Wednesday, May 31, 2017

Einstein was not the aether slayer

A anonymous commenter repeats the belief that credits Einstein for abolishing the aether:
Once Einstein's relativity theory of popularized by Minkowski, many papers were written, and references to Einstein (and Lorentz) were abundant. For example, in 1910, Wilhelm Wein proposed Lorentz and Einstein jointly for the Nobel prize for relativity. Einstein was famous among physicists as the originator of special relativity and the "ether slayer" long before he became a popular celebrity. Poincare's paper was nearly forgotten (Pauli had to be prompted by Klein to mention it in a footnote in his 1921 encyclopedia article) until the 1950's when historians of science started to notice it.
The notion of Einstein as an "ether slayer" (or aether slayer, in the old-fashioned spelling) is a widespread misconception. To show how wrong this is, I repost a 2011 article that quotes what Lorentz, Einstein, and Poincare actually said about the aether.

There are many claims [in the Relativity priority dispute article on Wikipedia] that Lorentz and Poincare clung to a stationary aether, while Einstein abolished it. It is much more accurate to say that Lorentz and Einstein had the same beliefs about the aether, and Poincare abolished it.

Lorentz's 1895 paper says, after a discussion of previous aether theories:
It is not my intention to enter into such speculations more closely, or to express assumptions about the nature of the aether. I only wish to keep me as free as possible from preconceived opinions about that substance, and I won't, for example, attribute to it the properties of ordinary liquids and gases. ...

That we cannot speak about an absolute rest of the aether, is self-evident; this expression would not even make sense. When I say for the sake of brevity, that the aether would be at rest, then this only means that one part of this medium does not move against the other one and that all perceptible motions are relative motions of the celestial bodies in relation to the aether.
Einstein's 1905 paper only says this about the aether:
The introduction of a “luminiferous ether” will prove to be superfluous inasmuch as the view here to be developed will not require an “absolutely stationary space” provided with special properties, nor assign a velocity-vector to a point of the empty space in which electromagnetic processes take place.
So Lorentz said that he was not expressing assumptions about the aether, and Einstein said that the introduction of aether was superfluous to his presentation. Lorentz said that the absolute rest of the aether makes no sense, and Einstein said that absolutely stationary space was not required.

In the three years after 1905, there is no record of Lorentz or Einstein expressing any disagreement about the aether, or of anyone else finding any such difference. Their theory was called Lorentz-Einstein theory. After 1908, the Poincare-Minkowski spacetime approach became popular, and the Lorentz-Einstein theory was obsolete.

Poincare wrote:
Whether the ether exists or not matters little - let us leave that to the metaphysicians; what is essential for us is, that everything happens as if it existed, and that this hypothesis is found to be suitable for the explanation of phenomena. ... while some day, no doubt, the ether will be thrown aside as useless. [1889]

There is no absolute space, and we only conceive of relative motion; and yet in most cases mechanical facts are enunciated as if there is an absolute space to which they can be referred. 2. There is no absolute time. When we say that two periods are equal, the statement has no meaning, and can only acquire a meaning by a convention. [1901]
It is very strange that anyone would attach such great importance to the aether, when it played no part in Poincare's theory.

See also this 2012 post where I discuss some confusing Einstein writings about the aether in 1907 and 1909.


  1. "Lorentz said that the absolute rest of the aether makes no sense, and Einstein said that absolutely stationary space was not required."

    That's a complete mis-reading of Lorentz. He was saying it's meaningless to talk about the ether being at absolute rest, because he was a Galilean relativist, but he unwaveringly asserted that the ether has a definite state of motion, and it is the seat of electromagnetic fields, etc. Einstein, in contrast, unequivocally declared the ether concept to be superfluous, surely influenced by his previous paper, completed just weeks before, on the photo-electric effect, in which EM energy propagates inertially more like a ballistic theory in vacuum than a wave theory.

    The papers of Lorentz and Poincare, both before and after 1905, continue to refer to the ether, but totally absent from Einstein's writings and those of the growing number who adopted his new kinematics based on the inertia of energy.

    "In the three years after 1905, there is no record of Lorentz or Einstein expressing any disagreement about the aether..."

