Talk:Twin paradox/Archive 9

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Need to show why can assume one frame of reference is stationary

Both twins would perceive the other as accellerating due to a force. The 'stationary twin' may well be accellerating relative to an arbitrary point in the universe. If the laws of physics are the same in all inertial frames of reference but not accelerating ones then there must be an experiment each could do to determine their absolute acceleration. Everyone in the universe could then do this experiment and deduce the absolute frame or reference. AnnabelBuxton 14:46, 24 May 2007 (UTC)

The stationary twin would read zero on his accelerometers. The travelling twin would not. DVdm 15:25, 24 May 2007 (UTC)

The notion of the accelerometer is interesting and the best way of making progress here. To avoid two threads about the same thing I have referred to it below. AnnabelBuxton 15:40, 24 May 2007 (UTC)

However since you avoided the question in the thread below by getting in a huff I'll repeat it here to help you develop your understanding - you are claiming the acclerometer measures absolute acceleration. Accelleration is a vector quantity. Therefore absolute accelleration implies an absolute co-ordinate system - Yes or No. AnnabelBuxton 09:02, 27 May 2007 (UTC)

See Proper acceleration, Accelerometer, Inertial frame of reference and Special relativity, or, if you don't trust the Wikipedia, find a good textbook on A Guide to relativity books, or use Google and find some academic site where things are explained the way you like it. Other than that, the subject of this talk page is the article. Its purpose is not to provide answers to your very simple questions. Experience shows that this only leads to avalanches of even simpler questions. DVdm 09:08, 27 May 2007 (UTC)

If you read a decent book you will find that the twin paradox is about conficting results from the two frames of reference. There is nothing interesting or controversial about one twin being younger, having done the calculation in only one frame of reference. I refer you to Rindler. He resorts to some hand waving in regard to the twin paradox, but at least he states the paradox correctly. AnnabelBuxton 17:15, 27 May 2007 (UTC)

Three frames of reference. But there's no conflict if you do the calculation correctly. See, for instance, Usenet Physics FAQ: The Twin Paradox.

—wwoods 23:36, 27 May 2007 (UTC)

The frame of reference of the 'homebody' and the frame of reference of the traveller. That's two. AnnabelBuxton 09:53, 28 May 2007 (UTC)

Essence of paradox versus "Both Viewpoints"

Taken out of the article:

The essence of the paradox is that because in relativity there is no absolute frame of reference (such as an ether), both twins are equally correct in assuming their own frame of reference to be stationary. They both perceive the other as accelerating. To resolve the paradox we must perform the calculation in the frame or reference of both twins and show that the results are consistent. Alternatively we must provide details of an experiment each twin could do to show which was the itinerant twin and which was stationary, and hence show how the laws of physics differ in each frame. AnnabelBuxton

The essence of the 'paradox' is failing to understand that the twins are not equally correct in assuming their own frame of reference to be stationary. One twin remains stationary. The other twin does not: he either has to jump from one stationary frame to another, or he has to undergo accelerations.

To resolve the paradox we must calculate both times and compare them. That is what the article does.

The article calculates the integral

$\Delta t'=\int {\sqrt {1-(v(t)/c)^{2}}}dt\$

which is what you call "the calculation in the frame or the stay at home twin".

If you want "the calculation in the frame or the travelling twin", you need to calculate the integral

$\Delta t=\int {\sqrt {1-(v(t')/c)^{2}}}(1+a(t')x'(t'))dt'\$

where a(t') is the proper acceleration felt by the traveller and x'(t') the distance to the stay-at-home at time t' according to the traveller. This calculation is much more difficult and messy, but obviously it gives the same result.

Note that the form of the second integral is equally suited to calculate from the point of view of the stationary twin, in which case the proper acceleration is trivially zero.

You can verify the calculation and the results in this (quick and dirty) maple sheet: Accelerated Twin - viewpoints. Verify the one but last columns of the tables: t(T) and T(t). The last column contains the numerically approximated value of the integral. I repeat - this is a quick and dirty one.

Anyway, this is clearly not the "essence of the paradox" and I think it is much too elaborate for the article itself.

DVdm 15:10, 24 May 2007 (UTC)

Stationary relative to what? How do you define stationary? What is the definition of proper acceleration? From the point of view of a star at the center of the universe the 'stationary' twin is jumping between frames. What is you definition of absolute accelleration (are we agreed stationary means absolute acceleration is zero)? How do I measure my proper acceleration? How does either know if he is the stationary one? AnnabelBuxton 15:34, 24 May 2007 (UTC)

See reply in previous section. DVdm 15:28, 24 May 2007 (UTC)

By which you mean the accelerometer? What is your definition of proper accelleration? It is a very simple question. With regards to an accelerometer - does such a thing exist - if I had one on myy desk what value would it show? How does it measure it? I am accelerating relative to the sun as well as all sorts of other bodies. Would it show this? Relative to which body would the value be zero? Or put more simply. What would a zero value on such a device tell me? AnnabelBuxton 15:34, 24 May 2007 (UTC)

