Talk:Twin paradox

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To: Wikipedia Twin Paradox Entry Administrator(s)

Some people (physicists) contacted me with concerns about this entry. I have studied the Twin Paradox in depth for around 40 years and, having read the entry, shared their concerns. I contacted others whom I’ve corresponded with over the years on the Twin Paradox for their assessment – they have written many papers and books, or sections thereof, on the Twin Paradox. They, like I, aside from noting specific errors, focused on two main, common concerns: 1) The current entry misses the essence of the Twin Paradox. Even if the existing errors were corrected, the naïve reader would come away with major misconceptions about the Twin Paradox. Note that just because we have an in depth knowledge of the topic does not mean we want to go into the topic in greater depth. It just needs to be dealt with fundamentally differently. Currently, it’s like an entry on the “French and Indian War” that mentions something about British troops but doesn’t mention the French or the Indians, on either side, or that there was a war.

2) The sections containing the math/“physics” contradict each other.

We propose an alternative version. (Many sent responses that included personal resolution or non-resolution conclusions. These personal opinions have not been included just the factual history treated in a conceptual and readable way.) I apologize for being new to Wikipedia and will greatly appreciate constructive guidance on formatting, etc. (One or two others have limited experience with updating Wikipedia and have given a few tips.) As the rep, I will continue to read up on that important topic. We have a great many references that I will need to reformat for Wikipedia. However, hopefully, we can focus on content. I will check with the above referenced group on any substantive changes. Looking at the topic, it would appear that your group gave it your all and made a very significant and sincere volunteer effort to contribute to Wikipedia – you are to be congratulated on that. Your list of references is excellent and we plan to add to that. However, a quick look at history, suggests to me that you have consistently been reluctant to accept excellent suggestions from outside your (de facto) group. Hopefully, we can work together constructively to get a good entry for the sake of physics and for the sake of Wikipedia. The Twin Paradox topic can be extremely rich and interesting and instructive!

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Alternative Twin Paradox Entry:

Early History In 1905, Einstein submitted a paper called “On the Electrodynamics of Moving Bodies” that laid out the conceptual foundation for what would later be called special relativity. In that paper, he derived the (special relativity) time dilation equation that said that all inertial (i.e., non-accelerating) observers would observe all other inertial observers’ clocks to be running slow by the reciprocal of the Lorentz factor. So the greater the relative velocity between two inertial observers the slower they would observe each other’s clock to be running.

While counterintuitive and not immediately accepted by all, this time dilation equation was not seen to be anymore paradoxical than, for example, the assertion that two people who are moving away from each other would see each other apparently shrinking in size. However, in the same paper, directly following the derivation of the time dilation equation, Einstein wrote that one consequence of the (symmetric) time dilation equation was that if two identical clocks started together and then one clock made a round trip, the “traveling” clock would arrive back showing a smaller amount of elapsed time – smaller by the amount one would calculate using the time dilation equation.

The above assertion started what was initially called the “clock paradox” debate. On the one hand, from its derivation and using basic logic, it was clear that the time dilation equation was describing symmetric observations of clock slowing between two inertial observers in relative motion. The time dilation equation did NOT also say that both clocks were “actually” running slower than the other. That would be more than counterintuitive that would be counter-logical. In addition, it wouldn’t address the net difference in proper time recorded by the two clocks as it applied equally to both twins.

So many asked “Since special relativity says that the time dilation equation applies equally to the stay-at-home twin and the traveling twin, why can’t the same logic be used to show that it’s the stay-at-home clock rather than the traveling clock that loses time?”

Basically, the answer was “Because the traveling twin underwent a turnaround acceleration and changed inertial frames, hence, we can’t view the whole trip from his frame. We can just view it from the stay-at-home frame’s perspective.”

While this did point out a clear asymmetry between the twins, it remained unsatisfying to many as nothing in special relativity justified that view (i.e., special relativity was not said to be unusable for observers/clocks who had undergone acceleration or who would undergo acceleration in the future – such a claim would be much more damning of special relativity than any alleged paradox.) In addition, it was pointed out that if things were changed slightly so that the “stay-at-home” twin, in the middle of the scenario, did the same amount of accelerating as the traveling twin, but in a way that brought him back to his starting location, then theory still predicted virtually the same net time difference even though the asymmetry had been eliminated.

In 1911, Paul Langevin described a scenario much like Einstein except that instead of focusing on the clocks, he focused on twins as two observers who aged at different rates. From then on, the name changed to the Twin Paradox debate. (Langevin disagreed with Einstein’s position and suggested that special relativity implied the existence of a stationary ether and stated: "Every change of speed, every acceleration, has an absolute sense".)

In 1918, Einstein was developing General Relativity and he updated his rationale for the Twin Paradox and employed gravitational time dilation. However, for the first forty to fifty years of the Twin Paradox, the net proper time difference (or aging difference) was most often explained by using special relativity’s time dilation equation. The time dilation equation was applied to show how much the traveling twin’s clock slowed during his constant velocity outbound and inbound legs of the round trip.

Dingle Then Herbert Dingle entered the debate and gave it a much higher profile in physics. His position changed over time. First, he held that the net time difference should be explained in terms of relative simultaneity. Then he thought that special relativity did not predict any net time difference. Finally, he held that the paradox showed that special relativity was logically flawed. A very public heated debate ensued in the journals and in publicized letters between Dingle and his foes.

Dingle’s attacks on special relativity brought strong reaction as special relativity was one of the key foundation blocks of modern physics and had been verified by many experiments to the nth degree. Hence, one common reaction to Dingle was “If special relativity is invalid, what’s the alternative.” Dingle had none.

Dingle who had previously shown himself to be well versed in special relativity and physics was treated with contempt and called a quack, etc., etc. and was said “to not understand special relativity.” However, much later, H. Chang, then of Harvard, embarked on an extensive, objective review of the Dingle debate and concluded that the questions raised by Dingle had never been rebutted – in fact, they had never really been addressed by his opponents. However, Chang concluded that, in his opinion, Dingle was asking for physical causes of the net time difference and this was an invalid approach. This view, like everything else in the Twin Paradox debate, found supporters and foes.

Post Dingle While Dingle did not get many pats on the back for probing the Twin Paradox, he does seem to have had significant influence. Perhaps, persuaded that the time dilation equation approach did have some problems, physicists put forth a whole array of explanations of the Twin Paradox. Some of these explanations seemed to be equivalent to the time dilation equation approach and seemed to share the same alleged flaws even if they were somewhat more difficult to see. Other explanations were clearly mutually exclusive with the time dilation equation approach.

One popular group of explanations explained the net time difference in terms of the turnaround acceleration. However, for many, it was difficult to see how, for example, a turnaround acceleration that both twins observed as taking less than an hour could account for, say, a million hours of net proper time difference. Many other objections were raised as well.

Historical Summary On the one hand, it’s generally assumed that “there is no paradox”. On the other hand, for those who hold that position, there is great disagreement on the detailed explanation of the net proper time difference. Similarly, for those who hold “there is a paradox”, there is equal disagreement on their detailed positions. When it comes to the details, no one holds the majority position.

Many times in the history of physics there have been prolonged debates between well respected physicists that have pointed to important advances. Sometimes both sides were partially correct. For centuries, physicists debated whether light was a particle or a wave before it was determined that light had both particle and wave characteristics. Also, many times physicists have tried to sweep “loose ends” under the rug because they were inconsistent with current theory only to find later that the “loose end” served as a clue to major breakthroughs. Will the Twin Paradox have a similar role? Only “time” will tell.

Proposed Solutions and Associated Questions This section gives a conceptual overview of the wide variety of explanations for the net time difference in the Twin Paradox and some of the alleged rebuttals.

Many different explanations/causes of the net time difference have been put forward (e.g., special relativity’s time dilation, relativity of simultaneity, lines of simultaneity, relativistic Doppler effect, turnaround acceleration, changing frames, virtual gravitational fields, Kerr metric, EIFSO time dilation). A few brief comments are shown below about the different classes of such reconciliation arguments and their alleged flaws so that the reader can get a feel for the nature of the Twin Paradox debate. None of the arguments are given in rigorous detail, but are described conceptually to give the reader the flavor of the debate.

I) Function of Relative Velocity In the “Early History” section above, we discussed some pros and cons about using special relativity’s time dilation to explain the net time difference. These comments also apply to arguments that use equations, typically special relativistic equations, that are functions of relative velocity and that would normally be applied symmetrically to both of the twin observers.

