Max Born was Minkowski’s assistant, and had studied the papers of Lorentz and Poincare, but never heard of Einstein until 1907, when Professor Loria from Crackow came to Gottingen for a visit, and was told by Professor Witkowski “A new Copernicus is born! Read Einstein’s paper!”. Loria and Born went to the library, found a copy of vol 17 of the 1905 An der Phy, and read the paper. Born later wrote: “Although I was quite familiar with the relativistic idea and the Lorentz transformations, Einstein’s reasoning was a revelation to me… which had a stronger influence on my thinking than any other scientific experience”.A Copernicus analogy for relativity was first used in Poincare's long 1905 relativity paper:
We cannot be satisfied with simply juxtaposed formulas which would agree only by a lucky stroke; it is necessary that these formulas are so to speak able to be penetrated mutually. Our mind will not be satisfied before it believes to see the reason of this agreement, at the point where it has the illusion that it could have predicted it.What is Poincare saying here?
But the question can still be seen form another point of view, which could be better understood by analogy. Let us suppose an astronomer before Copernicus who reflects on the system of Ptolemy; he will notice that for all planets one of the two circles, epicycle or deferent, is traversed in the same time. This cannot be by chance, there is thus between all planets a mysterious binding.
But Copernicus, by simply changing the axes of coordinates regarded as fixed, destroyed this appearance; each planet does not describe any more than only one circle and the durations of the revolutions become independent (until Kepler restores between them the binding which was believed to be destroyed).
Here it is possible that there is something analogue; if we admit the postulate of relativity, we would find in the law of gravitation and the electromagnetic laws a common number which would be the speed of light; and we would still find it in all the other forces of any origin, which could be explained only in two manners:
Either there would be nothing in the world which is not of electromagnetic origin.
Or this part which would be, so to speak, common to all the physical phenomena, would be only apparent, something which would be due to our methods of measurement. How do we perform our measurements? By transportation, one on the other, of objects regarded as invariable solids, one will answer immediately; but this is not true any more in the current theory, if the Lorentz contraction is admitted. In this theory, two equal lengths are, by definition, two lengths for which light takes the same time to traverse.
Perhaps it would be enough to give up this definition, so that the theory of Lorentz is as completely rejected as it was the system of Ptolemy by the intervention of Copernicus. If that happens one day, it will not prove that the effort made by Lorentz was useless; because Ptolemy, no matter what we think about him, was not useless for Copernicus.
Lorentz invented relativity as an electromagnetic theory. Poincare showed in this paper that the same principles could be applied to gravity and everything else.
There are two obvious explanations for this coincidence: (1) gravity and everything else have an electromagnetic origin; or (2) relativity is really a theory about our methods of measurement.
These two explanations are as different as Ptolemy and Copernicus.
Lorentz tried to explain everything in terms of electromagnetism. Poincare was not saying that Lorentz was wrong or useless, but rather claiming to have a distinctly superior interpretation of relativity.
The latter explanation is what is now accepted. The core of relativity is that it is a spacetime theory, and it redefines what we mean by measuring space and time.
Einstein does not say anything like this until several years later. Poincare was the first to make relativity a spacetime theory, and Minkowski popularized it in 1908.
Update: I further explain the Poincare Copernicus analogy in the comments below.
Roger,
ReplyDeletemeasuring space and time is not the problem with relativity. The problem is orienting time orthogonally to x,y, an z spatially as if it was another spatial dimension, and then claiming it means something. It does not.
Time is not in an orthagonal relationship with spatial dimensions in any way, and comparing three dimensional space to timeless gridded rubber sheets where nothing can interact (as per the model) makes no sense whatsoever unless you are somehow viewing the gridded space time from a three dimensionally external to the model (which is where exactly??), and suggesting there is a 'down' gravitationally speaking in order to pretend the model represents an actual mechanism for how gravity works or how things can move in relation to the modeled gravity. Space time is a contrivance to side step the issue Einstein did not want to deal with, that we have no idea of how gravity affects mass, we only know that it does affect mass.
"Space time is a contrivance"
DeleteIt's mathematics that is a contrivance. Poincare was right that relativity can even be conceived of in flat space. See David Hestenes and geometric algebra.
