Talk:Twin paradox/Archive 8

NPOV removal
The article's neutrality is just fine. Trolls in the talks page need to get a newsgroup. Keep the theoretical work off of this space. Tailpig 19:28, 12 December 2006 (UTC)


 * Instead, please address the issues in the section above where it is being discussed. Harald88 19:56, 12 December 2006 (UTC)

The discussion lacks from precision. For example (from time dilation, easy to see): The formula for determining time dilation in special relativity is:


 * $$ \Delta t = \gamma \Delta t_0 \!$$

where
 * Δ t is a time interval measured by an observer in a stationary frame of reference,
 * Δ t0  is that same time interval as measured by an observer in the moving frame,


 * Do you know why the twin paradox is called a paradox? It's called paradox since one cannot solve it using methods of special relativity theory. The twin paradox includes both acceleration of inertial frames and gravitational time-dilation; the special relativity theory explains none of that, to actually solve this paradox one will have to use the general theory of relativity. Lady Stardust 12.29, 24 february 2007

These equations are incomplete. No information, which time interval is measured and how. This to causes confusion. ErNa 20:13, 12 December 2006 (UTC)


 * Irrelevant! Go write a paper and get it peer reviewed.  As indicated on the page, "This article or section is in need of attention from an expert on the subject."  Tailpig 20:23, 12 December 2006 (UTC)


 * Irrelevant indeed: The discussion happens to be about opinions as expressed in peer reviewed papers! Several experts on the different subtopics are participating in this discussion already, but much clutter is added by non-experts. The discussion is fresh and ongoing but is now moved to the archives.
 * Here follows a copy of the start of the discussion, but more open pieces of the discussion are scattered above. Harald88 07:56, 13 December 2006 (UTC)

- While the "GRT solution" is notable, also notable criticism must be mentioned with some of the best examples. Einstein's "GRT" solution was never published in the English literature except in discussions and criticisms; nowadays that solution is rarely advocated. Those facts must be mentioned and explained, citing peer reviewed sources following WP:V. This is both required by WP:NPOV and out of respect for the readers who should be properly informed. Similarly, the different notable explanations must be cited in stead of suppressed; I notice now that also Langevin's explanation has been so much truncated that it is effectively suppressed, while also the reference has been deleted against WP:V (see NPOV_tutorial). Harald88 14:56, 2 December 2006 (UTC)
 * Correction: it was never published in an English language journal, but I now found that an English translation of Einstein's 1918 paper exists. Harald88 07:56, 13 December 2006 (UTC)


 * I've reproduced (in italics) the deleted paragraphs below for reference. The first paragraph is not clear and therefore difficult to evaluate as to content. Personally I am not totally convinced by the alleged solutions using SR. Although I have yet to carefully read the SR solutions in the article, from my previous studies and presumption as to the article's content, I am not sure about their validity. E.g., when using the frame jumping method, is the behavior of the traveler's clock adequately analyzed at the instantaneous turnaround, or is this issue swept under the rug? ... Concerning the critique below of Einstein's GR solution, I am not sure I understand the claim that using the equivalence principle requires the assumption of an instantaneous propagation of the gravity field to the stationary twin. Whether one uses SR or GR, one always calculates based on local observations, and then applying the principles and transformation equations of the theory being used. Otoh, for there to be a real difference in clock readings, we must be dealing with bonafide differences in gravity fields. In this view, Builder's critique would seem to have merit. ... In sum, I think this entire issue needs to be thought through with much care before we leave the GR section trucated. green 12.30.216.138 04:20, 1 December 2006 (UTC)

''It is sometimes claimed that the twin paradox cannot be resolved without the use of general relativity, by which it might be meant that age difference cannot be calculated by the travelling twin without general relativity, something we have tried to show can be done. On the other hand, the claim that general relativity is necessary, may be a claim that someone who doesn't believe the argument which rejects the first (erroneous) calculation by the space-ship crew is strong enough to convince the crew that they should perform the second correct calculation instead. The general relativity explanation says: if you are going to claim your reference frame is good, and deny the implications of changing reference frames, you will need to consider the inertial forces as equivalent to gravity forces and then account for the physical effect of gravity.''