Secondly, one of the most important and ubiquitous themes in the Twin Paradox debate is that when one uses a physics equation to compute the “right” net proper time difference, one is explicitly or implicitly describing the physics of his argument. Hence, if one uses an equation that is normally interpreted as describing “observed” time to describe the traveling twin’s proper time, then that is an invalid use of that equation. For example, let’s look at using relative simultaneity remembering that simultaneity is just an agreed on convention of what an observer will call simultaneous. When the traveling twin turns around at the mid-point, he changes his view of what he sees as being simultaneous, but that shift in relative simultaneity does not affect what his clock reads. It is not valid to say or imply that that shift in view of what’s simultaneous explains any difference in clock readings at the end.. In contrast, had the traveling twin reset his clock to reflect that jump in relative simultaneity, then that indeed would have been relevant in explaining any difference in clock readings at the end.

Third, any explanation that holds that the net proper time difference is a function of the traveling twin’s relative velocity must address cases of nested, “simultaneous” Twin Paradox scenarios. If twin “B” is first the traveling twin in one scenario and then also the stay-at-home twin in another, nested, “simultaneous” scenario, consistent application of an explanation using relative velocity leads to the conclusion that twin B’s clock is running both slower and faster than clocks in the original, stay-at-home frame.

Fourth, if the Twin Paradox scenario is modified so that it begins with an arbitrarily near miss at constant relative velocity rather than with than an initial acceleration, theory says that the clocks can still be synchronized and that approximately the same net proper time difference is expected. Further, it can be arranged that either twin can do the turnaround acceleration so both twins are on equal footing for the constant velocity outbound leg. Hence, the alleged cause, (acceleration) of which twin’s clock was running slower occurs after the constant velocity outbound leg.

II) Turnaround Acceleration Explanations that say or imply that the turnaround acceleration causes the net proper time difference to accumulate must address the following questions.

First, data on cosmic rays and particle accelerators show conclusively that the clock slowing phenomenon is a function of velocity and not acceleration.

Second, one can construct a Twin Paradox without any turnaround acceleration. An outbound traveler (and clock) has an arbitrarily near miss with an inbound traveler at the “turnaround” point where they compare clock settings. The theoretical net time difference of accumulated proper time remains the same. The outbound leg and inbound leg are traversed in different frames. Yet, neither clock has been subject to acceleration or even the effects of changing frames.

Third, the basic physics of the turnaround acceleration is independent of how long the round trip is. In other words, one can arrange the turnaround acceleration for two simultaneous Twin Paradox scenarios that vary greatly in duration to have identical turnaround accelerations (i.e., the same amount of acceleration, in the same place, at the same time) and yet are alleged to have effects on identical clocks that vary by many orders of magnitude.

Similarly, if one varies the Twin Paradox scenario slightly so that the traveling twin comes to rest at different points in the stay-at-home frame, then the effect of the turnaround acceleration is only determined long after the turnaround acceleration has completed.

Fourth, most turnaround acceleration explanations use spatial separation from the stay-at-home twin to get the right answer. However, that implies that the amount of proper time gained or lost during the turnaround acceleration versus clocks in the stay-at-home frame is a function of spatial separation. Yet, it’s normally accepted that all clocks at rest in an inertial frame, other things being equal, accumulate proper time at the same rate. Hence, it’s invalid to hold that, between the two well defined events of starting and completing the turnaround acceleration, the traveling twin’s clock loses very different amounts of proper time versus various clocks in the stay-at-home frame all ticking in unison.

Similarly, if the explanation’s logic is applied consistently, then the initial acceleration and ending acceleration yields virtually no net proper time difference. Yet, if the traveling twin does an endless loop of Twin Paradox scenarios, the ending acceleration and initial acceleration for one roundtrip are also the turnaround acceleration for another round trip and the explanation would give contradictory predictions as to how much net proper time difference that pair of accelerations would yield.

Fifth, if the net proper time difference is being explained by the turnaround acceleration, that implies that during the constant velocity parts the twins’ clocks are accumulating proper time at the same rate. The turnaround acceleration period can be made arbitrarily small with respect to the duration of the constant velocity legs of the trip. Hence, it’s difficult to see how, for example, the traveling twin’s clock can lose one million hours in a period that both twins observe as being less than an hour.

III) Absolute Time Dilation Some have proposed that the net proper time difference must be caused by an asymmetric time dilation effect that is a function of velocity relative to a special frame. Unexpectedly, it turns out that this approach yields the standard net proper time difference regardless which frame is selected as the stay-at-home frame and as such no paradoxes/problems have been raised with this approach to date.

This view, again like everything else in the Twin Paradox debate, has many variations amongst its supports. Some say this proves that special relativity is invalid. Some say this phenomenon is independent of and compatible with special relativity. Some say this phenomenon is a necessary extension of special relativity. Hence, depending on which flavor one chooses, many have theoretical problems with this type of solution.

IV) Nature of Space-time Possibly, because of the above enumerated complexities some simply say that the net proper time difference is due to “the nature of space-time”. Since the Twin Paradox clearly seems to be in the domain of space-time physics, this assertion would appear to be true. However, by itself, it does not seem to give much insight. One might expect to be able to know what specific property or characteristic of space-time explains the net time difference.

Some assert that a Minkowski diagram explains the net proper time difference in terms of space-time. However, a Minkowski diagram, by definition, must be consistent with special relativity and such a diagram drawn in the stay-at-home frame depicts observed time for the traveling twin and not proper time. A Minkowski-like diagram that depicts proper time for both twins describes a new phenomenon, namely, asymmetric absolute time dilation. Since asymmetric absolute time dilation cannot be a function of symmetric relative velocity, it must be the function of absolute velocity and must be the same asymmetric absolute time dilation as described in the prior section – with the same theoretical opposition.

References

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• H.E. Ives, The Aberration of Clocks and the Clock Paradox, J. Opt. Soc. Am. 27, 305 (1937).
• H.E. Ives and G. R. Stilwell, An Experimental Study of the Rate of a Moving Clock, J. Opt. Soc. Am. 28, 215 (1938).
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[Note on References: Since the references to the above papers came from the References/Bibliography sections of published papers and various journals have different standards not all the references include paper titles, but will try to fill in that info - also any citation gurus are welcome to fill in that info. Dingle was by far the most well known proponent of there being a paradox. Of his many critics, McCrea was the most vocal. Before Dingle, Ives was also a well known proponent of there being a paradox. Geoffrey Builder was well known for developing ideas on resolving the paradox. Prokhovnik built on those ideas - pro and con. Many, many others added their own insights.] TwPx 04:04, 30 October 2007 (UTC)

That's an interesting read, however there are too many Dingle-exclusionsists on wikipedia, as well as the hard to miss effort to keep WP:Fringe out of Wikipedia which will affect any mention of anti-SR opinion. The article sounds like aether theory and I did not see any references. I score it 0 out of 5 and predict it will be noted as WP:OR and removed. Don't take it too hard. Try reading Max Jammer. Jok2000 21:05, 30 October 2007 (UTC)

Agreed. Original research by someone who, after having "studied the Twin Paradox in depth for around 40 years", writes (emphasis mine):

• "Secondly, one of the most important and ubiquitous themes in the Twin Paradox debate is that when one uses a physics equation to compute the “right” net proper time difference, one is explicitly or implicitly describing the physics of his argument. Hence, if one uses an equation that is normally interpreted as describing “observed” time to describe the traveling twin’s proper time, then that is an invalid use of that equation."

and concludes:

• "It appears that any valid explanation of the net proper time difference must avoid referencing equations/constructs that are generally accepted as describing observed time as opposed to proper time."

This WP:SPA seems to fail to understand

1. the definitions of (and difference between) proper time and coordinate time,
2. that, in order to explain the predicitions of a theory, one should be allowed to use the equations of the theory,
3. that there is no "Twin Paradox debate". There is a bunch of people trying to (sometimes patiently, sometimes impatiently) explain what the paradox (a seeming contradiction) is about and how it is explained not to be a real contradiction, to another bunch of people who have no idea what special relativity is about. As interesting a sociological phenomenon it might be, it is not a debate. Debates require symmetry.

Sigh. - DVdm 09:00, 31 October 2007 (UTC)

RE: Jok2000: I think that in the past some have tried to argue against SRT and/or for aether theory and you naturally tend to think, after a quick read, “Here is more of the same .” However, those are not my personal views nor am I trying to argue for them. As stated in my introduction, I am factually stating what prominent physicists have published on both sides of the argument – really there are many, many sides. I am trying to accurately write the conceptual history of the Twin Paradox. I do this because I think that most people who come to an encyclopedia to find out about the “Twin Paradox debate)” will be doing so in a context to either just read the first paragraph or to get a feel for what the controversy (i.e., the conceptual history) was about.

