The real twin paradox.
in [Relativity]
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From: Sue... on 2 Dec 2007 09:14 On Dec 2, 8:44 am, "papar...(a)gmail.com" <papar...(a)gmail.com> wrote: > On 2 dic, 03:59, "Sue..." <suzysewns...(a)yahoo.com.au> wrote: > > > > > > > On Dec 1, 9:12 pm, "papar...(a)gmail.com" <papar...(a)gmail.com> wrote: > > > > None of the twins can (realistically) see anything from the other twin > > > but the signals he receives. This is a really problem of communication > > > of information. That is the reason why a geometric view helps to see > > > what is going on. That is the reason why using a third twin, who stays > > > at Earth, eases the drawings and understanding of the problem (any > > > frame of reference can be used with the same results but using the > > > Earth frame helps). From the graphic representation, one can see that > > > each travelling twin experiences time dilation, with respect to the > > > Earth frame, both in the outward and inward legs of the trip, the > > > effect being caused by them moving at relativistic speeds. Information > > > received by one of the twins from the other two, is clearly dependent > > > on whether his ship is going outward (and so the signals take a longer > > > time to reach him) or coming inward (where signals take less time to > > > reach him). Final result: both travelling twins arrive back to Earth > > > having experienced the same length of time (according to their local > > > clocks), but during the trip they "saw" the signals coming from the > > > other twin doing strange changes of rates (very slow in the first part > > > of the trip, then quite normal in the middle part and, finally, quite > > > fast in the last part. Those observations say nothing with respect to > > > the time dilation experienced (as it has been pointed out they will > > > notice nothing peculiar in their voyages), which finally manifest > > > itself when both twins compare their clocks with the third twin who > > > remained at Earth, observing that they are indeed younger. > > > This is a violation of the Principle of Relativity. > > > > Acceleration is not really relevant in this problem, as long as the > > > acceleration period is small with respect to the inertial period (just > > > a little bit over a couple of years of acceleration at 1 g will take > > > the ship to near 0.99c, or shorter if larger g's are used). > > > If the Twins agree on the number of orbits made by Jupiter's > > moons, you have quite an argument in the field of biology > > if you want to say the twins hair length should differ > > because of their relative motion. > > > Sue... > > Because the orbits made by Jupiter's moons are also by all means > "information", and that information firstly, can be considered to be > sent from an inertial system No... the information from the Jovian system has no definite relation to emitter or absorber. It moves at the speed of light with respect to the free-space dielectric. <<A Lorentz transformation or any other coordinate transformation will convert electric or magnetic fields into mixtures of electric and magnetic fields, but no transformation mixes them with the gravitational field. >> http://www.aip.org/pt/vol-58/iss-11/p31.html If there is the *appearance* of some relation, between light and inertia it is because the Jovian system holds the dielectric in its gravitational field. http://en.wikipedia.org/wiki/Free_space http://www-ssg.sr.unh.edu/ism/what.html > (like Earth) and, secondly, takes a long > time to arrive to the travelling twins (if they can received it at > all), then it is obvious that the rate of changing of that information > will be observed sometimes slow, sometimes equal and sometimes faster > than the actual number (or ticks), as the graphical representation > puts in evidence if you take the time to do it. You were also invited to take the time to understand the mathmatical problems with that sort of graph. http://arxiv.org/abs/physics/0606233 Thus far Bz has advanced the best argumenent but I have doubts nationality and alam mater really fits well in scientific investigation. > It is also evident > that, at the end of the voyage, the number of orbits as counted by all > the twins will be the same. However, the travelling twins will notice > that (using numbers from my example) while to the Earth twin there > were N orbits in 20 years (measured by his local clock), for the > travelling twins there were N orbits in 16 years (measured by their > local clocks). So you are saying the hair length disagrees and the counted Jovian orbits disagree? Is there any part of relativity that your scenario does not destroy? Sue... > > Miguel Rios- Hide quoted text - > > - Show quoted text -
From: Dono on 2 Dec 2007 09:50 On Dec 1, 11:15 pm, colp <c...(a)solder.ath.cx> wrote: http://michelemiller.blogs.com/photos/uncategorized/dumb_people_jpeg.jpg
From: Bryan Olson on 2 Dec 2007 10:08 colp wrote: > papar wrote: >> None of the twins can (realistically) see anything from the other twin >> but the signals he receives. > > These signals can be described as clock ticks. According to SR, while > the twins are in inertial frames the ticks that are sent by the other > twin will be sent at a slower rate than the ticks that are sent from > the twin's local clock. > > It doesn't matter how long it takes for the tick signals to get from > one twin to another. All that matters is that the rate that the ticks > are generated by the other twin is slower becuase of the time dilation > while they are in inertial frames. In SR, a twin's observation of the other's clock ticking slowly is based on "how long it takes for the tick signals to get from one twin to another." Twin A sees the ticks arrive, and figures how long ago each B, traveling at c in A's frame. > Every signal than is sent must be > received by the other twin in the experiment. Sure. Early in twin A's voyage, the ticks from B arrive very slowly, even slower than B's clock is running in A's frame. Just after