''This explanation was popular among a number of physicists (Møller 1952) and continues to find adherents today. However, that calculation and its related interpretation have met with serious criticism. For example, after remarking that the general relativity calculation only corresponds to perceived reality for the traveler, According to Builder (1957)[1], Einstein's solution of the twin paradox is invalid because the induced field must appear everywhere at the same time:''

''The concept of such a field is completely incompatible with the limited value c for all velocities [...], so that the specified field would have to be created simultaneously at all points in S' and be destroyed simultaneously at all points in S0. Thus the principle of equivalence can contribute nothing of physical significance to the analysis.''

Similar opinions have been expressed more recently by others[2].

Thus in later years, physicists have increasingly treated general relativity as a theory of gravitation, while including acceleration with special relativity; consequently, acceleration is commonly regarded as "absolute" after all.


 * I see that the neutrality issues have not been corrected but the banner has been removed. Please don't remove the banner without addressing these issues, thanks! Harald88 22:41, 5 December 2006 (UTC)


 * I see neutrality issue with the included text. It gives Undue weight to an opinion that is held by very few people in the field.  Builder's objection is known to be mistaken, and the second citation is for the Unnikishkan (sp?) article that you have been told over and over again is anti-relativity and wholely unaccepted in the field.  You have also been told over and over again why the Unnnikrishkan article is not a reliable source due to its being published in an obscure journal with minimal peer review.  Yet you seen to feel that this viewpoint deserves prominent billing because you have found citations.
 * You need to realize that it is very important to put material like this in context. Wikipedia is not an attic.  --EMS | Talk 15:24, 13 December 2006 (UTC)
 * Builder's objection to Einstein/Moller's argument of the relativity of acceleration (where is Einstein's POV now?) happens to be the one that you yourself also expressed by not even considering what you both reject; thus either you are both mistaken or both not. The Unnikrishan article isn't an issue since we unanimously agreed to scrap it.
 * I suggested to add references to writings by for example Janssen, and I now provided a reference to an overview article that happens to refer to Builder as well.
 * As you claim that this article now fairly discusses the different opinions as required by WP:NPOV, please show that by citing the fair descriptions of the different opinions, since I dont't see them but I could have overlooked the new passages that do so. Thanks in advance.
 * Harald88 21:44, 13 December 2006 (UTC)
 * Harald - NPOV does not require that any alternate viewpoints be listed unless they are held by a "significant minority". The "Alternate theories" section of black hole does reflect that such a minority exists in opposition to the black hole concept, yet at the same time the size of that section says much about the size of that group.  You don't have that level of discomfort with regard to the twin paradox.  Certainly once I got more oriented I realized that the viewpoints being presented in opposition to the Einstein/"GR" solution represented a misunderstanding of relativity.


 * If you want to document a significant counter-view, then be aware that the twin paradox has been used down through the years as a disproof of relativity theory. It may be worthwhile to document that stream of opinion and the counter-arguments to it.  Just be aware that it must be made clear that this view is universally panned in the scientific community today.


 * Beyond that, I would appreciate your indicating what the overview article that you are refering to above is and how I can either read or obtain it. Indeed, listing your suggested sources here may be worthwhile and could give us a framework for discussing this issue more productively. --EMS | Talk 02:56, 14 December 2006 (UTC)

-

In a nutshell: Mention of other opinions has been deleted including the opinions as expressed in some cited papers. Instead, only the "apparent paradox" -as one recent review paper calls it- is discussed and only the popular POV is mentioned.

