The Symmetric Twin Paradox
in [Relativity]
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From: Inertial on 17 Jun 2010 19:24 "colp" <colp(a)solder.ath.cx> wrote in message news:bd7d4a85-d7b3-40e3-884c-720b9255f608(a)11g2000prv.googlegroups.com... > 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. So you just don't bother doing the math and just ASSUME that it isn't important and then wonder why you get stupid results Your fault.. not SR Get an education.
From: K_h on 17 Jun 2010 21:39 "Transfer Principle" <lwalke3(a)lausd.net> wrote in message news:bf6929a8-2236-4b82-a181-0b17fe7ebf30(a)s9g2000yqd.googlegroups.com... 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> > 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 problem for a closed universe. The answer depends on how mass and energy are distributed throughout the universe and how each twin moves relative to that matter and energy. Since the distribution of mass and energy cause the closure there is no problem with relativity. _
From: rotchm on 17 Jun 2010 22:08 > That is true, but don't forget they are not using SR Yes they are. Read the text carefully. > They are using Galilean transformations No, they are using SR and make the mistake to use V + V = 2V. Read the text carefully, especially the paragraphs above their V+V = 2V. The authors have admitted to that mistake.
From: colp on 17 Jun 2010 22:08 On Jun 18, 11:24 am, "Inertial" <relativ...(a)rest.com> wrote: > "colp" <c...(a)solder.ath.cx> wrote in message > > news:bd7d4a85-d7b3-40e3-884c-720b9255f608(a)11g2000prv.googlegroups.com... > > > > > 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. > > So you just don't bother doing the math and just ASSUME that it isn't > important and then wonder why you get stupid results Maths is consistent with logic. Your snipped my argument as to why the turnaround cannot logically compensate for the SR time dilation.
From: Cosmik de Bris on 17 Jun 2010 22:37
On 18/06/10 14:08 , rotchm wrote: > > >> That is true, but don't forget they are not using SR > > Yes they are. Read the text carefully. > >> They are using Galilean transformations > > No, they are using SR and make the mistake to use V + V = 2V. Read > the text carefully, especially the paragraphs above their V+V = 2V. > > The authors have admitted to that mistake. Oh yes I see what you mean. They then go on to a thought experiment and completely forget about using Lorentz transforms. I saw the Galilean transforms and assumed that it was the usual LET stuff, instead it is completely wrong. Cheers |