See Proper acceleration, Accelerometer, Inertial frame of reference and Special relativity, or, if you don't trust the Wikipedia, find a good textbook on A Guide to relativity books, or use Google and find some academic site where things are explained the way you like it. Other than that, the subject of this talk page is the article. Its purpose is not to provide answers to your very simple questions. Experience shows that this only leads to avalanches of even simpler questions. DVdm 16:43, 24 May 2007 (UTC)

The accelerometer referenced here is like a speedometer. It is calibrated to a fixed frame of reference, and would therefore give a value of zero on my desk. Any vector quantity is dependent on a co-ordinate system (frame of reference). Please have a think over the weekend and if you haven't modified the article by Monday I shall re-instate my commments in the article. The article in its current form reintroduces an absolute frame of reference a priori. Proper acceleration as defined there is defined relative to a particular frame of reference, and again in the frame of reference of the 'travelling' twin the 'stationary' twin would have a proper acceleration according to the mathematical definition you have referenced. Proper time relies on a concept on 'same place' which trivially depends on a chosen frame of reference. I studied Rindler's book as part of my Physics degree. Simple questions expose misunderstandings in my experience. I think your misunderstanding is in the word 'proper'. It does not mean one frame of reference is 'right' and the other 'improper'. It simply a shorthand for 'in our CHOSEN frame of reference'. You can choose either twins frame of reference to be proper with equal validity, as each twin stays in the same place in their own frame of reference. To say one stays in the same place but the other does not assumes an absolute frame of reference AnnabelBuxton 18:56, 24 May 2007 (UTC)

In order to avoid the predicted avalanche, just a short and final reply to your phrase "reintroduces an absolute frame of reference". Proper acceleration is defined as the proper time derivative of the four-velocity in the so-called Instantaneously co-moving inertial frame in which the object is instantaneously at rest. See [1], or [2] or [3] or [4] or Bell's spaceship paradox etc...

But again, we are merely discussing your skepticism and/or ignorance here. That is not the purpose of this talk page. I suggest you take it back to a place like sci.physics.relativity DVdm 19:30, 24 May 2007 (UTC)

You are airing you ignorance. Look at Rindler. The twin paradox is that both twins expect each other to be younger. It is NOT that it is surprising that time dilation occurs (as implied by this grossly inaccurate article.). I have taken the argument from Rindler about the twin paradox put it at the end of your calculation. Hope that helps you to understand it better. If not enrol on a physics course and talk to someone about these issues - rather than quoting equations you have googled and plainly do not understand There is no such thing as AT REST, objects can only be at rest in relation to a particular frame of reference. There is no such thing as a frame of reference which is inertial or not in absololutum. Frames can only be inertial or not (moving at constant velocity) relative to each other AnnabelBuxton 07:54, 25 May 2007 (UTC)

I strongly suggest that you wade through the 6 archives of this talk page (in which you will find a large number of treatments of your misconceptions), and then take your ignorance and trolling elsewhere. DVdm 08:04, 25 May 2007 (UTC)

I am simply stating the standard version of relativity to you. Before Einstein people believed in an ether i.e. an absolute frame of reference. Time dilation and length contraction occured relative to this ether frame (the Lorentz equations predated Einstein). Your article is a pre-Einstein Lorentzian view of relativity. In the Lorentzian view of relativity there is no twin paradox, but then you are stuck with asking why should there be an absolute frame of reference and which one is it or what is it? Post Einstein trained physicts believe there is no ether frame or absolute frame of reference. We therefore cannot make statements like at rest, without basing them on a chosen frame of reference. I hope that helps. If you get a formal education in Physics then you will be exposed to this in more detail. Abandoning an absolute frame of reference is quite counter intuitive at first and people not used to it do keep talking about at rest or accelerating without specifying their frame of reference for quite a while - but your Profs will drum such 'sloppy' statements out of you eventually. If you are interested in the subject then go for it. Your article is a nice try - and very eminent people argued along the same lines as you pre-Einstein so your mistakes are nothing to be ashamed of. I intuitively would have argued along such lines too. However I would add that calling someone an ignorant troll when they are taking the time to ask you questions to help sharpen your understanding is something you will need to grow out of if you are to train as a scientist. In summary and for the final time, accelleration is a vector quantity, so any argument that posits absolute acceleration also posits an absolute co-ordinate system. Good luck in your training.AnnabelBuxton 11:14, 25 May 2007 (comment extended 27 May) (UTC)

I know I shouldn't be taking a trolls' bait, but in summary and for the final time, just a repeat of a short and final reply to your phrase "reintroduces an absolute frame of reference": proper acceleration is defined as the proper time derivative of the four-velocity in the so-called Instantaneously co-moving inertial frame in which the object is instantaneously at rest. See [5], or [6] or [7] or [8] or Bell's spaceship paradox etc... DVdm 09:27, 27 May 2007 (UTC)