I propose to shortly mention that in the course of time other viewpoints have been offered and debated, and link to an overview in an article "History of the Twin paradox". Harald88 07:56, 13 December 2006 (UTC)


 * A history article or section may be worthwhile. At least it can put material into its proper context, and there can be discussion as to what has become over viewpoints like Builder's.  (Unnikrishkan you should never mention again.) --EMS | Talk 15:24, 13 December 2006 (UTC)


 * Harry, why do you keep trying to introduce your OWN biased POV at any expense. What you are trying to do is very transparent, you are trying your darnest to cast doubt on the validity of relativity, all your "interventions" reek of that. Do you really think that we are THAT naive? Please stop slapping NPOV tags on all the items that don't conform to your attempts to bring back Lorentz aether theory over the Einstein relativity. Please stop this barrage of obscure antirelativity papers. Yours is the most biased POV, far from a neutral one Moroder 16:03, 13 December 2006 (UTC)


 * It hardly needs mention that user:Morodor is still trying to block any mention of notable minority views (including Einstein's) in Wikipedia articles, which is against WP:NPOV policy. Harald88 21:51, 13 December 2006 (UTC)


 * Harald - I will support Moroder's advice but not his words. The Unikrishkan article is the only anti-relativity one that I have seen you hype like this, but you have failed to put it in its proper context.  I understand your being upset at what you perceive as its inappropriate removal, but your not getting your way does not mean that an NPOV violation exists. --EMS | Talk 19:03, 13 December 2006 (UTC)


 * EMS, I already agreed repeatedly with the non-inclusion of that article for the reasons discussed earlier (Pjacobi's argument). You may have overlooked that due to the enormous amount of clutter on this page.
 * If you read my explanation again with the knowledge that your preconceived idea is mistaken, you may understand why I put the NPOV tag here.
 * For a fair presentation of views, only a few lines are required that mention the different views (even the mainstream view about the deeper issue was not and still is not explicitly mentioned!), similar to for example the Black holes article.
 * A more elaborate overview of the different debates (which, BTW, according to the scientific literature still are going on -incl. the American journal of physics) can then be given in a separate article that discusses the deeper, philosophical issues.
 * Regards, Harald88 21:44, 13 December 2006 (UTC)


 * Hmm, Harry left the same "marks"(NPOV tags, inclusion of antirelativistic papers) on the Maurice Allais, Dayton Miller and until recently, Luminiferous aether articles.Moroder 19:39, 13 December 2006 (UTC)


 * Yeah and guess why? See the Talk pages, and look at the recent actions of Morry! Harald88 21:44, 13 December 2006 (UTC)

Message from Moroder
"green" you are also "sock pupeteering" by using a second account : 4.227.136.248 Moroder 16:21, 12 December 2006 (UTC)


 * The wireless server connection I usually use stopped working for awhile, so I used the phone line with my other server. Is this a problem for you? green 12.30.216.138 21:08, 12 December 2006 (UTC)


 * Then get a user name like everyone else. Moroder 16:47, 13 December 2006 (UTC)


 * I see no need for one. green 12.30.216.138 16:58, 13 December 2006 (UTC)


 * Here's a good reason to get an account. green 74.101.25.251 03:51, 14 December 2006 (UTC)


 * Moroder, I was software engineer. What you did takes little creative effort. Is this what's called "cock suckerteering"? green 12.30.216.138 04:07, 14 December 2006 (UTC)


 * You just demonstrated that you are a disgusting troll and should be banned. Moroder 04:31, 14 December 2006 (UTC)


 * I think that you are both making yourselves look silly. BTW - I will wait a day and then either archive, delete, or move this thread to the IP's talk page.  --EMS | Talk 04:54, 14 December 2006 (UTC)


 * Troll? Who sent the message in the first place? What is a "sock pupeteering", really? What does it sound like? Is this the level of "deep thought" you apply to Einstein's GR solution? green 12.30.216.138 05:26, 14 December 2006 (UTC)


 * A sock puppet is a second account meant to look like another user but which is in fact just you again. This is most often done by a user attempting to evade a block, but there are other illegitimate uses for sock puppetry and even a few legitimate ones.  I for one find it a little disingenuous to accuse an anon of "socking" when they end up with a different IP.  While we would much rather you get an account, I for one think that we must respect it when an editor is operating within the rules.
 * As for trolling, please see the last message I left you on your de-facto talk page. --EMS | Talk 05:42, 14 December 2006 (UTC)

