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. 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 a later picture showing the light fronts just reaching O1
simultaneously.

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

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 question:

Does the light from both lightning strikes reach O2 simultaneously?

On May 6, 9:12*am, kenseto wrote:
On May 5, 10:46*am, " wrote:

On 5 mayo, 09:43, kenseto wrote: On May 4, 10:43 pm, PD wrote:

On May 3, 10:03 am, kenseto wrote:

On May 2, 1:45 pm, PD wrote:

On May 2, 9:35 am, kenseto wrote:

What's wrong with these pictures???

1. In the twin paradox scenario SR claims that the traveling clock is
running at slower rate than the stay-at-home clock.

SR makes no such claim. Where are you reading such crap?
What SR tells you is precisely what will be *measured* -- that is, how
much time each twin will say has elapsed between the time of their
departure and the time of their reunion. SR does NOT make a claim
about which clock is running faster or slower in between.

So you are now saying that the SR stay-at-home observer doesn't claim
that the traveling clock is running at a slower rate....right??

Read what I said.

Previously you admitted that every SR observer claims that all clocks
moving wrt him are running slow.

I said no such thing. In fact, the last time you said it, I corrected
you.
What I said is that an *inertial* observer will claim that all clocks
moving *inertially* with respect to him are running slow. This doesn't
apply to the traveling twin, which is precisely the pedagogical point
of the twin puzzle to begin with. This seems to elude you and has
eluded you for a dozen years or more.

But no clock is in a state of inertial motion (including any Sr
observer's clock).....so are you saying that SR is not valid because
it is based on inertially moving clocks?

Is this not a valid claim anymore?

This means that
the passage of a stay at home clock second corresponds to the passage
of less than a clock second on the traveling clock. However when the
traveling clock rejoins the stay-at-home clock, the traveling clock
second is compared with the stay-at-home clock second *directly to
reach the conclusion that the traveling clock is younger. It seems
that SR is making the contradictory claims that: (a) the passage of a
traveling clock second does not correspond to the passage of a stay-at-
home clock second. (b) the passage of a traveling clock second does
correspond to the passage of a stay-at-home clock second.

2. In the pole and the barn paradox scenario:
SR claims that a physically longer pole can fit into a physically
shorter barn for a brief instant. However SR also claims that nothing
is physically happening to the pole. The question is: If nothing is
physically happening to the pole how can a physically longer pole can
fit into a physically shorter barn?

And the reverse question to you is: Why would you think that something
physical MUST happen to an object for its length to be different?

Because you said that the physically longer pole can fit into a
physically shorter barn.

But it's not physically longer. The pole is physically shorter, which
is why it fits in the barn.

This is an assertion. No moving pole is measured directly to be
shorter.

I have no problem with the SR explanation if you say that length
contraction is just a perspective geometric projection effect. But you
also insisted that the contraction of the pole is physically real.

Yes. This doesn't mean that something physical had to happen to the
pole to make it shorter.

Yes it does.

That where the problem comes in.

No problem.

Yes there is problem.

After all, I can record the kinetic energy of a rock from two
different reference frames and will have different answers for the
same rock, even though I never did anything physical to the rock to
add energy to it. The same thing is true for length.

Also, what about from the pole's
point of view? How can it fit into an already physically shorter barn
when the barn is under go further physical contraction?

The answer to this question has to do with what "being inside the
barn" means. What does it mean for the pole to be inside the barn for
an instant in the barn frame?

It means that the physical length of the pole is really shorter than
the physical length of the barn in the barn frame.

I think you can do better than that.
Here, let me give you a hint: The ends of the pole are both inside the
barn at the same moment. Right?

Right ....that's what you claimed and that's real physical
contraction.

Again it seems that SR is making contradictory claims.

3. The SR concept of Relativity of Simultaneity: Einstein used the
train and lightning strikes example to derive his concept of RoS.

No, not to derive it. He used it as a teaching example to explain it,
but the RoS lives independently of this example.

He
said that the track observer sees the strikes to be simultaneous
because the speed of light is isotropic in the track frame and the
track observer is located at equal distance from the strikes when the
strikes occur simultaneously.

No, that is NOT what he said. What he said is that BECAUSE the track
observer sees the strikes to be simultaneous and because the speed of
light is isotropic in the track frame and because the track observer
is located at equal distances from the strikes, THEN the strikes are
simultaneous.

NO....the strikes are stipulated to be simultaneous before the track
observer can see them to be simultaneous.

Not so. Where are you reading such crap? Cite the reference.

The stipulation that the track observer are at equal distance and the
speed of light is isotropic automatically stipulates that the strikes
are simultaneous.
Besides the RoS violates the PoR. Why? Because RoS means that the laws
of physics are different in the train than in the track.....in the
track frame the speed of light is isotropic and RoS says that the
speed of light in the train is anisotropic.

You have it backwards. Where are you reading such crap?

