The Symmetric Twin Paradox
in [Relativity]
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From: xxein on 18 Jun 2010 20:08 On Jun 16, 7:16 pm, "Androcles" <Headmas...(a)Hogwarts.physics_z> wrote: > "Peter K" <pe...(a)parcelvej.dk> wrote in message > > news:4c194a22$1(a)news.xnet.co.nz...| "Androcles" <Headmas...(a)Hogwarts.physics_z> wrote in message > > |news:jKbSn.51002$y%5.50212(a)hurricane... > | > > | > "Peter K" <pe...(a)parcelvej.dk> wrote in message > | >news:4c194121$1(a)news.xnet.co.nz... > | > | "colp" <c...(a)solder.ath.cx> wrote in message > | > | > | >news:267c724a-a11c-4cfe-ae6d-b5b9395cf382(a)a39g2000prb.googlegroups.com.... > | > | > 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. > | > | > > | > | > 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." > | > | > | > | The only way to check this, is to send a couple of watches out on a > | > | journey - say one to paris and back, and one to New York and back. > Then > | > when > | > | they get back to NZ we can check the time on each of them! Sheesh, how > | > hard > | > | was that? > | > > | > Even easier, GPS satellites orbit the Earth in 12 hours. Ask any of them > | > the > | > time > | > whenever you feel like it, they'll all visit NY and come back to NZ > | > eventually, > | > none ever show any time dilation and they've been travelling for years > | > now. > | > http://en.wikipedia.org/wiki/Satellite_constellation > | > | Hi - interesting comment. According to another wikipedia link, there ARE > | time dilation effects seen in GPS satellites, and other relativistic > effects > | as well! Who to believe? > | > | See this for example, under the "Relativity" section: > |http://en.wikipedia.org/wiki/GPS > > I refuse to consider any article in Wackypedia (the encyclopaedia anyone > can write) written by usenet bigots previously defeated here. They just > want a wider audience for their ignorant preaching. xxein: But you cite articles in Wiki without any understanding of what you cite.
From: xxein on 18 Jun 2010 20:29 On Jun 17, 10:14 am, stevendaryl3...(a)yahoo.com (Daryl McCullough) wrote: > colp says... > > >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. > > This is only a paradox to those incompetent at mathematics. Let's > look at an analogous "paradox" in Euclidean geometry: > > You have two cities, Startville and Endville. Endville lies 1000 miles > due west of Startville. There are two different routes to get from > Startville to Endville: One route goes straight west for 1000 miles. > The other route starts off traveling northwest then at the halfway > point turns to travel southwest the rest of the way. > > From the point of view of a traveler following the straight path, > the bent path looks longer: it travels away to the north for a > while, and then it travels south for a while, and the total length > is given by the Pythagorean theorem. > > From the point of view of a traveler following the bent path, > it might seem that it is the *first* traveler who travels away > to the *south* for the first half of the trip, and then travels > to the *north* for the second half of the trip. So is it right > for the second traveler to claim that the *other* traveler is > following the bent path? Clearly no. > > In Euclidean geometry there is a "relativity" of directions. > You pick any direction you like and call it your coordinate > axis. There is nothing special about traveling west: you can > let your axis travel to the northwest just as well. > > But there is *no* relativity when it comes to bent paths > versus straight paths. All observers, regardless of how > they set up their coordinate systems, can tell the difference > between a straight path and a bent path. > > In SR, the analogy of "straight path" is "unaccelerated path" > and the analogy of "bent path" is "accelerated path". Whether > an observer is at rest or not is a matter of relativity, but > whether an observer is accelerated or not is not relative: > all observers agree about who it is that accelerates. > > -- > Daryl McCullough > Ithaca, NY xxein: You drank a different Kool-Aide?
From: Daryl McCullough on 18 Jun 2010 20:55 colp says... > >On Jun 18, 4:18=A0pm, stevendaryl3...(a)yahoo.com (Daryl McCullough) >wrote: >> There is no paradox here! > >The paradox is that SR predicts that each twin will be younger than >the other at the completion of the experiment. No, it doesn't. The prediction of relativity is that for a clock traveling at speed v for a time t, the elapsed time on that clock is given by: T = square-root(1-(v/c)^2) t where v and t are measured relative to any *inertial* coordinate system. Show me how to get from there to the prediction that "each twin will be younger than the other at the completion of the experiment". >It is the case because the two different ways to calculate the age of >the other twin are apparent from the experiment. No, there isn't. You can use any inertial frame you like to calculate the age of either twin at the end of the trip, and you will get the same answer. >One way is to >determine if Taurai will be older than Taurwi by evaluating the >predictions of SR from Taurai's frame of reference, and the other way >is to determine if Taurai will be older than Taurwi by evaluating the >predictions of SR from Taurwi's frame of reference. As I said, you can use any inertial coordinate system you like to compute the ages, and you will get the *same* answer. There is no paradox. Do the calculation! -- Daryl McCullough Ithaca, NY
From: Dono. on 18 Jun 2010 21:06 On Jun 18, 5:55 pm, stevendaryl3...(a)yahoo.com (Daryl McCullough) wrote: > > Do the calculation! > > -- > Daryl McCullough > Ithaca, NY It's not going to happen, you and PD have been conversing with the Australian fake idiot (who has changed his tactics).
From: Peter Webb on 18 Jun 2010 21:16
"Koobee Wublee" <koobee.wublee(a)gmail.com> wrote in message news:d2a227db-259a-41ab-9999-1baecf366c6e(a)u20g2000pru.googlegroups.com... On Jun 18, 8:45 am, Tom Roberts wrote: > In this case, the usual "twin paradox" has been implemented > experimentally, and > the result is as predicted by SR. The "symmetric twin paradox" has not > been > implemented experimentally AFAIK, These two statements contradict each other. You are saying the twins� paradox is already and is not yet resolved by experiment(s) at the same time. Correct me if I am wrong. ________________________________ You are wrong. The Twins paradox has been tested by experiments on numerous occassions. In fact, you have been provided with the experimental evidence, and in a previous post you have agreed that moving objects experience time dilation exactly as predicted by SR. So given that you agree that the time dilation is real - and you agree it has been confirmed by numerous experiments - what is your problem, exactly? Are there *any* experimental predictions of SR that you believe to be wrong? What are they? |