I'll ignore the Kevin the teenager remarks about trolls. If a frame it truly comoving then the proper accelleration will always be zero. To have a comoving inertial frame that does not always track a body exactly then you have to say a body has moved relative to its (supposedly comoving) inertial frame. To say this you have to say the intertial frame moved at constant velocity and the body didn't. So you are dependent on another frame to say the comoving inertial frame was moving at constant velocity and the body wasn't. i.e. the inertial frame is moving at constant velocity relative to what? AnnabelBuxton 10:55, 27 May 2007 (UTC)

This is not the place to teach you the basics. See pointers and suggestions given to you earlier. If you fail to do that, you are disrupting and sabotaging the purpose of this talk page, i.o.w. trolling. DVdm 11:20, 27 May 2007 (UTC)

There are only two answers to the question. An inertial frame is either in constant motion relative to an absolute frame of reference or to the observer. The correct answer is the latter. Therefore if the 'travelling' twin is the observer then the 'homebody' twin is undergoing a proper accelleration i.e. the situation is symmetrical. You really have trouble with the Socratic style of debate. It is clear you are a googling teenager so I was not asking to be taught. I am trying to help you understand your mistakes. I give up. Please correct the article or I'll request intervention from an administrator when I get some time off in a few months. AnnabelBuxton 16:55, 27 May 2007 (UTC)

[Reseting indent]

There's no such thing as an absolute frame of reference. However, an inertial frame is in constant motion relative to every other inertial frame. If the traveling twin is coasting, then neither twin will see the other as accelerating, so, yes, the situation is symmetrical.

—wwoods 23:36, 27 May 2007 (UTC)

The symmetry during the coasting phase is not in dispute, its the claimed asymmetry in the accellerating phase that is in dispute. 'An inertial frame is in constant motion relative to every other intertial frame' can't be true. As every possible laboratory frame is accellerating due to the expansion of the universe, even if you get out of the orbits of earth, sun etc. i.e. we would never be in an inertial frame to do any measurements, or if we were in one of these priviledged frames we would only be momentarily in one. The concept of inertial frames can only be relative to the observer. The experimental tests of relativity have been done in frames accellerating round the center of the earth and sun and the results deemed acceptable because the frame of atomic clocks, decaying particle etc was in uniform RELATIVE motion. Every frame in inertial for someone in that frame (accellerometers don't measure the acceleration round the center of earth, sun). So if A is accelerating relative to B their own frames are inertial for each of them - but the frame of B is not inertial relative to A and vice versa. The B frame is an equally valid inertial frame as long as you do the whole calculation in that frame. Sorry to 'preach' but I tried the polite ask questions to highlight issues form of debate and you can see the results. NB I ought to clear up this illusion of an accellerometer and 'feeling inertial forces'. You only feel Gs because you are temporarily in a different frame of reference to your seatbelt, the air etc. If instead of an engine in your car/plane every cell in your body had a mini-rocket attached so you were always in the same frame as your surroundings you would feel no forces. It is the same principle as a hanging weight - the forces do not get translated from one end to another so the two ends get out of sync if its hanging by a thread, so you get a deflection. If its hanging by a steel rod you get no deflection. i.e. if ALL of an accellerometer is always in the frame of an accellerating body it always measures zero. Hence why an accelerometer on the surface of the earth can measure zero despite all the accelerations due to motion round earth/sun etc. Any deflection is a relative accelleration between two frames (and two parts of an accellerometer) and you can say with equal validity that either part has accellerated AnnabelBuxton 10:01, 28 May 2007 (UTC)

Annabel, from your edit summaries it appears that you have access to Rindler: "Relativity: Special, General, and Cosmological". Since you apparently find him more credible than Wwoods and DVdm, you ought to (re)read his explanation of the Twin paradox. In my edition it begins on page 64-68. Here is a small quote from page 67:"From a modern point of view it is difficult to understand the earlier fascination with this problem, or even to recognize it as a problem." and from page 68: "But inertial frames have a real existence too, and relative to the inertial frames there is no symmetry between the buckets and no symmetry between the twins, either." Rasmus (talk) 12:57, 28 May 2007 (UTC)

On these points he is wrong. An accellerometer in freefall reads zero (because all parts undergo equal accelleration). There have been endless papers about hypothetical accelerometers that can detect absolute accelleration. As absolute accelleration is (to date) undetectable Rindler was handwaving when he declared that inertial frames have a real existence. I accepted his definition of the paradox, not his handwaving. This wikipedia article in its current form is plain dishonest as it doesn't even state the problem, let alone solve it. I did however look up my notes from a conversation with Higgs. He used the example of a billiard table. If you strapped a rocket to table the balls would fly to one side (this is how accellerometers 'work'). However if the billiard table and players were in freefall (or undergoing another force that acted uniformly on all parts of the 'system') then you could have a game of billiards and be none the wiser. Inertial frames are undetectable, and therefore in a measurement based science they are not 'real'. AnnabelBuxton 12:10, 10 June 2007 (UTC)

An accellerometer in free-fall is in an inertial frame (or technically an inertial trajectory). Once gravity enters the equation, you have to consider General Relativity and curved space-time. Inertial frames/trajectories are exactly those frames in which an accelerometers reads zero. We can't perform experiments to distinguish between travelling at a constant velocity in an inertial frame far from any gravity fields and travelling in an inertial trajectory in a gravity field, but luckily General Relativity tells us we don't need to.