Yes, part of the final sections deals with some points that were raised that can be indirectly related to aether theory, but the final sections are not a conclusion – rather they are just the last sections – I put them at the end as they are of lesser relevance (and the reader might not get down that far) and a lesser part of the controversy. Aether theory was not mentioned and I was not thinking of it as even a minor theme.

However, if what I intended to write is commonly read to be different than what I intended, I really want to rewrite to correct the ambiguity or unfortunate phrasing. If you can be more specific and say “You wrote ‘xyz’ which I took to mean ‘(some anti-SRT statement)’ ”, then I can see how you interpreted it to mean something different than I intended and rewrite it.

I’m glad you raised the question about Fringe as it should be discussed. If I took one of the Fringe resolutions and said that that was the correct resolution of the Twin Paradox, then clearly that would be Fringe. However, I simply gave the accepted resolutions and gave the key concepts and questions for each as part of the history. (I don’t think I mentioned any Fringe resolution except indirectly by mentioning Absolute Time Dilation which is one of the major themes of the Twin Paradox (e.g., Langevin).)

The Wikipedia page on Fringe Theories, WP:Fringe, notes, “Even demonstrably incorrect assertions and fringe theories like the Face on Mars can merit inclusion in an encyclopedia - as notable popular phenomena .” To tell people what they come to an encyclopedia to learn about the “Twin Paradox (debate)”, one may not have to include the fringe theories, but one does have to give the reader a basic idea about what the controversy between accepted theory and Fringe was about. So one must bring in Fringe at least indirectly. For example, the entry on Herbert Dingle factually discusses his views including Fringe views.

I don’t know if your comment “there are too many Dingle-exclusionsists on Wikipedia ” applies to the Twin Paradox entry. If it does, it would be unfortunate for Wikipedia readers in the same sense as it would be infortunate to not mention Stalin in relevant sections of Russian history just because one is, understandably, not pro-Stalin.

References: I believe that I addressed your point about references in my introductory remarks, “We have a great many references that I will need to reformat for Wikipedia. However, hopefully, we can focus on content. … Your list of references is excellent and we plan to add to that".”

You “predict it will be noted as WP:OR and removed.” Yes, I agree as I do see a very well documented history of bogus use of that and other Wikipedia rules used to get around the most basic rules and spirit of Wikipedia and as an excuse to delete anything they disagree with.

You wrote, “That's an interesting read.” Thank you. Yes, the Twin Paradox with its associated interplay and evolution of conflicting ideas is a most interesting topic.

RE: DVdm: Some parts of the section above to Jok2000 apply to DVdm as well.

DVdm, I believe, is asserting that two quoted passages are “original research”. The quotes seem to me to be stating the obvious and not at all new. I think they spell out for the reader some basic concepts and are helpful. They’re clearly not original research. However, re-reading them, I do see a subtle difference between them and the bulk of the rest of the (alternative) article which enumerates the basic themes of specific papers whereas the two quotes, while echoed in papers many times in the context of a specific argument, are phrased as summaries of many papers. So I will reflect on possible changes and make changes - I’m not wedded to them. (By the way, I don’t see how the first quote, “studied the Twin Paradox in depth for around 40 years”, with emphasis added by DVdm, supports or is relevant to the (bogus) “original research” claim. I would certainly agree that Wikipedia is not the place to publish original research.)

DVdm then makes three claims without supporting logic. First, he claims that I “fail to understand the definitions of (and difference between) proper time and coordinate time”. Actually, the whole group which reviewed the article understands it well. DVdm has made a derogatory comment without supporting logic. Please give the specifics that back up this claim.

DVdm claims that I “fail to understand that, in order to explain the predictions of a theory, one should be allowed to use the equations of the theory.” I don’t know what that claim is based on. I agree you should be allowed to use equations. I chose to write the factual history treated in a conceptual and readable way, but that in no way implies what you seem to read into it. If adding an equation or two will help readability, then it should be done.

Someone once said, “Women make better teachers than men, because women tend naturally to focus on helping the student learn whereas as men are interested in showing what they know.” I don’t know if that’s true, but it makes a good point. As I read, the later sections of the current article, I get the impression that the author “knows it and wants to show it” as opposed to being really focused on what the typical reader is looking for.

Since you are interested in physics, you probably heard that when Stephen Hawking discussed writing his “A Brief History of Time”, his savvy editor told him that for each equation in the book, expected sales would be cut in half – not just that people would skip those sections, but that when they skimmed the book and saw equations, their eyes would glaze over and they would go elsewhere. I think it’s a rare reader who will come to the Wikipedia Twin paradox article wanting to crawl through a set of equations. Even for that rare reader, the best approach is probably to guide him to some source intended for technical exposition as in “For a more in depth discussion see Jones’ ‘ABC of Relativity’ and for the full treatment see Smith’s ‘A To Z of Relativity’.” The typical reader may come to the article because there was some reference to the ‘Twin Paradox’ or ‘Twin Paradox debate’ in a newspaper, magazine, scifi book, etc., but he probably will not be using it to supplement his reading a special relativity text book. However, again, if adding an equation really can be seen to help the typical reader, then it should be added.

DVdm writes that “that there is no ‘Twin Paradox debate’. There is a bunch of people trying to (sometimes patiently, sometimes impatiently) explain what the paradox (a seeming contradiction) is about and how it is explained not to be a real contradiction, to another bunch of people who have no idea what special relativity is about.” I agree that that’s a reasonable summary of the authors’ approach to the current Twin Paradox article. I think this view misses the essence of the Twin Paradox topic and does a great disservice to readers. (Such a view would not interfere with doing a text book as that would be aimed at teaching accepted theory and not history of science.) The authors don’t think there is or was a debate and have edited it out. However, readers will come across references to the ‘Twin Paradox debate’ and want to know what it’s about and some will want to know what the controversy was about regardless of whether both sides were equally strong. This is why I became interested in improving this article.

DVdm refers to me as an WP:SPA and one possible characteristic is “pushing an agenda”. I’ve explained my agenda above. Similarly, DVdm has articulated his agenda above. When a person or small group exercises absolute editorial power, one can tend to become dismissive of suggestions from outside the group and not really read and analyze outside input, but just give any criticism that comes to mind and then judge outside contributions as invalid. On the alternative version, I agree with the serious suggestions that references need to be added and the two quoted sentences need to be reworked. If reasonable arguments are given as to why the alternative approach is not good, then I’ll be receptive. So let’s agree to implement the alternate or have constructive discussions on it or have us begin making changes in good faith or moving (rapidly) along Wikipedia’s resolution roadmap, Wikipedia:Dispute resolution? Thanks TwPx 20:32, 2 November 2007 (UTC)

Just one comment to opening line

"DVdm, I believe, is asserting that two quoted passages are “original research”. The quotes seem to me to be stating the obvious and not at all new."

==> You believe wrongly. The two quoted passages are not original research. The entire "Alternate Twin Paradox Entry" will probably be recognised as original research, but as far as I'm concerned, that is really irrelevant in the context of my comment. I picked the two quoted passages, one of which nota-bene being the very conclusion of the entry, as the most obvious examples of "not at all new" common basic misunderstandings. None could be less original - we get them here all the time.

Since your first two sentences already require me to write a significant multiple of that, and since I really have nothing to add to my previous comment that could possibly help you in any way, and of course, since this talk page is not really the place to do that in the first place, this is, also due to energy shortage, where I will stop commenting.

DVdm 21:36, 2 November 2007 (UTC)

To TwPx: There is as of yet, no dispute. We have so far tried to bring you up to speed on the edit history of the page, as regards to the placement of SRT, Dingle and WP:OR complaints that pop up from time to time. I propose that you attempt consensus with the other editors who come to this page once in a while one issue at a time. As a suggested start, if you look at the edit history of this page, you will see that I recently cited Max Jammer. Please read the page cited and let me know if it causes you any issues with your proposed changes. I am of course open to dropping irrelevant citations I may have added. More to the point, I believe the citation I listed Oct 14, prior to your arrival is in conflict with one or more statements in your summary. Jok2000 22:17, 2 November 2007 (UTC)

In the 8 o'clock day-1 department, try reading the first 2 sections of Talk:Twin_paradox/Archive_01 and tell me what you think. Jok2000 22:42, 2 November 2007 (UTC)

Thanks for trying to be helpful. I looked quite far back here and in the archives/history searching on Jok2000 and Jammer, but got no hits. I see no entry for you for Oct 14. I read the first 2 sections of your reference and don't see the direct relevance to what I wrote above. I've read a great deal of the history.

TwPx 03:44, 5 November 2007 (UTC)

Proposed Update

In the "To: Wikipedia Twin Paradox Entry Administrator(s)" section above, I proposed an alternative version. I still favor the alternative.