No you are the one who has it backward. If the strikes were not
stipulated to be simultaneous no observer at equal distance from the
strikes can see them to be simultaneous.

Also the track observer is not moving
wrt the light fronts from the strikes.

Of course he is. If the train observer were not moving relative to the
light fronts, they'd never reach him.

Hey idiot I said that the track observer is not moving wrt the light
fronts. Do you have a reading comprehension problem?

Sorry, I mistyped. If the track observer were not moving relative to
the light fronts, they'd never reach him.

Sigh....the light fronts are doing the moving isotropically. That's
why that speed of light is isotropic in the track frame.

OTOH he also claimed that the train observer is moving wrt the light
fronts from the strikes....

No, he didn't. Where are you reading such crap?

Hey idiot.... are you saying that Einstein didn't say that the train
observer is rushing toward the light front from the front of the train
and receding from the light front from the rear of the train and thus
he will see that light front from the front before he sees the light
front from the rear?

Yes, he did say this, and this is what the *track* observer says about
the light and the train observer. This is *not* what the train
observer would say is happening, of course.

This is where you gone wrong. What you said is based on the bogus
assertion that the RoS is correct. It is not. The correct SR
interpretation by the track observer on what the train observer will
see is as follows:
1/2 of the train = L
The light path length from the strikes in the train = L*gamma
Therefore the transit time for the light fronts to arrive at the train
observer = L*gamma/c
Therefore the track observer predicts that the train observer will see
the strikes to be simultaneous at a later time of (L*gamma/c)

You are so stupid.

the light front from the front of the train
will reach the train observer before the light front from the rear of
the train. This is why the train observer will not see the light
fronts to be simultaneous.

No, that's how the track observer makes physical sense (that is,
consistency) from his CONCLUSION that the strikes are simultaneous and
the FACT that the train observer does not see the strikes
simultaneously.

Sigh the train observer must make his own conclusion whether the
strikes are simultaneous.

And he concludes they are not. The track observer concludes they are..

Your assertion is based on the bogus concept of RoS. The train
observer makes no such conclusion. He concludes that the strikes are
stipulated to be simultaneous and the speed of light in his frame is
isotropic and therfore he too will see the strikes to be simultaneous.

The track observer cannot make that decision
for him. However the track observer can predict what the train
observer will see as follows:
The light path length from both strikes in the train = gamma*L
The transit time in the train for both light fronts to reach the train
observer = gamma*L/c
Therefore the train observer will see the strikes to be simultaneous
at a later time of (gamma*L/c).

That is certainly not what the train observer sees. Moreover, that is
not what the track observer predicts the train observer will see in
Einstein's writings.

That is certainly what the train observer will see. Otherwise the
speed of light in the train is not isotropic. Of course this disagrees
with what Einstein said because he bogusly believed that the train
observer is moving wrt the simultaneous light fronts.

However Einstein failed to realize that his
explanation violates his postulate that the speed of light is also
isotropic in the train.....at the time the strikes occur
simultaneously

But they don't strike simultaneous in the train frame. They only
strike simultaneously in the track frame.

Assertion is not a valid argument. The strikes are stipulated to be
simultaneous to be with.

Cite the reference. Title, publisher, page number, quotation, please..

That's what Einstein said in his book. That's what the text book "The
Fundamental of Physics" by Resnick and Holliday said. The strikes are
stipulated to be simultaneous to begin with. One oberver sees the
strikes to be simultaneous because he is not moving wrt the light
fronts and the other observer sees the strikes to be not simultaneous
because he is moving wrt the light fronts.

Ken Seto

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.

That's correct. Notice these are the ONLY TWO stipulations. There IS
NO stipulation that the strikes are simultaneous. You can look all you
want in this passage. It isn't there.

What he DOES say is this: What we *mean* by the two strikes being
simultaneous is that
1. The observer is equidistant between the strikes.
2. The speed of light is isotropic.
3. The observer SEES the light arriving simultaneously from the two
strikes.

If ANY of these conditions is not met, then the strikes are not
simultaneous.

You have a tendency to read into material that which isn't there, Ken.

These stipulations automatically specfied that the strikes were
simultaneous to begin with.

In the track frame, that's the proper conclusion. It isn't for the
train frame, however. Repeat: There IS NO stipulation that the strikes
are simultaneous. That is something you made up in your own head and
cannot seem to remove it.

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.

Well, when you say SR (which is what Einstein was describing) says
something other than what is WRITTEN in black and white, Ken, then it
should serve as a suggestion that you do not understand what is
WRITTEN.

What he said above violates the isotropy of the
speed of light in the train and it violates the PoR.

It does no such thing. The speed of light is still isotropic in the
train frame. This preserves both the isotropy of the speed of light
and 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.

Correct.

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

Careful, the strikes do not happen at the same time in the train
frame.

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

Sorry, the above sentence is not a postulate of SR, nor is it one of
the things the train observer observes.

