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The accelerating twin's "gravity field"

"Green" wrote above:

Einstein assumes that the traveler knows he is accelerating (which is OK), but then misapplies the EP to erroneously infer the instantaneous (or even lightspeed) existence of a non-local gravity field.

Let me take a crack at demonstrating the flaw in this logic. First of all, let we need to consider what is meant by a "gravity field" or rather a gravitational field. In general relativity, gravitational fields exist due to spacetime curvature. When a mass is accelerated, this information must be propagated through spacetime as a corresponding change in the spacetime curvature. Such changes are known to theoretically propagate only at the speed of light. That obviously in the genesis of the above complaint.

The problem is that in relativity, a gravitational field can also be present in an accelerated frame of reference, as indicated by the equivalence principle. However, this is a very different type of field, as it is based on the observer's view of spacetime instead of being part of the structure of the spacetime itself. In this case, there is no change in the structure of spacetime, and therefore there is no field to propagate. In fact, nothing is being propagated.

Except for the caveat noted below I am in agreement and stated much the same in different words. green 12.30.216.138 02:48, 11 December 2006 (UTC)

The gravitational field of the accelerating twin is of the second kind, and exists only in that twin's frame of reference. For the same events, no gravitational field exists for the stay-at-home twin! What has changed in the traveling twin's view of the universe, not the universe itself! There is no problem with the traveling twin's description of the universe changing for everywhere in the universe instantaneously, as what has changed is the traveler and not the universe.

I agree except for one important, perhaps crucial point; the fact that the twin is accelerating will objectively slow his clock as compared to the stationary clock. This is because the traveling clock now defacto exists in a frame-localized gravity field. green 12.30.216.138 02:48, 11 December 2006 (UTC)

You really don't understand gravitational time dilation. That is a change is in the rate of a distant clock as observed by an accelerated observer. It does not affect the local clock, and for the traveling twin his clock is the local clock. So we see clocks at higher potentials ticking faster than our own (if there is no velocity time dilation involved). Similarly, from the viewpoint of an observer at a higher potential, our clocks tick slow. To be considered as tickng slow due to gravitation, the stay-at-home twin must see the traveling twin as being in a gravitational field. That is not the case as the traveling twin's acceleration is due to his firing his rockets. For the stay-at-home twin, no gravitation field exists and therefore SR's velocity time dilation is all that is applicable to the traveling twin's clock rate.

I hope this settles the issue. --EMS | Talk 03:27, 11 December 2006 (UTC)

You presume too much, way too much. I do understand, quite clearly in fact, that the local clock always appears to 'tick' normally. I also understand that for the traveling twin, his clock is the local clock. (Btw, I think you have a typo in your second sentence of longer paragraph above. I think you mean that the time dilation is the change in the clock rate as observed by the non-local observer; that is, the observer in a different frame who may or not be accelerating.) As for your analysis that follows, except for your concluding comments, you seem to be arguing against a strawman since I never claimed that the non-traveling observer sees the traveler in a gravitation field. In fact, I explicitly denied it! I wrote what you are now concluding; that for the stay-at-home no gravitational field exists (because there's no field propagation resulting from firing rockets). Well, in your effort to correct my allegedly unenlightened (idiotic?) views, you have essentially repeated what I earlier wrote on this subject. green 12.30.216.138 06:03, 11 December 2006 (UTC)

