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I have just been looking at the Dingle-McCrea debate, particularly McCrea's refutation, here it is:-

Dingle's example involved two pairs of synchronised clocks, in a state of uniform translatory motion.

  N--------------B  ---> velocity v
      A----------H  'stationary'

N+B is the 'moving system' and A+H is the 'stationary' system, no acceleration is involved.

Dingle defined Event 1, When B is adjacent to H.

At event 1, there are clock readings of B and H.

Then Dingle infers that at the moment of this event, A reads the same time as H (because A and H are synchronised).

McCrea said that Dingle was not allowed to say that A read the same time as H, because A was not _AT_ event 1, and it didnt matter that the two clocks were synchronised. To allow this would restore the notion of distant simultaneity. Therefore all of Dingle's results were meaningless, and there was no contradiction.

I would be interested to hear from the relativity crowd, whether they think McCrea's argument is valid. Is Dingle allowed to say what the time on clock A is, when B is adjacent to H? Swanzsteve 01:31, 6 August 2007 (UTC)

Which article do you refer to? McCrea's "refutations" were hardly relevant except for illustrating how much Dingle was misunderstood - he didn't understand what Dingle meant, as Chang explains (any sharp reader will see that the two were completely mis-communicating). Harald88 08:58, 6 August 2007 (UTC)

Sorry I should have said, this is from their exchange in Nature in 1967. I may be mistaken, but the impression I get is that McCrea's is the only refutation Dingle got which dealt with his actual example. Was McCrea correct when he said Dingle was not allowed to infer the time displayed by clock A when B and H were adjacent (A and H are sychronised in the 'stationary' system) ? Swanzsteve 13:43, 6 August 2007 (UTC)

Thanks. The way you present it, it sounds as if they simply misunderstood each other due to lack of precision ("when" is relative), as so often happens in such debates. I should have those articles somewhere (hardcopy). I'll have a look at them later if I can find them back. Harald88 13:58, 6 August 2007 (UTC)

Dingle spoke unpalatable truths. That is why we are witnessing so many fanatical editors crowding in to block him out.

One really needs to enquire into why these editors are so keen to stand in front of Dingle, blocking him out, and claiming that he was wrong. They are clearly trying to hide something.

They are motivated by alot more than merely wanting to present the current stae of human knowledge. (217.43.69.32 10:17, 6 August 2007 (UTC))

(Swansteve, I took the liberty to move your question to the proper section. Hope you don't mind. - Dvdm)

I dont want to get too far ahead but it appears from the lack of an answer that McCrea made a mistake in his refutation, and never answered Dingle's question, are we allowed to put in the article that the most famous refutation of Dingle's argument contains a trival error by McCrea? Swanzsteve 13:56, 6 August 2007 (UTC)

That sounds like more WP:OR to me, and "mistake" is a big word. :-))

If you know a quality source that draws that conclusion, then we may cite that source as "according to" so-and-so. At least one referenced quality source expressed that McCrea misunderstood Dingle, so you may quote from that. Harald88 14:25, 6 August 2007 (UTC)

Here's a quote of Chang that summarizes it nicely: "it seems that many physicists didn't even understand what Dingle was trying to say". [... ] The controversy ended with neither a consensus nor a clear refutation of either side." Harald88 15:37, 6 August 2007 (UTC)

Swanzsteve, please keep your McCrea stuff in the previous section. Although related, this section can stand on its own. See my remark below. Thanks. DVdm 14:04, 6 August 2007 (UTC)

With respect to the above illustration and the words "Dingle infers that at the moment of this event, A reads the same time as H (because A and H are synchronised)": In the "stationary" frame (in which A and H were synchronized), yes. In the moving frame (where B and N were synchonized), no. McCrea's statement that "Dingle was not allowed to say that A read the same time as H, because A was not _AT_ event 1" is correct since there is no universal notion of "at the same time" in relativity. (See relativity of simultaneity.) Instead in reltivity any such statement must be made in the context of a given frame of reference. --EMS | Talk 15:34, 6 August 2007 (UTC)

Curiously, according to Chang it was Dingle who stressed the conventionality of simultaneity while others didn't even understand what he was talking about. Thus it would be surprising (although not impossible of course) if indeed Dingle made such a mistake on a topic that he understood so well. Harald88 15:52, 6 August 2007 (UTC)

EMS - you say: 1) In the "stationary" frame (in which A and H were synchronized), yes (Dingle is allowed to infer the time of clock A) 2) McCrea's statement that "Dingle was not allowed to say that A read the same time as H, because A was not _AT_ event 1" is correct

These two statements seem to contradict each other. It doesnt matter what event-1 was, we can say at all instants that the time displayed by clock A is the same as the time displayed by clock H, because we have synchronised them (according to Einstein's method). If we are ever adjacent to any synchronised clock in the A-H system we can say that, that is the time throughout the A-H system, no matter how distant the other clocks in the system are. Swanzsteve 05:16, 7 August 2007 (UTC)

I now have the article under my eyes, together with my old handwritten comments. The following is not sourced but is just meant for editors of this Talk page, to understand better what the debates were about.