"Lorentz invented relativity as an electromagnetic theory. Poincare showed in this paper that the same principles could be applied to gravity and everything else."
ReplyDeleteCouple of errors: (1) Lorentz showed in 1904 how Lorentz invariance could apply to everything (except gravity), not just electromagnetism, (2) Poincare didn't add anything of substance to Lorentz, except to correct the charge transformation, and Poincare's idea that gravity could be made compatible with special relativity turned out to be wrong.
"Poincare was not saying that Lorentz was wrong or useless, but rather claiming to have a distinctly superior interpretation of relativity."
No, he says that perhaps someone will come along some day and give a coherent account of all these phenomena in terms of some new kinematic framework. Actually, in a paper published the previous year BEFORE Poincare's paper appeared, someone had already done just that.
"The core of relativity is that it is a spacetime theory, and it redefines what we mean by measuring space and time."
Right. This is described with amazing fullness and maturity for the first time in Einstein's 1905 papers, in the year preceding the publication of Poincare's Palermo paper.
"Einstein does not say anything like this until several years later."
As Prof Witkowski said "Read Einstein's paper! A new Copernicus is born!" You should take his advice. Pay special attention to the Kinematical Part, but don' neglect the Electromagnetic part, because it includes the new dynamics as well.
"Poincare was the first to make relativity a spacetime theory..."
That's not entirely true. Physics has always worked in 4 dimensions, three space and one time. If you mean a transformation that mixes space and time coordinates, this was not Poincare's invention, it was being done by Larmor, Lorentz, and others around the year 1900. If you mean the recognition that the coordinate systems related by Lorentz transformations are actually the inertial coordinate systems, this was implicit in Lorentz's 1904, but by his own admission he didn't recognize it, and neither did Poincare, who even to the end of his life was still talking about the ether frame and violations of action-reaction and generally failing to grasp the dynamical basis of the relativistic kinematics. Lorentz, Minkowski, and everyone else (including Poincare, if Moszkowski's report is to be believed) all credited Einstein with "the step". That's why Born was speaking for his whole generation when he said reading Einstein's 1905 (even after reading Lorentz and Poincare) was a revelation, and had a greater effect on him than any other scientific experience.
You persist in arguing that Poincare did not understand relativity, even tho he got everything right ahead of Einstein. Now you say that when Poincare boldly claimed a new theory like Copernicus, and he was just predicting Einstein's paper!
ReplyDeleteI don't know anyone can believe anything so ridiculous. Can you give any other example, in the history of science, where someone said all the right things in a huge breakthru, and yet did not understand what he was doing?
Yes, Poincare's Palermo paper was published a few month's after Einstein's famous paper, but Einstein's library had a copy of Poincare's summary a couple of weeks before Einstein's submission. Poincare may have influenced Einstein, but there is no chance Einstein influenced Poincare.
Yes, Lorentz had the essence of relativity, and important early work was done by FitzGerald, Larmor, and others. Poincare advanced the theory in 1905 by making it explicitly a spacetime theory, adding gravity, and showing the covariance of Maxwell's equations.
I will address your other points in a separate post.
"You persist in arguing that Poincare did not understand relativity, even tho he got everything right ahead of Einstein."
ReplyDeleteBut Poincare didn't get everything right. In fact, he failed to get the single most important thing, which is that the inertia of energy implies that inertial coordinate systems are related by Lorentz transformations. To the end of his life, Poincare continued to say momentum conservation was violated unless we assign the missing momentum to the ether, which he rightly dismissed as cheating (since the ether is undetectable). He also consistently failed to grasp the full extent of the kinematic consequences of the Lorentz transformations.
"Now you say that when Poincare boldly claimed a new theory like Copernicus, and he was just predicting Einstein's paper!"
You are grossly misreading his words. He has not described a new kinematics based on a new understanding of the relationship between inertial coordinate systems, rendering all the relativistic effects trivial (as Einstein had done in his paper of the previous year), he merely comments that something analogous to Copernicus' revolution might occur, and Lorentz's theory would be overthrown as surely as was Ptolemy's, but Poincare surely never claimed to be overthrowing Lorentz's theory. You are falling prey to the tendency to retroactively view things, and read into them more than is really there. Poincare had most of the pieces of the jigsaw puzzle, but didn't put them together - something Einstein had already done.