However, your concluding remarks contain an analysis that shows a major divergence of our viewpoints. You claim that for the stay-at-home twin, since no gravitation field exists, SR's velocity time dilation is "all that is applicable to the traveling twin's clock rate". I strongly disagree because the traveler's acceleration -- which can be ascertained to exist by internal measurements -- not only has an objective reality because of this measurement fact, but exists asymmetrically by virtue of the statement of the Twin Problem. That is, the asymmetry of the acceleration is the only asymmetry in the problem, and therefore the only factor capable of destroying the kinematic symmetry which leads to the paradox. Hence, from a logical pov, this asymmetry is indispensible in resolving the paradox. But you defacto claim it is irrelevant. Further, since the acceleration is an objectively existing phenomenon, one cannot explain away its local effects as merely perceptual. That is, I believe there is an objective effect on the traveler's clock (via the EP) even though the traveler observes his clock ticking normally. Although the stay-at-home does not observe any resultant field propagate in his direction or any resultant change in spacetime in his vicinity, he has knowledge of the acceleration's objective effect on the traveler's clock, and from this information he can and will conclude that the traveler's clock rate is slower in comparison to his stationary clock. This probably departs from orthodox GR but this what I think is the reality. I could be totally in error, but this is how I presently see it. green 12.30.216.138 06:03, 11 December 2006 (UTC)

As an aside, the reason these issues are worth discussing here is because if we are going to write about relativity, it would be nice to have confidence that we know the material. In a free discussion, points of contention invariably arise, among them, e.g., my belief that the CMBR can be used to define absolute, or if your prefer, universal rest, and yet does not contradict the Principle of Relativity. I was looking forward to your response to my explanation, but have yet to receive one. green 12.30.216.138 06:03, 11 December 2006 (UTC)

One final note: The "field" in this case does not have its change propagate instantaneously anyway. Instead it "propagates" backwards in time along the past light come leading to the event of the change of acceleration! EMS | Talk 01:49, 11 December 2006 (UTC)

The field either propagates, or it does not. I say it does not. Time reversed scenarios are generally not plausible. E.g., we don't observe anything from the future, so why should this case be an exception? green 12.30.216.138 02:48, 11 December 2006 (UTC)

---

Green - I am done with this. If you do not accept that only the speed of the traveling twin is relevant to computing the time dilation experienced by that twin in the reference frame of the stay-at-home twin, then you do not accept relativity theory. I am not accepting any more of this B.S. about general relativity being relevant to this issue. I wasted too much time explaining why it is not relevant. For anyone proficient in GR, what I am stating is obvious. For those not proficient in GR, the issue is not relevant. It's that simple, and I am now done arguing with you about this. --EMS | Talk 06:24, 11 December 2006 (UTC)

Hey, as long as we're on the subject of "BS", where does your reversed time causality scenario for solving the twin problem fall on the credibility scale? green 12.30.216.138 07:26, 11 December 2006 (UTC)

See light cone, and remember that an acceleration chenges the view of the universe, not the universe. Once you have read that, the answer should be obvious. --EMS | Talk 15:53, 11 December 2006 (UTC)

Don't patronize me with trivial links. I know about light cones. They don't justify reversed time causality. Have we ever detected a signal from the future? green 12.30.216.138 19:36, 11 December 2006 (UTC)

Imo, you have a totally wrong-headed view of acceleration. At every level -- galaxy clusters, galaxies, star systems, planetary systems, planets, asteroids, and on down to the molecular, atomic and subatomic levels -- we see systems that are rotating; that is, accelerating. Acceleration is a truly fundamental phenomenon in the universe, not merely someone's "view". green 12.30.216.138 00:24, 12 December 2006 (UTC)

P.S. Green wrote above:

This probably departs from orthodox GR but this what I think is the reality.

Let me put it to you this way: If it departs from the orthodox GR view, then is makes no difference if it is real. Unless it is documented in the literature and accepted by a subtantial minority in the relativity community, it does not belong here, even in this discussion page. See WP:NPOV. I don't bring my theory into either the articles or their talk pages, and IMO you should abide by the same rules with your views. --EMS | Talk 06:43, 11 December 2006 (UTC)

On the other hand, some of what I believe might indeed be in the literature. Iirc, in the old version of the GR section, there were references criticizing the "perceptual" solution of the paradox. Builder comes to mind, but there were other references, e.g., Moller. In any event, I might accept a viable argument disproving my pov -- why not? -- this is what I seek -- the truth as they say. But in the final analysis all you are really capable of offering are pronouncements from on-high. I was looking for something richer -- like some attempt at explaining how your proposed "perceptual" solution using SR-only velocity-induced time dilations overcomes the kinematic symmetry that is causative of the paradox in the first place. If Einstein got his GR solution wrong as some contend, maybe you have as well. Relativity, along with QM, has brought us to a dead-end. Maybe the politically correct word is "impasse". A little thinking out of the box might help. green 12.30.216.138 06:58, 11 December 2006 (UTC)

The question here is what was being validated by which reference. I don't believe that the Moller reference related to this issue at all.