Reset Indent: I'm not a troll and not a "sock puppet". I am sick and tired of any and all accusations. I am just someone interested in physics, who has formally studied it (but not GR) who sees no need for a Wiki account, and disagrees with you on some basic relativity issues (which you find intolorable), and how this disagreement should effect the article. I am not trying to change a Wiki article to include my research, but merely to make the case that if your evaluation is wrong, it will bias the article in a way that does a disservice to the readers. But to show you, that notwithstanding your expertise you are likely wrong, there was no alternative but to engage a discussion. The discussion is over. Check the equivalence principle as discussed below, and, if you wish, indicate to the editors here whose position it supports. green 12.30.216.138 06:52, 14 December 2006 (UTC)

More trolling
Green - I am going to continue to remove content until and unless you stop pushing your own personal viewpoint here. Your questions are good, but they belong on USENET, not here. That article has major issues, including obtaining the proper citations. You have become a major distraction from the issue of editing the article, and that is the issue I have with you now.

I may or may not e-mail you. You have no comprehension of what I have been trying to tell you, and instead have shown that you lack the conceptual framework needed to bridge the gap between our positions. I am not here to be your personal relativity teacher. --EMS | Talk 16:57, 13 December 2006 (UTC)


 * Please be advised that I am not interested in any email contact with you, or any editing of the article. I am also sick and tired of your attitude, accusations, and censorship. green 12.30.216.138 17:06, 13 December 2006 (UTC)


 * If you are not interested in editing the article, you definitely shouldn't be contributing to its talk page.
 * Apologies to everyone for this comment - it is not about the article either. It belongs on a meta-talk page.
 * DVdm 17:31, 13 December 2006 (UTC)


 * I put it here because I wasn't sure how to get the message to EMS. I also wanted everyone to see what a control freak he is. I won't be a thorn in his side any more, as I have no intention of further participation here. green 12.30.216.138 17:46, 13 December 2006 (UTC)


 * I gather that you never noticed the "talk" link in my signature. you also could have edited your own IP's talk page to respond.  Either is standard procedure here.  (To all: This was originally posted on the talk page for "green"-s IP.  He has no concept of user talk pages or watchlists I see.  Then again, as he refuses to get an account, he has neither.) --EMS | Talk 17:57, 13 December 2006 (UTC)


 * I've noticed the "talk" link, of course, but I wasn't sure if it would allow me to communicate with you if I didn't have an account. Since I didn't feel like researching this issue I posted here. To repeat, I am sick and tired of your "trolling" accusations, self-serving censorship and misinterpretations of my intent, so I've decided to cease further interaction with you. green 12.30.216.138 19:09, 13 December 2006 (UTC)

The purpose of the talk pages
Green - You may not be intending to troll, but even so your actions do amount to trolling. I see where you are coming from: You want the content of the article to be mathematically and conceptually vetted. That is all fine and dandy, but that is not what the talk pages exist for. The issue is what the content of the article should be, and that is fundamentally driven by what the literature on the issue says. Whether of not the view in the literature is correct is a whole other issue which is beyond the scope of Wikipedia.