I now specifically propose replacing the current article's History section with the alternative's Early History, Dingle, Post Dingle and Historical Summary sections.

I think this would be a very constructive move and I await your comments. TwPx 22:35, 2 December 2007 (UTC)

Removed burst of unsourced speculations, musings and weasel words by twpx

• Undue weight to Dingle.
• Speculation and weasel words like "So many asked", "Basically, the answer was", "Perhaps, persuaded", "explanations seemed to be equivalent", "seemed to share", "alleged flaws", "were clearly mutually exclusive", "for many, it was difficult to see", "Many other objections were raised as well.", "it’s generally assumed", "there is great disagreement on the detailed explanation", "equal disagreement on their detailed positions", "no one holds the majority position", ...
• Soapbox statement like "Many times in the history of physics there have been prolonged debates between well respected physicists that have pointed to important advances. Sometimes both sides were partially correct. For centuries, physicists debated whether light was a particle or a wave before it was determined that light had both particle and wave characteristics. Also, many times physicists have tried to sweep “loose ends” under the rug because they were inconsistent with current theory only to find later that the “loose end” served as a clue to major breakthroughs. Will the Twin Paradox have a similar role? Only “time” will tell."

DVdm (talk) 16:20, 12 December 2007 (UTC)

On 10/30/07, I posted what I added on the Discussion page and what DVdm deleted on 12/12/07. DVdm did respond to the 10/30/07 posting. However, DVdm did not make any of the comments given here. Instead, DVdm did make a number of other unsubstantiated claims. For example, DVdm claimed that TwPx “fail[s] to understand the definitions of (and difference between) proper time and coordinate time”. TwPx then requested that DVdm give the specific logic that backs up his claim. No response was ever given. Please respond or retract. (Looking at the history of this article and other related articles, I see this was not an isolated occurrence for DVdm. Also, the history shows a tendency to delete while only giving some peripheral or irrelevant comment.)

I'll address the three issues raised by DVdm:

1) Undue weight to Dingle: Starting in the fifties, the "Twin Paradox" and "Dingle" were near to being synonymous. If one heard "Twin Paradox", one thought of "Dingle" and vice versa. If one studied the topic and was familiar with the literature, one was aware of many other authors - some of whom played significant roles. However, even then, Dingle was the most prominent name. Often those who maintained that "there is no paradox" referred to those who maintained that "there is a paradox" as "Dinglites".

Hence, adding a discussion of Dingle is just an attempt to be accurate and note that there was a group who held that "there is a paradox" - as personified by Herbert Dingle who became their most well known spokesman.. In addition, readers who come to Wikipedia to find out more about the "Twin Paradox" because of something they read might well come in a context where a discussion of “Dingle” is relevant.

I don't argue that Dingle's ideas were of special importance, I'm just reporting the facts. Dingle and his debates and papers and book made a big splash and made the Twin Paradox a prominent issue and virtually anyone who read about the Twin Paradox was aware of him and those debates.

In replacing, the proposed enhanced section with the old, one deletes any reference, in the body of the article, to Dingle or to any other person who claimed it was a paradox. So one could claim that change gave "too little weight to Dingle (or anyone like him)".

(Actually, Langevin is mentioned in the article, but the article says, "It should be stressed that neither Einstein nor Langevin considered such results to be literally paradoxical". While this is technically true, it gives the naive reader a false impression of Langevin's position and a false impression of the discussion of the paradox in those early years. So the only two physicists referenced are said to not think it paradoxical so the naive reader tends to come away from reading the article thinking that "Twin Paradox" was a misnomer and it should have really been called something like the "Twin Scenario".)

If the article was on Special Relativity, then bringing up Dingle or something like aether theory could indeed be a case of giving undue weight to those topics that are not part and parcel of Special Relativity. However, explaining the "Paradox" part of the "Twin Paradox" is part and parcel of the "Twin Paradox". Furthermore, the context for a large group of readers coming to the article will include the "Paradox" aspect and, in many cases, even include reference to Dingle.

One could mention others such as Geoffrey Builder, who played an important role in the debate, and by adding these others that would diminish the relative emphasis on Dingle. However, I felt that a thorough review was not the best way to go and just selected the most well known representative of the "Paradox" side. That addition seemed to make the article more balanced and more understandable and responsive to a large group of potential readers.

Of the three papers in the current Notes, one is a fifty page discussion of the Dingle debates.

DVdm's own User page, as of this writing, has one section entitled "A trivial refutation of one of Dingle's Fumbles" which discusses Dingle and the Twin Paradox (although admittedly in the context of the Dingle article). I understand that DVdm is contemptuous of Dingle, and of many (new) editors in the article’s history. Deleting all reference to Dingle and others is consistent with his stated view that “that there is no ‘Twin Paradox debate’". However, this does not seem like a neutral view.

The discussion of Dingle is really a once over lightly treatment and doesn’t go into any detail on his logic arguments. To make Dingle less prominent, I can change the Heading of the “Post Dingle” section to something like “Recent History”.

2) Speculation and weasel words: All the quoted phrases are partial sentences and, hence, with no context.

We all know from political debates that mudslinging and name calling can be very effective as words can have a subliminal effect. Hence, the reader can read the quoted phrases and automatically think "Oh! How weaselly!" However, I don't see how, for example, "So many asked", "Basically, the answer was", of necessity meet either allegation. Further, most of the quotes will be seen to accurately reflect the literature if one is familiar with the literature.

Where I used words like "Perhaps" and "seemed", it was to report on those papers, but remain neutral (i.e., avoiding absolute pronouncements).

The old section had no Notes. The deleted section had 10 Notes (i.e., footnotes, sources) tied to specific statements. In addition, the existing References give significant support to the deleted section. In addition, the section of the Discussion where the deleted section was first placed contains a list of additional References which while being more specific to the following sections, also support the partial quotes as one should be aware.

3) Soapbox: Claiming someone is on a "Soapbox" is just another way of saying that you disagree with what's being said. It’s no more inherently a "Soapbox" statement than, say, "It should be stressed that neither Einstein nor Langevin considered such results to be literally paradoxical" or “that there is no ‘Twin Paradox debate’".

In the referenced paragraph, the initial statements are true, "Many times in the history of physics there have been prolonged debates between well respected physicists that have pointed to important advances. Sometimes both sides were partially correct. For centuries, physicists debated whether light was a particle or a wave before it was determined that light had both particle and wave characteristics. Also, many times physicists have tried to sweep “loose ends” under the rug because they were inconsistent with current theory only to find later that the “loose end” served as a clue to major breakthroughs". To add "Will the Twin Paradox have a similar role? Only “time” will tell.'" is a light way to end and leaves it as an open question rather than a Soapbox sales pitch.

I think that most who are familiar with the discussion of the Twin Paradox and who wanted to give an accurate, neutral account would cover the earlier material in a similar way as the deleted section up to this last paragraph. I see the last paragraph as making an interesting, neutral point, but if there's a better way to wrap it up, please, all, give suggestions.

All those who agree with DVdm's style and content above and in the rest of the Discussion section for this article (and, if you so wish, the Discussion for other articles), please so indicate below. Thanks. TwPx (talk) 00:05, 14 December 2007 (UTC)

Gads. Hard to know what to respond to here. My bias is that I primarily want to have the physics of the twin paradox explained well in the article, and I find that like virtually every other article having to with special relativity, it fails miserably. From a physics point of view, no one has ever shown me anything approaching an unresolvable twin paradox. I thought the addition by TwPx was completely ridiculous. Were I interested in disrupting the encyclopedia to make a point (which I'm not, but dang it, I do consider having some sock puppet hoedowns), I would have added sections on nascent-Dingle, adolescent-Dingle, puberty-Dingle, bar-age Dingle, and finally full-blown adult Dingle. Cripes, I actually got his book 'Crossroads' when the Dinglerama was taking place at his article talk page. The book goes into great detail complaining that physicists ignored him. Exactly who are these people who "heard twin paradox" and immediately "thought Dingle"? More importantly, where are the sources? All kinds of rot can be included in wikipedia if you can source it.

Another thing. Geoffrey Builder? You've got be to kidding. He was a radio engineer, not a physicist, who wrote a few papers in his waning years that to my knowledge got hardly any citations from serious phisicists. I've seen his name trotted out before under questionable circumstances, so it makes me curious. If people like Dingle and Builder were at the forefront of thought about the twin paradox, how come physicists didn't notice?