I know for a fact that Builder was dead wrong about the "propagation" of the gravitational field perceived by the accelerated observer being an issue.

Didn't Builder criticize Einstein's claim that the traveling twin was at a higher potential than the stay-at-home (in context of Einstein's proposed GR solution of twin problem in his 1918 paper) since it would imply or require an instantaneous propagation of the "field" allegedly created, via the EP, by the traveler's acceleration? If so, whatever else Builder might have thought, his view here is the same as yours! Is he still "dead wrong" or do I have my facts confused? -- which is possible since most of what I believe on this issue is second hand from the older version of the GR section. green 12.30.216.138 19:36, 11 December 2006 (UTC)

Btw, I've managed to disentangle myself from the disinformation and arrogant polemics received on the issue we've been discussing lately -- mostly from wannabe physicist Moroder -- wrt his "answer" to my question about the whether the SR calculation he provided is approximate or exact. Maybe he's just a lousy teacher who didn't completely understand my question. You did much better, but still fell short of greatness since there's a straightforward answer to my question that someone intimately familiar with GR could have offered at the get-go! NO CALCULATIONS REQUIRED!!! Stay tuned. Preview below. green 12.30.216.138 19:36, 11 December 2006 (UTC)

THE PRINCIPLES OF GENERAL RELATIVITY STATE THAT THE GEOMETRY OF SPACETIME, AKA GRAVITY, IS CAUSED BY THE MATTER-ENERGY DENSITY, NOT BY THE EQUIVALENCE PRINCIPLE. green 12.30.216.138 19:36, 11 December 2006 (UTC)

See general relativity#Fundamental_principles. Also see my above comments on this issue. The "AKA GRAVITY" part of the capitalized mtext is just plain wrong.

If you wish to show otherwise, get me citations of articles in the literature. Kindly note that the issue is what is known and/or beleieved to be true in the field, not what either of us believes to be true. --EMS | Talk 21:33, 11 December 2006 (UTC)

LOL. You're going trivial on me. The principles you cite (and wrote?) in the article are old hat. I don't disagree. I'm referring to the deeper principles that should also be described as such since they're not derivable within the theory, but assumed; e.g., what the article states later on, and so forth: "The Einstein field equations (EFE) describe how stress-energy causes curvature of spacetime ... " Btw, wrt "AKA GRAVITY", all I was trying to get across is that what was formally thought-of as the gravitational force or field, is now interpreted geometrically as the curvature of spacetime. Maybe you could express it better, but "wrong" it is not. green 12.30.216.138 00:41, 12 December 2006 (UTC)

I am not here to indulge your ignorance. Curvature is not gravitation, but instead is a cause gravitation. You seem to have no concept of that, or of how a gravitational field which can be turned off legitimately exists for an observer in an spaceship firing its engines. I'm here to edit Wikipedia, not to be your relativity teacher. Giving you some advice and help dealing with subtle points is one thing. This continuous sparing is another. --EMS | Talk 04:39, 12 December 2006 (UTC)

Curvature is the cause of gravitation. That's what I meant, obviously, because without curvature, we have a flat geometry, SR, wherein gravity is absent. You ought to give other people more credit. Who knows, you might learn something now and then. green 12.30.216.138 04:45, 12 December 2006 (UTC)