    Einstein and Lorentz didn't correspond at all during those few years, so your comment is meaningless. Even for the people that did correspond with Einstein during those early years, (Planck, Laue, Laub, Wein, Stark, etc) there was a slow process of assimilating the significance of Einstein's ideas. Even in 1907 Planck writes to Einstein and refers to "the absolute vacuum (free ether)". Many in the older generation never did completely stop talking in terms of the ether. Once they began to correspond, Einstein and Lorentz had much to say to each other on the subject. Lorentz gave his reasons for disagreeing with Einstein that the luminiferous ether was superfluous, and Einstein re-iterated his reasons for thinking that it was superfluous.

    "After 1908, the Poincare-Minkowski spacetime approach became popular, and the Lorentz-Einstein theory was obsolete."

    That's ridiculous. You're confusing the physical theory with a convenient formalism. To this day we sometimes use the 4D formalism and sometimes the 3+1 formalism, but it's the same physical theory discovered by Einstein, founded on the electro-dynamical theory of Lorentz.

    "It is very strange that anyone would attach such great importance to the aether, when it played no part in Poincare's theory."

    To the end of his life Poincare was writing about a non-viscous ether fluid - in Galilean space and time - with the properties necessary to explain the apparent Lorentz invariance of phenomena. He was also deprecating the spacetime "convention" of Einstein and his followers.

  2. I am not sure how later views are relevant. Einstein's entire knowledge of Lorentz's views might have been only that 1895 paper, since you argue he didn't know about the 1904 paper, and maybe not the 1899 paper either. If Einstein wanted to stake out some new view of the aether, he would need to say so in that 1905 paper. But Einstein's 1905 paper takes a view of the aether that is nearly identical to what is written in Lorentz's 1895.

    You say that I am mis-reading Lorentz, because of other views that Lorentz was known to have. Even if you are right about that, maybe Einstein mis-read Lorentz the same way. There is a striking similarity between what Lorentz wrote about the aether in 1895 and what Einstein wrote in 1905. There is little reason to believe that Einstein was trying to say anything different from what Lorentz said in 1895.

    Maybe Lorentz and Einstein did not correspond directly, but they did describe their differences in published works soon after 1905. Lorentz described Einstein in his 1906 Columbia U lectures. Lorentz credited Einstein with noticing that the inverse to a Lorentz transformation was another Lorentz transformation. Einstein wrote a 1907 survey, and said that the main difference was recognizing that "local time" was the same as locally-observed time.

    These are fairly trivial differences. Lorentz probably did know these things. If he didn't, Poincare certainly included these things as being parts of Lorentz's theory.

    The idea that there were major differences between Lorentz and Einstein was a myth that was invented years later.

  3. Some relevant background info was typed into the comments of the "Poincare is Copernicus" post, but seem to have gotten blocked. So I'll just mention that Lorentz's 1895 said that to account for Michelson-Morley "one would have to imagine that the motion of a solid body through the resting ether exerts upon the dimensions of that body an influence which varies according to the orientation of the body..." Likewise in his 1904 he still talks about the ether, whereas in Einstein's 1905 he does not invoke the ether at all, except to say it is a superfluous concept. You say if Einstein wanted to stake out some position about the ether he would have said something... but he DID. You can even find this in his private correspondence going back to 1899 when we wrote that he had become convinced that no physical meaning can be associated with the word "ether".

    To say that noticing the reciprocity of Lorentz transformations, and that the "local time" was actually the time of the inertial coordinate systems, were "fairly trivial differences" is astonishing. These are the very keys to the transition from the 19th century ether-based physics to the symmetry-based modern physics. And both were entailed by Einstein's positivist rejection of the ether, which is why he became the darling of the early logical positivists.

    The profound shift from the Lorentzian to the Einsteinian point of view was not a myth. The significance of this shift was shown more and more with the passing years, not only with the creation of general relativity, but also Dirac's relativistic quantum mechanics.

  4. That Lorentz quote is just saying that the motion causes a contraction everywhere, ie, throughout the aether. There are physicists today who use synonyms for the aether, such as spacetime or quantum vacuum. Einstein himself once said general relativity requires an aether. Unless you are talking about some particular property, the aether is just a figure of speech.

    The reciprocity and local time were important, but not big leaps from what Lorentz said. Poincare seems to have made these deductions without comment. Einstein and Minkowski later made claims about this, but Poincare was earlier. I believe I read somewhere that Lorentz got the Nobel Prize in 1902 and Poincare's recommendation for him particularly praised his ingenious concept of local time.

