On May 7, 8:34*am, jem wrote:
kenseto wrote:
On May 6, 10:58 am, jem wrote:
kenseto wrote:
On May 5, 10:46 am, " wrote:
This is what Einstein exactly said in "Albert Einstein (1879-1955).
Relativity: The Special and General Theory. *1920.", chapter 9.
"Up to now our considerations have been referred to a particular body
of reference, which we have styled a "railway embankment." We suppose
a very long train travelling along the rails with the constant
velocity v and in the direction indicated in Fig. 1. People travelling
in this train will with advantage use the train as a rigid reference-
body (co-ordinate system); they regard all events in reference to the
train. Then every event which takes place along the line also takes
place at a particular point of the train. Also the definition of
simultaneity can be given relative to the train in exactly the same
way as with respect to the embankment. As a natural consequence,
however, the following question arises:
Are two events (e.g. the two strokes of lightning A and B) which are
simultaneous with reference to the railway embankment also
simultaneous relatively to the train? We shall show directly that the
answer must be in the negative.
V - * * ‡ * * * M' * * *‡ * */ Train
----==========================---------
* * * * *A * * * M * * * B * * *Embankment
When we say that the lightning strokes A and B are simultaneous with
respect to the embankment, we mean: the rays of light emitted at the
places A and B, where the lightning occurs, meet each other at the mid-
point M of the length A -- B of the embankment.
Right that's because Einstein stipulated that M is at equal distance
from the strikes and that the speed of light is isotropic in the track
frame. These stipulations automatically specfied that the strikes were
simultaneous to begin with. Otherewise the track observer will not be
able to sees the strikes to be simultaneous.
But the events A and B
also correspond to positions A and B on the train. Let M' be the mid-
point of the distance A -- B on the travelling train. Just when the
flashes of lightning occur, this point M' naturally coincides with the
point M, but it moves towards the right in the diagram with the
velocity v of the train. If an observer sitting in the position M' in
the train did not possess this velocity, then he would remain
permanently at M, and the light rays emitted by the flashes of
lightning A and B would reach him simultaneously, i.e. they would meet
just where he is situated. Now in reality (considered with reference
to the railway embankment) he is hastening towards the beam of light
coming from B, whilst he is riding on ahead of the beam of light
coming from A. Hence the observer will see the beam of light emitted
from B earlier than he will see that emitted from A.
This point of view of the track observer by Einstein is wrong and
bogus.....it appears that Einstein didn't fully understand his own
theory and postulates. What he said above violates the isotropy of the
speed of light in the train and it violates the PoR. The track
observer must use the postulates to predict what the train observer
will see. According to SR the speed of light in the train is isotropic
and the laws of physics in the train is the same as in the track. From
these two postulates the track observer predicts what the train
observer will see as follows:
1/2 the length of the train = L
Therefore at the time of the strikes both M and M' are at equal
distance fron the strikes.
The light path length for the each light front to reach the M'
observer = gamma*L
The transit time for the light fronts to reach M'= gamma*l/c
Therefore the train observer will sees the strikes to be simultaneous
at time = gamma*L/c according to the track clock.
The track observer will see that he sees the strikes to be
simultaneous at time L/c according to the track clock.
What this means is that the strikes in the track frame occur
simultaneously at an earlier time of L/c and the strikes occur
simultaneously at a later time of (gamma*L/c) in the train.
This arguement preserve the isotropy of the speed of light and the PoR
in the train.
The argument, Seto, preserves the general consensus that you have the
mind of a 4-year old. *

The argument jem made preserves the general consensus that he has the
mind of a runt of the SRians.

Here's another opportunity to confirm it.

Here's a picture showing 2 lightning strikes L1 and L2, with light
fronts from the strikes traveling toward 2 observers, one of whom (O2)
is moving to the right relative to the other (O1).

L1...).........O1...O2.....(...L2

Here's where your runtiness comes in. It is irrelevant how O1 and O2
move wrt each other. The postulates of SR says that the speed of light
is isotropic in O1 and O2....period.
Here's a later picture showing the light fronts just reaching O1
simultaneously.

L1............)O1(.....O2......L2

If the light fronts reach O1 simultaneously then the strikes were
simultaneous to begin with. Otherwise O1 will not be able to see them
to be simultaneous. Again it is irrelatevant how O2 moves wrt O1. What
O2 sees depends on:
1. were the strikes simultaneous to begin with?
2. was he at equal distance from the strikes?
3. is the speed of light isotropic in the train?

The answers to all these questions are YES. Therefore the train
observer will also see the strikes to be simutaneous.
Challenging questions for 4-year olds:

In the second picture, has the light from either lightning strike
reached O2? *Has the light from either lightning strike not reached O2?

Bonus teaching for a runt of the SRians: The second picture is wrong.
Relative motion and direction of relative motion has no effect on the
isotropy of the speed of light in the train. The track observer sees
the strikes to be simultaneous at time L/c according to the track
clock. The train observer sees the strikes to be simultaneous at time
gamma*L/c according to the track clock.
Bonus question:

Does the light from both lightning strikes reach O2 simultaneously?- Hide quoted text -

Bous teaching for a runt of the SRians: The light fronts from both
strikes reach O2 simultaneously at time gamma*L/c according to the
track clock. The light fronts from both strikes reach O1
simultaneously at time L/c according to the train clock. What this
means is that a train clock is running at a slower rate than the track
clock....in other words the train clock second contains gamma second
of track time. This agrees with the SR math completely. Also this
analysis eliminates the need for the bogus concept of relativity of
simultaneity which BTW violates both postulates of SR.

Ken Seto

I take it back, Seto - you don't have the mind of a 4-year old, and my
apologies to 4-year olds for having suggested that you did.- Hide quoted text -


ROTFLOL...this runt of the SRians failed to come up with a valid
argument so he back paddled.