I also accept that my opinion must be secondary to the current state of opinion in the field as it is documented. However, the only current support for this view that Harald could name for Builder's opinion was the Unnikrishnan article. Note that Unnikrishnan's article is blatantly anti-relativity, published in an obscure journal, and uncited elsewhere, such that is is not a reliable source. Without anything usable documenting current (or at least long-term) support for Builder's view, I cannot in good faith allow it be in this article. I am happy to yield to reality if my current understanding of the views in the field is mistaken, but at this time I have no data on which stand by if I am to support inclusion of Builder's view in this article. --EMS | Talk 15:53, 11 December 2006 (UTC)

Within 10 hours 40 edits! ErNa 06:48, 11 December 2006 (UTC)

And your point is what? Think of it as an orgasm. It will peak and you can go back to sleep if you wish. green 12.30.216.138 06:58, 11 December 2006 (UTC)

Maxwell tried to find a mathematical description of electro magnetical behaviour. His sketches show, that he was thinking in mechanical models. But he was aware of the fact, that the (as a function of time and distance) oscillating medium couldn't be normal matter. Sometimes, the unknown was given the name of ether (in greek mythology a personalised cosmic idea). His set of equations -or physical laws- was dependend of the inertial frame used, that is: galileian tranform changed the phyics. Therefore there had to be a special frame of reference at absolute rest. Experiments showed: velocity of light is always the same. It was discovered, that Lorentz transformation makes Max.Equ. independent of a special frame at rest. Now the physical laws are independend of absolute movement. I believe, that this does not imply, that there is no absolute rest. The twin paradox arises from the fact, that one says: if I do not know for sure, if and how I move, every assumption is correct. Tis is just plain nonsence. Before Einstein, time was absolute. But not the actual value of time was absolute, only the distances in time between to events were equal for all observers. This setting was replaced by: the (spacial) distance between to events, measured by independend observers, which don't feel acceleration, reduced by the time distance, multiplied with a constant of dimension velocity, is equal. There is one impreciseness: we can not feel gravitational forces. Therefore, gravitational forces have to be excluded from our thought experiment. (And this implies: there is no need for GR to "explain" twin paradox.) What is the impetus to argue against SR: 1. people fight SR, for they are confused. 2. SR is not complete, and some people prefer special store (tiffanys) from general stores, the cannot see, that SR is worse than GR. (Aren't they true? who can profit from GR?)

And what is the impetus to fight against those, that argue against SR? To me it seems, most just defend a holy gral! Every thing is relative. Even friendly fire!

Two object moving inertialy can not meet twice! Therefore you either have to change direction -this obviously is non inertial movement- or you have to install another ability. ErNa 10:22, 11 December 2006 (UTC)

What are the basics, we undoubtedly agree upon?

Let' produce a piece of peace! Calm down. If you understand, why I cannot follow your arguments, that is, why YOU are not understandable, you can express yourself more simple, so that even the biggest dummy can learn from You, and You are the most profound teacher! But have have to begin from the very beginning!

Sorry, ErNa. Your words are rough enough so I am ABSOLUTELY NOT interested in such discussion. I beg your pardon for being not understandable. Happy New Year. JM3

Sorry, JM3. Everything is relative. So I understand: you are not interested in discussions, where every side fixes his point of view step by step more precise, but You are interested to take part in discussions, that turn round and round and round, endlessly. Good luck, but You're welcome.

I am not interested in discussions where people are humiliating each other, ErNa. You are treating me as if I were a foolish kid. Anyway, thanks for the welcome and good luck to you too. JM3

Object exist and they pass time and they are not united and they communicate by light and they have size. Is this ok? ErNa 11:18, 11 December 2006 (UTC)

See and comment: http://cmapspublic.ihmc.us:80/servlet/SBReadResourceServlet?rid=1165836351303_1869226839_30184&partName=htmltext

and let us go on step by step until we agree on our differences ;-)

You can edit this map by using CmapTools ErNa 11:44, 11 December 2006 (UTC)

We have to fix our starting point. This is absolutely necessary, if we see this statement: In special relativity, the time dilation effect is reciprocal: as observed from the point of view of any two clocks which are in motion with respect to each other, it will be the other party's clocks that is time dilated. found in time dilation! Undisputed! ErNa 19:40, 11 December 2006 (UTC)

How do You vote?

