some remarks about Bucherer are ungrammatical. —Preceding unsigned comment added by 87.194.34.71 (talk) 12:15, 25 April 2009 (UTC)

Better now? --D.H (talk) 15:37, 25 April 2009 (UTC)

## Why Censor the article ?

the link to Relativity priority dispute was censored, please restore it ! 173.169.90.98 (talk) 16:53, 30 June 2009 (UTC)

No need for redundant links: History of special relativity#Priority. --D.H (talk) 18:03, 30 June 2009 (UTC)

## Local time

D.H has put in this sentence: "He [Poincare] also continued (1908) to describe coordinates and phenomena as local/apparent (for moving observers) and true/real (for observers at rest in the aether)." What is the source for this? I checked "Science and Method", published in 1908, and it uses the term "local time" but it does not use apparent time, true time, or real time. It does not use the phrase "observers at rest in the aether". I say that this sentence is inaccurate, and should be replaced with some statement about the terminology that Poincare actually used. Roger (talk) 10:39, 20 September 2009 (UTC)

To make things more clear:
1. I think we both agree that Poincaré invented at least 90% of special relativity before Einstein. (light synchronisation, relativity principle, philosophical relativity of time, etc.). Well, this is also the opinion of most (not all) historians of science.
2. Do you also agree that Wikipedia articles have to be based on reputable secondary sources? (At least when there are many secondary sources available - and concerning the history of SR, there are plenty of them....)
3. And most (not all) historians argue that it was Einstein who brought the relativity of time into physics - not Poincaré. And that it was Einstein, who clearly understood that this requires that the immobile ether of Lorentz and Poincaré is a useless concept within special relativity. (I'm not talking about general relativity, where things are more complicated).
4. Now, to the "local time" problem: The section is about coordinates (and phenomena) - not only about "time". Poincaré uses those expression (apparent, local, ideal, etc.) on many occasions (this is why most historians say that Poincarße failed to invent SR, or like A. Pais said, failed to grasp all consequences of SR). A few examples:
a) See his 1904-paper s:The Principles of Mathematical Physics, where he wrote: Nor for an observer carried along himself in a translation he did not suspect could any apparent velocity surpass that of light; there would then be a contradiction, if we recall that this observer would not use the same clocks as a fixed observer, but, indeed, clocks marking "local time”. He also distinguish between "true" and "local" time, and "apparent" and "real" mass etc.
b)See his 1906-paper s:fr:Sur la dynamique de l'électron (juillet)/VI. He uses words like "ideal (idéal) electron", "ideal charge, "ideal system" versus "real (réel) electron", "real charge" etc.
c) See also his 1908 paper s:The New Mechanics, He uses "apparent inertia", "apparent mass", "fictitious mass", "real mass". He called "local time" the product of a measurement by "wrong" (1908) watches. etc.
5. So we have "local time", "apparent velocity of light", "apparent mass", "ideal electron" for moving observer, and we have "true time", "real mass", "real electrons", real speed of light for observers resting in the aether. Those are not useful concepts within special relativity, although they gave the same experimental results (see Holton, Miller etc. for more infos).
6. PS: I placed a lot of historical papers on relativity at s:Wikisource:Relativity, if someone is interested in the original works of Poincaré, Lorentz, Abraham, etc.. Regards, --D.H (talk) 11:53, 20 September 2009 (UTC)
Yes, I agree about most historians, and about secondary sources. But if you are going to make a statement about what Poincare said, then it should accurately reflect what he actually said. If wer are going to accuse Poincare of saying something that is confusing or misleading or useless or wrong, then we should give a source so the reader can judge for himself.
I do not agree that Poincaré failed to bring the relativity of time into physics. His 1904 paper said, "The most ingenious idea has been that of local time." He repeatedly stressed the importance of what he called local time.
I do not agree that Einstein's position on the uselessness of the aether was much different from Poincare's. Poincare's 1902 book said, "some day, no doubt, the ether will be thrown aside as useless."
Of course my personal opinions here are of little consequence, except that they help explain why I want accurate statements and sources.
Poincare's use of "apparent velocity" was in describing something that he says is wrong. It is very misleading to quote this as if Poincare did not understand relativity.