Final thing. The Chang article. I've never read it, but I did suggest it be readded to the Dingle article, and I think no one responded to my suggestion. It's not available without subscription, and it's unclear whether it belongs in this article at all. Again, if the material in that article is so relevant, where are the physicists commenting about it? Tim Shuba —Preceding comment was added at 22:55, 14 December 2007 (UTC)

"... sections on ..., and finally full-blown adult Dingle." - You forgot the realy final, most relevant one. Sorry, couldn't resist, DVdm (talk) 09:02, 15 December 2007 (UTC)

Regarding Tim Shuba's, "My bias is that I primarily want to have the physics of the twin paradox explained well in the article", that seems reasonable. The proposed sections describe some of the physics concepts that have been written about in the Twin Paradox debate. For a better, specific, detailed discussion of the physics, I think you should comment on the current sections that attempt to give those details.

Since I've already written a lot re DVdm that applies to Tim Shuba, please see my responses to DVdm above and below for the general points.TwPx (talk) 05:50, 17 December 2007 (UTC)

Proposed Update 2

Obviously, we would like to see the enhanced history section restored - with changes as discussed in our response above.

The only other major change to the article would be to insert the "Proposed Solutions and Associated Questions" section (see the "To: Wikipedia Twin Paradox Entry Administrators" entry above) after the current "Specific Example" section and before the current "Resolution of the paradox in special relativity" section.TwPx (talk) 04:08, 14 December 2007 (UTC)

To me it obvious that TwPx is trying to sneak an originally researched essay into Wikipedia. The central thesis of the essay is that the twin paradox is an ongoing symmetric debate with no clear outcome, between those who think that special relativity is a valid theory and those who don't. As I already stated, this is false. There is no debate. There is a group of lay people failing to understand the basics of a somewhat advanced part of physics. Misguided by the trivial mathematics which is used in this part, they feel they should be able to understand this, but they just don't. Putting Herbert Dingle central in this (see removed sections "Dingle" and "Post Dingle") is putting heavy undue weight to a person who made an eternal fool of himself in his -sorry- pathetic "Science at the Crossroads". Clearly TwPx thinks that Dingle had a case. Dingle did not have a case. If TwPx thinks otherwise, then TwPx clearly is a member of the aforementioned group of lay people. Taking into account the fact that TwPx "studied the Twin Paradox in depth for around 40 years" and fails to see how, for example, Dingle's central theme is trivially refuted, and thus still fails to understand the basics of special relativity, my well-meant advice is that he should seek another hobby. Wikipedia is not a publishing service for essays.

There is no open debate with no clear outcome among biologists about whether religious fanatics have a point pushing creationism. They don't have a point.

There is no open debate with no clear outcome about whether some people have a point thinking that the 1-2-3-4-5-6-7 lottery combination is far less likely than any other combination. They don't have a point.

DVdm (talk) 12:13, 14 December 2007 (UTC)

Once again, DVdm's argument is based on perjorative words and unsupported statements, e.g., "sneak", "this is false", "There is no debate", "group of lay people failing to understand the basics", "Misguided by the trivial mathematics", "they should be able to understand this, but they just don't", "fails to see", "is trivially refuted", "fails to understand the basics of special relativity", "he should seek another hobby". I also don't see the last two paragraphs adding logic that supports DVDm's assertions.

I think that I've been clear in my comments about what I wanted to do and in the actual proposed sections. DVdm has not said why the proposed section should be considered as something inherently objectionable (e.g., "an essay") as opposed to what's currently written for this article or any other Wikipedia article. DVdm seems to have misread the proposed sections. I'm simply accurately recording what was said about the Twin Paradox. I wrote about what the literature contains as represented in summary form by the references given above.

I nowhere say that Dingle was correct. I mentioned his views including the fact that those views changed and that when he was asked for an alternative to special relativity, he had none. I also quoted what was the most recent indepth review of Dingle Twin Paradox debate . If DVdm thinks Prof. Hasok Chang "fails to understand the basics of special relativity" and "should seek another hobby", then DVdm should give a specific quote from the referenced paper and give the detailed logic that refutes what Chang has written. The Chang paper was one of 3 Notes already in the article when I first read the article, I did not add it. I think Chang is very intelligent, professional and objective who thoroughly analyzed all written material and wrote a well reasoned paper.

Personally, I'm not a Dingle-ite. I've always thought special relativity was a valid theory. I have not made any assertions that special relativity isn't valid. I have accurately stated the ideas in the literature whether or not those ideas were put forward by people whose opinions agreed with mine.

Twice DVdm has mockingly quoted that TwPx "studied the Twin Paradox in depth for around 40 years". Actually, that forty year in depth study of the Twin Paradox literature is relevant. From reading DVdm's objections (e.g., what he erroneously referred to as speculations), it seems that many of DVdm's objections stem from not having the same broad exposure to the literature and misinterpreting my review of the literature as my expressing my personal views.

(For the 2nd time above, I asked DVdm to give supporting logic or retract his claim that TwPx “fail[s] to understand the definitions of (and difference between) proper time and coordinate time”. There's still no answer from DVdm.)

The alternative was entered into the Discussion on 10/30/07 (I since suggested it be broken into two sections and added (the first section as an enhanced History) to the current document.) You can read DVdm's comments. Everyone, including wwoods and Gscshoyru, should make his views known below as to whether they agree or disagree with DVdm's (and Tim Shuba's) content and style. (I see by DVdm's insightful comment following Tin Shuba's remarks that he's in agreement with Shuba.) If DVdm/Shuba don't represent the consensus view, then we can move on. If DVdm/Shuba do indeed represent the consensus view, it looks like we will go to Arbitration and we would like to be efficient and just go once so all who agree with DVdm/Shuba can be dealt with collectively. ThanksTwPx (talk) 05:45, 17 December 2007 (UTC)

Above, in this section, I proposed an addition. DVdm objected. I noted that DVdm's assertions could not be supported and then asked if anyone agreed with DVdm. No support has been given for DVdm's position. I will therefore add the section.TwPx (talk) 20:38, 3 January 2008 (UTC)

No one agreed with your additions. No support has been given for your position. There is no consensus. The fact that no-one replied to your proposal does not imply that "DVdm/Shuba don't represent the consensus view".

Reverted back for reasons already stated. Wikipedia is not a soapbox, nor a publishing service for originally researched essays. Try a private publisher or a blog on your personal website. Good luck, DVdm (talk) 21:27, 3 January 2008 (UTC)

The reasons DVdm gave above were clearly rebutted. No reply was given. DVdm continues to make unsubstantiated claims. DVdm has routinely deleted additions made in good faith by others. The deletion is not consistent with Wikepedia guidelines - see WP:Revert.TwPx (talk) 22:27, 3 January 2008 (UTC)

Repeat: No one agreed with your additions. No support has been given for your position. There is no consensus. The fact that no-one replied to your proposal does not imply that "DVdm/Shuba don't represent the consensus view". DVdm (talk) 22:38, 3 January 2008 (UTC)

DVdm continues to avoid the points raised and gives no substance. The reasons DVdm gave above were clearly rebutted. No reply was given. DVdm continues to make unsubstantiated claims. DVdm has routinely deleted additions made in good faith by others. The deletion is not consistent with Wikepedia guidelines - see WP:Revert.TwPx (talk) 01:52, 4 January 2008 (UTC)

Two applicable Wikipedia policies in this situation are the prohibitions against original research and constructing novel narratives from available sources. In addition, many of your statements are simply mis-representations of the alleged sources. For example, Einstein's 1905 paper does not say what you say it says. Your entire proposed section consists of original research, novel narrative, and misrepresented sources. Granted, the fact that your original research is idiotic drivel and your novel narrative is pure crackpotism may prejudice some editors against your proposal, but those facts are irrelevant. Simply by virture of being original research and novel narratives and misrepresentation, your proposal must be rejected. There's no need for (and no point in) any detailed rebuttal of your research and narrative.Lumpy27 (talk) 08:16, 4 January 2008 (UTC)

Lumpy27 follows the standard mode of DVdm of citing this or that Wikipedia policy as the reason for deleting contributions from others - in this case, "Original Research". At the same time, you and DVdm have consistently shown total disregard for following Wikipedia policy. For example, being rude and insulting (e.g., "idiotic drivel", "pure crackpotism"). Regarding the "Original Research" charge, I've already rebutted that above. Again, if you were familiar with the literature, you'd be aware that it's an accurate portrayal of the Twin Paradox Debate. You conclude, "There's no need for (and no point in) any detailed rebuttal of your research and narrative." That's a very convenient position since you unable to point out specific problems.