    Physicists only later thought there was a profound shift to the Einsteinian point of view because Poincare and Minkowski were dead.

  5. Lorentz is self-avowedly referring all motions to the putative unique rest frame of the ether. This is the crucial distinction with Einstein's later remarks (at Leiden, to please Lorentz) that we could use the word ether for spacetime, but only with the understanding that it has no rest frame, which distinguishes it fundamentally from Lorentz's ether. This was "the step", depriving the ether of its last mechanistic attribute, that of having a definite rest frame.

    It isn't just a figure of speech. The difference between (1) conceiving of the ether (as Lorentz and even Poincare did) as defining a unique rest frame in Galilean space-time, albeit undetectable, for the electromagnetic fields that were coincidentally Lorentz invariant, and (2) regarding the vacuum as truly empty and regarding the fields as energy with their own inertia and momentum flows in inertial coordinate systems related by Lorentz transformations, is enormous. Making this step was the discovery of special relativity.

    Lorentz's "ingenious concept of local time" is firmly in (1), not (2).

    "Physicists only later thought there was a profound shift to the Einsteinian point of view because Poincare and Minkowski were dead."

    That's just crazy talk. Again, Max Born was Minkowski's assistant and they had made a special study of the works of Lorentz, Poincare, and others. Then in 1907, they finally read Einstein's 1905 paper (in An der Phy, the most prominent German physics journal, which belies your notion that everyone was instantly familiar with every published paper back then), and the simple reasoning from basic ideas about the meanings of our measures of space and time was a revelation to them.
    "Read Einstein's paper! A new Copernicus is born!" Your ideas are simply disconnected from the facts.

    When Lorentz says explicitly he is talking about motions relative to the rest frame of the ether, you say Oh, that's just a figure of speech, he wasn't really talking about an ether. And when Einstein explicitly says he is NOT referring anything to an ether, which he says is a superfluous concept, you say Oh, he was really talking about an ether, just like Lorentz. It seems clear that, for whatever reason, you have a strongly biased and distorted view of this subject, and your polemics are specious.

  6. Lorentz and Poincare usually said that the aether is unobservable, and that it does not make any difference whether you believe in it or not. Lorentz said in 1910 that it does not matter if you accept an unobservable preferred rest frame. He said "To which of both ways of thinking one adheres to, we can leave to the judgment of each individual." In 1914 he said "it makes no great difference, whether one speaks of vacuum or aether." Quotes are here.

    If Einstein disagreed with this, then Einstein was the one who was wrong. Most cosmological models today have a preferred rest frame, and no one thinks that there is anything wrong with it.

    Saying that there no preferred frame may be a useful pedagogical device, but it is not, and has never been, part of relativity theory. The correct statement is that any inertial frame can be transformed into any other, preserving the laws of physics.

    You give examples of physicists who were very impressed with relativity theory. Yes, Born and Witkowski were very excited to learn about it in Einstein's paper. But they do not credit Einstein over Lorentz and Poincare. Saying "Read Einstein's paper" means that the paper is a good exposition of the theory, but not that the paper is original. There is no reason to believe that they even had any opinion about the originality of the paper. Saying "A new Copernicus is born!" is not saying that Copernicus was original or that Einstein was original or that Einstein was the new Copernicus. It only means that there is an exposition of a theory with a different view from what is usually taught.

    Nobody credits Einstein over Lorentz and Poincare with the sort of language or reasoning you use. No one says: "Lorentz and Poincare wrote some interesting papers, but they failed to make the crucial distinction or step that makes relativity a great theory". That rationale for crediting Einstein is a pure fiction that was invented many years later.

    1. Einstein was just wrong! We have the casimir effect, metric tensor, vacuum energy, quantum mechanics, gravity waves... he was on the wrong track with just about everything. Even GR can be described n FLAT SPACE with geometric algebra. Even his theory of Brownian motion wasn't original and has been superseded by better approaches that don't break down. The man is a myth!

  7. "Lorentz said in 1910 that "To which of both ways of thinking one adheres to, we can leave to the judgment of each individual."

    Right, and the two ways were Einstein's way or Lorentz's (and Poincare's) way. So Lorentz is saying it matters not whether one thinks in Ptolemy's way or Copernicus's way, it's purely up to the individual. Well, it's true that someone can choose to describe things in terms of an earth-centered coordinate system, but it's wrong to say that the difference doesn't matter. It would never have been possible to discern Kepler's laws and hence Newton's physics in the Ptolemaic way of thinking.