So to keep it simple, let the twins be in separate spacecrafts, each with their own billiard tables. Now observe the billiard tables during the experiment. The balls on the stationary twins billiard tables are stationary, while the balls on the travelling twins table will move one way during take-off, another way when the twin turns around and back again when he stops. Clearly, we can distinguish between the two twins, so there is no paradox here. Note that you can't perform the experiment without having the balls on the stationary twins table move. If both twins stay in the same inertial frame, hey will stay together. In order for one of the twins to move to another inertial frame/trajectory he will have to accellerate, which will cause the balls to move. Now, this is Wikipedia, not sci.physics, so if you want to prove us wrong, you will have to come up with some credible sources that confirm your view (and please don't suggest Subhash Kak :-) ). Rasmus (talk) 07:12, 11 June 2007 (UTC)

Good point, although I would rather recommend sci.physics.relativity which was created to keep this stuff out of sci.physics. :-)

As for the billiard balls table example, in this respect Griffiths' remark (Introduction to Electrodynamics, page 477) is rather interesting and might come handy for those who for some reasons have a problem with the concept of an accelerometer:

"This raises an awkward problem: If the laws of physics hold just as well in a uniformly moving frame, then we have no way of identifying the "rest" frame in the first place, and hence no way of checking that some other frame is moving at constant velocity. To avoid this trap we define an inertial frame formally as one in which Newton's first law holds. If you want to know whether you're in an inertial frame, throw some rocks around--if they travel in straight lines at constant speed, you've got yourself an inertial frame, and any frame moving at constant velocity with respect to you will be another inertial frame."

DVdm 13:12, 11 June 2007 (UTC)

No Discussion Why This Is A Paradox

The discussion does not explain why there is a paradox. This is an important issue in the history of relativity that is being neglected. The following should be included as an external link. [9]72.64.37.102 17:39, 19 July 2007 (UTC)

It does not explain why because the overwhelming consensus of scientific opinion is that the really is on paradox. The link you provide may be useful as a source of historical data on the topic, but as an authoritative demonstration that relativity is invalid it fails to hold water. More importantly, to the best of my knowledge it has failed to attract the kind of attention in the scientific community that would make in notable and require its inclusion in the article including a mention of its conclusion. --EMS | Talk 20:39, 19 July 2007 (UTC)

This is a pretty dumb answer. The title of this article calls it a paradox, and the response is that there is no paradox. So why call it the twin paradox? Everyone calls it by this name because it is an unsolved paradox! The statement that the scientific community agrees on the solution is unproven. Lets take a vote on it. While we are doing that, lets let everybody, not just scientists vote on every scientific issue. All you have done, and this article does, is assert an opinion. Is that scientific? Is that objective assessment of the issue? What you want to do is to censor science information and you are using Wikipedia to help you do it. That is a false version of science. You want to impose censorship on scientific thought. This article needs major revision to present the problem in an objective scientific manner, rather than promoting false opinion, which can not be proved in any way, as "mainstream" science. The article is basically false and incorrect. It needs to be completely rewritten and not presented as a vehicle for the presentation of false and unproved opinion. There is nothing scientific about this article other than the subject matter. There is, in fact, no solution of the twins paradox within the special theory of relativity, that is why it is a paradox. As a minimum, in order to redress the damage this article does to objective science, the above link shold be included, along with others so that a correct an objective assessment of this problem can be presented to the reader.72.84.77.246 13:19, 24 July 2007 (UTC)

The proposed link is to a paper that is not peer-reviewd, has no references, and mixes in the author's opinions about special relativity with other people's alledged opinions. Not a worthwhile link in my view. E4mmacro 03:39, 26 July 2007 (UTC)

That is nonsense. The referenced work is a review and evaluation of different opinions expressed on the twins paradox. It addresses why Dingle decided special relativity is wrong. This subject is not addressed in this article, which is an attempt to suggest that the twins paradox is a settled problem, when it has not been adaquately solved. Apparently Wikipedia does not desire to reflect the most recent up to date research, and prefers to repeat the misinformation contained in outdated textbooks. This is an area in which papers are published every year, and the reason for this is that there is no satisfactory solution to this problem. The opinion of the editors seems to be that misinformation is better than exposing the reader to a problem which is controversial and unsolved. —Preceding unsigned comment added by 71.251.178.128 (talk • contribs) 05:08, 26 July 2007