As I suspected, the error was a misunderstanding by Dingle of Einstein's way of synchronization; he thought that Einstein refused the ether, and with that there seemed to be no possible cause for any desynchronization such as happens with Bell's rockets. I cite: "the process by which, according to Einstein A and H, and B and N, respectively, are synchronized does not synchronize them on Lorentz's theory, because one pair, at least, must be moving in the ether."

Thus he argued that the theory as presented by Einstein implies universal synchronization - a rather common error. And strangely enough, he claimed that the Lorentz transformations "require one clock to to work both faster and slower than another" (did he think that Lorentz did not use the Lorentz transformations?!). Not surprisingly, McCrea only noticed Dingle's mistake and commented on that instead of addressing Dingle's argument. Harald88 23:39, 8 August 2007 (UTC)

Harald88 - the parts you have quoted are not from the Dingle-McCrea articles in Nature 1967. Dingle synchronises the clocks by Einstein's method. McCrea makes no mention of clock synchronisation in his reply. The 'mistake' McCrea points out is, in fact, a mistake by McCrea, where he says Dingle is not allowed to infer the time on a synchronised clock A in the 'stationary' system, at the instant of event 1 involving clock H in the 'stationary' system. Clocks A and H are synchronised in the 'stationary' system. Clearly an error on the part of McCrea.

Where are your quotes from? Swanzsteve 03:42, 9 August 2007 (UTC)

Nature vol.216 Oct.14, 1967 pp.119-122 (Dingle) and pp.122-124 (McCrea)- original photocopies that I made myself. Thus:

1. I wonder where you got your copies from!

2. I found a new paradox: You claim that "McCrea makes no mention of clock synchronisation" AND that "he says Dingle is not allowed to infer the time on a synchronised clock A ..." :-)

Harald88 18:14, 9 August 2007 (UTC)

Harald - answers

1) I have the book

2) You got me:-) but I can solve this particular paradox - I could have put this more clearly, I meant McCrea makes no mention of an error in Dingle's method of clock synchronisation, in fact, at the beginning of his refutation (p.240 in the book, presumably p.122 in the article) he says "let similar clocks be fixed to the rod at points along the rod, and let them be synchronised by a standard procedure (that described by Dingle)".

AND

What mcCrea actually identifies as Dingle's error is this: "Just before his formula (3), Dingle proceeds to state 'between events E0 and E1, A advances by t1...'. Because A is never at E1, this phrase is meaningless and so Dingle's (3) is meaningless. Correspondingly his (4) is meaningless." - however, clock A is synchronised with clock H, in the stationary system, and clock H _IS_ at Event 1, so Dingle is entitled to infer the time of clock A from the time of clock H. This is McCrea's error.

The quote "the process by which, according to Einstein A and H, and B and N, respectively, are synchronized does not synchronize them on Lorentz's theory, because one pair, at least, must be moving in the ether." occurs in his discussion afterwards, contrasting Einstein's Theory and Lorentz's Theory. In his example, he synchronises the clocks using a standard method clearly approved of by McCrea. Swanzsteve 05:38, 10 August 2007 (UTC)

Harald - the bit about: "require one clock to to work both faster and slower than another", this is the same as saying clock A is slow from B's point of view and vice versa, i.e you could say from A's point of view B is running slower than A, but from B's point of view B is running faster than A - so B is running faster than A, and B is running slower than A.

Sure - regretfully Dingle didn't seem to understand that: "this can be seen to be contradictory in advance of observation" (top of p.121). Harald88 18:14, 9 August 2007 (UTC)

Dingle was talking about clocks ACTUALLY running slow, not just appearing to run slow when viewed from the other reference frame. Swanzsteve 05:43, 10 August 2007 (UTC)

In [1] on page 230, Dingle writes:

(start quote)

Thus, between events E0 and E1, A advances by t1 and B by t'1 = a t1 by (1). Therefore

...

Thus, between events E0 and E2, B advances by t'2 and A by t2 = a t'2 by (2). Therefore

Equations (3) and (4) are contradictory: hence the theory requiring them must be false.

(end quote)

Dingle should have written as follows:

(start correction)

Thus, between events E0 and E1, A, which is not present at both events, advances by t1 and B, which is present at both events, by t'1 = a t1 by (1). Therefore

...

Thus, between events E0 and E2, B, which is not present at both events, advances by t'2 and A, which is present at both events, by t2 = a t'2 by (2). Therefore

Equations (3) and (4) are consistent: hence there is no reason to say that the theory requiring them must be false.

(end correction)

I propose we include this part in the article about Dingle. Any comments?

