The real twin paradox.
in [Relativity]
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From: harry on 23 Nov 2007 02:24 "colp" <colp(a)solder.ath.cx> wrote in message news:d44fb984-12e6-4a0d-8af1-3990ae9789e8(a)s8g2000prg.googlegroups.com... > On Nov 22, 11:16 pm, "harry" <harald.vanlintelButNotT...(a)epfl.ch> > wrote: >> "colp" <c...(a)solder.ath.cx> wrote in message >> >> news:45e50819-65f6-46a3-a821-5c3698dd146a(a)p69g2000hsa.googlegroups.com... >> >> >> >> > On Nov 21, 11:40 pm, "Dirk Van de moortel" <dirkvandemoor...(a)ThankS-NO- >> > SperM.hotmail.com> wrote: >> >> "colp" <c...(a)solder.ath.cx> wrote in >> >> messagenews:06b84031-18aa-4644-bfb7-43f49f46ae6a(a)i37g2000hsd.googlegroups.com... >> >> > This thought experiment is like the classic twin paradox, but in >> >> > this >> >> > expirement both twins leave earth and travel symmetric return trips >> >> > in >> >> > opposite directions. >> >> >> > Since the paths taken by the twins in this experiment are symmetric, >> >> > they must be the same age when they meet on their return to earth. >> >> >> > In this experiment the twins maintain constant observation of each >> >> > other's clocks, from when they depart until they return and find >> >> > that >> >> > their clocks tell the same time. >> >> >> > Special relativity says that each twin must observe that the other's >> >> > clock is running slow, and at no time does special relativity allow >> >> > for an observation which shows that the other clock is running fast. >> >> >> No, special relativity says much more precise than that >> >> "moving clocks" are running slow. >> >> > The Lorentz-Fitzgerald transform is more precise that my description, >> > but that doesn't mean that my description is wrong. >> >> >> It says something about intertial observers who measure >> >> times between ticks on remote, moving clocks. >> >> >> When your two clocks fly apart, each clock will measure >> >> this time to be longer and conclude that the other clock >> >> is "running slower". >> >> While clock A is coasting, according to clock A, each >> >> tick on clock A is simultaneous with some tick on clock B >> >> with a smaller time value. >> >> While clock B is coasting, according to clock B, each >> >> tick on clock B is simultaneous with some tick on clock A >> >> with a smaller time value. >> >> > Yes, that is the standard theory. >> >> >> After clock A has made its turnaround, it has shifted to >> >> another inertial frame, in which according to clock A, each >> >> tick on clock A is simultaneous with some tick on clock B >> >> with a larger time value. >> >> After clock B has made its turnaround, it has shifted to >> >> another inertial frame, in which according to clock B, each >> >> tick on clock B is simultaneous with some tick on clock A >> >> with a larger time value. >> >> > Wrong. The other clock tick is still observed to have a smaller time >> > value. >> > This is because in the Lorentz-Fitzgerald transform the relative >> > velocity term is squared, making the the issue of the clocks >> > separating vs the clocks approaching irrelevant to the amount of time >> > dilation. >> >> >http://en.wikipedia.org/wiki/Time_dilation >> >> That is indeed irrelevant but you are still mistaken because time >> dilation >> is ALSO irrelevant at the instant of switching reference frames. > > Straw man. Time dilation requires a finite amount of time to be > observable, so time dilation is not observable at the instant of > switching reference frames. You SNIPPED the explanation that TIME DILATION IS ALSO IRRELEVANT. Therefore, probably you're too stubborn too listen. Too bad. Harald