 * You still don't get. Sure I want the article conceptually vetted at a minimum. This means that I want Einstein's solution presented as he stated it. However, since in this particular case the argument against it has such a high degree of plausibility despite your "expert" claims to the contrary, the counter-arguments must surely be in the literature and should be found and presented as well (a balanced view as it were). I posed some probing questions and know enough about the subject to see that your rebuttals are not at all convincing. As long as you remain convinced, e.g., that the EP is used appropriately in Einstein's GR solution, you will insist on the omission of the critiques, to the detriment of the reader. Now don't give me a load of bull that I don't know what I am talking about. As a exercise, please review equivalence principle and be sure to report back (one way or the other) if you find anything in the article remotely suggesting that the EP can be used as described in the GR solution. I've also read parts of Rinder's discussion of the EP in "Essential Relativity" and the same conclusion applies; i.e., I've never read anything that remotely suggests it is applicable globally -- which indeed is how it is applied in the GR solution. I know enough physics to know the difference between "local" and "global". If your turnaround twin believes that the gravity field extends to the stationary twin for the purpose of calculating the gravitational time dilation, then, defacto, he is applying the EP globally. Never, except in Einstein's GR solution, have I come across the claim that it applies in a case where acceleration is caused through a conscious act of the observer. The main form is always stated in terms of an impossibility -- of the observer to locally distinguish the forces of acceleration from gravity. green 12.30.216.138 06:37, 14 December 2006 (UTC)

To help to orient a newbie on the technical aspects of a subject like the twin paradox is one thing. However, going in circles over whether the GR solution is correct or not is another. The issue here is whether the GR solution should be presented, and if so how the related facts should be presented. If you lack the knowledge needed to make sound judgements on those points, you should not be discussing that aspect of the subject. --EMS | Talk 05:10, 14 December 2006 (UTC)


 * I have little interest in communicating with someone who persists in the illusion of knowing somewhat more than he does, while consistently under-evaluating others (who now and then have useful insights). I make errors as I go along due to lack of technical knowledge, as GR is not one of branches of physics I formally studied, but the main thrust of my argument on this issue is likely correct. Please stop sending me private messages. I don't need your ill-conceived put-downs (which is not to say you're wrong in every instance) and rationalizations for censorship. Do as you wish with the article. green 12.30.216.138 06:37, 14 December 2006 (UTC)


 * To further clarify, the misapplication of the EP is not "global versus local" as I stated above, as the fact that the EP is MISinterpreted by the turnaround -- and hence those advocating the GR "solution" -- to mean that gravity and acceleration are identical phenomena. That is, when the turnaround sees the stationary or inertial twin accelerating, he interprets this observation to mean, ipso facto, that a gravitational field exists. HOWEVER, as a reading of equivalence principle makes clear, the EP makes a much weaker assertion; namely, that in a specific circumstance, the phenomena of gravity and acceleration are indistinguishable. Obviously, of course, for the turnaround, they are NOT indistinguishable since he knows that by firing his rocket he has caused the stationary twin to appear to be accelerating. In summary, the claim that the EP is applicable in the GR solution is one of those "sleights of hand" that is based on a sloppy inference of what "equivalence" means. But don't take my word for it. Read the referenced Wiki article. green 12.30.216.138 18:21, 15 December 2006 (UTC)


 * So what? What's your purpose?  What do you hope to achieve with this paragraph?  Is there a change you would like done to the article?  Perhaps an additional external reference?  State your intentions clearly and provide proper sources.  Tailpig 21:19, 15 December 2006 (UTC)


 * What's my purpose? I stated it clearly in my first paragraph in this section. How can you guys edit anything when you can't read plain English? green 12.30.216.138 23:19, 15 December 2006 (UTC)


 * Tailpig - "Green" wants the "GR" solution to be conceptually and mathematically validated to him before he will accept its correctness. There are two difficulties that I have with this.  The first of is that it is not our job as editors to validate the work of others, but instead to report what that work is.  Einstein did this "GR" solution, and it should be reported on as such.
 * Green also misses the meaning of the equivalence principle. I have tried to show him his error, but have only ended up with the point he has chosen to make above getting more and more shrill.  Because of that, I now prefer to fall back one the basics of what Wikipedia is.  If "green" can show me reputable sources that back his position, then it will be considered.  Otherwise, "green" should not be trying to act like a reputable source for the content of this article. --EMS | Talk 03:47, 16 December 2006 (UTC)


 * I rendered this point moot. See the peer-reviewed paper (Foundations of Physics Letters 2006) that gives the complete SR and GR treatment and shows that they give identical answersMoroder 16:14, 18 December 2006 (UTC)