DVdm 12:18, 6 August 2007 (UTC)

I have a comment, you didnt answer the question - Was McCrea correct when he said Dingle was not allowed to infer the time displayed by clock A when B and H were adjacent (A and H are sychronised in the 'stationary' system) ? Swanzsteve 13:45, 6 August 2007 (UTC)

Swanzsteve, regrettably McCrea expressed himself in a rather sloppy way, but that is irrelevant for this new section I created here. And, please add your next comments (not pertaining to the previous section, but to this one) at the botttom? Thanks. DVdm 14:04, 6 August 2007 (UTC)

I assumed you had created this new section in response to the McCrea 'refutation'. You say McCrea was 'sloppy', but was he correct to say you cannot infer the time displayed by a synchronised clock, when you read the time of another clock in the same system? Also your example, as far as I can see, you have just inverted Dingle's equation 4. Why have you done that? Swanzsteve 03:19, 7 August 2007 (UTC)

Ignoring your remark and question on McCrea for reasons well documented below, I see your question why I "have just inverted Dingle's equation (4)". Can't you really see why I did that? In his text Dingle divides coordinate time between two events by proper time between these events, and then compares that with the result of dividing proper time between two events by coordinate time between the events. Then he complains about a contradiction! In stead of comparing physically related and comparable quantities, Dingle compares similarly named quantities. He is not doing physics. He is doing algebra.

I'm afraid that the fact that you ask this question, effectively shows that, just like the anonymos (and as a matter of fact, just like Dingle when he wrote this), you really haven't got a clue about page one of special relativity. Now, that would be okay, there are many people who haven't got that clue, but most of them don't try to "contribute" here like you seem to do. But you don't see that, do you? DVdm 10:49, 7 August 2007 (UTC)

DVdm - it would have been a good idea to include your explanation along with your refutation. You keep sneering at people on this page, for some reason, for not having "a clue about page one of special relativity". I would just like to point out that McCrea, hopefully, did have "a clue about page one of special relativity". He did not produce your refutation, and, in fact, his refutation also refutes your refutation. I would like to hear what you would have said to McCrea, when he dismissed your refutation out of hand (because A is never AT event 1, etc). Swanzsteve 14:29, 7 August 2007 (UTC)

Adressed below. DVdm 15:26, 7 August 2007 (UTC)

All you did was to change the problem prosed by Dingle into a different problem posed by you by redefining events and the way time is to be measured. Both proofs are correct. The question is what physical interpretation is to be applied to the two different solutions? Please answer this. 72.64.52.209 13:02, 6 August 2007 (UTC)

Different problem, no way. I changed nothing to his setup. I expressed it with care. Just open the link and start reading [2] on page 229, starting with the sentence "Consider the following situation...".

Actually, I showed that Dingle had set up a trivially debunkable construction, so incredibly elementary and obvious, that, to me, it almost seems to have been on purpose. All it would have taken to decide not to proceed with it, was a simple space-time diagram. Try it yourself. If you really honestly don't get this, I'm afraid there is not much hope for you. This is absolutely elementary. DVdm 13:11, 6 August 2007 (UTC)

Let me add to this... if you don't understand it, then try at least to remember it, because you will stumble over this kind of trivialities with every paragraph you will ever read about relativity. DVdm 13:27, 6 August 2007 (UTC)

I'm afraid that you can't do that: it's called WP:OR. Our task is to report on such discussions as found in the literature. Thus, it can only be added if we find a similar rebuttal in the literature to which we may refer. I also happened to notice some errors in Dingle's book, but he didn't claim that SRT was mathematically self-contradictory. Harald88 13:43, 6 August 2007 (UTC)

Harry, I know about WP:OR, although I don't think that this kind of baby-triviality should be called "original research".

I just don't understand what on Earth drives people to insist on taking this Dingle character so seriously.

DVdm 14:04, 6 August 2007 (UTC)

He had been a well-known teacher of SRT who contributed to the Encyclopedia Brittannica if I'm not mistaken; I guess that that's all. Harald88 14:23, 6 August 2007 (UTC)

Yes, and then after his career, he stumbled over stuff like this. How sad :-( DVdm 14:27, 6 August 2007 (UTC)

You did not answer the question as to what physical interpretation is to be assigned to the two different solutions. You claim they are the same but that is clearly impossible since you assign a different mathematics to yours which is different from that assigned by Dingle to his. Since your claim rests upon this, you need to back it up.72.64.52.209 14:33, 6 August 2007 (UTC)

Anonymous, I'm sorry but I really cannot help you, before you at least fully understand and acknowledge that I changed nothing to Dingle's setup. All it takes for you, is to actually read [3] and what exactly I added (not modified) in order to clarify it for those who fail to understand. If you don't see this, don't bother replying any further. DVdm 14:46, 6 August 2007 (UTC)

Your non-responsive answer, invalidates your proof and it should be ignored.72.64.52.209 15:13, 6 August 2007 (UTC)

What Dingle showed was that the definition of time used in discussions of relativity was not very clear and precisely defined. The common statement that moving clocks run slow, reflects this lack of rigor in definition of time. He showed that a common interpretation of this was logically inconsistent because it demanded that two clocks both run slower than the other one. Hence if B was slow relative to A then A is fast relative to B. Since this assertion conflicted with what had been taught in textbooks for a very long time it was disputed. The correct statement should be that if the clock B appears slow relative to an observer using clock A as reference, then A appears slow relative to an observer using clock B as reference. But that there is no difference in the proper times of either clock A or B. In the above discussion, Dingle's proof applies to the first interpretation and the refutation of it applies to the second definition. Both can be correct mathematically but they apply to different interpretations of the physical situation.72.64.52.209 15:38, 6 August 2007 (UTC)