The statement is correct:

The statement is false: ErNa 19:45, 11 December 2006 (UTC)

Note for Harald

http://simple.wikipedia.org/wiki/Special_relativity

"In 1908, Max Plank endorsed Einstein's theory and named it "relativity". In that same year, Minkowski gave a famous speech on Space and Time in which he showed that relativity is self-consistent and further developed the theory."

green 12.30.216.138 01:14, 12 December 2006 (UTC)

Fine; But sorry, I have no clue why you bring this up. Which paragraph is concerned? Harald88 19:59, 12 December 2006 (UTC)

Earlier on this page you expressed an interest in Einstein's displeasure with the name given to his theory, and I told you that he preferred "Theory of Invariances". I then stated that I thought Minkowski gave the name, but it was Planck. green 12.30.216.138 20:54, 12 December 2006 (UTC)

Section Discussion: "Resolution of the Paradox in General Relativity"

I just read the revised version of this section and I think it should be clearly specified what problem is being solved! When the article refers to "the Earth", should we take this to mean a gravitating body, or are we in fact considering two observers floating in inertial space, separating and returning due to the acceleration of one only? When this is clarified, I will have additional comments, but as a preview I get the feeling that it is important to comment in the article on the consensus view of Einstein's 1918 solution. If the twins are in inertial space, there is something awry with this application of GR; without mass-energy, there can be no spacetime curvature, hence no "gravity", hence no gravitational dilation (used to solve the problem). green 12.30.216.138 02:57, 12 December 2006 (UTC)

I understand that my views concerning the weirdness of the GR "solution" are irrelevant wrt what should be in the article. However, I get the feeling that some of these weirdnesses were recognized earlier on, and therefore are relevant from an historical perspective, certainly for those readers who wish to pursue the subject to the next, deeper level. That said, it is certainly weird to assume -- as the article does -- that a traveler who fires a rocket producing, say, one g acceleration, would conclude (even if only "perceptually") that a body with the Earth's mass had just been created, or spontaneously appeared in his vicinity by virtue of his action. There's nothing logical about this conclusion except that the traveler had lost his marbles. Would really he apply the EP to infer a gravitational field when he knew he had just fired his rocket? Yet the article claims that this is what the observer would do in order to apply GR. Makes no sense whatsoever. green 12.30.216.138 04:30, 12 December 2006 (UTC)

If you are saying that firing ones engines does make this a GR solution, I agree with you 100%. Maybe the section should be retitled. Maybe I should just drop it again. However, the gravitational time dilation does exist, but the cause of it is not GR's spacetime curvature at all. --EMS | Talk 04:52, 12 December 2006 (UTC)

Removal of content

As of now, I am removing new content by "green" added to this talk page. This silliness on his part needs to stop. We must discuss that article, not the theory, and most certainly not green's research. --EMS | Talk 06:06, 12 December 2006 (UTC)

This is shameful. I answered a question you (defacto) asked me wrt the GR section and the solution you wrote up. The value of thinking through these issues, aka, "research", would be to suggest that valid contentions exist in the literature that should be cited, since I don't think I am unique in raising them. But you knew that already. green 12.30.216.138 06:31, 12 December 2006 (UTC)

I agree. The discussion goes forth and back and green gives clear statements. But I am disappointed. Nobody here is ready to give a clear statement, what the basis of his thinking is. My question above is not answered. The twin paradox has so many weak points. For example, the relevance of GR. If we do not focus on the core, we will discuss for ever and I will have much more opportunity to improve my english ;-> ErNa 06:33, 12 December 2006 (UTC)

What EMS deleted, was a summary of conclusions I reached, and why, in my discussion with Moroder, and its relevance to the GR section. I learned a lot in the process. green 12.30.216.138 06:40, 12 December 2006 (UTC)