I really don't think that you want to criticize Poincare for using terms like "apparent mass". I don't think that there is agreement even today about what is the best terminology, and people continue to use terms like "relativistic mass" and "rest mass".
I don't think that this is really the place for badmouthing Poincare. There is a separate article for priority issues. Just say that Poincare said, in his actual and preferred terminology. And the term he liked to use was "local time". Roger (talk) 22:44, 20 September 2009 (UTC)
The article already gives a detailed account on Poincaré's brilliant and important contributions to relativity - but most historians deny the notion that Poincaré completed special relativity as a theory of relativity of space and time (as it was done by Einstein). Maybe the majority of historians will change their position some time - but this is not the case so far.
I'm neither "badmouthing" nor "criticising" Poincaré. On the contrary, Poincaré's statements ("real", "true" - versus "apparent", "local", "wrong") are totally consistent within Lorentz's aether theory. Unfortunately not within special relativity - that's the point. And of course it was Poincaré who stressed the importance of "local time" - but as it was said, the distinction between "local" and "true" time is nor very "relativistic"....
BTW: There are a lot of links to papers by Lorentz, Poincaré etc. within the article. So if one don't like the mainstream-historian's opinion, read the original papers and form your own opinion. - --D.H (talk) 06:26, 21 September 2009 (UTC)
It is just meaningless to say that "most historians of science argue that Poincaré failed to invent what is now called special relativity". They do say that he invented 90% of it, more or less. Maybe some of them think that the essence of SR is in the last 10%, I don't know. At any rate, it is better to just say what Poincare and Einstein invented, and avoid attributing vague and undefined failures to them.
You have examples of Poincare using the terms "local time" and "apparent mass". I accept that. But you have no example of him using "apparent time" and "real time". You have one example of him using the term "true time", but I checked the context, and he disavows true time! He says, "The watches adjusted in that manner do not mark, therefore, the true time; they mark what one may call the local time, so that one of them goes slow on the other." Therefore I am changing the article to reflect what Poincare and the historians actually say. Roger (talk) 07:51, 21 September 2009 (UTC)
a) I tried to explain to you that "local time", "ideal system", "apparent mass", "ideal electron" are all interconnected terms. You simply don't understand it, that's all. b) And secondly, it's totally irrelevant what you think or say. Most historian say that Einstein, not Poincaré invented SR - Wikipedia has to reflect this. If you don't like it - go and publish a paper were you disprove those historians, but do not use Wikipedia for your crusade against the mainstream. BTW: Please don't remind me "what historian actually say": I have read the books of Holton, Pais, Galison, etc. - your edits show you don't read their books. --D.H (talk) 14:57, 21 September 2009 (UTC)
The quotation above "The watches adjusted in that manner do not mark, therefore, the true time; they mark what one may call the local time, so that one of them goes slow on the other" far from "disavowing true time" does exactly the opposite: it explains that "the local time" differs from "the true time" thus actually asserting that (in his view) there is such a thing as true time, otherwise the quote would make no sense. -- 18:19, 21 September 2009 (UTC)
Quite indeed, this is 100% orthogonal to "disavowing true time". It looks like Schlafly's "I checked the context, and he disavows true time!" is a nice example of wp:synth and wp:nonsense and wp:npov all at the same time. DVdm (talk) 18:32, 21 September 2009 (UTC)
D.H, I see that you are back to insulting me, instead of addressing what I say. I corrected your sentence so that it attributes to Poincare the terms that Poincare actually uses. Your personal opinion about what terms are interconnected are irrelevant. I say that a statement that Poincare used particular terms should quote the actual terms that Poincare used, and give a source. Your statement does not do that.
To the others, I gave a quote to back up what I said. The Poincare sentence says that watches measure local time and not true time. The sentence does not say anything about whether true time exists. If I say, "the animal in the picture is a gorilla and not a bigfoot", then the statement says nothing about whether bigfoot exists. Roger (talk) 23:04, 21 September 2009 (UTC)

