Simultaneity of Relativity
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From: glird on 10 Oct 2009 10:48 On Oct 10, 9:52 am, PD wrote: > mpc755 wrote: > > I understand exactly what is > > occurring in Einstein's Train > > Thought experiment. > > Not as Einstein explained it, no you > don't. > > You understand the MPC Train Thought > Experiment, which is something > completely different than the > Einstein Train Thought Experiment. Yes. > << Lightning strikes at A/A' and B/B' behave exactly like the waves of pebbles dropped into stationary pools of water on the train and stationary pools of water on the embankment. If there are stationary pools on the train and on the embankment, the waves the pebbles create from A and B reaches M and the light from A' and B' reaches M' simultaneously. If there are stationary pools on the train and on the embankment, the light waves from A and B reach M and the light wave from A' and B' reach M' simultaneously. >> > > See? That's the MPC Train Thought > Experiment, not the Einstein one. PD is right. In Einstein's, A and A' coincide when a given ray hits point AA', and B and B' coincide when ray 2 hits BB'. In MPC's, A and A' are different points than each other in 3-d space and so are b and B'. In Einstein, the space between AA' and BB' is empty and light moves at c wrt to it while the train - thus points A', B' and midpoint M' - moves to the right at v. in mpc, a luminiferous aether is trapped within the moving train and is therefore moving wrt to the outside aether taken as at rest wrt the embankment. Therefore, as PD said, mpc's conclusions are unrelated to Einstein's. BTW, this gedanken experiment by Einstein is to the layman, and doesn't explain why simultaneity is relative to the states of motion of different observers' clocks. glird them ir point
From: mpc755 on 10 Oct 2009 11:48 On Oct 10, 10:48 am, glird <gl...(a)aol.com> wrote: > On Oct 10, 9:52 am, PD wrote: > > > mpc755 wrote: > > > I understand exactly what is > > > occurring in Einstein's Train > > > Thought experiment. > > > Not as Einstein explained it, no you > don't. > > > You understand the MPC Train Thought > > Experiment, which is something > > completely different than the > > Einstein Train Thought Experiment. > > Yes. > > > << Lightning strikes at A/A' and B/B' behave exactly like the waves of > > pebbles dropped into stationary pools of water on the train and > stationary pools of water on the embankment. > If there are stationary pools on the train and on the embankment, the > waves the pebbles create from A and B reaches M and the light from A' > and B' reaches M' simultaneously. > If there are stationary pools on the train and on the embankment, the > light waves from A and B reach M and the light wave from A' and B' > reach M' simultaneously. >> > > > > > See? That's the MPC Train Thought > > Experiment, not the Einstein one. > > PD is right. In Einstein's, A and A' coincide when a given ray hits > point AA', and B and B' coincide when ray 2 hits BB'. In MPC's, A and > A' are different points than each other in 3-d space and so are b and > B'. > In Einstein, the space between AA' and BB' is empty and light moves > at c wrt to it while the train - thus points A', B' and midpoint M' - > moves to the right at v. in mpc, a luminiferous aether is trapped > within the moving train and is therefore moving wrt to the outside > aether taken as at rest wrt the embankment. > Therefore, as PD said, mpc's conclusions are unrelated to > Einstein's. > > BTW, this gedanken experiment by Einstein is to the layman, and > doesn't explain why simultaneity is relative to the states of motion > of different observers' clocks. > > glird > > them ir point It makes no difference if the points A and A' coincide side-by-side or not in Einstein's Train Thought Experiment. Saying it makes a difference shows your limited understanding of the Einstein's Train Thought Experiment. The only thing that matters in Einstein's Train Thought Experiment is the flash at A/A' occurring in a single instant and the flash of light at B/B' occurring in a single instant and for A and B to be equi- distant from M and for A' and B' to be equi-distant from M' and for the distance from A to M and B to M to be the same as the distance from A' to M' and B' to M'. Let me ask you about Einstein's Train Thought Experiment with the following variation. As described in the above sentence, if there is are simultaneous lightning strikes at A and A' and there are simultaneous lightning strikes at B and B', if the light from A and B reaches M simultaneously does the light from A' and B' reach M' simultaneously? And in terms of simultaneous, I am referring to any frame of reference. In other words, from the perspective of an observer on the embankment, if the light from A and B reaches the observer at M simultaneously, does the light from the lightning strikes at A' and B' reach M' simultaneously?