EMS, If you had more integrity, you would simply cross out what I wrote and let others decide whether it has value, for the article and inherently. green 12.30.216.138 06:38, 12 December 2006 (UTC)

Green - It would be irresponsible of me to let you continue to persue your personal research here. Wikipedia is not a debating society. You are claiming that the SR twin paradox result is "inexact" for reasons that appear nowhere in the literature. I have tried to tell you why that is the case, and you have refused to listen. BTW - Do note that I added this message so that others would be aware of my actions, and not believe that you had not tried to respond to my last posting. --EMS | Talk 15:32, 12 December 2006 (UTC)

No, he is not claiming this! He just says: there is no twin paradox. As Einstein did! The simple truth is: there is no absolute time, that can be measured, for time is measured by clock and clocks tick in dependance of their state of movement. You can not convince him, so answer simple questions of simple people. There is a spectrum of colours. ErNa 15:43, 12 December 2006 (UTC)

[Removed more inappropriate content. This is not Wikipedia U.] --EMS | Talk 16:48, 13 December 2006 (UTC)

12/12/06 This article should be reverted to the version of 1 month ago

Oh dear oh dear oh dear. Geometer 14:38, 12 December 2006 (UTC)

B Class is generous! This article is totally misleading at present. It should be ignored by students. Geometer 14:43, 12 December 2006 (UTC)

To reach this state 1 month later again? I would like very much be able to follow all these arguments. But I do not understand what is meant. And we are jumping where we should walk. I own a clock and a pocket rule. The clock is always with me. The clock is connected to one end of the pocket rule. I do not feel any force and I can not see any mass close to me, therefore I believe, I am not accelerated. The clock ticks by flashing. At the other end of the rule is placed a mirror. The reflected light of the flash conincides with the light of the next flash in a detector, which is a integral part of the clock. To me, this is a setup to ask a question. Or is there any degree of freedom to misinterpret, what was stated? ErNa 15:18, 12 December 2006 (UTC)

Please give us a link to the version you want to revert to, so that this can be judged. (I have done "major reverts" in the past. Oddly, they tend to stick.) --EMS | Talk 15:35, 12 December 2006 (UTC)

BTW - Are you complaining about the "Alternate resolution" section? If so, I have just removed it. It was added earlier today by a user named "DingleGhost". Given who Dingle was, I need to keep an eye on this ghost. --EMS | Talk 15:44, 12 December 2006 (UTC)

Why does this article attract so many crackpots? Thank you for dealing with Dingle's disciple. For your enjoyment, here is Dingle's error: http://www.mathpages.com/home/kmath024/kmath024.htmMoroder 16:02, 12 December 2006 (UTC)

This page has been fairly "safe" in the past, but it was also ignored. I'm not sure what to make to the current crop of editors here at this time. Green should take his concerns to USENET as I cannot get him to see his error. I will admit that we are close, but he has no concept of how curvature, acceleration, gravitational fields, and the equivalence principle relate. Without that I cannot communicate effectively with him, and I am done with trying. The Pound-Rebka experiment is enough to show that the traveling twin will observe gravitational time dilation, but Green has no concept of how the equivalence principle equates ourselves with an accelerating observer, nor is he aware that gravitational time dilation is not a curvature effect. --EMS | Talk 17:03, 12 December 2006 (UTC)

I just read the link. Gravitational red shift was confirmed. I know about this result. On its face, however, it doesn't relate in any obvious way to the question of whether an accelerating twin in inertial space will "experience" gravitational time dilation. If it's not a curvature effect, why does the adjective "gravitational" appear in its description? green 12.30.216.138 20:37, 12 December 2006 (UTC)

Apriori, your claim makes no sense (which doesn't mean it's wrong). In the Hafele-Keating experiment, to calculate the gravitational time dilation, they needed to use the difference in gravitational potentials. How could the potentials exist without gravity, that is, without spacetime curvature? If the difference in potential were zero (no gravity, no curvature), there would have been no gravitational time dilation. green 12.30.216.138 20:48, 12 December 2006 (UTC)

