The Symmetric Twin Paradox
in [Relativity]
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From: Rich80105 on 16 Jun 2010 20:27 On Thu, 17 Jun 2010 00:16:21 +0100, "Androcles" <Headmaster(a)Hogwarts.physics_z> wrote: > >"Peter K" <peter(a)parcelvej.dk> wrote in message >news:4c194a22$1(a)news.xnet.co.nz... >| "Androcles" <Headmaster(a)Hogwarts.physics_z> wrote in message >| news:jKbSn.51002$y%5.50212(a)hurricane... >| > >| > "Peter K" <peter(a)parcelvej.dk> wrote in message >| > news:4c194121$1(a)news.xnet.co.nz... >| > | "colp" <colp(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. So give an alternative url.
From: eric gisse on 16 Jun 2010 20:31 colp wrote: [...] > Your proposal does not test the paradox [...] "I do not understand" is not a paradox, it is a condition.
From: Peter K on 16 Jun 2010 20:40 "Androcles" <Headmaster(a)Hogwarts.physics_z> wrote in message news:mcdSn.101410$Ny7.76954(a)hurricane... > > "Peter K" <peter(a)parcelvej.dk> wrote in message > news:4c194a22$1(a)news.xnet.co.nz... > | "Androcles" <Headmaster(a)Hogwarts.physics_z> wrote in message > | news:jKbSn.51002$y%5.50212(a)hurricane... > | > > | > "Peter K" <peter(a)parcelvej.dk> wrote in message > | > news:4c194121$1(a)news.xnet.co.nz... > | > | "colp" <colp(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. Fair enough, and I do agree one must be careful. I for one can't judge if the wikipedia article you yourself linked to, or the one I linked to is "most correct" or relevant.
From: train on 16 Jun 2010 20:50 On Jun 17, 5:22 am, "Androcles" <Headmas...(a)Hogwarts.physics_z> wrote: > "Peter K" <pe...(a)parcelvej.dk> wrote in message > > news:4c19 SNIP stuff that will make this too long > | >> was that? > | > > | > Your proposal does not test the paradox because the paradox involves > | > observations of time dilation of non-local frames of reference. Your > | > watches only record the passage of time for their own local frame of > | > reference. > | > | Oh. But when they get back can't I see what they measured? Then I've at > | least observed the effects on a "non local frame of reference". > | > | Otherwise, could we get the watches to continually send small signals back > | to me when the travel? The could send a "tick" and a "tock" for each of > | their seconds - and I could compare them to the "ticks" and "tocks" on a > | third watch I'm holding. Would that work? > | > A devout relativist will argue black is white in support of his religion. I have brought this up before, in my opinion this is where SRT contradicts itself, but never mind- 1. If the twins start off at rest, in space, accelerate for 10 seconds, and fly apart Twin A is seen to be aging faster than B and twin B is seen to be aging faster than A, in the age of live video transmissions, then, if A and B transmit a video of themselves to each other what will they see? 2. If both of the twins constantly writes on a piece of paper - "my twin, I see, is aging slower than myself" and they are brought back together again, what will each piece of paper show? 3.If there is an outward and inward journey consisting of acceleration, constant velocity, acceleration in the opposite direction, and constant velocity followed by the final constant acceleration to bring the twin spaceships together again, does the `slow aging of the other twin` take place throughout the journey or is there an unknown effect during the acceleration? Isn` t this unknown effect the same value in each case and leave us to calculate only the time dilation due to velocity? 4. An astronaut in space holds two atomic clocks in each hand, close to each other, all synchronized when stationary using any method you want. He suddenly draws them apart, stretching his arms and brings them back together again. Do the atomic clocks agree? Do they agree with the clock fixed to his helmet? Has anyone thought of this before ? :)
From: Transfer Principle on 16 Jun 2010 21:16
On Jun 16, 12:21 am, Koobee Wublee <koobee.wub...(a)gmail.com> wrote: > On Jun 15, 11:25 pm, colp <c...(a)solder.ath.cx> wrote: > > In the symmetric twin paradox both twins leave Earth, > > setting out in opposite directions and returning to Earth at the same > > time. > Thanks, yours truly has brought this up earlier. <shrug> I usually don't post in these anti-Einstein threads, especially as they are crossposted to sci.math as well as the physics newsgroups. 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...) Note that my posting in this thread does _not_ mean that I necessarily oppose Einstein, any more than my posting in one of AP's Atom Totality threads means that I am necessarily an Atom Totalitarian. |