Poincaré uses "apparent", "local", "ideal" for many phenomena in moving systems, and "true", "real" etc. for those in the aether system - and it's not my personal opinion that these terms are interconnected. For example, read Holton, Miller, Galison, Goldberg etc. As I said, you have to disprove those historians by publishing a paper in a reputable journal - don't use Wikipedia for that. --D.H (talk) 13:31, 22 September 2009 (UTC)

I still question the above statement. I have looked at some of those sources, and I cannot find any example of Poincare using "true time" for clocks used by observers at rest in the aether. Some of the secondary sources suggest this, and some suggest otherwise. If it is just a matter of opinion, then I say it belongs over on the Relativity priority dispute where there is some attempt to give balanced opinions. The article should not attribute something to Poincare unless he actually said it. Roger (talk) 21:05, 25 April 2010 (UTC)

## Lorentz's theory

Can anyone explain what this means, Joseph Larmor (1897, 1900) created a model very similar to Lorentz's. However, he went a step further and extended the Lorentz Transformation for second order terms. So Larmor was the first to put the Lorentz Transformation in an algebraically equivalent form, which is used to this day? Martin Hogbin (talk) 20:27, 20 September 2009 (UTC)

Hmmm..try this one: "A very similar model was created by Joseph Larmor (1897, 1900). Contrary to Lorentz, Larmor extended the Lorentz transformation to second order in v/c. So Larmor was the first one to put this transformation into a form, which is algebraically equivalent to the modern version." --D.H (talk) 20:50, 20 September 2009 (UTC)
Sorry but I still do not follow. Is this correct? Larmor created a model that was not quite right (I presume correct only to a first order). He then corrected it to be equivalent to the modern LT. He did this before Lorentz published his correct results. Martin Hogbin (talk) 21:25, 20 September 2009 (UTC)
Oh, the former version was incorrect. Here is the corrected version: "Contrary to Lorentz, Larmor extended the Lorentz transformation to all orders in v/c. So Larmor was the first one to put this transformation into a form, which is algebraically equivalent to the modern version. However, Larmor stated that those transformations preserve the form of Maxwell's equations only to second order in v/c."
a) Lorentz (1895) got the time transformation to first order (t'=t-vx/c²),
b) Larmor (1897m 1900) to all orders (t'=t/γ-γxv/c²), although Larmor stated that they preserve the form of Maxwell's equations only to second order.
c) Lorentz (1904) showed that this transformation is valid to all orders - except for the transformation equations for velocity and charge density.
d) Poincaré and Einstein (1905) corrected and perfected Lorentz's result. See also "History of Lorentz transformations". --D.H (talk) 21:58, 20 September 2009 (UTC)

"Larmor was the first to put Voight's transformations into a form algebraically equivalent to the modern Lorentz transformations, however, he stated that his transformations preserved the form of Maxwell's equations only to second order of v/c. Lorentz later noted that these transformations did in fact preserve the form of Maxwell's equations to all orders of v/c "
Have I got this right? Martin Hogbin (talk) 09:59, 21 September 2009 (UTC)

Yes, absolutely correct. But instead of using "Voigt's transformation" I would use "Lorentz's 1895-transformation" - there is no evidence that Larmor knew Voigt's paper. --D.H (talk) 15:01, 21 September 2009 (UTC)
Let us go with that then. Martin Hogbin (talk) 15:20, 21 September 2009 (UTC)

## Lorentz invariance

Does anyone know when the term 'Lorentz invariance' was first used used. It is used in the article in some places what I suspect is an anachronistic way. In other words, we perhaps should substitute the term with something like 'what is know known as Lorentz invariance' or similar. It is just odd to read that Lorentz's theory was not Lorentz invariant, even thought it was not. Martin Hogbin (talk) 21:45, 20 September 2009 (UTC)

Terms like "invariance" or "covariance" (in connection to the Lorentz group) were introduced by Minkowski in 1908 (As described in History of special relativity#Minkowski's spacetime). For Minkowski's article, see s:de:Die Grundgleichungen für die elektromagnetischen Vorgänge in bewegten Körpern.... --D.H (talk) 22:04, 20 September 2009 (UTC)
Thanks. On looking through the article again I cannot find the section that I thought should be changed, so ignore this comment. Martin Hogbin (talk) 22:17, 20 September 2009 (UTC)

## Poincaré

While it is perfectly appropriate to include Poincaré's material leading up to special relativity, most historians of science do not credit him with the discovery. We, therefore, should not either. This edit takes the pendulum a bit too far. - 2/0 (cont.) 17:20, 22 September 2009 (UTC)

Let's stick to the facts and not worry about who should get credit for "the discovery". There is no "the discovery" here, there are many discoveries, and all important contributions to modern relativity theory should be included. That most historians have or had a certain POV is not sufficient justification for falsely representing opinion as fact. (BTW, you are linking to a minor edit, which I presume is not the edit to which you want to refer, but it remains unclear which edit you thought went too far). Flegelpuss (talk) 18:25, 22 September 2009 (UTC)
Sorry, I was looking through what needed to be stripped out and what should be kept; link fixed. For instance, the spelling correction to Joseph Larmor should be included in all future versions of this article.
On the contrary, we are constrained to accurately reflect the reliability-weighted preponderance of sources. In this case, we tell the story the same way most historians do; if the sources do not consider a particular development important in this context, it is original research to include it, regardless of how logical it may be. - 2/0 (cont.) 19:21, 22 September 2009 (UTC)
Flegelpuss is right. Statements like "Most historians of science argue that Poincaré did not invent what is now called special relativity" are wrong and inappropriate. SR is a set of discoveries, and all of those historians agree that Poincare found many of them. Let's stick to the facts, and leave opinions about credit elsewhere. Roger (talk) 19:31, 22 September 2009 (UTC)

@Flegelpuss/Schlafly: "That most historians have or had a certain POV is not sufficient justification for falsely representing opinion as fact." Unfortunately for you both: This is not how Wikipedia works - we have to rely on secondary sources, written by reputable historians in reputable journals. So the only thing that counts is: Are most (not all) of the historians the opinion that Einstein invented SR? Yes. And Poincaré? No. And the article has to reflect that (as I already told you on your talk page). BTW:What are you complaining about? There are not many pages, in which Poincaré's contributions to relativity are given so much room as in this article. PS: Today I have given additional sources for Poincarés expressions "apparent" and "real" etc, Schlafly (and before him Flegelpuss) also deleted those sources.....--D.H (talk) 19:48, 22 September 2009 (UTC)

