Simultaneity of Relativity
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From: glird on 11 Oct 2009 11:30 On Oct 11 1:04 am Bruce Richmond wrote: > On Oct 10 10:21 pm, mpc755 wrote: > > Why is the aether not like other > > mediums in my thought experiment? > >< Possibly because it has no mass. Possibly because it carries the signals we use to synchronize our clocks. Possibly because there is only one aether as opposed to the multiple aethers you are trying to imagine. > The classical aether had no mass because mass is measured by weighing a bit of matter and that aether has no weight. Even so, there is only one kind of matter, and whether organized into particles or in free form and whether locally stationary or locally moving, it carries the signals used to set clocks via Einstein's method. In mpc's case, some of this one material aether was stationary wrt the embankment and some of it was trapped inside a train moving thereto, thus was at rest wrt the train. Therefore, if light signals were used to esynch clocks of the embankment, and similarly wrt those of the train, both sets of clocks would be synchronized and would have identical times as all the others, moving or not. That, however, has nothing to do with Einstein's theory or his train- embankment discussion, in which the aether - if we insist on ignoring his denial that it exists - and the embankment are at rest in space and the train movs relatively to both of them, thus is an open system, not a closed one as in mpc's case. Hence, in Einstein's treatment of how we are to set clocks of a given system, those of the embankment would be truly synchronous while those on the train would be offset compared to each other by -vx/c^2 seconds; where x is the distance between two such esynched clocks and v is the velocity of the train wrt the "empty space" in which Einstein postulated that light travels at c. Be it noted that the value of v isn't known nor does it have to be in order for this method to give those results.
From: glird on 11 Oct 2009 11:49 On Oct 10, 10:35 pm, Tim Little wrote: > On 2009-10-10, mpc755 wrote: > > > If you think no, why is aether > > different than other mediums light > > travels through? > > If by "aether" you mean "vacuum", it > is different because the relative > speed of light is always observed to > be constant in it, regardless of > motion of source and/or observer. > That is why analogies with sound or > water waves are poorly made. If we used sound waves or water waves to set clocks of a given system moving wrt air or water, the results WOULD be analogous to Einstein's; and the speed of sound or water waves would be constant in both directions. As to remaining a constant in ALL directions, if - as denied by present relativists - the length of a moving unit rod deformed by a given amount per direction, the speed of sound and light and water waves would each remain constant in all directions as plotted by clocks set that way.
From: mpc755 on 12 Oct 2009 10:36 On Oct 11, 1:04 am, Bruce Richmond <bsr3...(a)my-deja.com> wrote: > On Oct 10, 10:21 pm, mpc755 <mpc...(a)gmail.com> wrote: > > > On Oct 10, 8:29 pm, Bruce Richmond <bsr3...(a)my-deja.com> wrote: > > > > On Oct 10, 6:44 pm, mpc755 <mpc...(a)gmail.com> wrote: > > > > > Einstein believed the propagation of light required an aether. > > > > That may be, but he wrote that it didn't matter as far as his theory > > > of relativity was concerned. > > > Why is the aether not like other mediums in my thought experiment? > > Possibly because it has no mass. Possibly because it carries the > signals we use to syncronize our clocks. Possibly because there is > only one aether as opposed to the multiple aethers you are trying to > imagine. How do you know the aether has no mass? How do you weight the lowest common denominator of matter? The aether has mass or there would be no mass.