It does not make any sense to answer to a question that is based on the blatantly erroneous assumption that I changed anything to the setup. Come back when you understand and acknowledge that I did not change anything whatsoever to the setup. I don't want to insult you, but your arrogant way of showing your total failure to even begin to try to understand, is really embarrassing. I feel sorry for you. DVdm 15:51, 6 August 2007 (UTC)

DVdm - I must agree with Harald88 that your exercise, while corrent, fails WP:NOR because it is not published in the literature (or at least you haven't provided a reference for it). Wikipedia is not a scientific journal. Let's stick to that which is already in the literature and which amply refutes Dingle.

EMS, yes, no problem about the WP:NOR: even I agree with Harry on that, although it didn't take much research to begin with. I remember reading this part in Dingle's work, and merely bursting out in laughter. My main point was to try to provide some elementary education to these people, and at the same time to show what a fuss they are making about such a simple and silly matter. I am truly astonished. DVdm 16:03, 6 August 2007 (UTC)

Your astonishment is due to a misunderstanding: Dingle's objections were not (or at least, not primarily) about calculations or mathematics. Thus your attempt was misplaced. Perhaps you would understand it a little better from reading Chang, as he took the liberty to rephrase some issues that Dingle had in possibly clearer language. Harald88 23:04, 6 August 2007 (UTC)

Harry, I'm not interested in Chang. I showed a blatant and obvious error from Dingle's own text, and I showed the correction that, frankly, I would expect even you should be able to judge on its merits. DVdm 08:42, 7 August 2007 (UTC)

Dirk, your purpose here as editor is supposedly to transmit what Dingle had to say as well as how physicists and philosophers reacted. Chang found it relevant to mention that Dingle made mistakes, but only because that badly affected his reputation and credibility - his mistakes and sloppy phrasings were mostly irrelevant for the issues that he raised. According to Swanzsteve, this is what Dingle had to say about the mathematical consistency of SRT:

"I have enough mathematical insight to see that it is a waste of time to look for mathematical flaws in the theory", H.Dingle in Nature, October 14, 1968, p.19. "

Harald88 11:14, 7 August 2007 (UTC)

Sure, no lack of mathematical insight, but I wanted to show that he seemed to have lacked the physical insight. In the cited text Dingle's words "Equations (3) and (4) are contradictory: hence the theory requiring them must be false", are completely and trivially wrong, as I dare to assume you wholeheartedly agree. That phrase de-facto highlights a glaring lack of physical insight, at least at the time when he wrote it, and when he subsequently built upon it. In this statement, he merely showed some rather trivial highschool level mathematical insight. As you also know, this happens all the time.

"purpose here as editor" ==> Sure, I repeat, I don't object to WP:NOR - I had expected that. I have put this forward as an attempt to show to certain people here what kind of moot (if not silly) cause they are defending. DVdm 11:52, 7 August 2007 (UTC)

Or possibly he misunderstood SRT and tried too hard to find mistakes (how old was he when he wrote that?). Anyway, it's baffling indeed! Harald88 13:18, 7 August 2007 (UTC)

To the anon - The issue is that "at the same moment" means one thing for observer H and another for observer B in the illustration of the previous section. Observer B will not find clocks A and H reading the same time "at the same moment" in the B-N frame of reference becuase the clocks were not synchronized in that frame of reference. In relativity, it is not just the passage of time that is affected by relative motion by also its "alignment": Events that occur at the same time in one frame of reference do not necessarily occur at the same time in another frame of reference. --EMS | Talk 15:56, 6 August 2007 (UTC)

Observer B, will not _observe_ the 2 clocks in the stationary A-H system, displaying the same time, but we are talking about, an event where he is adjacent to one of the clocks and _infers_ the time displayed on the other synchronised clock in the same system. This isnt quite the same thing. In Mcrea's 'refutation' he says he is not allowed to infer the time on clock A at the instant he reads the other (synchronised) clock H in his own 'stationary' system. Swanzsteve 03:49, 7 August 2007 (UTC)

I am not interested in McCrea. Keep your comments in your McCrea section. This section stands on its own. DVdm 08:42, 7 August 2007 (UTC)

DVdm - I just noticed, your refutation has already been refuted by McCrea - you (apparently) have no right to say what the time of clock A is, because it is not AT event 1, so your equation 3 is meaningless and your equation 4 is meaningless. So if you think McCrea's argument was valid, your refutation fails. Oh, the irony :-) Swanzsteve 05:28, 7 August 2007 (UTC)

Again, I am not in the least interested in McCrea. Keep your comments in your McCrea section. Whatever you say about McCrea in this section is a straw man. This section stands on its own. Just read Dingle's own text and have a careful look at how I trivially corrected it. Draw a spacetime diagram, that is, since I don't think that engineers are introduced to them in their introductory courses, if you have any idea about what a spacetime diagram is to begin with.