D.H., WP:NPOV says exactly what I have said: "Assert facts, including facts about opinions—but do not assert the opinions themselves." It also states "A neutral characterization of disputes requires presenting viewpoints with a consistently impartial tone" and "The tone of Wikipedia articles should be impartial, neither endorsing nor rejecting a particular point of view." Flegelpuss (talk) 20:13, 22 September 2009 (UTC)

I have far more quarrel with D.H.'s unselective mass-reversions of a variety of prior edits than with 2over0's more careful reversions. I'm not sure whether the current reversion or Schlafly's version of the historians' opinion is better: best may be just to refrain from raising the sticky "who discovered relativity" debate in this article (there's actually another whole article dedicated to that topic). I too find the sentence "Lorentz’s local time was not the time measured by watches, but only an auxiliary mathematical tool" quite odd. Did Lorentz actually say such a thing, or is that the bizarre imputation of one historian? Obviously the spelling correction should stay in. Flegelpuss (talk) 20:13, 22 September 2009 (UTC)

D.H, if you are going to make a factual statement about what Poincare said, then it should be sourced to some actual Poincare paper, and not to some opinion by some historian. You don't even describe the opinions of those historians correctly. You say the historians credit Poincare for anticipating Einstein's vocabulary but not his special relativity. The historians say the opposite. They say that Poincare anticipated Einstein's kinematics and dynamics, but failed to use the proper terminology. Roger (talk) 20:40, 22 September 2009 (UTC)

@Flegelpuss: It's impossible to wright an article about the history of SR, without mentioning the fact that it is almost universally attributed to Einstein - this is a fact, not simply a opinion. And of course we have to say why nearly all physicist and most of the historians say that. In doing so, we have to rely on reputable secondary sources. Now please read: "Our policy: Wikipedia articles usually rely on material from secondary sources. Articles may include analytic, synthetic, interpretive, explanatory, or evaluative claims if they have been published by a reliable secondary source." So it's quite clear what NPOV and No-Original-Research (within Wikipedia) means - and it is also clear what most historians say.... You should listen to 2over0, he already explained it to you.
Concerning local time: Yes, Lorentz said it - see Ref. to "Lorentz 1927" in the article. (But even if he hadn't said that - most historians do, so we have to include that.) --D.H (talk) 21:02, 22 September 2009 (UTC)

@Schlafly: No, it's not only about "proper terminology" (please read the text more carefully). Most historians (including Holton, Pais, Miller, Goldberg, Galison, etc). say that Poincaré used this terminology (local, apparent, ideal) in relation to an preferred (but undetectable) aether system. That's the point. Obviously it's not a point for you or Flegelpuss, but most historians think that Einstein's abandonment of the immobile Lorentz-Poincaré aether was a radical and revolutionary step - because it is essential for the relativity of space and time.... PS: And as I said in WP we cannot simply use Poincaré's papers and do some original research without consulting reputable secondary sources.. --D.H (talk) 21:32, 22 September 2009 (UTC)

D.H, I still say that you are misrepresenting those secondary sources. I will try to post a more complete answer when I have time to post quotes from those sources. Roger (talk) 04:25, 30 September 2009 (UTC)
It depend on the "secondary sources." Most of the "historians" he invokes are mere popularizers who didn't read or didn't understand Poincaré's papers. The latter is understandable, since his papers consist of little more than dense mathematics, while Einstein wrote primarily in clear and simple prose. The difference between Poincaré and Einstein is like the difference between Maynard-Smith/Trivers/Hamilton and Dawkins wrt the modern theory of the evolution of animal behavior. The first three invented the theory, but Dawkins was the first to write about it (in The Selfish Gene) clearly enough that large numbers of people (including the slower peers in his field) could understand it for the first time. It is well known among physicists who have take the time to work through Poincaré's papers (as opposed to scientifically illiterate popularizers, who should not be treated as credible authorities) that invoking a "postulate of relativity" as Poincaré did does not even make sense if an immobile aether is necessary to the theory. The postulate of relativty renders the aether a mere optional "convention" as Poincaré put it, or "superfluous" as Einstein put it. Both Einstein and Poincaré also later stated that the aether did not contradict their relativity theories. Whether aether exists or not doesn't change relativity theory in any experimentally distinguishable way, but with the lessening need for aether to explain the wavelike nature of light (quantum mechanics with its probabilistic wave functions, not relativity, is the main thing that made the aether irrelevant), the aether has gone the way of the Newton/Einstein "light ray." It is true that Poincaré kept using the term "aether" more than Einstein, for two reasons: (1) he often used it as a mere synonym for an absolute coordinate system, to which he compared his relativity theory, and to which physicists today still often resort to as a matter of convention to simplify certain mathematics, since an absolute coordinate system is isomorphic to relative coordinates, and (2) in the pre-quantum mechanics world, he and many others kept exploring the issue of whether light was waves in something that behaved mathematically like a material medium. Before QM a theory was needed to explain why light was wavelike and aether was that theory. Planck and Einstein, as pioneers of the early vague QM, had an often vague statistical/thermodynamics understanding of light as randomly bouncing particles, and didn't bother with aether for that reason (it took Heisenberg and Schroedinger to actually explain light waves as probability waves -- the understanding of Planck and Einstein in this regard was closer to the truth than aether, but still way off). Planck and Einstein didn't claim or show that aether doesn't exist, they just stopped talking about it, preferring the statistical-particle view of thermodynamics. In that regard Einstein was more advanced, and because of Einstein's clear prose and publication in Protestant journals he was far more influential in Protestant countries. Einstein's view was thermodynamic Newtonianism, not QM: he was so far into Newton's old particle theory of light that he even frequently used the obsolete term "rays" for light, an ancient optical theory which the wavelike nature of light (esp. shown by early 19th century slit experiments) had long shown to be false. BTW, here is a good reference written by careful physicists commenting on (and republishing good translated versions of) the original papers: Jong-Ping Hsu and Yuan-Zhong Zhang, Lorentz and Poincaré Invariance: 100 Years of Relativity, World Scientific 2001. (Note the centennial they are celebrating). Here it is at Google Books: [1]. Here it is at Amazon.[2]