From: mpc755 on 12 Oct 2009 10:40 On Oct 11, 11:30 am, glird <gl...(a)aol.com> wrote: > On Oct 11 1:04 am Bruce Richmond wrote: > > > On Oct 10 10:21 pm, mpc755 wrote: > > > Why is the aether not like other > > > mediums in my thought experiment? > > >< Possibly because it has no mass. Possibly because it carries the signals we use to synchronize our clocks. Possibly because there is only one aether as opposed to the multiple aethers you are trying to imagine. > > > The classical aether had no mass because mass is measured by > weighing a bit of matter and that aether has no weight. Even so, there > is only one kind of matter, and whether organized into particles or in > free form and whether locally stationary or locally moving, it carries > the signals used to set clocks via Einstein's method. > In mpc's case, some of this one material aether was stationary wrt > the embankment and some of it was trapped inside a train moving > thereto, thus was at rest wrt the train. > Therefore, if light signals were used to esynch clocks of the > embankment, and similarly wrt those of the train, both sets of clocks > would be synchronized and would have identical times as all the > others, moving or not. > That, however, has nothing to do with Einstein's theory or his train- > embankment discussion, in which the aether - if we insist on ignoring > his denial that it exists - and the embankment are at rest in space > and the train movs relatively to both of them, thus is an open system, > not a closed one as in mpc's case. Hence, in Einstein's treatment of > how we are to set clocks of a given system, those of the embankment > would be truly synchronous while those on the train would be offset > compared to each other by -vx/c^2 seconds; where x is the distance > between two such esynched clocks and v is the velocity of the train > wrt the "empty space" in which Einstein postulated that light travels > at c. > Be it noted that the value of v isn't known nor does it have to be > in order for this method to give those results. I don't know who you are referring to in terms of 'if we insist on ignoring his denial that it exists' but it can't be Einstein: 'Ether and the Theory of Relativity by Albert Einstein' http://www-groups.dcs.st-and.ac.uk/~history/Extras/Einstein_ether.html "Recapitulating, we may say that according to the general theory of relativity space is endowed with physical qualities; in this sense, therefore, there exists an ether. According to the general theory of relativity space without ether is unthinkable; for in such space there not only would be no propagation of light, but also no possibility of existence for standards of space and time (measuring-rods and clocks), nor therefore any space-time intervals in the physical sense. But this ether may not be thought of as endowed with the quality characteristic of ponderable media, as consisting of parts which may be tracked through time. The idea of motion may not be applied to it." I'm disagreeing with the last sentence, "The idea of motion may not be applied to it." Why not?
From: mpc755 on 12 Oct 2009 10:44
On Oct 11, 12:04 am, mpc755 <mpc...(a)gmail.com> wrote: > On Oct 10, 7:02 pm, mpc755 <mpc...(a)gmail.com> wrote: > > > > > On Oct 10, 3:39 pm, Bruce Richmond <bsr3...(a)my-deja.com> wrote: > > > > 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. > > > My thought experiment: > > > Embankment water stationary relative to the embankment. > > Train water stationary relative to the train. > > Pebbles dropped simultaneously at A on the embankment and A' on the > > train. > > Pebbles dropped simultaneously at B on the embankment and B' on the > > train. > > If the waves created by the pebbles at A and B reach M simultaneously, > > do the waves created by the pebbles at A' and B' reach M' > > simultaneously? > > > Yes. > > > Replace the pebbles with flashes of light. > > > If the light waves created by the flashes at A and B reach M > > simultaneously, do the waves created by the flashes at A' and B' reach > > M' simultaneously? > > > Yes. > > > Replace the water with aether, ice, air, or glass. > > > If the light waves created by the flashes at A and B reach M > > simultaneously, do the waves created by the flashes at A' and B' reach > > M' simultaneously? > > > Yes. > > > If you think no, why is aether different than other mediums light > > travels through? > > If light waves created by the flashes at A and B reach M > simultaneously, the light waves from the flashes at A' and B' reach M' > simultaneously. > > A and B are light years from M. A' and B' are light years from M'. The > membrane between the embankment frame of reference and the train frame > of reference is thin enough to allow light waves to travel through but > not the stationary aether associated with each frame of reference. At > the time of the flashes, A and A' are extremely close together and so > are M and M' and B and B'. > > M and M' are moving away from each other at a high rate of speed. > > The light reaches each observer accordingly: > > The light from B reaches M' and the light from A' reaches M > simultaneously, then > The light from A and B reaches M and the light from A' and B' reaches > M' simultaneously, then > The light from A reaches M' and the light from B' reaches M > simultaneously. > > http://www.youtube.com/watch?v=jyWTaXMElUk Stationary aether in each frame of reference allows for Simultaneity of Relativity. |