Also the proposed link paper (by Ricker) seems to misrepresent Ives' exchange with McCrae (April and August, Letters to the editor, Nature 1951). Both McCrae and Ives agree on which clock (or which twin) comes back younger, they merely differ in how they explain it. Ricker suggests Ives agrees with what seems to be Ricker's own view, that the twins/clocks show the same age when reunited. I say again - a poor quality paper in a poor quality "journal". E4mmacro 03:47, 1 August 2007 (UTC)

This is one of those little things that drives me crazy. Most textbooks claim that the twins paradox is "not really a paradox" because, even thought it is a bit unintuitive,it has a resolution, completely ignoring the definition of a paradox! Unfortunately I can't cite any specific sources on this, so I'm not going to change the article, but it's pretty evident if you look at the definition of paradox. --Starwed 17:37, 27 July 2007 (UTC)

The paradoxes of relativity are contradictions and imply a false conclusion because of an error in the logic. Either the premises are false or the conclusions are. However, paradoxes are contradictions which are not beleived to be true, so by calling the contradictions paradoxes, the conclusion that the assertions are false is avoided. A discussion of this problem in the context of the special theory of relativity is given at: A Contradiction Is Not A Paradox!.71.251.179.46 14:54, 28 July 2007 (UT

Mr E4mmacro should apologise for making deliberately false statements. The referenced paper does not do as he asserts, but merely notices the difference in viewpoints in a very brief manner by providing sample quotations from the papers. An apology is due to Mr Ricker and the discussion group.72.64.51.94 16:16, 1 August 2007 (UTC)

Introduction

Always keep an introduction simple and to the point. This article is about the twin paradox. The introduction should give us all a brief explanation of what the paradox is.

Whoever wrote the previous introduction seemed to be more intent on giving a long explanation of why he thinks that there is no paradox. It doesn't matter whether there is a paradox or not. The article is entitled 'The Twin Paradox' and so all we need to know is what the paradox is claimed to be. (217.41.240.15 12:59, 26 July 2007 (UTC))

That is standard relativity BS. They either say that a paradox is not really a contradiction, or that it is only a seeming contradiction. In fact the term paradox is wrong, it is a contradiction, but the word paradox has become standard usage in this problem.71.251.178.128 13:58, 26 July 2007 (UTC)

The above comment presents a problem which is not well understood. Relativists present the paradox as being the unusual result that the twins age differently. According to them, it is paradoxical that the travelling twin returns younger than the stay at home twin. That is not the paradox. The paradox is that this result does not follow from the principle of relativity and contradicts the mathematical formalism of the special theory of relativity. This explains why Einstein tried to solve it using general relativity in his 1918 paper. But that attempted solution failed, and no really adaquate solution has been found yet.71.251.178.128 14:05, 26 July 2007 (UTC)

Here are my suggestions, anonymous:

(1) Sign up for an account so I don't have to call you anonymous

(2) Be bold, and make the corrective edits you believe are necessary - make sure to include authoritative references, please!

(3) Important: Make sure to read and absorb the following warning which is printed below the edit box:

If you don't want your writing to be edited mercilessly or redistributed by others, do not submit it.

(4) Also Important: Make sure to read and absorb this: Wikipedia is not a soapbox

Regards, Alfred Centauri 23:32, 26 July 2007 (UTC)

The boring discussion over the meaning of the word "paradox" could be avoided by calling the article ' The twin "paradox" ' E4mmacro 22:48, 28 July 2007 (UTC)

Or just link to Paradox: "A paradox is an apparently true statement or group of statements that leads to a contradiction or a situation which defies intuition. Typically, either the statements in question do not really imply the contradiction, the puzzling result is not really a contradiction, or the premises themselves are not all really true or cannot all be true together." In this case, the puzzling result is not really a contradiction.

—wwoods 23:12, 28 July 2007 (UTC)

Vandalism

Gscshoyru, you are a vandal. You are reverting edits before you have even had time to read them. This article is about the twin paradox. If you hover over this article trying to deny the paradox you are imposing your own opinion. This is vandilism.

The article is not here to afford the opportunity for people like you to give long discourses on what the likes of Paul Langevin has to say on the matter. (217.41.240.15 13:14, 26 July 2007 (UTC))

I'm not a vandal. Deletion of so much content should be discussed first, with people who understand what the article is about, and whether or not the content you remove really is unnecessary. Wholesale removal of content is considered vandalism. Gscshoyru 13:19, 26 July 2007 (UTC)

The stuff that was removed was waffle that was designed to undermine the very existence of the article in question. It was all pure opinion.