In Einstein's lexicon, a "gravitational field" exists whenever one finds that inertially moving objects are accelerating with respect to one's self. So "centrifugal force" is evidence of a gravitational field according to Einstein, along with other fictitious forces. If the gravitational field exists locally, the observer is in an accelerated frame of reference. What curvature does is to make it so that the gravitational field varies in strength and/or direction based on one's position. In SR, the only permitted gravitational field is one due to the observer's acceleration, and in that case the field is of a single strength and direction throughtout the past light cone leading to any given event on the observer's worldline, and comes and goes (or changes strength and direction) with the acceleration.

That is, what I mean, when I say: "precision" . Long ago, David made use of centrifugal forces and that had nothing to do with gravitational field. Gravitational field took care for Goliath falling down to earth! Centrifugal force's counterpart is centripedal force. And this force can be gravitational force, but that is not a must. We would have less to discuss, if Einstein had written everything, what he did not write and gave us the task, to find the rest. ErNa 22:00, 12 December 2006 (UTC)

On the surface of the Earth, we are in an accelerated frame of reference according to the equivalence principle. So the Pound-Rebka experiment measured the gravitational redshift which exists due to our physical acceleration. That is exactly the same gravitational redshift that I am saying the traveling twin observes during turnaround.

Feel free to ask more questions, but I do not want to start going in circles again with you like we did before. If I don't continue making good progress with you, I am closing this down again FAST. --EMS | Talk 21:00, 12 December 2006 (UTC)

Firstly, a note about the politics of discusssion. All along we have been discussing twins in inertial space and Einstein's proposed GR solution using the EP. But when you and Moroder appeal to authorities to disprove some of my beliefs or conjectures, you use experiments performed in non-inertial space where gravitational fields exist, e.g., the Hafele-Keating experiment and Pound-Rebka experiment. For this reason, I have referred to such references as inapposite, since they don't prove what is alleged by those offering them. An unkinder view would interpret such a methodology as manipulative. green 12.30.216.138 01:08, 13 December 2006 (UTC)

That said, I'm still thinking about your preceeding comments, but one issue that immediately comes to mind is this; do they reflect plain-vanilla GR, or one of the perhaps several existing interpretations of the theory? I raise this question because if appealing to experiments is legitimate, I can ask whether a test mass used by the stationary twin would detect a gravity field as he observes the acceleration of his twin at turnaround. You claim that a gravity field exists in SR whenever an observer sees an accelerating object. But what kind of field can this be if experiment will almost certainly falsify its existence? green 12.30.216.138 01:08, 13 December 2006 (UTC)

Further, assuming a "real" field exists and is of a single strength throughout as you allege, then its potential must be constant. Why would the stationary observer claim that a non-zero gravitational time dilation exists when comparing his clock to the traveling twin, if theory told him that he is at the same potential as the traveling twin? green 12.30.216.138 01:08, 13 December 2006 (UTC)

I can't respond to you further here. Either get an account or e-mail me, but this discussion does not belong here. (These questions are no all that bad, but the level of misunderstand of GR that they reveal just makes it clear that I cannot respond to you furhter here after this.) For the record, two simple answers will do:

1. This is "plain vanilla GR" that I am refering to. There are no disagreements on this issue amongst relativists.
2. There is no gravitational field for the stay-at-home twin: That twin is never in an accelerating frame of reference. Only the traveling twin at turnaround is in that situation.

--EMS | Talk 03:50, 13 December 2006 (UTC)

That's OK. Would email be acceptable? I will keep the questions to a minimum and very focused. My email address is edward.greenberg@netzero.com .

