Talk:Special relativity/Archive 3

message: In the statement of the second postulate, I have removed the sentence: "This postulate has been verified experimentally." For my reasons, I will quote what I wrote on Wikipedia:Featured article candidates/Special relativity:
:"In general experiments don't and can't verify theories, they can only falsify them.  Repeated attempts to falsify the predictions of a theory constitute not proof of, but evidence for a theory. In the case of special relativity there is a considerable body of experimental evidence consistent with the predictions of special relativity.  There might be (and some claim there are) other theories which are also consistent with this body of experimental evidence.  To say that the second "postulate has been verified experimentally" is sloppy and misleading at best. It should be removed, in favor of a section titled something like "experimental evidence for special relativity". Paul August 23:00, Dec 11, 2004 (UTC)"
As I said above, someone needs to write a section on the experimental evidence in support of this theory. Paul August 15:21, Dec 15, 2004 (UTC)
      A Wee Bit of Free Advice for Anyone Who
      Wishes to Contribute to the Proposed
      SR Experimental Evidence Section
:All of the results of special relativity (SR) are explicitly given via its math, aka its Lorentz transformation equations.
:Since these equations cannot be derived sans the use of at least two clocks in each frame, all of SR's math (and thus all of SR itself) is dependent upon Einstein's definition of clock synchronization and its inherent lack of absolute simultaneity.
:Thus, all of the results of SR are given by man, not nature, so none are laws of nature, and all of SR's two-clock results are incorrect due to the absence of absolute simultaneity.
:Therefore, all of the results of SR are either circular or incorrect. 
:For example, its one-way light speed invariance is fully circular because it is given at the start via a mere definition from man.
:For another example, its "length contraction" is an incorrect result due to the SR observer's inability to pin down (or locate) the endpoints of a passing rod absolutely simultaneously.
:For yet another example, "time dilation" is an incorrect result again due to SR's lack of absolute simultaneity. (A passing clock is always compared with two of Einstein's absolutely asynchronous clocks in a given frame, with the incorrect result that the passing clock has "slowed.")
:Here is a simple proof that SR does not even pertain to intrinsic or actual clock rhythms: Although a single, passing, steady-velocity atomic clock cannot possibly have more than one internal atomic rhythm, SR's observers in various frames find that the clock "runs at many different rates." (And similar proofs apply to SR's "length contraction" and its "momentum variance.")
:It is not possible to experimentally test the sole basis of SR (aka the second postulate) because this postulate gives its result at the start. In other words, if one manually forces one's clocks to obtain one's prechosen one-way light speed invariance/isotropy, then of course one's clocks will obtain it. (They will also obtain the relativistic results, such as SR's "time dilation" and "length contraction.")
:To top it off, SR does not physically explain the Michelson-Morley experiment (whereas Lorentz's theory does). 
:Cadwgan Gedrych 19:41, 15 Dec 2004 (UTC)
thread_title:  Removed claim of experimental verification for 2nd postulate 

message: Cadwgan, quite rightly (if I understand him correctly), points out that the postulates as they are often stated (including in Einstein's 1905 paper, as well as in many textbooks) contain a certain circularity: the speed of light is postulated to be constant in all frames, but velocity is measured by times at different points in a frame, and times at different points were synchronized by Einstein by assuming that the speed of light is constant.  On the other, hand, modern papers (e.g. Wolf and Gerard, above) circumvent this difficulty by rephrasing the question as one of the equivalence between Einstein's light-pulse synchronization and classical slow clock transport.
Still, it is an interesting question — it would indeed be surprising if there were a new objection to relativity on purely philosophical grounds, and in fact Cadwygan's argument turns out to be quite old.  So old (nearly a century), in fact, and disposed of so long ago, that I had to spend some time in the library and look through a couple of dozen books to find any reference to it at all.
Early writers, including Einstein himself, were apparently content to state that the theory was internally consistent and leave it at that, a treatment that was carried over into a number of textbooks (though most don't even broach the subject of circularity).  However, the question was apparently debated in the first half of the 20th century, and the conclusion was the same as the one I came to above: there is an implicit postulate that Einstein's light-based definition of measures of length and time at different points must be consistent with the pre-relativistic definition via slow transport of "clocks" and "rulers".  This postulate can be and has been tested against experiment (such as in the Wolf and Gerard paper, above).
This resolution is discussed, for example, in a textbook by Born and another by Pauli, although the clearest discussion I found was in a ~1950 textbook by a French experimental physicist (whose name escapes me).  I have a long list of interesting quotes on the subject in my office, and perhaps tomorrow I will write up a short article for Wikipedia that the present page can link to.
—Steven G. Johnson 06:33, Dec 16, 2004 (UTC)
Steven noted:
::"... modern papers (e.g. Wolf and Gerard, above) circumvent this difficulty by rephrasing the question as one of the equivalence between Einstein's light-pulse synchronization and classical slow clock transport."
As I have said, rephrasing the question does not circumvent the difficulty.
Here is the relevant equation:
:::the 2nd postulate ≠ slow clock transport
Steven further noted:
::"Still, it is an interesting question — it would indeed be surprising if there were a new objection to relativity on purely philosophical grounds, and in fact Cadwygan's argument turns out to be quite old. So old (nearly a century), in fact, and disposed of so long ago, that I had to spend some time in the library and look through a couple of dozen books to find any reference to it at all."
I have made no mere philosophical objection, and my objection was not disposed of long ago (or even yesterday).
The only way to dispose of my objection is to explicitly admit that special relativity does not call for invariance/isotropy in the case of light's one-way speed between two same-frame clocks, and that this is not given via definition prior to the "measurement," making it purely circular, trivial, and not given by nature (so it is not a law of nature).
And while you are at it, please prove that Einstein's one-way, two-clock invariance is the correct result. (I have already proved experimentally that it is not, but this simplest of experiments was simply ignored, which usually means "it is correct.")
Also ignored was my citation of the 1992 paper which proved that invariance and isotropy are not necessarily the results of the two-clock, one-way light speed measurement.
Cadwgan Gedrych 16:18, 16 Dec 2004 (UTC)
replies: text: Where's the proof you're referring to here?  Is it the one where you incorrectly analyzed a relativistic situation using classical mechanics? --Carnildo 20:29, 16 Dec 2004 (UTC)
replies: text: http://www.bartleby.com/173/7.html
All I am looking for is one brave soul who will show this derivation.
Cadwgan Gedrych 21:41, 16 Dec 2004 (UTC)