The article is entitled 'The Twin Paradox'. We therefore want to know what the twin paradox is. We can then make our own minds up about whether or not it is a paradox. We don't need somebody butting in to warn us in advance that it is not really a paradox. (217.41.240.15 13:25, 26 July 2007 (UTC))

What most people think of as the definition of paradox is actually incorrect. A paradox is a seeming contradiction, not simply just a contradiction. It is in fact a paradox, whether or not it is a contradiction. The way that that paradox is resolved is perfectly fair game for article inclusion. Gscshoyru 13:29, 26 July 2007 (UTC)

While I think that some of the stuff discussing why it is not a paradox could be reworded to fit more appropiatly with WP:NPOV, deleting it altogether definatly violates WP:NPOV, especially since the reasons why it is not a paradox are fairly widely accepted.Mdlutz 13:31, 26 July 2007 (UTC)

In that case, keep the introduction factual and then open up a new section for reasons to suggest that the paradox does not exist. (217.41.240.15 13:33, 26 July 2007 (UTC))

Sounds Fair to me. Lets leave the introduction as a definition asto what the paradox IS, and move the controversial stuff to a section called "Possible Explainations", "Other Viewpoints" or something similar. I think that will satisfy WP:NPOV without deleting relavant information to the topic. If you want to do that, I will support it.Mdlutz 13:43, 26 July 2007 (UTC) I

Same. Gscshoyru 13:44, 26 July 2007 (UTC)

While you are solving this, I suggest that you read the referenced link given above so that you can understand the historical context of the problem.71.251.178.128 13:51, 26 July 2007 (UTC)

No Solution To Twins Paradox

The article attempts to make the claim that there is an adaquate solution to the twins paradox. However, I have in front of me five papers published in the European Journal Of Physics since 2002 that attempt to solve the paradox. Therefore, since attempts to solve it continue to be published, it is clear that it has not been solved, and the article should reflect this fact.71.251.178.128 14:21, 26 July 2007 (UTC)

Here are my suggestions, anonymous:

(1) Sign up for an account so I don't have to call you anonymous

(2) Be bold, and make the corrective edits you believe are necessary - make sure to include authoritative references, please!

(3) Important: Make sure to read and absorb the following warning which is printed below the edit box:

If you don't want your writing to be edited mercilessly or redistributed by others, do not submit it.

(4) Also Important: Make sure to read and absorb this: Wikipedia is not a soapbox

Regards, Alfred Centauri 23:32, 26 July 2007 (UTC)

I concur with the first, but as for being bold, well, this article has been around a while. To avoid some of the merciless editing, propose any drastic changes on the talk page first. And the idea that the paradox is unsolved is ridiculous; any decent introductory-level textbook on SR should explain it.

—wwoods 07:36, 27 July 2007 (UTC)

I guess I am confused. If the paradox is solved in any textbook, as you say, then it is a mystery why editors are continuing to publish solutions which differ with the textbooks. Do you know why? Do you read the Journals to keep up to date?72.84.64.47 16:15, 27 July 2007 (UTC)

Reputable physics journals do not publish "solutions" to the twin paradox; in fact, there are no journals that could, because plain special relativity is not a current area of theoretical research anymore. (Quantum field theory, general relativity to some degree, and of course quantum gravity all are still active of course.) Journals which do publish such things may either be journals of fringe physics, or be duped into publishing such solutions because of lack of expertise. -- SCZenz 16:21, 27 July 2007 (UTC)

Ah! I've found the source of the confusion; see this page. The European Journal of Physics collections articles that are useful for undergraduate-level education, not current research. -- SCZenz 16:25, 27 July 2007 (UTC)

The Acceleration is also Symmetrical

The argument that the one who accelerates is the one for whom time slows down is a total nonsense of an argument. If one accelerates relative to the other, then they both accelerate relative to each other. So we still have the symmetry.

Besides that, I can't see anything in the time dilation equation that would remotely get Einstein off the hook by introducing acceleration into the matter. The time dilation equation unequivocally poses a logical inconsistency because it doesn't specify who the time slows down for.

Whoever first pulled the defensive stunt about the one who accelerates has simply made it up off the top of the head. It forms no part of Einstein's theory. Einstein's theory as it stands is logically inconsistent due to its inherent symmetry.

People like SCZenz can't seriously believe in relativity. I think that they just pretend to believe it because it looks cool. It's all a bit of a priestcraft kind of cult in which pseudo-scientists try to deceive the masses by pretending to believe things that nobody else could possibly understand..(217.44.98.235 00:34, 29 July 2007 (UTC))

I recommend you take an introductory course in special relativity, so you understand it a bit, and then debunk it. From the article: "Special relativity does not claim that all observers are equivalent, only that all observers in inertial reference frames are equivalent." Your complaint is analogous to asking how F=ma can be true, because when you jump up and down the whole universe moves down and up from your perspective, without any force.

Regarding your complaints about priestcraft, are you claiming that all practicing physicists are "deceiving the masses"...? That would be hard to do. Most experiments would produce nonsensical results, or simply not work, if relativity were false—for example, particle accelerators would lose their beams out the side because the magnets would be operating at the wrong tempo. -- SCZenz 07:30, 29 July 2007 (UTC)

SCZenz, that of course was a typical priests reply. It began with 'go and read the bible'. It then went on to cite so called experimental evidence that nobody is in a position to confirm or deny apart from knowing that the theory upon which the experiments are based is faulty.