 * I noticed it. It certainly helps to nail the case that the two are identical.  Maybe we can now return to the issue that bug me:  Should that section even be there?  I keep seeing something that is very advanced and very subtle.  I understand how it works and why it works, but is it fair to expect others to understand that?  I honestly suspect that the difficulties that "green" has with this are indicative of what we can expect from the average reader.  Maybe that should be a seprerate article, if it is to be present in Wikipedia at all. --EMS | Talk 21:53, 18 December 2006 (UTC)


 * The treatment should be at the highest possible level, I feel that the addition of the paper by the two college professors has just attained that. People can elect to read the prose or, if they are more advanced, they can read the paper. I think the section should stay where it is. Moroder 00:53, 19 December 2006 (UTC)

Reading the above comments, I sense that the "experts" do not deeply understand much of what I have been complaining about.

Firstly, the section on Einstein's GR solution appeals to the equivalence principle, but if the reader goes to that article, he will find nothing in the statements of any version of the principle that implies what EMS added in response to my comments on this Talkpage, namely, "It is important to note that any accelerated frame of reference has a gravitational potential associated with it." Iow, a ubiquitous gravity field is implied by the EP for any accelerating frame, but there's nothing in the statements of the forms of the EP that contain this key point. If this is "shrill", so be it. Istm, there's something fundamentally deficient in the EP article, given that something as important as EMS's addition does not follow from, or is not explicitly stated, in any version of the equivalence principle. This state of affairs will surely confuse the average reader, but he/she will likely not know the source of his/her confusion when trying to connect the EP as stated in Wiki, with the static homogeneous gravity field implied by the EP, due to the turnaround twin's acceleration. As distinguished from an "average reader", it was clear to me that Einstein's GR solution as stated in the TP article, when juxtaposed to the EP article which it references, causes Einstein's solution to take on an ad hoc appearance -- that is, un-principled as in not following from basic principles.

Secondly, the fact that the SR and GR solutions are identical is obviously important and the article Moroder found should be an included reference. However, this was not an issue I was addressing, so I fail to see what point Moroder thought he had rendered "moot". My issue all along was the nature of the gravity field implied by the turnaround's accelerating frame and its justification based on the EP, and whether Builder's critique of Einstein's GR solution was worthy of inclusion. I've been looking over his 1957 paper and find some compelling issues. green 4.227.130.159 07:56, 25 December 2006 (UTC)

Looking again at the article on the equivalence principle, near the beginning, it seems that in his 1911 paper, Einstein postulated what I would call a general equivalence principle, that does go beyond what is contained in, or implied by, the three forms of the principle given prominence in the article. I find it misleading that the three forms that are usually given prominence, seem less powerful than the one stated in Einstein's 1911 paper, and this has been a source of my confusion on this issue. green 12.30.216.138 07:09, 29 December 2006 (UTC)

Btw, for those interested, Einstein was NOT using the Weak Equivalence Principle when analyzing the twin at turnaround, as EMS claimed. He was using the more general EP, stated in 1907 and/or in 1911, which is not featured in the EP article. This looks like another case of the "experts" giving misleading information and explanations. green 12.30.216.138 15:30, 29 December 2006 (UTC)

Semi-protection
This talk page has been semi-protected due to block evasion by a chronically disruptive unregistered editor. Durova Charg e! 15:09, 16 December 2006 (UTC)
 * Semi-protection lifted. Durova Charg e!  17:52, 20 December 2006 (UTC)

Does the spaceship twin catch up upon arrival?
An aquaintance who is a physics major explained to me that the twin in the spaceship would slow his ageing during acceleration, but would regain the lost time during deceleration when arriving back at Earth. Is this accepted theory? If so is it represented in the article? I didn't see it stated simply, if it was there. —The preceding unsigned comment was added by Panserbjørn (talk • contribs) 04:28, 24 January 2007 (UTC).