Flegelpuss (talk) 06:46, 30 September 2009 (UTC)

Those historians are not "popularizers", but highly reputable and well known experts on the field, like Gerald Holton, Abraham Pais, Arthur I. Miller, Roberto Torretti, de:Klaus Hentschel, de:Jürgen Renn and many more. On the other side, we have E. T. Whittaker, Elie Zahar, and others - also important historians but they present a minority view. So the article doesn't say that all historians think that Poincaré didn'd invent SR, it says most historians do that - and a historical article has to rely on historians.... As I said above: Please avoid original research, we cannot put it in the article (including speculations on a possible connection of the Lorentz-Poincaré aether, and Einstein's "aether of general relativity" presented in two semi-popular lectures in the 20ies.). --D.H (talk) 13:47, 30 September 2009 (UTC)

Pais wrote, in his 1984 Einstein biography, "In all his life, Poincare never understood the basis of special relativity." [p.21] That is just laughable. If I have to choose between Poincare or Pais understanding special relativity, I am going with Poincare. Miller's objections to Poincare are almost entirely based on terminology. It true that some Einstein biographers have high opinions of Einstein and badmouth his rivals, but I suggest omitting these obviously biased opinions, and sticking to the facts. If the opinions are included, then they should stick to what the biographers actually say. Roger (talk) 00:19, 1 October 2009 (UTC)

Comment to Flagelpuss: D.H. has a lot of expertise in this area. The reason you are not quite right about Poincare is that you are seeing the correct mathematics, and cannot imagine that the correct mathematics could be accompanied by incorrect physical interpretation. But this is exactly the issue with Poincare/Lorentz/Fitzgerald. They saw the Lorentz transformations as properties of electromagnetism, and not as a property of space/time. This means that for them, while there is no way to tell how fast you are moving, there still "is" a rest frame. For them, it is possible that there is a different type of electricity and magnetism which is very weak, and has a different speed of propagation than c, and is invariant under different Lorentz transfomations. This would not shock them, becuase for them, Mawell's equations come first, and Lorentz invariance is only true for electromagnetic phenomena.

But they also believed that nearly everything was an electromagnetic phenomenon. So they believed that Lorentz invariance would be true in the world, simply because everything was electromagnetic. It took Einstein to say "No, the relativity comes first, and the electromagnetism comes second".Likebox (talk) 03:22, 17 February 2010 (UTC)