    "Most cosmological models today have a preferred rest frame..."


    "Saying that there no preferred... The correct statement is..."

    You do realize that your statements (one that you say was never part of relativity, and the other that you say is the essence of relativity) mean the same thing, right?

    "But they do not credit Einstein over Lorentz and Poincare."

    I don't think you read my post. Again, Born, et al, had made a special study of all the authors on the subject, including Lorentz and Poincare. Then they belatedly read Einstein's paper, and "the reasoning was a revelation to me... it had a stronger effect on me than any other scientific experience". How can you say this is not saying Einstein's paper had a greater effect than Lorentz's and Poincare's?

    I'll pass over the (frankly sad) verbal contortions attempting to suppress your cognitive dissonance over the meaning of "Read Einstein's paper! A new Copernicus is born!", and your purported conclusion that no one said Einstein had done something that Lorentz and Poincare did not.

  8. I looked for some Born relativity papers, and found this on rigid electrons in 1909 and 1910. He relies heavily on Minkowski. He also cites Einstein. He mentions Lorentz but does not cite any of his papers. He does not mention Poincare.

    So Born may have never understood what Poincare had done, and might have used secondary sources for Lorentz.

    Yes, one can use an earth-centered coordinate system or a sun-centered one, and one might be more useful for certain purposes. It was Poincare who made the analogy of Ptolemy/Copernicus to two views of relativity, not Einstein. That is one area where Poincare went beyond Lorentz.

    I guess you are agreeing that it was not wrong if Lorentz suggested that there could be an unobservable preferred frame. If you are saying that there is an advantage to a different point of view, then that is what Poincare said in his 1905 paper, but Einstein failed to say.

  9. Neither Lorentz nor Poincare described the Copernican view. That is what Poincare failed to do in his 1906 paper (please keep the dates straight), and what Einstein succeeded in doing in his 1905 paper.

    Poincare's 1906 just repeats Lorentz's comments about assuming inertial forces transform in a way that perfectly disguises the ether frame, but Einstein's 1905 introduces the Copernican view that inertial coordinate systems are actually related by Lorentz transformations. This led to the inertia of all forms of energy (not just electromagnetic) and hence the momentum flows of all energy fluxes, which disproved Poincare's life-long belief that Lorentz's theory violates conservation of momentum for palpable entities.

    Again, saying that Born (Minkowski's assistant) never understood what Poincare had done is obviously self-defeating for your thesis, on multiple levels.

    Born was referring to papers in the years leading up to 1905, not 4-5 years after. Born's papers in the later years did lead to the concept of Born rigidity. He would have had no reason to refer to Poincare for anything in these papers.

  10. Saying Einstein 1905, Poincare 1906, makes it sound as if Einstein wrote his paper before Poincare. The complete dates are that Einstein's paper was received June 30, and published September 26, 1905, in the big German journal. Poincare's paper was in two parts: a 5-page abstract that was published June 5, 1905 by the French Academy, and a 50-page full version that was received July 23, 1905, printed December 14-16, 1905, and bearing a publication date of January 1906 in the Palermo journal. So Einstein could have read Poincare's abstract, but Poincare could not have read Einstein's paper.

    If you want to argue by authority, there are lots of big-shot brilliant physicists today who over-credit Einstein for relativity. Normally that would be pretty convincing, except that they are not historians, have not read the original papers, and are relying on textbooks that I can show to be wrong.

    If Born or some modern scholar or anyone were to explain how Einstein had some insight that was superior to Lorentz and Poincare, then I would have to consider that. There are some historians who credit Einstein for oddball reasons, and I have discussed such arguments on this blog. But Born gives no argument, and shows no sign of even having read Poincare.

  11. Here is a later Born quote, where he says he spent 3 years trying to convince Whittaker to credit Einstein over Lorentz and Poincare! Born says Whittaker "insisted that everything of importance had already been said by Poincaré, and that Lorentz quite plainly had the physical interpretation." Born tried to badmouth Lorentz, and cite Pauli, but it didn't work. Of course not. If Whittaker read Poincare and could plainly see that everything of importance is there, why would he care about Pauli's opinion many years later?