The one specific charge was "Einstein's 1905 paper does not say what you say it says." Please give the details. What did I write that was "wrong" and what specific statements in the 1905 paper do you think it contradicts - no generalities, be specific. ThanksTwPx (talk) 17:19, 4 January 2008 (UTC)

It's rather odd that you object to people basing their rejection of your edits on Wikipedia policy, rather than by giving explanations of the specific errors in your proposed material. Wikipedia policy is supposed to be the basis for evaluating edits. Editors are explicitly prohibited from basing their edits on anything else. For example, the "no original research" policy was formulated explicitly to deal with physics cranks, because the founders of wikipedia realized that it is impossible to ever convince a physics crank of the erroneousness of his beliefs. That's more or less the definition of a crank. So, rather than allowing wikipedia to lapse into a giant forum for endless arguments with physics cranks over content, the "no original research" and "no novel narrative" policies were created. Here is some relevant excerpts from official wikipedia policy explanations:

Just been reading the link to your page "A trivial refutation of one of Dingle's Fumbles". Wasn't clock A synced (using Einstein's method for clocks stationary to each other) to clock H, therefore making rate of A identical to rate of H? Ditto clocks B and N? I think Dingle tried to explain this on page 229.

--Jimbo2x (talk) 00:10, 9 January 2008 (UTC)

"Wikipedia's founder, Jimbo Wales, has described original research as follows: The phrase "original research" originated primarily as a practical means to deal with physics cranks, of which of course there are a number on the Web. The basic concept is as follows: It can be quite difficult for us to make any valid judgment as to whether a particular thing is true or not. It isn't appropriate for us to try to determine whether someone's novel theory of physics is valid; we aren't really equipped to do that. But what we can do is check whether or not it actually has been published in reputable journals or by reputable publishers. So it's quite convenient to avoid judging the credibility of things by simply sticking to things that have been judged credible by people much better equipped to decide. The exact same principle will hold true for history" (WikiEN-l, December 3, 2004).

The phrase "original research" in this context refers to untested theories; data, statements, concepts and ideas that have not been published in a reputable publication; or any new interpretation, analysis, or synthesis of published data, statements, concepts or ideas that, in the words of Wikipedia's founder Jimbo Wales, would amount to a "novel narrative or historical interpretation".

If a viewpoint is held by an extremely small (or vastly limited) minority, it doesn't belong in Wikipedia ... regardless of whether it's true or not; and regardless of whether you can prove it or not.

What counts as a reputable publication?

Reputable publications include peer-reviewed journals, books published by a known academic publishing house or university press, and divisions of a general publisher which have a good reputation for scholarly publications."

So, you see, the question is not whether your proposed research and narrative is "true", the question is whether it reflects the point of view of more than just a very small minority of individuals, and this question is to be answered by citing reputable sources, and those sources must be presented in proportionate fashion. In other words, if 1000 reputable sources say X, and 3 reputable sources say Y, then Y deserves only about 3/1000 as much attention in the article as X, and since most articles are of a length that 3/1000 would be virtually nothing, there is an effective lower bound on viewpoints held by extremely small minorities. Such viewpoints do not belong in wikipedia, per the editing guidelines. You are trying to insert into this wikipedia article material that is explicitly prohibited by wikipedia policy. You should stop trying to do that.Lumpy27 (talk) 18:29, 4 January 2008 (UTC)

I understand the statements in bold and agree with them completely. However, as you should know, it's not relevant to what I wrote. I'm not proposing anything new. I'm simply, as you should know, recounting what was written about in the Twin Paradox Debate. I've gone into this, including the rationale, in great detail above.

If I tried to discuss Lorentz Aether Theory (LAT) in the Special Relativity article, then what you wrote would be relevant. However, this topic is different as discussed in detail above. I'm glad you brought up the point about reputable sources as virtually all the literature on the Twin Paradox discusses the "Proposed Solutions and Associated Questions" I discuss. Few if any have the main topic that there never was a Twin Paradox debate.TwPx (talk) 22:22, 4 January 2008 (UTC)

Your proposed addition is entirely original research and novel narrative. Just to give one simple example so you have some idea what I'm talking about, we need go no further than the second sentence in your essay. (The first sentence is rather poor as well, but might be passable.) Your second sentence is

"In that paper, he derived the (special relativity) time dilation equation that said that all inertial (i.e., non-accelerating) observers would observe all other inertial observers’ clocks to be running slow by the reciprocal of the Lorentz factor. So the greater the relative velocity between two inertial observers the slower they would observe each other’s clock to be running."

Presumably your source for this sentence is Einstein's 1905 paper, but you have not quoted the paper, you have instead offered your paraphrase, which unfortunately embodies the very ambiguities and misconceptions that underlie the fallacies in all crackpot "reasoning" about special relativity. The paper nowhere says "inertial observers would observe all other inertial observers’ clocks to be running slow". That's a meaningless assertion as it stands, because it doesn't define what it means for an observer to observe a moving clock. The paper refers, instead, to the rate of a clock when viewed from (i.e., in terms of) "the stationary SYSTEM" or from any "SYSTEM in uniform motion". The crucial word there is 'system'. This word has been defined previously and very carefully in the earlier section of the paper. Anyone who grasps the difference between what Einstein wrote in the cited paper and how you paraphrased it will also understand all the fallacies and non sequiturs in the remainder of the proposed alternative version of this article. And this is just the second sentence. Each of the subsequent sentences is crammed full of just as much (or more) misrepresentation and original research and novel narrative.

As a constructive suggestion, I recommend that you withdraw your current proposal, and re-write it, this time without paraphrasing. When you want to tell the reader what Einstein said, tell the reader what Einstein said, verbatim. I also suggest that you focus on presenting the history of the subject as it is presented in any of the numerous reputable sources that are widely available. Do not go back and dig up letters to the editors of Nature in 1956 and string them together with your own interpretations, and then claim that you are not engaging in original research or novel narrative. If you base your summary on the 99.99% consensus views expressed in reputable sources, rather than your own interpretation of the 0.01% views of a couple of retired engineers and armchair philosophers, I think the result will be more likely to be accepted here in Wikipedia.Lumpy27 (talk) 01:01, 5 January 2008 (UTC)

Here is a quote from Einstein's 1905 paper, for reference:

Further, we imagine one of the clocks which are qualified to mark the time t when at rest relatively to the stationary system, and the time $\tau$ when at rest relatively to the moving system, to be located at the origin of the co-ordinates of k, and so adjusted that it marks the time $\tau$. What is the rate of this clock, when viewed from the stationary system?

Between the quantities x, t, and $\tau$, which refer to the position of the clock, we have, evidently, x=vt and

$\tau ={\frac {1}{\sqrt {1-v^{2}/c^{2}}}}(t-vx/c^{2}).$

Therefore,

$\tau =t{\sqrt {1-v^{2}/c^{2}}}=t-(1-{\sqrt {1-v^{2}/c^{2}}})t$

whence it follows that the time marked by the clock (viewed in the stationary system) is slow by $1-{\sqrt {1-v^{2}/c^{2}}}$ seconds per second, or--neglecting magnitudes of fourth and higher order--by ${\frac {1}{2}}v^{2}/c^{2}$.

From this there ensues the following peculiar consequence. If at the points A and B of K there are stationary clocks which, viewed in the stationary system, are synchronous; and if the clock at A is moved with the velocity v along the line AB to B, then on its arrival at B the two clocks no longer synchronize, but the clock moved from A to B lags behind the other which has remained at B by ${\frac {1}{2}}tv^{2}/c^{2}$(up to magnitudes of fourth and higher order), t being the time occupied in the journey from A to B.

It is at once apparent that this result still holds good if the clock moves from A to B in any polygonal line, and also when the points A and B coincide.

If we assume that the result proved for a polygonal line is also valid for a continuously curved line, we arrive at this result: If one of two synchronous clocks at A is moved in a closed curve with constant velocity until it returns to A, the journey lasting t seconds, then by the clock which has remained at rest the travelled clock on its arrival at A will be ${\frac {1}{2}}tv^{2}/c^{2}$ second slow. Thence we conclude that a balance-clock⁷ at the equator must go more slowly, by a very small amount, than a precisely similar clock situated at one of the poles under otherwise identical conditions.

--Jimbo2x (talk) 22:30, 8 January 2008 (UTC)

Stationary in relation to which frame?

In section 3 (Resolution of the paradox in special relativity), it is stated that "his position is constant in space, moving only in time" (that is the position of the first, Earth bound twin).