No, what you say is completely false. Poincare explicitly said that the Lorentz transformations apply to all the laws of physics. Lorentz applied them to gravity in 1900, and Poincare did also in 1905. Einstein did not until 1908. Poincare had several pages arguing that gravity must propagate at the same speed as light. Roger (talk) 16:15, 17 February 2010 (UTC)
That's debatable regarding Poincare. Regarding Lorentz/FitzGerald it is certainly true. If you look at the physical explanation of "FitzGerald contraction", it is due to the symmetries of Maxwell's equations, extended to matter on the basis of the idea that the microstructure of matter is electromagnetic in origin.
However Poincare does go further. He states in 1900 that all the laws of physics need to be made Lorentz invariant. But he does not do so, and he backpeddles in 1905 after getting confused on mass/energy. He first realizes that energy has to carry inertia in order to make center of mass work out, but fails to see that this is physics, not mathematics, and entirely renounces this point of view in 1905 (probably after getting heckled a lot by physicists).
Poincare doesn't do relativistic energy/momentum, nor does he complete Newton's laws and Maxwell's for relativity. He does a few things which are very notable, but these constitute less than 50% of the theory, not 90%.Likebox (talk) 17:37, 17 February 2010 (UTC)
You seem to be backing off of what you said about Lorentz, Fitzgerald, and Poincare, and making new arguments. Can you please give a quote to back up your claim that Poincare "backpeddles in 1905"? It is true that Poincare did not do an energy/momentum 4-vector, but neither did Einstein. It was done by Minkowski in 1908, I think, and Einstein had nothing to do with it. Not sure what you mean by "complete Newton's laws and Maxwell's for relativity". Einstein went no farther than Poincare. Also, just what is that 50% that Poincare did not do, and who did it? Roger (talk) 18:25, 17 February 2010 (UTC)
Correcting myself, it appears that Minkowski did not have the energy/momentum 4-vector either. Maybe it was due to someone else after 1908. I would still like to see the proof that Poincare backpeddled on anything, or that he missed some part of relativity that someone else had. Roger (talk) 05:39, 21 February 2010 (UTC)

## Synthetic spacetime

Hi Dirk, I noticed this edit of yours. Did you check the bottom of the page?

I think this link should become part of a proper citation for the section Non-euclidean reformulations of special relativity, as "Edwin Bidwell Wilson and Gilbert N. Lewis (1912) introduced a non-euclidean vector-calculus". This looks like a job for Rgdboer. Regards, Paradoctor (talk) 14:37, 26 October 2009 (UTC)

Agreed. DVdm (talk) 15:17, 26 October 2009 (UTC)

## Oh boy--- Hassenohrl again

Will this Deutsche-Physik stuff never die? Please get Hassenhorl right: he claimed E=8/3 mc^2, and corrected it to E=4/3mc^2 to match Max Abraham after getting a letter from Abraham. His paper is just one more attempt to get the mass-energy relationship for electromagnetic fields to give a mass energy relationship for matter based upon speculation on the internal constitution of matter.

Einstein did it differently--- he noted that the relation between mass and energy has nothing to do with light or electromagnetism, it follows only from the relativity postulates. This discussion is repeated, the sources were painstakingly reviewed by User:D.H., who read the original german papers for mass-energy equivalence. Planck didn't like Einstein's argument, but it is both obviously correct and generally accepted as correct. Planck gave a more detailed discussion, which included chemical binding energy, but Planck accepted relativity, and did not follow Hassenhorl or his buddies.

The problem with this is that there is discredited pro-Aryan literature which claims that Hassenhorl got mass-energy equivalence first. We must make sure that such literature is represented in line with Undue-Weight.Likebox (talk) 21:40, 15 February 2010 (UTC)

## Non-euclidean reformulations of special relativity

The current article includes a section entitled "Non-euclidean reformulations of special relativity", but it doesn't make sense (to me). Minkowski's formulation of special relativity is itself non-Euclidean (in fact, the Minkowski metric is not even positive-definite), so it doesn't make sense to talk about a non-Euclidean reformulation, implying that the standard Minkowski formulation is Euclidean. Also, Minkowski's approach was/is essentially just an application of hyperbolic geometry, so the article doesn't make sense when it claims that hyperbolic geometry represents an alternative to Minkowski's formulation. The citations in this section don't actually support the content, and frankly, it appears that the section was written by or for Mr Ungar, who imagines that he made a notable contribution to the history of special relativity. I challenge whether this is the case. I think the section should either be greatly clarified, so that it makes sense, or else deleted.Urgent01 (talk) 15:36, 18 April 2010 (UTC)