Two well defined observers, tied to resp. clocks A and B, each compare their measured or (correctly) calculated time intervals between two well defined pairs of events. Dingle fumbled and I merely showed you how he fumbled. If you don't understand it, at least try to remember it. Otherwise you are bound to make the same error over and over - it is a classic. DVdm 08:56, 7 August 2007 (UTC)

DVdm - I usually put my replies, where they are relevant to your comments. McCrea is relevant in this section, because HE refutes the validity of YOUR example. You need to explain why his argument doesnt refute YOUR example, because it apparently refuted Dingle's example, to the satisfaction of the editor of Nature (quote from Nature in 1967:- "McCrea's commentary on this argument will bring the controversy to an end for most people. It is earnestly to be hoped that it will also satisfy Dingle") and apparently to the rest of the scientific community. To paraphrase McCrea, "your equations 3 and 4 are meaningless" Swanzsteve 14:46, 7 August 2007 (UTC)

Since you fail to understand the basics of relativity, which has become obvious now, and since you fail to understand Dingle's elementary fumble, which has been obvious from the start of this section, I really hadn't expected you to understand that you can, excuse the language, get lost with your McCrea straw man. I'm afraid that, due to an elementary incompatibility between the two of us, I am unable to help you out of what I frankly gather to be your misery. Sorry.

Good luck with your hero :-) DVdm 15:26, 7 August 2007 (UTC)

DVdm - since this page is about Dingle and HIS arguments, I am trying to get a comment from you about McCrea's refutation in Nature. McCrea's refutation also disposes of your example. So either McCrea's refutation was incorrect,or YOUR example is incorrect. Which is it? try to answer without making snide remarks. Swanzsteve 18:35, 7 August 2007 (UTC)

Since you fail to understand (1) the basics of relativity, (2) Dingle's elementary fumble, and (3) what I just told you, I also don't expect you to understand (4) McCrea's point, and (5) whatever kind of answer I might give you. So, forget it, because (6) for me you have stopped being a technical conversation partner. DVdm 19:02, 7 August 2007 (UTC)

DVdm - you say you understand relativity, why dont you just enlighten the rest of us, and explain why McCrea's refutation of Dingle's example (which you have faithfully replicated) does not also invalidate your refutation of Dingle's argument. McCrea's argument hinged on event-1, where Dingle infers the time of clock A from the time of clock H, in the same 'stationary' frame. Others have commented that this is valid, McCrea didnt seem to think so. You have inferred the same thing in your refutation. So is it valid or not?. Why wont you answer the question? Swanzsteve 21:01, 7 August 2007 (UTC)

Swanzsteve - Dingle is claiming that the clock reading for A is the same as H in the B-N frame of reference, even though clocks A and H were synchronized in the A-H frame of reference. In relativity, synchronization only applies in the frame of reference the clocks are at rest in and synchronized within. So what McCrea is saying that in the B-N frame of reference, you cannot infer that the current time on A's clock is "x" because H's clock currently reads "x". I admit that in rekativity you can "infer" what time on A's clock using the Lorentz transformations, but that is not what McCrea was refering to. --EMS | Talk 16:35, 7 August 2007 (UTC)

EMS - I have just gone through Dingle's example again, equation 3 is the one to which McCrea refers. Equation 3 is concerned with 2 events as viewed from the 'stationary' system A-H, B adjacent to A and B adjacent to H. He calculates the time elapsed in the 'moving' system N-B, using the Lorentz transformation. He doesnt in this equation infer the time of N (in the 'moving' system) from the time of H, at event 1. This is the equation that McCrea disagrees with, in fact he says equation 3 is meaningless. If you look at it again I think you will agree that equation 3 is OK. Let me know what you think. (Swanzsteve - I forgot to sign in 213.107.15.23 22:42, 7 August 2007 (UTC)

There is nothing wrong with either equation! However, equation (3) is "good" in the A-H rest frame, while equation (4) is "good" in the B-N rest frame. The issue is that in relativity, because of the relativity of simultaneity, such a supposed demonstration of contradiciton has to occur within a single frame of reference. That is not the case for equations (3) and (4) above.

An anlogy would be if you had one person facing north and another person on the right side of the first on facing south and then claimed that their configuration is self-contrdictory becuase each one is to the right of the other one. Just as those two people have a different orientations in space, having a velocity with respect to another observer gives you a difdference orientation in spacetime that that of the other observer. --EMS | Talk 23:00, 7 August 2007 (UTC)

EMS - I'm glad you agree, I have since looked at Dingle's equation 4, and can't see anything wrong with that either. Except, as you say, it is from the point of view of the 'moving' N-B system. Since McCrea said equs 3 and 4 were meaningless, do we agree then, that McCrea's refutation was completely bogus? 213.107.15.23 02:11, 8 August 2007 (UTC)