From: PD on 10 Oct 2009 11:51 On Oct 10, 10:48 am, mpc755 <mpc...(a)gmail.com> wrote: > On Oct 10, 10:48 am, glird <gl...(a)aol.com> wrote: > > > > > On Oct 10, 9:52 am, PD wrote: > > > > mpc755 wrote: > > > > I understand exactly what is > > > > occurring in Einstein's Train > > > > Thought experiment. > > > > Not as Einstein explained it, no you > don't. > > > > You understand the MPC Train Thought > > > Experiment, which is something > > > completely different than the > > > Einstein Train Thought Experiment. > > > Yes. > > > > << Lightning strikes at A/A' and B/B' behave exactly like the waves of > > > pebbles dropped into stationary pools of water on the train and > > stationary pools of water on the embankment. > > If there are stationary pools on the train and on the embankment, the > > waves the pebbles create from A and B reaches M and the light from A' > > and B' reaches M' simultaneously. > > If there are stationary pools on the train and on the embankment, the > > light waves from A and B reach M and the light wave from A' and B' > > reach M' simultaneously. >> > > > > See? That's the MPC Train Thought > > > Experiment, not the Einstein one. > > > PD is right. In Einstein's, A and A' coincide when a given ray hits > > point AA', and B and B' coincide when ray 2 hits BB'. In MPC's, A and > > A' are different points than each other in 3-d space and so are b and > > B'. > > In Einstein, the space between AA' and BB' is empty and light moves > > at c wrt to it while the train - thus points A', B' and midpoint M' - > > moves to the right at v. in mpc, a luminiferous aether is trapped > > within the moving train and is therefore moving wrt to the outside > > aether taken as at rest wrt the embankment. > > Therefore, as PD said, mpc's conclusions are unrelated to > > Einstein's. > > > BTW, this gedanken experiment by Einstein is to the layman, and > > doesn't explain why simultaneity is relative to the states of motion > > of different observers' clocks. > > > glird > > > them ir point > > It makes no difference if the points A and A' coincide side-by-side or > not in Einstein's Train Thought Experiment. > > Saying it makes a difference shows your limited understanding of the > Einstein's Train Thought Experiment. No, I'm sorry, now you're using sentences that Ken Seto uses, and Ken Seto is insane. It's you that doesn't understand the Einstein gedanken. > > The only thing that matters in Einstein's Train Thought Experiment is > the flash at A/A' occurring in a single instant And at a single location. > and the flash of light > at B/B' occurring in a single instant And at a single location. > and for A and B to be equi- > distant from M and for A' and B' to be equi-distant from M' and for > the distance from A to M and B to M to be the same as the distance > from A' to M' and B' to M'. > > Let me ask you about Einstein's Train Thought Experiment with the > following variation. Why don't we take up the variation after you've correctly understood the unvaried case? > As described in the above sentence, if there is > are simultaneous lightning strikes at A and A' and there are > simultaneous lightning strikes at B and B', if the light from A and B > reaches M simultaneously does the light from A' and B' reach M' > simultaneously? And in terms of simultaneous, I am referring to any > frame of reference. In other words, from the perspective of an > observer on the embankment, if the light from A and B reaches the > observer at M simultaneously, does the light from the lightning > strikes at A' and B' reach M' simultaneously?
