From: Tim Little on
On 2009-10-10, mpc755 <mpc755(a)gmail.com> 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.


- Tim
From: mpc755 on
On Oct 10, 10:35 pm, Tim Little <t...(a)little-possums.net> wrote:
> On 2009-10-10, mpc755 <mpc...(a)gmail.com> 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.
>
> - Tim

The analogy between water and aether in my thought experiment is not
poorly made. In my thought experiment, if the light from A and B
reaches M simultaneously then the light from A' and B' reaches M'
simultaneously.

If you disagree with the above statement, explain why.
From: mpc755 on
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.

From: mpc755 on
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
From: Bruce Richmond on
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.