The (lack of) results of Google scholar seach and Google books search on the Ungar source are telling. Deleting the section on grounds of non-notabilty might be in order. DVdm (talk) 15:50, 18 April 2010 (UTC)
You get more results with Google books and Google Scholar. Bethnim (talk) 13:36, 17 July 2010 (UTC)
I've removed the Ungar section, but I don't think it's necessary to delete the whole section. But it's true that the current article gives the impression, that Minkowski's space time is fully "euclidean", so I've tried to rephrase it a little bit. See also Walter's paper, who wrote: The non-Euclidean style gave rise to a four-dimensional vector calculus like the space-time formalism, but one involving only real coordinates. The difference between the two formalisms hinges upon the treatment of the time coordinate ${\displaystyle t}$. In the space-time formalism, the temporal coordinate u is imaginary, ${\displaystyle u=ict}$, where ${\displaystyle c}$ is the universal light constant, and i=${\displaystyle {\sqrt {-1}}}$p. Imaginary coordinates are alien to the non-Euclidean calculus, which employs a different substitution for the temporal coordinate, ${\displaystyle \ell =ct}$. --D.H (talk) 17:40, 18 April 2010 (UTC)
Yes, and this is mentioned in the section #Absolute space and time. I think this is an excellent solution. DVdm (talk) 18:15, 18 April 2010 (UTC)
I think the change is an improvement, but I must say that I'm still very unclear about what the remaining section is trying to say. When I read the papers of Walter (for example), he says very clearly that it was Minkowski himself who introduced the non-Euclidean space-time description of special relativity, and that Born, Sommerfeld, Varick, Lewis, Robb, etc., were simply elaborating on this Minkowskian non-Euclidean space-time approach. The current article implies that Minkowski took a spacetime (and implicitly Euclidean?) approach, and the other people took (by implication) a NON-spacetime and non-Euclidean approach. (Note the last line in the section, which says "so Minkowski's space-time remained the preferred formalism", as if the other formalisms were not spacetime based. Surely this is not right. Is there perhaps some confusion here over the use of sqrt(-1) as a unit for the time coordinate? Is this the distinction that the article is trying to make? If not, what exactly is the Euclidean version of special relativity (if there is such a thing) and how does it contrast with Minkowski's non-Euclidean version? The Walter papers and articles make perfect sense to me, but this section of the Wikipedia article makes no sense to me at all.
The writings of Walter make it clear that the scandal of Minkowski (in Walter's phrase) was that he proposed to relace Euclidean 3-space with non-Euclidean 4-dimensional spacetime. All the subsequent writers mentioned in the section wrote about 4-dimensional non-Euclidean spacetime, just as Minkowski had described. Granted, they introduced some alternative notations, but this has no bearing on Euclidean versus non-Euclidean, nor on spacetime verses non-spacetime. So, here's how I would re-write the section (assuming it's not deleted altogether)
It was noted by Minkowski (1907) that his space-time formalism represents a "four-dimensional non-euclidean manifold", and soon after the publication of Minkowski's paper, and especially following his 1908 lecture, this non-euclidean spacetime style was adopted by many physicists, and it continues to be the predominant interpretation of special relativity to the present day. Sommerfeld gave a trigonometric formulation, Alfred Robb (1911) introduced the concept of Rapidity as a hyperbolic angle to characterize frame velocity. Edwin Bidwell Wilson and Gilbert N. Lewis (1912) introduced a vector notation for spacetime. Émile Borel (1913) derived the kinematic basis of Thomas precession. These activities didn't represent any new physical insights, they merely elaborated on the implications of special relativity, making use of Minkowski's four-dimensional non-Euclidean spacetime interpretation.
What do you think? Is this about right? Or is the current article trying to say something different? I would change the title of the section to something like "Minkowski's influence and subsequent elaborations"Urgent01 (talk) 02:33, 19 April 2010 (UTC)
Well, it's about Walter's distinction of "space-time formalism" (using an imaginery t) and a more pure "non-eucleadean style" (using a real t). So taking your approach, I would write:
It was noted by Minkowski (1907) that his space-time formalism represents a "four-dimensional non-euclidean manifold", in which a imaginary fourth coordinate was used. However, soon after the publication of Minkowski's writings, more radical steps to incorporate a non-euclidean style into Minkowskian space-time were undertaken, in which the fourth coordinate was defined as a real coordinate. Sommerfeld (1910) gave a trigonometric formulation, Alfred Robb (1911) introduced the concept of Rapidity as a hyperbolic angle to characterize frame velocity. Edwin Bidwell Wilson and Gilbert N. Lewis (1912) introduced a vector notation for spacetime. Émile Borel (1913) derived the kinematic basis of Thomas precession. These activities didn't represent any new physical insights, they merely elaborated on the implications of special relativity and the non-euclidean space-time of Minkowski. --D.H (talk) 07:07, 19 April 2010 (UTC)
Both versions sound OK. I have no preference. DVdm (talk) 10:40, 19 April 2010 (UTC)
Okay, I think I see what you're trying to say. I suggest a slight modification to your first couple of sentences, to make the (I think) intended meaning more clear:
It was noted by Minkowski (1907) that his space-time formalism represents a "four-dimensional non-euclidean manifold", but in order to emphasize the formal similarity to the more familiar Euclidean geometry, Minkowski noted that the time coordinate could be treated as imaginary. This was just a way of representing a non-Euclidean metric while emphasizing the formal similarity to a Euclidean metric. However, many subsequent writers have dispensed with the imaginary time coordinate, and simply written the metric in explicitly non-Euclidean form (i.e., with a negative signature), since it makes no difference to the content or results of the equations. It merely affects (slightly) their appearance. Today one still finds texts on special relativity that make use of an imaginary time coordinate, but most have adopted real-valued coordinates and a metric with negative signature. (The implications of the two different formalisms in the context of general relativity - as in the recent work of Hawking - are beyond the scope of this article.)
Does this accurately reflect your intended meaning?Urgent01 (talk) 14:52, 19 April 2010 (UTC)
Yes, thank you. --D.H (talk) 15:40, 19 April 2010 (UTC)