Wrt the article, I strongly disagree about the relevance of this discussion if we are to produce a coherent article. E.g., if the GR section is to remain, I think the readers will want to know -- the thoughtful ones that is -- why the accelerating twin would calculate the time dilation of the stationary twin's clock based on a gravity field that an experiment would obviously show is nonexistent -- and that he knows is nonexistent because it defies logic to assume that his local action could have such a profound non-local consequence -- since he would have to convince himself that firing his puny rocket, creates the effect of an Earth-sized mass (if he accelerates at one g). If this is the consensus view of relativists as to what relativity theory implies in this situation (as you allege), it is legitimate to wonder if the fundamental concept of falsification of theories via measurements and (in some cases) thought-experiments has been thrown out the window. This is breathtaking.

Wrt the EP, from what you write I suppose I was mistaken in what it means. I always thought, using the elevator that Einstein made famous, that if the occupant could not look out, it would be impossible via internal measurements to distinguish the effects of acceleration from gravity (for infinitesimal displacements). I never imagined that if the occupant directly caused his acceleration -- and therefore had no issue distinguishing it from gravity -- that the EP allowed him to infer the (perceptual-only?) existence of a nonlocal gravity field. I know relativity is difficult and subtle, but I had no idea it had apparently lost touch with reality as quantum theory has -- e.g., in its many-worlds interpretation. Again, breathtaking. green 12.30.216.138 05:26, 13 December 2006 (UTC)

First of all, I see the GR section as baggage that does not help the reader. I can be mentioned in a history section, but I now feel that if is to be covered in any detail then it should be an article on its own. As for the EP: It only applies locally, but in SR the infered field is global in extent. I will e-mail you on the issue of how an accelerated observer must perceive a gravitational time dilation effect. There is no loss of contact with reality here, just a theory that does not behave as you expect it to. --EMS | Talk 06:22, 13 December 2006 (UTC)

Reset indent: (Inappropriate response from "green" removed. This page is for discussing the article, not the theory.) --EMS | Talk 16:38, 13 December 2006 (UTC)

For anyone interested in thinking for themselves, I copied below what EMS deleted. It should have been obvious to EMS that what I wrote was my final statement of the state of things from my pov, and that I planned to continue any further discussions in private email. I am sure there are serious issues about the so-called GR "solution" that exist in the literature, and it is inconceivable that anyone who reads the GR section will understand or believe it. That was one of the main motivations for my discussion. But it is painfully clear that EMS has the mind-set of a conformist who cannot stand contrary opinions -- and here I am referring not to my opinions but to documented ones in the literature. This is why he removed Builder's reference. I won't be partipating here in the future. green 12.30.216.138 17:33, 13 December 2006 (UTC)

Theories can behave in any which way. However, if a theory is falsified by experiment, or in this case by two thought experiments as described above when applied to a particular situation, one has no alternative but to reject that it can be applied to that particular situation. If it cannot, it might have broader negative implications for the theory. As to the EP, it has been my understanding all along that it applies locally. However, it seems clear that the traveling twin applies it globally to infer the speeding up of the stationary twin's clock. So until I see something that makes sense, I hold to my position that the GR solution of the twin problem is nonsensical because it applies and depends upon an erroneous application of the EP. Fwiw, this was my position in my summarizing statement of conclusions from exchanges with Moroder (which you deleted), with the additional point that the SR calculation is exact because there is no EP effect. Nonetheless, I am open to the possibility of having my conclusions falsified, and I look forward to your subsequent analyses of these issues. green 12.30.216.138 07:03, 13 December 2006 (UTC)

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The mainstream called Boltzmann a crackpot. And he became insane. Newton was crazy. Obviously it is ennobeling to be called "mad". RIP, I can't ErNa 18:26, 12 December 2006 (UTC)

I support a revert to a past version. I liked the old one with a GR section and a short critique of it. Tailpig 20:02, 12 December 2006 (UTC)

I submit we revert to this version oldid=63968684. Tailpig 20:08, 12 December 2006 (UTC)

I don't see that is buys us anything to do this. What this article needs is a careful rewrite, but I don;t have time for that now. --EMS | Talk 03:54, 13 December 2006 (UTC)