"Can you give any other example, in the history of science, where someone said all the right things in a huge breakthru, and yet did not understand what he was doing?"
That's isn't what happened in this case. Poincare didn't say all the right things, he said some wrong things, and omitted many more things, and to the end of his life continued to espouse an etherist interpretation and the use of Galilean transformations for the true space and time.
"Yes, Lorentz had the essence of relativity..."
But you were saying Lorentz was Ptolemy, remember?
"Poincare advanced the theory in 1905 by making it explicitly a spacetime theory..."
He continued to espouse the ether, and even continued to argue that everything was electromagnetic. Any mathematician would see the invariants associated with the Lorentz transformations, the hyperbolic rotations, etc. Also, note that Einstein's 1905 said the LT's form a group, so it should be called the Einstein group, not the Poincare group.
"...adding gravity..."
He did not add gravity correctly. Gravity is incompatible with global special relativity.
"...and showing the covariance of Maxwell's equations"
Lorentz showed this in 1904, and Einstein showed it more simply in 1905. Crediting the to Poincare in 1906 is just silly.
Poincare very clearly says that his formulas have two interpretations: Lorentz's electromagnetic interpretation and a new one where the transformations would be due to our methods of measurement. The latter is another way of saying that it is a spacetime theory. Einstein says nothing like this.
ReplyDeleteYou say "Poincare surely never claimed to be overthrowing Lorentz's theory."
Poincare does say that in the latter interpretation, "the theory of Lorentz is as completely rejected as it was the system of Ptolemy by the intervention of Copernicus." He adds that Lorentz's theory would not be useless, just as Ptolemy's theory was not.
Again, Einstein says nothing like this, and does not reject Lorentz in any way.
The closest Einstein comes is to claim that he has a better understanding of the aether and local time, but he does that by misrepresenting Lorentz.
You keep saying that Poincare was wrong about things. Even if so, I am sure you know that Einstein was wrong about a few things also. But tell me this: Did Einstein ever point out any of these supposed Poincare errors?
Considering how aggressively Einstein tried to claim credit for himself, it is not plausible that he would have passed up an opportunity to show that he had some superior understanding of relativity to Poincare's.
As for the aether, I am sure you realize that relativity allows choosing a frame. Everyone chooses frames, including Einstein. Poincare sometimes called his frame the aether frame, or something like that. He also argued that the aether was undetectable. There is nothing incorrect about this. I guess you don't like his terminology, but there is nothing mathematically or physically wrong with his analysis.
I will address the Lorentz group separately.
You say "Poincare does say that in the latter interpretation, "the theory of Lorentz is as completely rejected as it was the system of Ptolemy by the intervention of Copernicus."
ReplyDeleteBut that is a lie. As you know very well, the quote is
"Perhaps if we were to abandon this definition [of
LENGTHS, not of time], Lorentz’s theory would be as fully overthrown as was Ptolemy’s system by Copernicus’s intervention. Should that happen some day, it would not prove that Lorentz’s efforts were in vain..."
I'm sorry, but it just isn't worth the effort to chase after you, correcting such blatant lies and mis-representations. Poincare has not described a new interpretation (and the hint he gave was wrong), he merely ruminates on the possibility of one. Saying it has something to do with how we measure things is a far cry from Einstein's 1905 paper founding special relativity.
I see it says "comment will be visible after approval". If this means censorship has been turned on, I'm out.
ReplyDeleteA couple of your comments got flagged as spam. I do not know why. I only censor spam, and I am glad to have someone prove me wrong about something.
ReplyDeleteI don't see you can say I was lying. I posted the whole quote. Go ahead and give me your own interpretation of it. When he says "explained only in two manners", isn't one of those manners like Ptolemy and one like Copernicus? Just what are those two manners, if you deny that Poincare described a new interpretation of relativity?