turnaround, A receives one of B's ticks per tick of A's own clock, because the ticks were sent in the same frame in which A now resides. Late in the journey, the ticks from B arrive faster than one per tick of A's clock. Twin A views B's time as dilated, in both directions, but that's after compensating for the transit time of the clock ticks. > The paradox isn't apparent when the events are viewed from a single > inertial frame. Minkowski diagrams represent events according to such > a frame. This "paradox" is only apparent if one misunderstands SR. [...] > The importance of acceleration is that it is the only situation where > a twin might be able to experience an effect which compensates for > the time dilation of the other twin. What is important is the change in frames at turn-around. In reality changing frames requires some acceleration period, but we can model the turn-around as instantaneous, as long as we account for the net difference between the two frames. Consider a tick arriving at twin A, at A's turn-around time. How long ago did it leave twin B? That depends on which frame we use. In A's outgoing frame, light moves at c relative to A's outgoing frame, and the tick left fairly recently. In A's returning frame, light moves at c relative A's returning frame, so the tick left long ago. The result is that A finds B's age has jumped forward. When I was baffled by the twin's paradox (the real one in which twins end up different ages), here's the explanation that helped me get SR: http://www.bartleby.com/173/9.html -- --Bryan
From: bz on 2 Dec 2007 13:48 "Sue..." <suzysewnshow(a)yahoo.com.au> wrote in news:6bad4ee2-091c-4c19-baa3- ba76f89afa02(a)e10g2000prf.googlegroups.com: > On Nov 30, 7:29 pm, bz <bz+...(a)ch100-5.chem.lsu.edu> wrote: > > [...] > BTW... There is a recent, well informed post on sci.physics.research > that discusses some of the causes of errors in the GPS. > > I realise you would take the opposite view but it left me > no confidence that the 7us/day correction can be attributed > to predicted motional effects wrt earth. Even if a science > quality geostationary oscillator was avalible as we discussed > it might take a Ouji board to pull the signal out of the > system's phase noise. > Put pencil to paper before you make such silly statements. Due to the speed of light, a 7 us / day represents an error of ~ 2.099 km / day in apparent satellite location. The ACTUAL satellite location (it travels at about 3.47 km/s) would only be off by about 1 inch but it be saying it was 2 km away from its actual location. Somehow, I suspect that a 2 km per day error in satellite position [or a 7 us error in the time it reports] would be noticeable. > > Where is Tom Roberts with his error bars when ya need him? ;-) > > The Sagnac interferometer at Wettzell > http://www.wettzell.ifag.de/LKREISEL/G/LaserGyros.html A 2 km displacement of the earths crust would probably be noticable with instruments a LOT less sensitive that this. > is now integrated with GPS so might be a good source of > data to settle that sort of issue without need for a dedicated > SV or heaven-forbid you and I have to take your 100Khz crystal > calibrator up there ourselves and show 'em how it's done. ;-) I would love to make the trip. I'll buy the crystals, you rent the rocket from the russians, ok? They should give you a special price because you like their physics. -- bz please pardon my infinite ignorance, the set-of-things-I-do-not-know is an infinite set. bz+spr(a)ch100-5.chem.lsu.edu remove ch100-5 to avoid spam trap
From: Sue... on 2 Dec 2007 14:19
On Dec 2, 1:48 pm, bz <bz+...(a)ch100-5.chem.lsu.edu> wrote: > "Sue..." <suzysewns...(a)yahoo.com.au> wrote in news:6bad4ee2-091c-4c19-baa3- > ba76f89af...(a)e10g2000prf.googlegroups.com: > > > On Nov 30, 7:29 pm, bz <bz+...(a)ch100-5.chem.lsu.edu> wrote: > > > [...] > > BTW... There is a recent, well informed post on sci.physics.research > > that discusses some of the causes of errors in the GPS. > > > I realise you would take the opposite view but it left me > > no confidence that the 7us/day correction can be attributed > > to predicted motional effects wrt earth. Even if a science > > quality geostationary oscillator was avalible as we discussed > > it might take a Ouji board to pull the signal out of the > > system's phase noise. > > Put pencil to paper before you make such silly statements. My pencil isn't that sharp. > > Due to the speed of light, a 7 us / day represents an error of ~ 2.099 km / > day in apparent satellite location. OK thanks for the calc. Well... maybe it wouldn't take a Ouji board with the geostationary control. > > The ACTUAL satellite location (it travels at about 3.47 km/s) would only be > off by about 1 inch but it be saying it was 2 km away from its actual > location. > > Somehow, I suspect that a 2 km per day error in satellite position [or a 7 > us error in the time it reports] would be noticeable. > > I think it is all lumped into the pre-launch correction and servo'd thereafter. > > > Where is Tom Roberts with his error bars when ya need him? ;-) > > > The Sagnac interferometer at Wettzell > >http://www.wettzell.ifag.de/LKREISEL/G/LaserGyros.html > > A 2 km displacement of the earths crust would probably be noticable with > instruments a LOT less sensitive that this. > > > is now integrated with GPS so might be a good source of > > data to settle that sort of issue without need for a dedicated > > SV or heaven-forbid you and I have to take your 100Khz crystal > > calibrator up there ourselves and show 'em how it's done. ;-) > > I would love to make the trip. I'll buy the crystals, you rent the rocket > from the russians, ok? They should give you a special price because you > like their physics. 'Till DVM makes good on gambling debts this is all I can afford: <<Incredible Adventures makes it possible for you to break the sound barrier and more in a real military jet fighter. >> http://www.incredible-adventures.com/migs/ Ya think that will make it? :o) Sue... > > -- > bz |