From: harry on 23 Nov 2007 02:27 "colp" <colp(a)solder.ath.cx> wrote in message news:3b9b6646-038c-47ff-94e1-f804966c2e47(a)d4g2000prg.googlegroups.com... > On Nov 23, 3:18 am, "harry" <harald.vanlintelButNotT...(a)epfl.ch> > wrote: >> "colp" <c...(a)solder.ath.cx> wrote in message >> >> news:43e6b051-fef5-444c-a97c-2f5500b8ca1e(a)b40g2000prf.googlegroups.com... >> >> > On Nov 22, 5:48 am, "Josef Matz" <josefm...(a)arcor.de> wrote: >> > <snip> >> >> Hello Dirk >> >> >> If you could mathematically demonstrate that the time delays of the >> >> symmetric clock A as viewed by B can be >> >> compensated somehow you have solved the paradox ! >> >> >> Would you tell us idiots how this runs in SR ? >> >> > A solution could include an argument from general relativity as well, >> > since the twins must spend time in non-inertial frames in order to >> > accelearate/decelerate and turn around. I don't think it would solve >> > the paradox though because the dilation effects can be increased >> > arbitrarily by extending the amount of time spent in inertial frames. >> >> http://math.ucr.edu/home/baez/physics/Relativity/SR/TwinParadox/twin_... >> >> http://en.wikipedia.org/wiki/Twin_paradox >> > > Those arguments depend on the asymmetry of the original thought > experiment. Since asymmetry is absent in the thought experiment > descriped in the OP, they do not solve the paradox described in this > thread. The OP is you, right? Anyway, it doesn't matter much: the same calculations apply only in the symmetrical case the result is that both clocks indicate the same (of course). Harald
From: colp on 23 Nov 2007 02:40 On Nov 23, 6:22 pm, bz <bz+...(a)ch100-5.chem.lsu.edu> wrote: > colp <c...(a)solder.ath.cx> wrote innews:f92c81d1-fbb0-47e3-8303-d4ce14366ebe(a)i12g2000prf.googlegroups.com: > > > On Nov 23, 3:50 pm, bz <bz+...(a)ch100-5.chem.lsu.edu> wrote: > >> colp <c...(a)solder.ath.cx> wrote > >> innews:eeaf80ee-faa5-489c-8a82-7f8224e631eb(a)b40g2000prf.googlegroups.com > >> : > > <snip> > >> > SR says that they won't read the same from the frame of reference of > >> > one of the twins. > > >> SR says that they do not read the same until the twins are reunited. > > > SR cannot explain the discontinuity between the clocks showing > > progressively different times and the clocks showing the same time at > > the end of the experiment. > > You are making a false assumption. You assume that they see each others > clocks as ticking slow, even when they approach each other. > In order to do that, they would need some faster than light communications > method so they could see what the other clock actually said. That isn't a false assumption. To consider the effect of signal propagation times makes the argument more complicated, but it doesn't change the element of time dilation which is the essence of the paradox. > But they have to depend on signals that travel at the speed of light. > Remember the Doppler shift I mentioned earlier? It effects the timing of > the time signals also. Yes, but the cumulative effect is nil. > As they head toward each other, they see the other persons clock ticking > FASTER than theirs is ticking. > As they get closer together, it takes less and less time for the clock > signals to travel the distance between ships > > If you work through the math, you find that as they come toward each other, > they see each others clocks running fast. > The clocks 'catch up', converging upon the same 'correct' reading as they > land. The apparent clock speedup due to the decreasing relative distance on the return leg is equal to the apparent clock slowing due to increasing relative distance on the outbound leg. > > Of course it will NOT be the same as their stay-at-home sisters clock. Her > clock will have accumulated more time than either of theirs. The paradox that I am talking about is desribed in the opening post. It does not have a stay-at-home clock.
