The real twin paradox.
in [Relativity]
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From: bz on 21 Nov 2007 13:29 "Sue..." <suzysewnshow(a)yahoo.com.au> wrote in news:a99fa604-6121-47d8-96a8-90c3c19d2e8d(a)l1g2000hsa.googlegroups.com: > normal clocks that are not responsive to motion > through a dielectric shouldn't change rate. I tried to buy a 'normal clock' at the clock store but they told me they are no longer made. They used to be made in Newton's days, but now EVERYTHING that is made of charged particles responds to motion through space, which is a dielectric medium. Maxwell managed to change the laws of physics with his equations. And the neutronium clocks are too heavy to carry around. So, let me borrow your 'normal clock' pleeeeze. I will gladly return it just as soon as my twin brings it back from his trip to the Andromeda Galaxy. -- 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: colp on 21 Nov 2007 16:14 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 fact that the Lorentz-Fitzgerald transforms are more precise that my description does not make my description incorrect. > > 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. O.K. That's 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 fact that the clocks now approach each other does not change the fact that time dilation is still observed. This is because the term for relative velocity is squared, making the relative direction unimportant. http://en.wikipedia.org/wiki/Time_dilation The only compensation for the time dilation occurs in the non-inertial frames, but the paradox will still occur for sufficiently long durations of the inertial frames.
From: Sue... on 21 Nov 2007 16:48 On Nov 21, 1:29 pm, bz <bz+...(a)ch100-5.chem.lsu.edu> wrote: > "Sue..." <suzysewns...(a)yahoo.com.au> wrote innews:a99fa604-6121-47d8-96a8-90c3c19d2e8d(a)l1g2000hsa.googlegroups.com: > > > normal clocks that are not responsive to motion > > through a dielectric shouldn't change rate. > > I tried to buy a 'normal clock' at the clock store but they told me they > are no longer made. They used to be made in Newton's days, but now > EVERYTHING that is made of charged particles responds to motion through > space, which is a dielectric medium. Maxwell managed to change the laws of > physics with his equations. Did you try to buy a light-clock specifically designed to respond to motion through media? If the clock store had one I think you would find most of the clocks you have are "normal" when you blow hydrogen gas at a significant fraction of c toward or past their cases. The gas moving between the light-clock's mirrors will cause it to slow however. > > And the neutronium clocks are too heavy to carry around. > > So, let me borrow your 'normal clock' pleeeeze. I will gladly return it > just as soon as my twin brings it back from his trip to the Andromeda > Galaxy. "normal" clocks are usually inertial mechanisms. Are you disputing this statement with your suggestion that a light-clock should behave the same way as an inertial clock ? <<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 you can, then you will be demonstrating that General Relativity is unnecessay and you'll have some evidence of an inertial ether to support your argument. > > And the neutronium clocks are too heavy to carry around. > > So, let me borrow your 'normal clock' pleeeeze. I will gladly return it > just as soon as my twin brings it back from his trip to the Andromeda > Galaxy. I'll trade you a normal clock for a light-clock. You might get a good deal on this one but you'll have to supply your own launch vehicle and figure out how to expose it to moving ism. http://funphysics.jpl.nasa.gov/technical/grp/sumo.html Sue... > > -- > bz >
From: bz on 21 Nov 2007 15:39 colp <colp(a)solder.ath.cx> wrote in 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.googlegroup >> s.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 I think you forgot that the observation of the others clock must take place via some signal that travels at c. Perhaps each clock digitally encodes the date and time and transmits it by radio, every second. This is cheaper than having an infinite set of observers for each inertial frame of reference so that the clocks can be checked by a nearby observer co-moving with the other ships frame of reference. In any case, While traveling away from each other the signals from the other ship are Doppler shifted downward in frequency and the time hacks come further apart than once per second. When traveling toward each other, the signal from the other ship is doppler shifted upward in frequency and the time ticks arrive faster than once per second. Once you correct for doppler shift (you do know the other ships tranmit frequency), you can correct the times and know that the other ships clock is ticking at the same rate as yours. -- 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: colp on 21 Nov 2007 18:48
On Nov 22, 9:39 am, bz <bz+...(a)ch100-5.chem.lsu.edu> wrote: > colp <c...(a)solder.ath.cx> wrote innews: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.googlegroup > >> s.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 > > I think you forgot that the observation of the others clock must take > place via some signal that travels at c. I didn't forget. The issue isn't critical in regard to the paradox, that's all. > Perhaps each clock digitally > encodes the date and time and transmits it by radio, every second. This is > cheaper than having an infinite set of observers for each inertial frame > of reference so that the clocks can be checked by a nearby observer > co-moving with the other ships frame of reference. O.K. > > In any case, While traveling away from each other the signals from the > other ship are Doppler shifted downward in frequency and the time hacks > come further apart than once per second. When traveling toward each other, > the signal from the other ship is doppler shifted upward in frequency and > the time ticks arrive faster than once per second. Technically I think it's called red & blue shift rather than doppler, which refers to sound rather electromatic radiation. > > Once you correct for doppler shift (you do know the other ships tranmit > frequency), you can correct the times and know that the other ships clock > is ticking at the same rate as yours. Redshift/blueshift shift would be a real issue, but it is a different one to Lorentz-Fitzgerald time dilation. Redshift/blueshift is proportional to relative velocity, but time dilation has a non-linear relationship to the absolute value of the relative velocity. http://en.wikipedia.org/wiki/Time_dilation |