No. McCrea was saying that the clock readings of the A-H B's frame of reference for equation (3) do not specify temporal relationships in the B-N A's frame of reference for equation (4). There is nothing wrong with that. Once again, you are ducking the explanation, and are turning McCrea's words upside down to suit your own needs. Also, even if McCrea's explanation could be shown to be invalid, that would not make Dingle right. --EMS | Talk 02:26, 8 August 2007 (UTC)

EMS - I'm afraid you are wrong there, McCrea did not say "that the clock readings of the A-H frame of reference of equation (3) do not specify temporal relationships in the B-N frame of reference of equation (4)"

McCrea says (p.242 Science at the Crossroads"): "Just before his formula (3), Dingle proceeds to state 'between events E0 and E1, A advances by t1...'. Because A is never at E1, this phrase is meaningless and so Dingle's (3) is meaningless. Correspondingly his (4) is meaningless.".

As we have just agreed, equ 3 is not meaningless. So McCrea was not justified in what he said. I am not saying that that makes Dingle right, I am trying to get at the truth Swanzsteve 02:55, 8 August 2007 (UTC)

I think McCrea is making an excellent straw man for you. Here is the issue now that I take another look at that quote. It says "'between events E0 and E1, A advances by t1...". If A is never at E1, then this is indeed an ambiguous statement. Why? Because Dingle never specifies the frame of reference in which A's advance is measured! Without that specification this statement is indeed meaningless since the event on A's world line which would be simultaneous with event E1 cannot be determined except within a given frame of reference. The same applies to B for equation (4). Now from the context, it can be infered that since B goes from events E0 to E1 and A from E0 to E2 that equation (3) must be for the B frame and equations (4) for the A frame (instead of the other way around as I wrote above in my now correct posting).

Note that having added the infered frames of reference, what I posted above now applies: Dingle is comparing things from two different reference frames, and making what in relativity in an inappropriate comparison.

(One more thing: Events E1 and E2 are not simultaneous in either reference frame if each observer gets to their event after the same amount of elapsed proper time from event E0. Instead, in their own frame of reference, each observer reaches their event before the other observer reaches theirs.) --EMS | Talk 04:04, 8 August 2007 (UTC)

EMS - In an article about Dingle, which necessarily involves his argument against SRT, and where the person who convinced the scientific establishment that Dingle had made an elementary error was McCrea, it is hardly sensible to say the question about whether McCrea made a mistake in his argument is a "strawman". I'm a bit puzzled as to why you are defending McCrea and avoiding the obvious conclusion. You then make a point which McCrea never made: he never said "Dingle never specifies the frame of reference in which A's advance is measured". Why didnt McCrea make this point?, because it is obvious from equation 3, which frame of reference A is in - the 'stationary'frame. And equally obvious from equation 4, which frame of reference B is in - the 'stationary' frame (I'm not sure but I think in your last post you have it the wrong way round). Dingle wrote to McCrea complaining about the nature of his refutation, McCrea never replied. If McCrea couldnt be bothered to defend his refutation why should you? Dingle's example does not contain any observers observing distant events, merely observers present at each event. Whether or not Dingle is making an inappropriate comparison is not currently the point at issue, as far as I am concerned, because McCrea never said he was making an inappropriate comparison, McCrea said his equations were meaningless. I am merely at the moment trying to get agreement that McCrea's refutation was erroneous.

Its a very interesting question, because if you look at the question Dingle puts in the preface to his book, he is obviously talking about inertial motion, and saying that you cannot specify which clock is moving and which is stationary (this example here only involves inertial motion) and if he raised this question now, everyone would just say, yes it is reciprocal, each clock just looks slow from the others reference frame. But at the time nobody said that, including McCrea, its quite baffling Swanzsteve 05:50, 8 August 2007 (UTC)

McCrea is not stating his assumptions and therefore leaving a large part of his reasoning to be inferred by the reader given his anti-relativity agenda. You simply insert what you want to see into those same gaps, and end up with what I call a "strawman". I will admit that part of the blame for that situation lies with McCrea.

Your statement that A and B are in the "stationary frame" is a joke: A and B are present in all reference frames! The issue is the reference frame in which the clocks of A and B are read. Since A and B are in motion, the stationary frame for A is not the stationary frame for B. So if Dingle is only saying that the clocks are being read in "the stationary frame", then once again the exercise is ambiguous and MeCrea's refutation stands. --EMS | Talk 14:50, 8 August 2007 (UTC)

EMS - McCrea's reasoning is stated totally unambiguously, I will repeat it (This is a direct quote from Nature): "Just before his formula (3), Dingle proceeds to state 'between events E0 and E1, A advances by t1...'. Because A is never at E1, this phrase is meaningless and so Dingle's (3) is meaningless. Correspondingly his (4) is meaningless.", nothing need be inferred by the reader. What dont you understand about McCrea's statement? What have I inserted in the gaps? Where are the gaps? Where could there be assumptions to be made in this statement? It couldnt be much clearer.