You were effectively saying 'we will continue to promote these lies until we realize that too many people have seen through us'.(217.44.98.235 09:12, 29 July 2007 (UTC))

Okay, even I can see how stupid you are. First off, as SCZenz made clear to me (clear enough that I'm kicking myself for not seeing it earlier), the twin who stays home keeps a constant (enough) speed, relative to the inertial frame. He keeps the speed that they both would have had if they had stayed put. However, the astronaut twin CHANGES his speed - this is what causes the timelag. As for your "priest" thing - okay, from what I can tell, you hate religion. You also think modern science is a religion, and continue your hate onto that. Unless we assume that you're merely trying to be annoying, and thus proving that your life is so meaningless that you spend your time trying to ignore editors on wikipedia, then you must still be attached to "classical" science - fire, earth, water, air. As I, and indeed, most of humanity, have seen and heard convincing arguments as to why that system is bunk, the burden of proof is on you to show why it is still somehow valid. If you cannot not, or especially if you refuse to, then the only logical conclusion is that you are a waste of O2.KrytenKoro 10:01, 29 July 2007 (UTC)

Above we have an example of an editor insulting a Wikipedia user. Talking down to a user because the editors opinion is not understandable is offensive and reflects badly on Wikipedia. It is the job of the editors to explain clearly the solution of the twin paradox. Since that has not been done here, they need to revise the article so that all the questions are clearly answered in the article. Insulting the user is unacceptable behavior.71.251.179.21 12:41, 29 July 2007 (UTC)

I apologize for being rude, 71, but it's plainly obvious that the person is trolling. "Typical priest's reply"? I don't see how that is at all typical "I disagree with your conclusion" argumentation between physicists.KrytenKoro 21:06, 30 July 2007 (UTC)

In the special theory of relativity, there are only inertial frames. These are defined as unaccelerated reference frames. However in the twin paradox explanation, the fact that one frame is different from another due to acceleration is the primary argument used to explain the solution of the paradox. However, it is not explained why this does not invalidate the use of the special theory, which is inaplicable to this case. Hence the argument is invalid until it can be proved why this is acceptable. In the particular case presented, the acceleration is relative to an absolute rest frame, which relativity claims can not exist. It then uses this fact to apparently prove that the traveling twin ages slower. Hence the argument appears to contradict the theory which it is supposedly confirming. This needs to be explained, before the reader can be expected to believe this claimed solution to the problem.Electrodynamicist 13:01, 29 July 2007 (UTC)

Concerning your remark "In the special theory of relativity, there are only inertial frames.", have a look at the Usenet Physics FAQ entry Can Special Relativity handle accelerations?:

For instance:

"It is a common misconception that Special Relativity cannot handle accelerating objects or accelerating reference frames. It is claimed that general relativity is required because special relativity only applies to inertial frames. This is not true. Special relativity treats accelerating frames differently from inertial frames but can still deal with them. Accelerating objects can be dealt with without even calling upon accelerating frames."

and:

"Accelerating reference frames are a different matter. In GR the physical equations take the same form in any co-ordinate system. In SR they do not but it is still possible to use co-ordinate systems corresponding to accelerating or rotating frames of reference just as it is possible to solve ordinary mechanics problems in curvilinear co-ordinate systems. This is done by introducing a metric tensor. The formalism is very similar to that of many general relativity problems but it is still special relativity so long as the space-time is constrained to be flat and Minkowskian."

While you are at it, also have a look at the entry The Twin Paradox.

Enjoy. DVdm 21:16, 29 July 2007 (UTC)

Its very easy to defend nonsense. All you have to do is talk nonsense. Nothing suits a pseudo-intellectual better than to be able to talk nonsense in order to defend a nonsense theory that he wishes to be seen to believe. Pseudo intellects are particularly drawn to Einstein's special theory of relativity because it involves the fascinating concept of time travel. No better way to impress your friends in the pub than to make them believe that you are a time lord who understands about time travel.

All these idiots above who are trying to defend relativity seem to be using the acceleration argument to duck the symmetry inherent in Einstein's special theory of relativity. Let's just, for the sake of argument, accept that acceleration makes the situation assymetric.

Can these relativists please show me how acceleration fits into the time dilation equation such as to rectify the situation? (217.44.98.235 09:39, 30 July 2007 (UTC))

As someone said a few days ago, please note that Wikipedia is not a soapbox.

Other than that, this page serving as a place to discuss the content of the article, and therefore not really the place to attempt to teach you and do something about your apparent ignorance of the subject, have a look at my quick and dirty SR treatment of arbitrarily accelerated motion, some of the equations of which are used in my even quicker and dirtier Viewpoints of both twins.