Can the frame of reference to which twin one is not moving here be explicitly mentioned? Is the the Earth frame of reference? Or the "absolute" frame of reference? Surely, it cannot be the frame of reference of the ship. —Preceding unsigned comment added by Jimbo2x (talk • contribs) 02:12, 2 January 2008 (UTC)

Agreed. I have edited the sentence to clarify. Timb66 (talk) 10:40, 2 January 2008 (UTC)

Thanks for that. Would it be possible for someone that is familiar with Minkowski's diagrams to prepare a set of diagrams for the twin in the space ship (i.e. for all x' coordinates). It would make the "no symmetry" point clearer. --Jimbo2x (talk) 22:11, 2 January 2008 (UTC)

Not sure what you have in mind there. Minkowski diagrams are not "for someone". They show events as points, and objects and observers as wordlines. One cannot draw a diagram "for the twin in the spaceship". One can draw a diagram that shows both twins. On such a diagram, the stay-at-home twin will live on a single straight line, and the travelling twin will either live on a curve (if the situation is modelled with accelerations), or on three different straight line segments (if we model it with 'frame jumping'):

• before departure and after return, on the line of the stay-at-home twin,
• while receding, on a tilted line (outbound),
• after turnaround, while approaching, on another tilted line (inbound),

Now you can choose one of those 3 lines (or yet another one) as the "vertical" line (and consequently orthogonal with the spatial axis) - see here. Is this what you have in mind?

Or are you thinking about a fancier version of a drawing like this? DVdm (talk) 12:05, 3 January 2008 (UTC)

I meant the first set of diagrams you pointed to (GIF) --Jimbo2x (talk) 18:45, 3 January 2008 (UTC)

Ok, but don't you think that all four 'views' show the asymmetry of the situation equally well as the little diagram in the bottom right of the section? After all, the stationary twin clearly lives on the straight line, whereas the travelling twin lives on the broken line,

so what kind of additional diagram would you like to see? DVdm (talk) 19:35, 3 January 2008 (UTC)

I think you're right, actually. One drawing seems sufficient. --Jimbo2x (talk) 20:19, 3 January 2008 (UTC)

Nobody picked up on it, but I proposed a diagram like this a few months ago, showing the events in all three reference frames:

v = c/√3   (γ = √1.5)

• O is the point at which the traveling twin leaves the stay-at-home.
• E is the point at which the traveling twin reverses course.
• D is the point at which the traveling twin returns home.

• A is the point simultaneous with turnover, in the outbound twin's rest frame.
• B is the point simultaneous with turnover, in the stay-at-home twin's rest frame.
• C is the point simultaneous with turnover, in the returning twin's rest frame.

The three frames of reference are the rest frames of the stay-at-home twin, the outbound twin, and the returning twin. The third is translated so that the traveling twin has the same coordinates after turnover as before. The arrows are the twins' worldlines, the thin lines are their lines of simultaneity at turnover. The dashed diagonal lines show the light cone from the start.

—WWoods (talk) 21:51, 4 January 2008 (UTC)

Looks excellent, but I'm afraid it's going to require a lot of supporting text and explanation, don't you think? And don't forget to include a 4th view where none of the frames coincides with the (- not too confused yet? -) lay reader :-) DVdm (talk) 22:03, 4 January 2008 (UTC)

• Oh sure, the purpose of the picture would be to illuminate the text.
• Does it really need a view from a none-of-the-above frame? This article doesn't have to explain the general concepts of inertial reference frame, the Lorentz transformation, or the relativity of simultaneity, though it needs enough to explain why the twin paradox is counterintuitive but not self-contradictory.

—WWoods (talk) 02:09, 5 January 2008 (UTC)

Doesn't really need that 4th view indeed, but while you're at it, I don't think it would be harmful. I recall a long Usenet exchange which only came to an end when that 4th view was shown. It sort of gives an attractive aerial view, at least i.m.o.

Feel free to download the "new" version here. Cheers, DVdm (talk) 11:37, 5 January 2008 (UTC)

I think it'd be better with the x and t axes for that frame, and the event coordinates need to be recalculated. What velocity relative to the others would be best? Halfway between those of the stay-at-home and the outgoing twins? Put the origin at the start as in the first two, or offset as in the third?

—WWoods (talk) 15:29, 5 January 2008 (UTC)

I wouldn't take halfway. Rather something like 2/3 vs 1/3, something that looks not too symmetric, and the origin as in the first two.

I also would -definitely- replace "point at which" with "event where" or "event when" or (ultimately) "event when/where", and -perhaps- "turnover" with "turnaround", but the latter is a matter of personal taste. DVdm (talk) 15:49, 5 January 2008 (UTC)

The symmetrical clock paradox

Some people get lost in the twin paradox presented here (with accelerations and all), so maybe a simpler, symmetrical paradox is in order. So, here is that "gedanken" experiment:

Let's have two identical rockets, carrying two identical high precision (in today's technology that would be atomic) clocks, with digital displays. The displays show the number of ticks (cycles) that each clock recorded (this could be for instance number of nanoseconds - a simple integer) since last reset. The rockets and clocks include a mechanism that fires the thrusters on detection of blue light and resets the clocks on detection of red light.

These two rockets are placed in space, away from any gravitational fields, so that they are pointed to one another, on a straight line. The rockets are far away from each other and we shall call the left one A and the right one B. Midway between rockets A and B we place a source of light we shall call S, capable of emitting blue or red light, each simultaneously to left and right, toward rockets A and B.

Rockets A and B, together with S form a single inertial frame of reference S for now (in other words, they are all stationary to one another).

Now we send blue light simultaneously from our source S toward rockets A and B. This starts the thrusters and the rockets burn their fuel, therefore being accelerated toward one another, on a collision course. The rockets burn all their fuel and each reaches constant velocity v in relation to our stationary frame of reference S, but in opposite direction. The speed at which the rockets are travelling is "normal" speed (i.e. not nearly close to the speed of light, but something a normal rocket could do).

After the burn is completed, we send red light simultaneously from our source S in the direction of rockets, therefore resetting the counters of our clocks. Now we have a system of three inertial reference frames, A - for rocket A, B - for rocket B and S - for our source of light S, in linear motion in relation to one another. And we have our clocks on rockets A and B synchronised, as observed from S.

Just before the collision occurs (i.e. when rockets A and B are in immediate vicinity of light source S) and if the trip of rockets is sufficiently long, we shall have the following situation in relation to clocks, as observed from different frames of reference, due to time dilation as per special theory of relativity:

• clock A displays N as observed from reference frame A
• clock A displays M (different from N) as observed from reference frame B
• clock A displays L (different from N and M) as observed from reference frame S

And due to symmetry of motion and identical construction of clocks:

• clock B displays N as observed from reference frame B
• clock B displays M (different from N) as observed from reference frame A
• clock B displays L (different from N and M) as observed from reference frame S

In comparison, such a system would show N on both clocks as observed from any frame of reference using only Newton's mechanics. --Jimbo2x (talk) 20:19, 3 January 2008 (UTC)

Since this is entirely original research we can't of course put it in an article, and it doesn't really belong on this talk page either. You might try Usenet. As a matter of fact it just so happens that someone (or you?) just asked exactly the same question on Usenet in sci.physics.relativity.

Anyway, I'll give you two hints here. (1) You write: "... in linear motion in relation to one another. And we have our clocks on rockets A and B synchronised." When they are in relative motion, they are not synchronized. They both see the other one's clock "run slower". (2) You created a symmetric situation, so you get symmetric results. Good luck on Usenet :-) - DVdm (talk) 21:44, 3 January 2008 (UTC)

Point taken about original research. I thought someone must have done this before (it seemed unlikely that this would be original). And it wasn't me on Usenet - so obviously not all that original ;-)

In terms of "synchronised" - they are synced in the sense that they are both running equally different as observed from S. About symmetric - yeah, that was my point. I think it would be useful to show that observers in different reference frames would read the same clock differently in immediate vicinity of each other according to SR.

--Jimbo2x (talk) 21:58, 3 January 2008 (UTC)

The idea of symmetry is of course not new, but I had never seen this kind of setup with the central light.

Little note on "... synchronised in the sense that...". Sure, but that's another kind of synchronization. From the three clocks in the setup, no pair of clocks is synchronized in any way. You could perhaps say that the clocks A and B are sort of equally desynchronized according to S, but as soon as you forget S, A and B are just two systems in relative motion - nothing special about them. In fact, one can construct a "central S" for every pair of systems in relative motion. That can't possibly make the pair physically special.

Do try the Usenet thread - it might become interesting :-)

Cheers, DVdm (talk) 22:25, 3 January 2008 (UTC)

There are only two clocks in the setup - A and B. If two equidistant stationary clocks can be synced by passing a beam of light simultaneously from the midway to them to "reset" them, so can the same two equidistant clocks in uniform opposing motion be synced as observed from S, unless the beam of light somehow travels to the left at different speed than to the right :-) Sure, from A, B is observed to be different (due to relative motion) and vice versa, but for an observer in S, they will be in sync (i.e. explicitly, both clocks display L when rockets meet, as observed from S). I never thought nor do I think that S would make A and B special. S is just another inertial frame of reference and an observer, just like you said.