I have read my comment again, it doesnt look ambiguous (nor does it look like a joke)

equation 3 - A is in the 'stationary'frame

equation 4 - B is in the 'stationary'frame

perhaps you forgot that either frame can be stationary in inertial motion:-)

Your comment: "A and B are present in all reference frames!", doesnt make sense. If you had said: "A OR B is present in all reference frames!", although pointless, is at least logical. A and B are in different reference frames.

I see no ambiguity in anything McCrea said, nor anything I said. So although you have already said that Dingle's equations 3 and 4 are not meaningless, for some reason, you say McCrea's refutation stands.

Since your last reply was complete gibberish, I have serious doubts about your self-proclaimd expertise in SRT, and I will not press you again, to admit that McCrea's refutation was wrong, since it seems you are determined not to acknowledge this obvious fact. Swanzsteve 00:24, 9 August 2007 (UTC)

I am now doubting that you even know Newtonian physics. A frame of reference defines a coordinate system to be imposed on a spacetime. It is not the spacetime itself. What McCrea is keying on is that the frame of reference is not well defined. Without that, equation (3) is meaningless.

Here is the issue: What is the state of motion of A in the "stationary" frame? What is the state of motion of B in that same frame? It makes a difference, since (3) is only valid when the "stationary" frame is one where A is at rest and B is moving, while (4) is only valid when the "stationary" frame is one where B is at rest and A is moving. If, as Dingle did, you leave this issue undefined then (3) and (4) become meaningless. Now why would the frame of reference be undefined? This is because Dingle specifies that both the A-H clocks and the B-N clocks have been synchronized according to theory. That means that each set of clocks has been been synchronized in their own rest frame under the rules of special relativity. The trouble is that this synchronization is not valid in a frame where the clocks are moving. So if the exercise occurs in the A-H rest frame (where (3) is valid), then (4) is invalid because the B-N clocks cannot read the same time at a given A-H time under the relativty of simultaneity. Similarly if the B-N frame is treat as the stationary frame, then equation (4) is valid but (3) is not.

So choose your poison: Say that (3) is valid and (4) fails. Say that (4) is valid and (3) fails. Or you can make no specification at all, in which case McCrea's refutation awaits you. --EMS | Talk 04:43, 9 August 2007 (UTC)

EMS - "A frame of reference defines a coordinate system to be imposed on a spacetime. It is not the spacetime itself"

give me a break, do you really think that anyone is impressed when you throw in stuff like this? Neither Dingle NOR mcCrea, thankfully, concern themselves with such irrelevancies.

Next: "What McCrea is keying on is that the frame of reference is not well defined."

McCrea, again, does not say this.

Next: "Here is the issue: What is the state of motion of A in the "stationary" frame? What is the state of motion of B in that same frame?"

This statement is quite baffling - you seem to think that A and B are in the same frame. You continue then to talk about A at rest in the stationary frame and B moving in the stationary frame. This is gibberish of the highest order. "B moving in the stationary frame" - what are you talking about man , get a grip.

You then proceed, with more irrelevance.

I'm sorry, but I'm trying to discuss McCrea's refutation of Dingle's example in Nature in 1967, not what you think McCrea was thinking or what you think he should have said. This discussion started off quite sensibly, you agreed, and I quote you from a previous post

"There is nothing wrong with either equation! However, equation (3) is "good" in the A-H rest frame, while equation (4) is "good" in the B-N rest frame"

In previous posts, you seemed to understand what a reference frame was, now you dont. I'm beginning to wonder if there may be two different people replying here.

I dont mean to be rude, it was quite pleasant discussing it with you for a while, but now its getting a bit tedious, pointing out your errors and irrelevancies, in your desperate attempts to defend McCrea. If you bother to reply please stick to the Dingle-McCrea exchange, what they say and their examples, and we might actually make some progress Swanzsteve 14:05, 9 August 2007 (UTC)

Swanzsteve wrote:

Next: "Here is the issue: What is the state of motion of A in the "stationary" frame? What is the state of motion of B in that same frame?"

This statement is quite baffling - you seem to think that A and B are in the same frame. You continue then to talk about A at rest in the stationary frame and B moving in the stationary frame. This is gibberish of the highest order. "B moving in the stationary frame" - what are you talking about man , get a grip.

You have just shown me that you have no concept of what a frame of reference is. Your whole posting is full of confusion about that concept, but that quote summarizes it at its best. If you don't understand how A and B can be in the same frame of reference, then you don't understand a basic concept of Newtonian physics which relativity also uses. This in turn meams that all of my attempts to describe McCrea's refutation above have been assuming a body of knowledge that you just plain don't have.

We are here (supposedly) to write an article on Dingle, not to hold a physics seminar. I am willing to work with you to find wording that is neutral and as kind as possible to Dingle, while still making it clear to people that the mainstream physics community does not support his views (or any anti-relativity views) at all. In the meantime, please stop pretending that you understand this stuff. If you want to understand, then please take a college-level physics course (preferably the introductory course for physics majors). --EMS | Talk 14:51, 9 August 2007 (UTC)

EMS - I was going to reply to you in a similar insulting tone but I have changed my mind and will stick to the facts.