If all this turns out to be somewhat over your head, you might consider finding a less demanding hobby. Cheers, DVdm 10:18, 30 July 2007 (UTC)

DVdm, I read your research articles and concluded that they are total nonsense. They are nonsense in their own right and they are also nonsense because they are not part of the special theory of relativity. They are your own extension to the theory of relativity.

If I were you, I wouldn't console myself with the deluded notion that this is all merely a failure on my part to comprehend what is going on.

The theme that is covered by the famous Aesop's fable about the Emperor's clothes is this very theme. It concerns the idea of certain people claiming to have a special kind of intelligence and a special ability to see certain things that everybody else can clearly see not to be true. Relativity is a modern day case in point of the emperor's clothes.

You console yourself that all us idiots are too stupid to understand it. Go on back to your pub and tell all your friends that you are a time lord and that you have a special understanding of the universe beyond their comprehension. Dazzle them all with those equations in your reserach articles. Your research articles didn't even explain why the acceleration was assymetric.(217.44.98.235 12:21, 30 July 2007 (UTC))

Oops, sorry. Make that a much less demanding hobby :-) DVdm 12:38, 30 July 2007 (UTC)

Then I'll explain the asymmetries, even though it was already explained. The twin at home stays in an inertial reference frame at all times -- no acceleration is felt. The twin in the spaceship, on the other hand, feels acceleration. He or she feels the g-forces acting on them. There is the major difference between the two twins. A worldly instance is a roller coaster -- when you're in it, you feel the forces of acceleration acting on you, but an observer on the ground does not. That is the difference between the two twins. And please keep yourself a little more WP:CIVIL. Thanks. Gscshoyru 12:40, 30 July 2007 (UTC)

I recommend that we stop responding to the anonymous user in this section. It's pretty clear that he or she is trying to yank our chains, rather than asking for information or even being a genuine relativity crank. Remember that talk pages are to be used for improving the attached article—I'm generally in favor of exceptions where someone learns something, but this is increasingly clearly not such a case. -- SCZenz 12:46, 30 July 2007 (UTC)

The special relativity time dilation equation doesn't say anything about frames of reference at all. It simply states the relationship between two times depending on their mutual velocity. The implication is that two clocks moving apart must both go slower than each other.

Regarding the attempts above to explain the role of acceleration in determining which clock goes slower, I notice that someone tried to say that it is the one that feels the forces. In other words a free fall acceleration under gravity is not good enough to make time slow down. According to Gscshoyru the acceleration must be of the kind associated with an electrostatically or electromagnetically based force acting on a rigid body.

Show me how this physical detail fits into the STR equations. (217.44.98.235 18:16, 30 July 2007 (UTC))

Repeating The Challenge To Explain The Claimed Solution

The challenge to explain remains ananswered. It is repeated here: In the twin paradox explanation, the fact that one frame is different from another due to acceleration is the primary argument used to explain the solution of the paradox. However, it is not explained why this does not invalidate the use of the special theory, which is inaplicable to this case. Hence the argument is invalid until it can be proved why this is acceptable. In the particular case presented, the acceleration is relative to an absolute rest frame, which relativity claims can not exist. It then uses this fact to apparently prove that the traveling twin ages slower. Hence the argument appears to contradict the theory which it is supposedly confirming. This needs to be explained, before the reader can be expected to believe this claimed solution to the problem. The challenge is to provide a convincing explanation for this problem. Here the emphasis is upon the word "convincing" for the reason that the argument presented in the article is not convincing.Electrodynamicist 01:07, 31 July 2007 (UTC)

Inertial reference frames are prefered in special relativity. However, there is no preference of one inertial frame over another. --EMS | Talk 02:15, 31 July 2007 (UTC)

Electro, your phrase "... not explained why this does not invalidate the use of the special theory...", shows that you think that non-inertial objects and frames are not allowed in special relativity. So I suggest you have a real look at the Usenet Physics FAQ entry Can Special Relativity handle accelerations?:

For instance:

"It is a common misconception that Special Relativity cannot handle accelerating objects or accelerating reference frames. It is claimed that general relativity is required because special relativity only applies to inertial frames. This is not true. Special relativity treats accelerating frames differently from inertial frames but can still deal with them. Accelerating objects can be dealt with without even calling upon accelerating frames."

and:

"Accelerating reference frames are a different matter. In GR the physical equations take the same form in any co-ordinate system. In SR they do not but it is still possible to use co-ordinate systems corresponding to accelerating or rotating frames of reference just as it is possible to solve ordinary mechanics problems in curvilinear co-ordinate systems. This is done by introducing a metric tensor. The formalism is very similar to that of many general relativity problems but it is still special relativity so long as the space-time is constrained to be flat and Minkowskian."

While you are at it, also have a real look at the entry The Twin Paradox.

Enjoy. DVdm 08:10, 31 July 2007 (UTC)

These are not answers to the challenge but evasions. They demonstrate that you can not produce the required proof. Please produce the proof that what you say is correct.Electrodynamicist 14:58, 31 July 2007 (UTC)