From: Sue... on 23 Nov 2007 02:42 On Nov 22, 9:38 pm, colp <c...(a)solder.ath.cx> wrote: > On Nov 23, 1:53 pm, "Sue..." <suzysewns...(a)yahoo.com.au> wrote: > > > On Nov 22, 7:20 pm, Bryan Olson <fakeaddr...(a)nowhere.org> wrote: > <snip> > > > > When my own trials of thought experiments yield > > > conflicting outcomes, as they often do, I have to ask > > > myself: Did I just refute the work of all those > > > scientists and mathematicians, or did I think I knew > > > more than I did? Turns out one of those possibilities > > > is quite a bit more likely than the other. > > > Perhaps you should compare the 1905 paper used > > by proponents of the twins myth with the 1920 > > paper which only couples to inertia by mass > > energy equivalence. > > If there is one thing that science doesn't like, it is having to say > that it can't explain the phenomena. Most of the experiments used to support the twin's myth barely qualify as science. http://en.wikipedia.org/wiki/Problematic_physics_experiments We don't have a photo of a wrinkley grey headed twin comparing his watch with his smooth skined fair haired sibling. Clocks can't *measure* time. They mark or simulate time's passages with some reference process. Because certain symmetries are the foundation of canonical physics we find a statement about time must also include a statement about energy. Both SR and GR run a bit wild in this regard. << invariance with respect to time translation gives the well known law of conservation of energy >> http://en.wikipedia.org/wiki/Noether's_theorem There is little doubt an atomic clock will run slower on Jupiter's surface than on earth's surface. You can draw you own conclusions about the life expectancy of the chap in this photo experiencing similar conditions. http://www.viewimages.com/Search.aspx?mid=2696350&epmid=1&partner=Google Once an experiment is published, the whole world is free to interpret it in any way they please and the most sensational interpretations will always the most exposure. Much of the confusion with SR stems from the student's inability to understand the limitiations of point source and wave models. http://nobelprize.org/physics/articles/ekspong/index.html Feynman artfully takes the best of each model and completely avoids the problem keeping most of the model in the Coulomb gauge. [2] http://en.wikipedia.org/wiki/Path_integral_formulation General relativty has its problems with time and energy too: << In general relativity, on the other hand, it has no meaning to speak of a definite localization of energy. One may define a quantity which is divergence free analogous to the energy-momentum density tensor of special relativity, but it is gauge dependent: i.e., it is not covariant under general coordinate transformations. Consequently the fact that it is divergence free does not yield a meaningful law of local energy conservation. Thus one has, as Hilbert saw it, in such theories `improper energy theorems.' >> http://www.physics.ucla.edu/~cwp/articles/noether.asg/noether.html [1] When Special Relativity is scaled back to the statement of the 1920 paper: << in reality there is not the least incompatibility between the principle of relativity and the law of propagation of light, >> http://www.bartleby.com/173/7.html ....there is no problem either mathematical or conflict with Maxwell's equations. Time-independent Maxwell equations Time-dependent Maxwell's equations Relativity and electromagnetism http://farside.ph.utexas.edu/teaching/em/lectures/lectures.html Maxwell's equations in classic electrodynamics (classic field theory)_ a) Maxwell equations (no movement), b) Maxwell equations (with moved bodies) http://www.wolfram-stanek.de/maxwell_equations.htm#maxwell_classic_extended http://en.wikipedia.org/wiki/Near_and_far_field Since causality demands that both twins have to agree on the number of orbits Jupiter's moons make during the experiment, it is rather absurd to claim one lived longer than the other. (Historical note) http://www.astrosociety.org/pubs/mercury/31_03/jupiter.html Sue... [1] This URL seems to honour any and all holidays http://www.physics.ucla.edu/~cwp/articles/noether.asg/noether.html "Google cache" http://209.85.165.104/search?q=cache:qYoxDxDuvD0J:www.physics.ucla.edu/~cwp/articles/noether.asg/noether.html+noether+hilbert+assertion&hl=en&ct=clnk&cd=1&gl=us [2] http://en.wikipedia.org/wiki/Gauge_fixing http://arxiv.org/abs/physics/0204034
From: colp on 23 Nov 2007 02:48
On Nov 23, 5:22 pm, Dono <sa...(a)comcast.net> wrote: > On Nov 21, 8:37 am, colp <c...(a)solder.ath.cx> wrote: > > > Wrong. The other clock tick is still observed to have a smaller time > > value. > > This is because in the Lorentz-Fitzgerald transform the relative > > velocity term is squared, making the the issue of the clocks > > separating vs the clocks approaching irrelevant to the amount of time > > dilation. > > >http://en.wikipedia.org/wiki/Time_dilation > > Bzzzt, wrong. Try reading this: > > http://en.wikipedia.org/wiki/Twin_paradox#Accelerated_rocket_calculation The opening post describes the scenario that I an arguing about. |