Hyperbolic geometry is *not* an elaboration of Minkowski geometry, but a different geometry. Different authors have used the phrase hyperbolic plane to refer both to (Lobachevskian) hyperbolic geometry and Minkowski geometry but these are two different geometries. Space-time is described by Minkowski space, but the velocity space is described by (Lobachevskian) hyperbolic geometry. There is also the Minkowski model in which hyperbolic space is represented by a hyperboloid in Minkowski space, but again just because there is a connection doesn't mean hyperbolic geometry is the same as, or similar to, or an elaboration of Minkowski geometry. Bethnim (talk) 12:58, 17 July 2010 (UTC)

There is no reason to remove all information regarding Varicak, Robb, etc. Can you explain on which secondary sources your edits are based? --D.H (talk) 16:07, 18 July 2010 (UTC)

The article suffers from a misunderstanding of relativity. The mathematics of relativity were off-the-shelf methods (see biquaternion#Algebraic properties). English readers had the advantage of exposure to William Kingdon Clifford, but his ideas were put into German literature by Corrado Segre and Theodor Vahlen so Göttingen was also exposed. Since relativity has turned into a huge popular and expert literature, the history naturally turns away from the mathematical substance of the subject, which is nothing less than the fusion of two of Kant's categories.Rgdboer (talk) 21:08, 17 July 2010 (UTC)

Relativity was based on the work of Lorentz, Larmor, Poincaré, Einstein etc. None of them (as far as I know) used Clifford's mathematics in their papers. --D.H (talk) 16:07, 18 July 2010 (UTC)

## Michelson-Morley experiment

We currently have:

Albert Abraham Michelson (1881) tried to measure the relative motion of earth and Aether (Aether-Wind), as it was expected in Fresnel’s theory, by using an interferometer. He could not determine any relative motion, so he interpreted the result as a confirmation of the thesis of Stokes. However, Hendrik Lorentz (1886) showed Michelson's calculations were wrong and therefore the experiment was not conclusive. This was admitted by Michelson himself.

and later in the same paragraph:

To clarify the situation, Michelson and Morley (1887) repeated Michelson's 1881-experiment. The now famous Michelson-Morley experiment did not detect the motion of the apparatus through the aether.

The implication of these two statement is that Michelson's calculations in the Michelson-Morley experiment were wrong and the conclusions therefore unjustified. Martin Hogbin (talk) 09:15, 19 April 2010 (UTC)

I thought it's clear that Michelson corrected the calculation in 1887, but here's another formulation: Albert Abraham Michelson (1881) tried to measure the relative motion of earth and Aether (Aether-Wind), as it was expected in Fresnel’s theory, by using an interferometer. He could not determine any relative motion, so he interpreted the result as a confirmation of the thesis of Stokes. However, Hendrik Lorentz (1886) showed Michelson's calculations were wrong and that he overestimated the accuracy of the measurement. This together with the large margin of error made the result of Michelson's experiment inconclusive....To clarify the situation, Michelson and Morley (1887) repeated Michelson's 1881-experiment, whereby they corrected the former errors of calculation, and they substantially increased the accuracy of the measurement. This now famous Michelson-Morley experiment again yielded a negative result, i.e., no motion of the apparatus through the aether was detected. --D.H (talk) 16:06, 19 April 2010 (UTC)

## Ruđer Bošković

Should Ruđer Bošković be mention in the article? --J. D. Redding 11:15, 11 December 2010 (UTC)

Because, according to Leland I. Anderson, Tesla said in an unpublished interview that Bošković created relativity 200 years before Einstein? Sounds a bit far-fetched (and second-hand hear-say) to me. If there is another source besides this one, perhaps. But I don't think this is notable. The remark is (perhaps) notable in the article Ruđer Bošković, but not here, I.M.O. DVdm (talk) 12:02, 11 December 2010 (UTC)
There's more about him, Bošković, than that ... but will list some references here later. --J. D. Redding 12:16, 11 December 2010 (UTC) [ps., seems that Bošković and Einstein have some crossover in history ...]
The influence of Bošković on special relativity may have come about in two ways. Firstly his ideas may have influenced Mileva Marić, the first wife of Einstein who discussed the concept of relativity with Einstein at an early stage. Secondly he influenced Vladimir Varićak, the originator of the hyperbolic theory of special relativity. Varićak made a special study of the work of Bošković and brought to light an early paper of his which had ideas close to those of relativity.JFB80 (talk) 20:11, 19 March 2012 (UTC)

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## MacCullagh

It might be possible to include James MacCullagh in this article. — Preceding unsigned comment added by 86.148.132.50 (talk) 14:30, 31 July 2012 (UTC)

## Acceptance of special relativity

Some recent anonymous edits have left this section confusing and misleading. Roger (talk) 01:39, 22 July 2014 (UTC)