--Jimbo2x (talk) 23:07, 3 January 2008 (UTC)

Well, you really do have a third clock in there. The minute you mention "reference frame S", you have it. No reference frame without a clock :-)

Do try Usenet for this - it's better suited for this kind of thing. This page is for discussions about the format and content of the article, not the subject. Cheers, DVdm (talk) 08:59, 4 January 2008 (UTC)

No worries. --Jimbo2x (talk) 09:41, 4 January 2008 (UTC)

What To Do About Crackpot Edits

It appears that TwPx is reverting every attempt to remove his POV essay from the article, and it flagrantly violating the 3rr rule. Multiple editors have explained why his essay is not suitable for this Wikipedia article, since it consists of original research and a novel narrative (along with numerous flat-out misrepresentations of alleged sources). I tried to make a constructive suggestion (see above) for how he might try to make his essay conform to Wikipedia policy, but he doesn't seem interested in making any changes to his crackpot essay. Maybe we should just place a banner at the top of the article stating that it has been taken over by a crackpot and should be ignored until further notice. Is there such a banner? If there isn't, there ought to be. This sort of situation will (I'm afraid) crop up more and more often. There needs to be some more efficient way of coping with determined physics cranks.Lumpy27 (talk) 04:09, 5 January 2008 (UTC)

I don't think that any special action is called for at this moment. TwPx seems to have been blocked for a while and the article has been reverted to its original state, so it certainly is not taken over. Regarding such a banner... perhaps... but then of course, insertion and removal should be restricted to admins, and they already have everything at their disposal to deal with this kind of disruption, provided they can base their judgment on properly documented reverts and 'sec' user page warnings. Cheers, DVdm (talk) 16:06, 5 January 2008 (UTC)

A more precise setup?

My impression is, that many discussions suffer from disputable experimental setups. A clock could be embodied by a counter, which counts the frequency of a certain emission mof a simple atom, e.g. hydrogen. Two clocks in relative movement compare their own radiation to the other ones. This is a undisputable setup, as I suppose. Undoubtly, with speed zero, the ratio observed/own frequency will be one. But what, if there is speed <> 0. Will the ratio be <1, >1, and will it be the same for both observers? ErNa (talk) 18:13, 10 January 2008 (UTC)

When clocks are considered in this article, they are always taken to be identical and as ideal as engineeringly possible.

Altough this is not really the place for the other question, for the ratio, take a look at the time dilation overview. Whether they are the same for both observers, you should be able to decide from the carefully explained meanings of the variables in the equation. DVdm (talk) 18:43, 10 January 2008 (UTC)

In the twin paradox, the persons measure time by aging and twins stands for ideal engineered. But to be carefull with identical: if there are two identical clocks, there has to be an observer to state this identity. In the twin paradox, there is no observer, but the twins observe themselves. That is, there has to be a first comparing mechanism as an integral part of the twin, which can compare a inner property (the own age) to an outer property (the twins age) and a second mechanism, that can compares the first results. The outcome of this second comparison tells us, whatever we are, which twin (clock) passes more time in between a period, determined by two events. We should or can debate the TP only after reaching an agreement about such an experimental setup. Anything else is just shouting to the wind. ErNa (talk) 06:47, 11 January 2008 (UTC)

Yes, but don't forget that one also cannot really start to debate the TP after reaching an agreement about the size and the colour of their underwear, and, by extension, about the gender of their guardian angels. And of course, don't forget that there has to be an additional observer to state and verify the latter. DVdm (talk) 09:25, 11 January 2008 (UTC)

Ok, but please don't devaluate my efforts to be more precise by making jokes, even good ones. To make the scenario most simple and unambiguous, we define, which abilities the "twins" have. A twin has a clock, creating ticks. A measure for the amount of time, that passes for this twin, is embodied by a counter, incremented with every tick. A possible mechanism for the clock is a resonator, tuned to the radiation of certain arrangement of elementary particles :-), lets say, hydrogen atom. This can be seen as a laser, and by tuning the resonator, the frequency and the wavelength can be determined. Now we have to presumtions: proton and electron will have certain energy levels and the speed of light is invariant. These presumptions give us scales to measure time and space. True for every single twin. Now there is need for an instrument to compare the radiation, generated by to occurances of such twins. This can be reached by broadening the capabilities: it take a grating and a detector to determine the deflection of an light beam (and a beam former too). To twins are situated in a distance with relative velocity 0 (We suppose, we can agree, who this is defined). The twin can measure the deflection of his own beam and of the beam, received from the other one and he can calculate the ratio of deflection of these two beams. Is this setup a mutual basis for exchanging arguments? ErNa (talk) 11:05, 11 January 2008 (UTC)

Ah. Since you didn't use a smiley with your previous reply, I didn't use one either, and I had assumed that we would understand each other. So, in case you are not joking around, feel free to read my previous reply as if I was not either. Cheers, DVdm (talk) 11:51, 11 January 2008 (UTC)

When I try to follow discussions on the field of relativity, I have the impression, that words are most inappropriate to guide a conversation. So, why should it be different here. True: a clock should be as ideal as engineeringly possible. But that says nothing about an engineers skills. And not, what a clock is! Therefore, the discussion goes round and round for years and ages. ;-) Einstein discovered the theory of (special) relativity. Since that time, space and time are no longer separate items, but entangled. One presumption was: the speed of light is invariant, therefore time and space can no longer be absolute. And this fact confuses many people. And very early some fought against this theory by creating a paradox from what Einstein said to be "eigentümliche Konsequenz". And we should help to make this paradox and the misuse of the SRT more obvious and easier to understand.ErNa (talk) 14:48, 11 January 2008 (UTC)

Are you saying the article needs a more rigorous definition of clocks and/or the biological aging process? It seems to me that the notion of a clock and an aging biological organism is fairly unambiguous in these circumtances. We're obviously not talking about sun-dials or hour-glasses. Take average wrist watches and average human beings. Is there some ambiguity here that you think has a significant effect on the description of the twins paradox?

As you may know, special relativity takes clocks and measuring rods as primitive entities. Einstein pointed out that this was not entirely satisfactory, since ideally the phenomena that we identify as clocks and rulers should emerge from the theory, rather than being the basis of the theory. But he also believed that physics was far from being able to give a fundamental theory of the most primitive aspects of nature, so in order to make any progress it is necessary to adopt some provisional concepts, and the ideas clocks and rulers are fairly basic. The fact that co-located atomic clocks seem to keep time consistenly with biological aging and wrist watches, etc., is not too surprising to most people, so I'm not convinced the article needs to dwell on this. I haven't checked, but there are probably Wikipedia articles on the more general subjects of time (and clocks) and space (and measuring rods), so those articles might be more suitable places for a philosophical consideration of the intelligibility of those concepts.130.76.32.182 (talk) 23:21, 11 January 2008 (UTC)

As I know, special relativity is a framework, that leaves physical laws unchanged when switching between different inertal frames of reference. Clocks or rods are just used to describe physical properties. Using the word clock we imply, what a clock does, but not, what it is and how it is done. Therefore I'm looking to find a setup, that has only the features, that are needed and, on the other hand, is physically existing and correctly described. So: two (flat) mirrors form a kind of resonator. Somehow a electromagnetic wave is exited in between these mirrors.... This description is incomplete, as long as we do not really know, what every object "is". The fact that co-located atomic clocks seem to keep time consistenly with biological aging and wrist watches, etc., is not too surprising to most people. That is true. But when discussion the twin paradox, then we HAVE TO aggree, that atomic clocks measure time. AND: two co-located atomic clocks measure time to the same amount. So, time is a quality and a quantity. And that is not clear to everybody. How can You determine, that every (lasting?/running?passing?)) second of an inertial moving clock (in a world without gravity, to make it more simple) represents the same amount of time? This is not as clear, as it seems! But it is true by definition! and coinsides with my private observation (only of statistical relevance ;-) ). That is the reason, why I think, we have to have this very elementary and undisputed setup. First: co-located elementary particles cannot be discriminated by properties. They are equal, wherever they came from and however they were "created". Second: For example, a proton and an electron, brought together, alway for a atom of hydrogen. Atoms of H can be exitated and emit electromagnetic radiation. Third: This radiation can create a standing em-wave between to mirrors if and only if the distance of this mirrors has certain values. And again, it is not obvious, how we can measure this distance! All these aspects have to be defined and aggreed on, before! we can discuss, what the twin paradox is and why! If not, it leads to endless discussions, frustration, people called crackpots, and, and, and. Suppose, I know a truth. And I am not able, to convince other people, that this will always be my fault, for I am not able, to express myself in a way, that other people can understand. The same is true for everyone. And we all know, even twins can be differently talented teachers. ;-] ErNa (talk) 13:52, 12 January 2008 (UTC)