The real twin paradox.
in [Relativity]
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From: Sue... on 29 Nov 2007 15:57 On Nov 29, 3:41 pm, stevendaryl3...(a)yahoo.com (Daryl McCullough) wrote: > Sue... says... > > > > > > > > >On Nov 29, 2:22 pm, stevendaryl3...(a)yahoo.com (Daryl McCullough) > >wrote: > >Sue wrote: > >> >Proper time is the appearace of a distant clock. > > >> It's hard to imagine a more incorrect answer than that. > >> No, that's completely wrong. Proper time is the time > >> shown on a *local* clock. Look at your watch. Note > >> the time. Now walk a couple of blocks and look at > >> your watch again. The difference in the two times is > >> the proper time for the path that you just took. > > >> It doesn't have anything to do with distant clocks. > > ><< A clock in a moving frame will be seen to be > >running slow, or "dilated" according to the Lorentz > >transformation. The time will always be shortest as > >measured in its rest frame. The time measured in the > >frame in which the clock is at rest is called the > >"proper time". >> > >http://hyperphysics.phy-astr.gsu.edu/hbase/relativ/tdil.html > > I have no idea why you think that passage supports your claim. > Here's another article that explains what I was saying: > > http://www.iep.utm.edu/ancillaries/Proper-Time.htm > > "Proper time is also called clock time, or process time. > It is a measure of the amount of physical process that a > system undergoes. E.g. proper time for an ordinary mechanical > clock is recorded by the number of rotations of the hands of > the clock." > > As usual, you have no idea what you are talking about. The semantic operator is not functional in physics (or any other branch of science) Your skills at shuffling equations and definitions is indeed admirable but I can recognise a rigid Newton background when I see it and it has never been detcted and its mathmatics are absurd whether it is Langenvin's version or colp's version. Learn some physics: http://farside.ph.utexas.edu/teaching/em/lectures/lectures.html http://web.mit.edu/8.02t/www/802TEAL3D/visualizations/light/index.htm http://www.ee.surrey.ac.uk/Personal/D.Jefferies/antennas.html Sue... > > -- > Daryl McCullough > Ithaca, NY- Hide quoted text - > > - Show quoted text -
From: Daryl McCullough on 29 Nov 2007 16:06 Sue... says... >On Nov 29, 3:41 pm, stevendaryl3...(a)yahoo.com (Daryl McCullough) >wrote: >> I have no idea why you think that passage supports your claim. >> Here's another article that explains what I was saying: >> >> http://www.iep.utm.edu/ancillaries/Proper-Time.htm >> >> "Proper time is also called clock time, or process time. >> It is a measure of the amount of physical process that a >> system undergoes. E.g. proper time for an ordinary mechanical >> clock is recorded by the number of rotations of the hands of >> the clock." >> >> As usual, you have no idea what you are talking about. > >The semantic operator is not functional in physics >(or any other branch of science) Whatever. You don't understand anything at all about physics, especially relativity. There is nothing *wrong* with that, most people don't understand technical topics in science. But most people are not as thoroughly dishonest as you are. They don't *pretend* to understand what they clearly don't understand. You are too lazy to actually learn what relativity says, and too arrogant to realize that that makes your opinions about it completely worthless. -- Daryl McCullough Ithaca, NY
From: kenseto on 29 Nov 2007 16:51 "Daryl McCullough" <stevendaryl3016(a)yahoo.com> wrote in message news:fimnjp0s6f(a)drn.newsguy.com... > Sue... says... > > >The page shows a young twin beside an old twin after > >one twin has traveled. > >Does one of the twins have a medical disorder or is the page > >it offering argument against the principle of relativity? > > One twin looks older because he is *older*. He has lived longer. > The "time" that is important for physical processes is not > coordinate time, but *proper* time. This would mean that you are comparing twin A's clock second directly with traveling twin B's clock second. Such comparison is not valid. In SR the passage of A's clock second corresponds to the passage of 1/gamma B clock second. Ken Seto > > ><< The general principle of relativity states that physical > >laws are the same in all reference frames -- inertial or non- > >inertial.>> > >http://en.wikipedia.org/wiki/Principle_of_relativity > > Yes, and what those laws say is that the amount of aging > of any twin is equal to the proper time since he is born, > where proper time is computed by: > > tau = integral of square-root(g_uv dx^u dx^v) > > -- > Daryl McCullough > Ithaca, NY >