 * I am afraid that you have misundestood something. The travelling twin remains younger forever according to special relativity. XCelam 05:41, 24 January 2007 (UTC)

Einstein article 'Dialog' 1918, available on wikisource
I have uploaded the following article to wikisource: Dialog about objections against the theory of relativity

This is a translation of the article 'Dialog über Einwände gegen die Relativitätstheorie' by Albert Einstein, published in 'Naturwissenschaften, 1918

In that article the following is discussed: can the Twin scenario be used to expose a self-contradiction in the framework of relativistic physics? Einstein explains why this is not the case.

I emphasize that the aim of the 'Dialog' is not to discuss the twin scenario, the aim is to discuss relativistic physics. The twin scenario is very counterintuitive, and Einstein makes no effort to lessen the experience of counterintuitiveness, no alleviation of the sense of puzzlement. What Einstein is interested in is to address the question whether there is a self-contradiction in relativistic, a self-contradiction that can be exposed with the twin scenario.

Einstein points out why no self-contradiction can be constructed, and on the basis of that Einstein declares the matter of alleged self-contradiction fully clarified. --Cleonis | Talk 01:12, 25 January 2007 (UTC)

Subhash Kak
Some media have reported that Subhash Kak has "resolved" the twin paradox. All the press releases and related newspaper articles are meaningless. Anyone who would like to edit the time dilation page because of this incident should first read the time dilation page, at least its introductory paragraphs, and the "time dilation" section at the talk page of the Subhash Kak page. There is nothing to "resolve" about the twin paradox. So I encourage everyone to calm down. Also, I have removed the "expert needed" tag from the time dilation page because it satisfies all standards of Wikipedia and doesn't have any major errors or misunderstandings - like embarrassing errors comparable to those found in Kak's press release. Of course, some incremental improvements and perhaps some simplication of the page is needed - but that's the case of other pages, too. Thanks, Lubos Motl, Harvard U., --Lumidek 19:26, 18 February 2007 (UTC)


 * Excellent. Thanks for the comments.  I do believe you meant to write twin paradox in the three places that time dilation is written above, so you may wish to strike those out and replace them. Tim Shuba 20:10, 18 February 2007 (UTC)

since the claim is that this paper has been "electronically published in the International Journal of Theoretical Physics", can anyone of you get a look at it? We should call it for what it is on the Subhash Kak article, but we obviously cannot do that before we've seen it. All we can say so far is that the LSU press release is utter gibberish. I am also under the impression that the IJTP is a serious journal, and I find it difficult to believe that they would accept a paper that can be recognized as bogus at a glance by any physics graduate, so that there is the possibility that just the press release, but not the article, may be bogus(?) dab (𒁳) 10:25, 19 February 2007 (UTC)


 * I think it is this one. Rasmus (talk) 12:50, 19 February 2007 (UTC)


 * That is essentially correct. The version as published by the journal is linked from this page, but a subscription is required.  Any differences between the two versions are likely minor.  Tim Shuba 15:01, 19 February 2007 (UTC)

uh, this dates from May 2006, and judging from the abstract, he is not claiming to have made any great progress, just that he did some calculation exercise on the topic. Maybe the hype isn't Kak's fault after all? dab (𒁳) 15:48, 19 February 2007 (UTC)

article needs revision for style, clarity
Considering that there are about 5 archived pages of discussion concerning this article, it is surprising how little has been done to polish the primary material and make it clearer. I am not specially qualified as a physicist or mathematician, but I have a layperson's interest in the subject, and I'm a good writer and proofreader. Here below are my suggestion for how the first few pars should read. If no one objects, next time I come around here, I will incorporate them, and continue on with the rest. In the meantime, feel free to comment here, or on my page.