text: No, I will not.  There is no point in it, as you have demonstrated that you will not listen.  If you had read that very work you cite beyond the point at which Einstein provides that equation, you would have seen Einstein show that the equation is incorrect.  Likewise, if you had read what I wrote under the heading of "Second Postulate", you would have seen me pointing out the inaccuracies.  I will not debate this with you any further. --Carnildo 22:00, 16 Dec 2004 (UTC)
thread_title:  On the "circularity" of the second postulate 

message: I removed the following sentence from the special relativity section of the Theory of relativity article:
'While developing this theory, Einstein wrote to his wife Mileva about "our work on relative motion".'
While it doesn't seem to belong there (that page seems to be just some kind of pseudo-disambig), mayhaps it should belong in this article? Intangir 20:43, 6 Jan 2005 (UTC)
replies: text: We'd need to know the context for the statement to make sense.  Who does "our" refer to? --Carnildo 00:11, 7 Jan 2005 (UTC)
replies: text: Good question. I'm not sure, I have a geometry/history book, "Euclid's Window" which mentions that correspondence blurb. The author seems to think 'our' refers to Albert and Mileva but more or less dismisses the notion that it was really a collaborative effort of the two of them. I have no clue as to it's significance, but someone who edited Theory of relativity felt it was at least worthy of mentioning. Intangir 01:28, 7 Jan 2005 (UTC)
thread_title:  "our work" 

message: *Dynamic Universe (DU) - a highly promising new model of the universe developed by Dr. Tuomo Suntola
I removed this link from the article.  From what I can find on the web, it is a replacement for GR that is based around the concepts of absolute space and absolute time.  As far as I can tell, very few people take it seriously, as it hasn't yet been verified that it explains everything GR does, much less make new, testable predictions (in particular, one back-of-the-envelope calculation shows it getting the orbit of Mercury wrong; another says that it doesn't handle the orbital decay of binary pulsars). --Carnildo 00:41, 4 Feb 2005 (UTC)
thread_title:  "Dynamic Universe" 

message: The Special Relativity page is excellent.  However, would you be in favour of a page called Relativity for Beginners that treats the subject at a simpler level? The subject has (at least) three levels of treatment: beginners, undergraduate, graduate. The maths and reasoning in the current article is junior undergraduate level or senior school maths/physics specialist level. A beginners text might be linked as such from the current main text. Loxley 20:32, 7 Mar 2005 (UTC)
thread_title:  Special Relativity for Beginners 

message: at end of "Motivation for the theory..." "SR can correctly predict the behaviour of accelerating bodies in the presence of a constant or zero gravitational field" --- isn't saying "or zero" redundant? Luke Stodola 22:03, 14 Mar 2005 (UTC)
thread_title:  nitpicking 

message: I took the liberty of moving all talk from before this month to an archive, see Talk:Special_relativity/Archive1.  It seemed things were getting a little bloated around here.  Terry 06:57, 20 Mar 2005 (UTC)
thread_title:  Archive created 

message: In the interests of NPOV and all, and given all the previous discussion on this talk page, I have opened up
a section on alternatives to special relativity at Status_of_special_relativity#Alternatives_to_special_relativity.  As you see it is extremely rudimentary at present, but perhaps some people here would have an interest in expanding it.  I might also suggest that discussion of these theories (or anything else relating to the theoretical, experimental, or cultural
status of special relativity) be sent to Talk:Status_of_special_relativity.  Terry 07:10, 21 Mar 2005 (UTC)
thread_title:  Alternatives to SR