From: colp on 29 Nov 2007 20:27 On Nov 29, 3:26 pm, "papar...(a)gmail.com" <papar...(a)gmail.com> wrote: > On 28 nov, 21:36, stevendaryl3...(a)yahoo.com (Daryl McCullough) wrote: > > > > > colp says... > > > >On Nov 29, 10:44 am, stevendaryl3...(a)yahoo.com (Daryl McCullough) > > >wrote: > > >> No, they aren't. The Wiki example, as you noticed, is about > > >> a case in which one of the twins remains *inertial*. In that > > >> case, you can talk about time dilation for that twin's inertial > > >> coordinate system. If *both* twins are accelerating, then you > > >> *can't* use the simple time dilation formula. > > > >The paradox does not rely on observations that are made from > > >accelerating frames. > > > If you calculate elapsed times using only *inertial* coordinates, > > then you don't get any contradictions. So you are completely > > wrong. > > > >The essential part of the paradox is that when the two twins are > > >travelling away from each other in inertial frames they expect to > > >receive fewer clock ticks than they send. > > > I don't care what they expect. The question is: what does > > Special Relativity predict? It predicts that in the > > symmetric case, the number of signals each twin receives > > from the other is the same. > > > -- > > Daryl McCullough > > Ithaca, NY > > My last effort in this subject. In the following web page (http://www.phys.unsw.edu.au/einsteinlight/jw/module4_twin_paradox.htm), there > is a good and detailed graphical explanation of the asymmetrical twin > paradox. As I see it, the crux of the argument is as follows (from the phys.unsw.edu.au page): "In order to create the twin paradox, one must assume that Jane has been in a single inertial frame throughout her out-and-back trip. As this assumption is false, there is no paradox." This argument is wrong because paradoxes are not limited to arguments based of observations made from only a single inertial frame. What seems to be the case is that whenever a set of observations are made from a single inertial frame no paradox will be evident. The problems arise when observers move between different inertial frames. According to SR Jane (the travelling twin of your example) observes the time dilation of any relativistically moving clock when she is in an intertial frame. That means that she observes the time dilation of Joe (the stay-at home twin) on both the outbound an return legs. In order to prevent a paradox she must at some time observe the time compression of Joe. The only time that this can occur is when she is accelerating or decellerating. Yet the standard explanations of the classic twin paradox don't quantify this. Your page argues that GR can be used to explain the effects of acceleration, yet the consesus reached earlier by this thread was that GR was not necessary to solve the paradox.
From: colp on 29 Nov 2007 20:51
On Nov 30, 3:28 am, stevendaryl3...(a)yahoo.com (Daryl McCullough) wrote: > colp says: > > > > > > >On Nov 29, 6:03 pm, Bryan Olson <fakeaddr...(a)nowhere.org> wrote: > >> colp wrote: > >> > Daryl McCullough wrote: > >> >> If you calculate elapsed times using only *inertial* coordinates, > >> >> then you don't get any contradictions. So you are completely > >> >> wrong. > > >> > The contradiction is as follows (the following points ar made with > >> > respect to the first twin's frame of reference): > > >> > A twin is travelling in an inertial frame, and observes the clock of > >> > the other twin, who is also in an inertial frame. > >> > SR predicts that time dilation of the other twin will be observed > >> > regardless of whether the other twin is approaching or retreating. > >> > When the twin gets to his turnaround point his proper time will be > >> > different to other twins apparent time when the other twin is at his > >> > respective turnaround point. > > >> Not so. In all frames, the clock traveling with A ticks the > >> same number of times before A turns around as B's local clock > >> ticks before B's turnaround. > > >The only way for that to happen is if B's clock does not appear to be > >dilated to A, and vice-versa. > > Colp, if you want to complain about what Special Relativity > says about the situation, you *MUST* understand what Special > Relativity says. You can't just make stuff up and then complain > that it doesn't make sense. What am I making up? SR says that time dilation is observed for a relativistically moving clock when the observer is in an inertial frame. That time dilation is observed regardless of whether the clock is moving closer or moving away. When A is moving away from B, A observes that B's time is dilated. When A is moving towards B, A observes that B's time is dilated. When A & B meet their clocks are the same. For their clocks to be the same time, A must have observed that B's time was compressed at some stage. SR does not describe time compression. Your descriptions of the events from the three frames appear to be self-consistent and I do not contest them. <snip descriptions> > In any *given* coordinate system, the facts are > perfectly consistent. But if you try to mix and > match facts from one coordinate system with facts > from another coordinate system, you get nonsense, > just as if you switched from using inches to using > centimeters in the middle of a calculation. That nonsense is the paradox that I am talking about. Facts from one coordinate system do get mixed and matched with facts from other coordinate systems. An example of the is clock synchronisation for GPS sattelites. |