I clearly understand 'this stuff' a bit better than you, since it was I that pointed out the flaw in McCrea's refutation to you. You initially agreed but have since back-peddled. I am not interested in your personal interpretation of what McCrea meant or what he should have said, or how you would refute Dingle's example, its not relevant. McCrea's refutation is there in black and white. It seems to have convinced most 'experts' at the time, but now it doesnt even convince you.

You seem to have developed your own non-standard terminology for discussing Inertial_frames in SR.

See Wiki Frame_of_reference: A frame of reference is a particular perspective from which the universe is observed. Specifically, in physics, it refers to a provided set of axes from which an observer can measure the position and motion of all points in a system.

See Einstein's 1905 paper: "Further, let the time t of the stationary system be determined for all points thereof at which there are clocks by means of light signals in the manner indicated in § 1; similarly let the time of the moving system be determined for all points of the moving system at which there are clocks at rest relatively to that system by applying the method, given in § 1, of light signals between the points at which the latter clocks are located."

The clocks are at rest in different inertial reference frames, Einstein doesnt talk of a clock 'moving' in the 'stationary' system.

Any reply should make some contribution to the discussion of McCrea's 'refutation' Swanzsteve 14:12, 10 August 2007 (UTC)

DVdm and EMS you both keep ducking the issue. Two synchronized cuckoo clocks both moving apart from each other. Which one does the stationary man at the starting line hear first?

If the Earth orbits the Sun once while the two clocks are moving apart, which clock is going slower?

Until such times as you can answer these two questions satisfactorily, we will have to conclude that you are both defending a theory which neither of you have properly thought through. (217.43.69.32 16:11, 6 August 2007 (UTC))

You have just asked two totally ambiguous questions, since there is no definition of what the "stationary" frame is for either question. You may accuse us of ducking the issue, but IMO it is just as fair for us to accuse you of ducking the explanatiopn. --EMS | Talk 16:35, 6 August 2007 (UTC)

This is not intended to be an insult of any kind, but I honestly can't help concluding that either this anon is a blatant troll, or he is astonishingly... well... less gifted, or most likely, some suitable combination of both. I'm not a religious person, but in this case: OMG. DVdm 17:48, 6 August 2007 (UTC)

The anon wrote above:

What Dingle showed was that the definition of time used in discussions of relativity was not very clear and precisely defined.

I now think that this is the real point of the discussion. If the complaint is that you cannot define the time at one event with respect to another event universally and unambiguously, then that is a point which we agree with the anon. However, unlike the anon we accept that as an attribute of relativity, and automatically accept that time cannot be expressed unambiguously except within a given frame of reference. OTOH, the anon is looking at that same ambiguity, and is crawling up a wall. That we can translate a well-defined time from one frame of reference into a well-defined time in another frame of reference is lost on him/her. Instead the issue for the anon is that time in one frame of reference is not the same as time in another frame of reference. --EMS | Talk 18:38, 6 August 2007 (UTC)

"real point of the discussion" ==> No really, this is not even a discussion. This is a totally hopeless attempt to explain something to someone who does not have the brain capacity nor the will to even begin to understand. Utterly hopeless. DVdm 18:47, 6 August 2007 (UTC)

DVdm - I agree with your overall assessment, but I would use the word "context" in place of "brain capacity". As mildly as possible, please let me remind you WP:CIVIL, but I do understand your frustration with people like this who not only don't understand, but don't understand that they don't understand. --EMS | Talk 19:10, 6 August 2007 (UTC)

ED, thanks for reminding me of WP:CIVIL again. Always appreciated. Cheers, DVdm 19:27, 6 August 2007 (UTC)

DVdm - since you are always insulting engineers, I thought you might like to see this quote I found, on a page about Einstein:- "In 1895 he failed an examination that would have allowed him to study for a diploma as an electrical engineer" :-) Swanzsteve 03:10, 7 August 2007 (UTC)

"always insulting engineers" ==> This not really being on topic, but IMO there's nothing wrong with engineers. My oldest son just graduated as one. YMMV, but I think there is something severely wrong with that special brand of engineers (usually retired, and quite common on Usenet and certain parts of the WP), who seem to confuse their lack of proper training combined with their failing to understand the very basics of a theory, with the invalidity of that theory. For some reason they seem to think that physics is some kind of exercise in algebra. As you can (or should be able to) see, in the section I created above, it isn't. DVdm 10:26, 7 August 2007 (UTC)

I'm glad you agree with Herbert Dingle that physics is not an exercise in algebra. Swanzsteve 04:45, 9 August 2007 (UTC)

Before publishing his 1905 paper on SRT, Einstein did, in fact, perform an experiment in Switzerland (where else?) to test the "Cuckoo Clock Paradox". The man with the starting pistol did hear cuckoo A first, in line with the predictions of Einstein's theory. But the experiment was declared inconclusive, when it was discovered that the chain had come off the other bike and strangled cuckoo B. The experiment has bever been repeated. Swanzsteve 03:30, 7 August 2007 (UTC)