From: mpc755 on 10 Oct 2009 11:58 On Oct 10, 10:48 am, glird <gl...(a)aol.com> wrote: > On Oct 10, 9:52 am, PD wrote: > > > mpc755 wrote: > > > I understand exactly what is > > > occurring in Einstein's Train > > > Thought experiment. > > > Not as Einstein explained it, no you > don't. > > > You understand the MPC Train Thought > > Experiment, which is something > > completely different than the > > Einstein Train Thought Experiment. > > Yes. > > > << Lightning strikes at A/A' and B/B' behave exactly like the waves of > > pebbles dropped into stationary pools of water on the train and > stationary pools of water on the embankment. > If there are stationary pools on the train and on the embankment, the > waves the pebbles create from A and B reaches M and the light from A' > and B' reaches M' simultaneously. > If there are stationary pools on the train and on the embankment, the > light waves from A and B reach M and the light wave from A' and B' > reach M' simultaneously. >> > > > > > See? That's the MPC Train Thought > > Experiment, not the Einstein one. > > PD is right. In Einstein's, A and A' coincide when a given ray hits > point AA', and B and B' coincide when ray 2 hits BB'. In MPC's, A and > A' are different points than each other in 3-d space and so are b and > B'. > In Einstein, the space between AA' and BB' is empty and light moves > at c wrt to it while the train - thus points A', B' and midpoint M' - > moves to the right at v. in mpc, a luminiferous aether is trapped > within the moving train and is therefore moving wrt to the outside > aether taken as at rest wrt the embankment. > Therefore, as PD said, mpc's conclusions are unrelated to > Einstein's. > > BTW, this gedanken experiment by Einstein is to the layman, and > doesn't explain why simultaneity is relative to the states of motion > of different observers' clocks. > > glird > > them ir point It makes no difference if the points A and A' coincide side-by-side or not in Einstein's Train Thought Experiment. The only thing that matters in Einstein's Train Thought Experiment is the flash at A/A' occurring in a single instant and the flash of light at B/B' occurring in a single instant and for A and B to be equi- distant from M and for A' and B' to be equi-distant from M' and for the distance from A to M and B to M to be the same as the distance from A' to M' and B' to M'. Let me ask you about Einstein's Train Thought Experiment with the following variation. As described in the above sentence, if there is are simultaneous lightning strikes at A and A' and there are simultaneous lightning strikes at B and B', if the light from A and B reaches M simultaneously does the light from A' and B' reach M' simultaneously? And in terms of simultaneous, I am referring to any frame of reference. In other words, from the perspective of an observer on the embankment, if the light from A and B reaches the observer at M simultaneously, does the light from the lightning strikes at A' and B' reach M' simultaneously?
From: Bruce Richmond on 10 Oct 2009 15:39
On Oct 10, 11:58 am, mpc755 <mpc...(a)gmail.com> wrote: > On Oct 10, 10:48 am, glird <gl...(a)aol.com> wrote: > > > > > > > On Oct 10, 9:52 am, PD wrote: > > > > mpc755 wrote: > > > > I understand exactly what is > > > > occurring in Einstein's Train > > > > Thought experiment. > > > > Not as Einstein explained it, no you > don't. > > > > You understand the MPC Train Thought > > > Experiment, which is something > > > completely different than the > > > Einstein Train Thought Experiment. > > > Yes. > > > > << Lightning strikes at A/A' and B/B' behave exactly like the waves of > > > pebbles dropped into stationary pools of water on the train and > > stationary pools of water on the embankment. > > If there are stationary pools on the train and on the embankment, the > > waves the pebbles create from A and B reaches M and the light from A' > > and B' reaches M' simultaneously. > > If there are stationary pools on the train and on the embankment, the > > light waves from A and B reach M and the light wave from A' and B' > > reach M' simultaneously. >> > > > > See? That's the MPC Train Thought > > > Experiment, not the Einstein one. > > > PD is right. In Einstein's, A and A' coincide when a given ray hits > > point AA', and B and B' coincide when ray 2 hits BB'. In MPC's, A and > > A' are different points than each other in 3-d space and so are b and > > B'. > > In Einstein, the space between AA' and BB' is empty and light moves > > at c wrt to it while the train - thus points A', B' and midpoint M' - > > moves to the right at v. in mpc, a luminiferous aether is trapped > > within the moving train and is therefore moving wrt to the outside > > aether taken as at rest wrt the embankment. > > Therefore, as PD said, mpc's conclusions are unrelated to > > Einstein's. > > > BTW, this gedanken experiment by Einstein is to the layman, and > > doesn't explain why simultaneity is relative to the states of motion > > of different observers' clocks. > > > glird > > > them ir point > > It makes no difference if the points A and A' coincide side-by-side or > not in Einstein's Train Thought Experiment. > > The only thing that matters in Einstein's Train Thought Experiment is > the flash at A/A' occurring in a single instant and the flash of light > at B/B' occurring in a single instant and for A and B to be equi- > distant from M and for A' and B' to be equi-distant from M' and for > the distance from A to M and B to M to be the same as the distance > from A' to M' and B' to M'. You were ok up to the last part. The flashes met at M'. They can only meet at one point on a line between the two strikes, and that one point is where M is. M' was not with M when the flashes arrived, so he did not see the flashes at the same instant. IOW he saw the flashes at different times. Since the strikes at A' and B' were equal distances from M' the strikes must have happen at different times. In the frame of M' the strike at the front of the train happen first, M' passed by M, and then the strike at the back of the train happen. By the time the strike at the back of the train happen the front had moved beyond where its strike happen. So the distance between A' and B' is greater than the distance between A and B. You only think they are the same distance because M says the two strikes happen at the same time. |