The Symmetric Twin Paradox
in [Relativity]
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From: Peter Webb on 17 Jun 2010 10:36 "colp" <colp(a)solder.ath.cx> wrote in message news:a36bbc65-85c5-46dd-b6bd-6b2d388603bf(a)v12g2000prb.googlegroups.com... On Jun 17, 5:56 pm, "Peter Webb" <webbfam...(a)DIESPAMDIEoptusnet.com.au> wrote: > > When > > this is tested by actual experiment, the travelling twin is younger. > > In the symmetric paradox that I spoke of in my previous post, both > twins travel and they are the same age, despite the predictions of SR. > I'm not going to argue about the classic paradox because the paradox > is much easier to show in the symmetric case. > > ________________________________ > If the situation is that both twins travel, and this is symmetric, then SR > predicts that they will have aged the same amount when re-united into the > same inertial frame. Wrong. SR predicts that one twin will observe time dilation of the other both on the outgoing and incoming legs. In no case does SR predict that that a twin will observe any kind of time compression of the other twin that would be necessary to compensate for the theoretically observed time dilation. Without such compensation for the observed time dilation, SR predicts that a twin will be older than the twin he observes, which contradicts with logical result of the twins being the same age. ______________________________________ That simply is not how the equations go, or what they mean. If you have two twins blasting off with equalt velocity in opposite directions, both see the same thing - the other twin ages more slowly when they are separating, but more quickly when they are approaching, so that when they rejoin they are the same age. > If you do believe SR predicts anything different, then > you are wrong about the predictions of SR. If I am wrong and you understand SR then why are you unable to identify any error in my reasoning? ________________________________ THe time compression - as you put it - does occur when they are approaching each other. That is the error in your reasoning. > > Can you produce a single experiment which shows that SR is wrong? Yes, I have described the thought experiment that shows that SR is wrong, and you have been unable to show any flaws in my argument. The experiment is described in full at the following page: http://adsabs.harvard.edu/abs/2008arXiv0804.2008N _______________________________ There are no logical flaws in SR in the sense of paradoxes or inconsistencies. It may be an incorrect theory, but that can only be determined by real experiments, not thought experiments.
From: Daryl McCullough on 17 Jun 2010 10:50 Transfer Principle says... >Still, I admit that I've once thought about this >"symmetric twin paradox." I also once asked myself >that if the universe is closed, the twins travelling >in opposite directions might end up meeting at the >other side of the universe -- then which twin would >be older? (But then I always waved this off by saying, >therefore, the universe _isn't_ closed...) No, a closed cylindrical universe is no more a problem for Special Relativity than the existence of cylinders is for Euclidean geometry. For a flat infinite sheet, all directions are equivalent, but if you wrap that paper into a cylinder, then there is suddenly a big difference between the direction around the circumference and the direction parallel to the axis. Similarly for a cylindrical universe in SR. For a flat infinite universe, all inertial frames are equivalent. But if you wrap the universe into a cylinder, there is a difference between the inertial frame of an observer traveling out the circumference and the inertial frame of an observer traveling parallel to the axis of the cylinder. -- Daryl McCullough Ithaca, NY
From: eric gisse on 17 Jun 2010 11:50 Peter Webb wrote: [..] Would it kill you to use a newsreader that can properly quote?
From: PD on 17 Jun 2010 16:14 On Jun 16, 1:25 am, colp <c...(a)solder.ath.cx> wrote: > The classic twin paradox is asymmetric in that one twin remains on > Earth while the other leaves (i.e. only one of them accelerates and > deaccelerates). In the symmetric twin paradox both twins leave Earth, > setting out in opposite directions and returning to Earth at the same > time. The conventional explanation for the classic twin paradox is > since only one twin accelerates, the ages of the twins will be > different. In the symmetric case this argument cannot be applied. > > The paradox of the symmetric twins is that according to special > relativity (SR) each twin observes the other twin to age more slowly > both on the outgoing leg > and the return leg, so SR paradoxically predicts that each twin will > be younger than > the other when they return to Earth. No. This is a basic misunderstanding due to oversimplification, and it is exactly the kind of thing that the original puzzle was intended to highlight for learners of relativity. The novice says, "The moving clock runs slow" and considers that effect during the outbound and incoming legs of the travel, but no consideration is given for what happens to the relative reading of clocks during the turnaround. And in fact, the analysis of the original puzzle reveals some pretty amazing things about what happens during that turnaround. So SR does not in fact say that the twins in the symmetric case will both be younger than the other. It does in fact say that they will rejoin having the same age. > > The symmetric twin paradox is described more fully in the following > paper: > > The Twin Paradox Revisited and Reformulated -- On the Possibility of > Detecting Absolute Motion > Authors: G. G. Nyambuya, M. D. Ngobeni > > http://adsabs.harvard.edu/abs/2008arXiv0804.2008N > > "We introduce a symmetric twin paradox whose solution can not be found > within the currently accepted provinces of the STR if one adopts the > currently accepted philosophy of the STR namely that it is impossible > for an inertial observer to determine their state of motion."
From: colp on 17 Jun 2010 17:33
On Jun 18, 8:14 am, PD <thedraperfam...(a)gmail.com> wrote: > On Jun 16, 1:25 am, colp <c...(a)solder.ath.cx> wrote: > > > The classic twin paradox is asymmetric in that one twin remains on > > Earth while the other leaves (i.e. only one of them accelerates and > > deaccelerates). In the symmetric twin paradox both twins leave Earth, > > setting out in opposite directions and returning to Earth at the same > > time. The conventional explanation for the classic twin paradox is > > since only one twin accelerates, the ages of the twins will be > > different. In the symmetric case this argument cannot be applied. > > > The paradox of the symmetric twins is that according to special > > relativity (SR) each twin observes the other twin to age more slowly > > both on the outgoing leg > > and the return leg, so SR paradoxically predicts that each twin will > > be younger than > > the other when they return to Earth. > > No. This is a basic misunderstanding due to oversimplification, and it > is exactly the kind of thing that the original puzzle was intended to > highlight for learners of relativity. It is true that I haven't discussed what happens at turnaround, but only for the reason that turnaround cannot possibly compensate for the SR time dilation. Imagine what would happen if a twin's observation of the other twin's clock was based on counting the number of pulses in a radio wave. When the twins return to Earth the number of pulses received by a twin must equal the number sent in order to avoid a paradox. SR predicts that the observed pulse rate will decrease during the outbound and inbound legs (ignoring the complication of the transit time of the signals), and SR does not describe an increased pulse rate which would reconcile the paradox. So, for the paradox to be resolved the observed pulse rate must increase according to the local rotation at turnaround, which could involve partial reversals. The problem is that that signals exchanged by the twins can also be observed on Earth, and you have the illogical situation where, for an observer on Earth, the signal rate of one twin depends on the rotation of the other twin - remember that it is the same signals that pass Earth that are received by the twins. > > The novice says, "The moving clock runs slow" and considers that > effect during the outbound and incoming legs of the travel, but no > consideration is given for what happens to the relative reading of > clocks during the turnaround. And in fact, the analysis of the > original puzzle reveals some pretty amazing things about what happens > during that turnaround. Yep, so amazing that the faith of the relativist makes all possibility of a paradox disappear. > > So SR does not in fact say that the twins in the symmetric case will > both be younger than the other. Wrong. In no case does SR predict a time compression which would compensate for the time dilation that is predicted by SR. Without such compensation the local time of the twin can never agree with the observed time of the other twin. But the observed time must agree with the twin's local time when the twins return to Earth otherwise a paradox ensues. |