 * In his famous work on special relativity in 1905, Albert Einstein predicted that when two clocks were brought together and synchronised, and then one was moved away and brought back, the clock which had undergone the travelling would be found to be lagging behind the clock which had stayed put. Einstein considered this to be a natural consequence of Special Relativity, not a weird paradox as some suggested, and in 1911, he restated and elaborated on this result in the following form: If we placed a living organism in a box ... one could arrange that the organism, after any arbitrary lengthy flight, could be returned to its original spot in a scarcely altered condition, while corresponding organisms which had remained in their original positions had already long since given way to new generations. For the moving organism the lengthy time of the journey was a mere instant, provided the motion took place with approximately the speed of light. (in Resnick and Halliday, 1992)


 * In 1911, Paul Langevin made this concept more vivid and comprehensible by his now-iconic story cum thought experiment of the twins, one of whom is an astronaut and the other a homebody. The astronaut brother undertakes a long space journey in a rocket moving at almost the speed of light, while the other remains on Earth. When the travelling brother finally returns to Earth, it is discovered that he is younger than his sibling, that is to say, if the brothers had been carrying the clocks mentioned above, the astronaut’s clock would be found to be lagging behind the clock which had stayed with the Earth-bound brother, meaning that less time had elapsed for the astronaut than for the other. Langevin explained the different aging rates as follows: “Only the traveller has undergone an acceleration that changed the direction of his velocity”.


 * Langevin means here that while it is doubtless that the twins experienced many things differently to each other in the years they were apart, there was only one event which the astronaut experienced which his brother did not and which had a direct bearing on the time differential between them: the astronaut experienced the acceleration necessary to turn his rocket around and head back to Earth, and his brother on Earth did not. The significance of the “Twins Paradox” hinges on this one crucial detail of asymmetry between them. (NOTE: Everyday English has "acceleration" as referring to "speeding up" only, but in scientific circles it equally refers to "slowing down" so that all the physical changes in speed and direction necessary to get the rocket to come back - slowing down, stopping, turning around, speeding up again - can be coverered by the umbrella term "acceleration". This is the way the word is used in this article.)


 * It should be stressed that neither Einstein nor Langevin considered these deeply counter-intuitive results to be literally paradoxical. A paradox in logical and scientific usage refers to results which are inherently contradictory, that is, logically impossible, and both men argued that the time differential illustrated by the story of the twins was an entirely natural and explainable phenomenon.

--Myles325a 14:01, 10 April 2007 (UTC)
 * I have now incorporated above pars. How are you loving it so far? Will continue with rest - beginning with the "example" a little later. Comments welcome

Myles325a 04:27, 14 April 2007 (UTC)


 * I have not participated for some months, and notice that what now is claimed about Langevin's argument is definitely incorrect (it's for sure not the only error). However, it was almost correct about half a year ago (in fact he did not present them as twins). Often people make changes according to their liking instead of according to the sources. Do you actually have a copy of the article that you paraphrase? Harald88 08:32, 2 May 2007 (UTC)

Scientific American on twin paradox
There was a special Scientific American article of several months ago, actuated by the ongoing controversy over whether the Twin Paradox is a consequence of Special or General Relativity, which gave a detailed and well-graphed account of this problem, noting at the outset that the Twin Parodox could be explained using Special Relativity only, without recourse to General Relativity. I will chase this up. Anyone else rem this? --Myles325a 01:24, 15 April 2007 (UTC)


 * The 1918 article that Cleonis linked here is the oldest mention of the clock paradox; Einstein presented it as a paradox for GRT but not for SRT. And if people mean that the problem can be calculated with SRT, Einstein already showed that in 1905! The main problem is that different people mean different things with the same words. Harald88 08:41, 2 May 2007 (UTC)

why does the example use such complicated numbers?
I can't think of any reason to not use some simple, round numbers for the twins paradox example. Having decimal points all over the place makes the article difficult to read and understand.

Numbers i'd suggest: ship velocity = 0.8c distance from earth to hypothetical nearby point in space = 2.4ly

this makes for much simpler results and therefore discusion: time passed on ship = 6 years time passed on earth = 10 years observed frequency factors = 1/3 and 3

131.227.230.61 13:01, 21 April 2007 (UTC)