ReplyDeleteI realize that it appears that I turned on comment moderation just to block a comment accusing me of lying. No, that is not correct. Google hosts this blog, and I have comment moderation turned on only for older postings and what Google says is spam. Occasionally a legitimate comment gets flagged as spam, or I slow to approve a comment on an old post. But any non-spam comment to a recent post normally appears right away, with no moderation.
ReplyDelete> I don't see you can say I was lying. I posted the
ReplyDelete> whole quote."
The problem wasn't the original quote, it was the later mis-quote when you said Poincare said "the theory of Lorentz is as completely rejected as was the system of Ptolemy by the intervention of Copernicus." That's not what he said, and this isn't just a nit. Everyone knows Poincare (like several others) stood on the precipice of special relativity, and the question is, did he cross over? The actual quote shows that he did not even claim to have crossed over, but your mis-quote suggests that he was claiming to have found the Copernican model and over-thrown Lorentz's theory. I think it's important to not base our views on mis-quotes.
> Go ahead and give me your own interpretation of it.
My "interpretation" is just the literal one, which is the only one consistent with the contents of the paper. He notes that Lorentz's equations apply to electromagnetism, but in order to explain complete relativity Lorentz allowed for the possibility of other forces (and Poincare knew there must be other forces), and Lorentz assumed [not derived] that those other (unknown) forces are also Lorentz invariant so they propagate at c.
Now, Poincare scratches his chin and says this reminds him of how the constant "365 days" shows up in the descriptions of all the wandering patterns of the planets in Ptolemy's model. Hmmm... Maybe some say we will discover a way of looking at Lorentz's theory that makes the appearance of c in all these forces not just a coincidence, but a result of how we measure things. Maybe if we reject Lorentz's view that the length of an object is proportional to the time it takes for light to traverse it, would have such a new way. Hmmm... If that day ever comes, maybe Lorentz will be overthrown, etc.
Well, it should go without saying that comments such as this do not amount to a discovery of the kinematics of special relativity. Indeed, even the little hint about rejecting the light-based definition of distance was wrong. The key was to clearly identify Lorentz's auxiliary coordinates (including the auxiliary time coordinate) with the inertial coordinates, i.e., to completely discard the Galilean transformation and replace it with the Lorentz transformation for inertial coordinate systems. Neither Lorentz nor Poincare ever embraced this. Even at the end of his life, Poincare still regarded Einstein's (and Minkowski's) switch to a Lorentzian-based spacetime as just a convention, and not a very appealing one at that. Born reports that at the end of Lorentz's life he was still of the same opinion. It was psychologically very difficult for men of that generation to make "the step".
But why would Poincare say all that about a new Copernicus, unless he had some Copernicus-like theory in mind? I cannot make any sense out of your explanation (or any given by anyone else either).
ReplyDeleteAs I see it, when he says "give up this definition", he is referring to the definition of measurement by comparison to "objects regarded as invariable solids", or meter sticks. By "the current theory", he means his own Palermo version of relativity, where length is defined by time and c.
I realize that is not the most recent definition in the text, so the grammar is clumsy. But the previous paragraph is about giving up one definition in favor of a second definition, so when he then says "give up this definition", I think he means the former definition, not the latter.
Here is the distinction that I think he is making.
In the Lorentz/Ptolemy theory, moving meter sticks are contracted, and do not show their true length. They cannot be used in the simple measurement definition.
In the Poincare/Copernicus theory, moving meter sticks are not contracted. They just look shorter, due to our methods of measurement.
In the Lorentz/Ptolemy theory, the apparent contraction might be caused by distortions in the electromagnetic fields holding together the meter stick.
In the Poincare/Copernicus theory, the apparent contraction is something happening in spacetime itself, and not electromagnetism.
In short, the Lorentz/Ptolemy theory is an electromagnetism theory, and the Poincare/Copernicus theory is a spacetime theory.
Poincare goes on to give a 4D presentation of relativity, and the Lorentz symmetries applying to electromagnetism or gravity or presumably anything else.
Einstein does not make this distinction at all.
Not only does Einstein fail to make the Copernicus interpretation, he rejects it years later.
ReplyDeleteIn 1911 someone asserted that Lorentz and Einstein had different interpretations of the length contraction, and Einstein denied that there was any such difference.