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.

That would be inconsistent with the laws of physics as seen by the
track observer. Moreover, it is inconsistent with the *OBSERVATION*
that the train observer actually makes. You continue to deny the
reality that this has been OBSERVED in experiment.


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.

Note that this claim is yours and yours alone, and should NOT be
ascribed to SR, because Einstein wrote (in the above) the DIRECT
OPPOSITE of what you claim.


This arguement preserve the isotropy of the speed of light and the PoR
in the train.

Observers who
take the railway train as their reference-body must therefore come to
the conclusion that the lightning flash B took place earlier than the
lightning flash A. We thus arrive at the important result:

This is a bogus conclusion. It violates the isotropy of the speed of
light in the train.

It does no such thing.


Ken Seto Events which are simultaneous with reference to the embankment are not
simultaneous with respect to the train, and vice versa (relativity of
simultaneity). Every reference-body (co-ordinate system) has its own
particular time; unless we are told the reference-body to which the
statement of time refers, there is no meaning in a statement of the
time of an event.
Now before the advent of the theory of relativity it had always
tacitly been assumed in physics that the statement of time had an
absolute significance, i.e. that it is independent of the state of
motion of the body of reference. But we have just seen that this
assumption is incompatible with the most natural definition of
simultaneity; if we discard this assumption, then the conflict between
the law of the propagation of light in vacuo and the principle of
relativity (developed in Section VII) disappears.
We were led to that conflict by the considerations of Section VI,
which are now no longer tenable. In that section we concluded that the
man in the carriage, who traverses the distance w per second relative
to the carriage, traverses the same distance also with respect to the
embankment in each second of time. But, according to the foregoing
considerations, the time required by a particular occurrence with
respect to the carriage must not be considered equal to the duration
of the same occurrence as judged from the embankment (as reference-
body). Hence it cannot be contended that the man in walking travels
the distance w relative to the railway line in a time which is equal
to one second as judged from the embankment.
Moreover, the considerations of Section VI are based on yet a second
assumption, which, in the light of a strict consideration, appears to
be arbitrary, although it was always tacitly made even before the
introduction of the theory of relativity."

OK, Ken, here is the bottom line. You have asserted that Einstein made
a statement that he clearly did not make. You have further asserted
that Halliday and Resnick have made a statement, and you have yet to
provide the citation you claim from that book.

I am happy to do the same thing that Miguel did, typing in the
relevant passage from Halliday and Resnick under fair use rules. You
will find, as a result of that exercise, that Halliday and Resnick do
not say what they think you say, either.

This means that NO ONE agrees with you about what SR says. This means
that you have misunderstood what little you have read about SR, in a
book for the lay public by Einstein and a freshman physics textbook.
As far as I know, you have read nothing else about SR other than these
two sources, since they are the only two you ever even vaguely
reference. Moreover, I don't think you even have these books handy
anymore, and you're operating only on dim memory. When the facts are
laid out in front of you, you refuse to acknowledge that your memory
or understanding of what is actually WRITTEN was wrong.

Ken, I don't know when you're going to muster the courage to say
"oops". It appears that you are mentally incapable of acknowledging a
mistake. Is your self-esteem so low that you cannot tolerate that
possibility? Are you *so* desperate to improve your self-image that
this is an unacceptable step?

PD



Miguel Rios

On May 6, 9:54*am, kenseto wrote:
On May 5, 10:28*am, PD wrote:



On May 5, 8:43*am, kenseto wrote:

On May 4, 10:43*pm, PD wrote:

On May 3, 10:03*am, kenseto wrote:

On May 2, 1:45*pm, PD wrote:

On May 2, 9:35*am, kenseto wrote:

What's wrong with these pictures???

1. In the twin paradox scenario SR claims that the traveling clock is
running at slower rate than the stay-at-home clock.

SR makes no such claim. Where are you reading such crap?
What SR tells you is precisely what will be *measured* -- that is, how
much time each twin will say has elapsed between the time of their
departure and the time of their reunion. SR does NOT make a claim
about which clock is running faster or slower in between.

So you are now saying that the SR stay-at-home observer doesn't claim
that the traveling clock is running at a slower rate....right??

Read what I said.

Previously you admitted that every SR observer claims that all clocks
moving wrt him are running slow.

I said no such thing. In fact, the last time you said it, I corrected
you.
What I said is that an *inertial* observer will claim that all clocks
moving *inertially* with respect to him are running slow. This doesn't
apply to the traveling twin, which is precisely the pedagogical point
of the twin puzzle to begin with. This seems to elude you and has
eluded you for a dozen years or more.

But no clock is in a state of inertial motion (including any Sr
observer's clock).....so are you saying that SR is not valid because
it is based on inertially moving clocks?

SR is certainly valid where the variation from inertial motion is
below experimental resolution. However, this doesn't mean that SR
analysis doesn't apply in cases where there is non-inertial motion.
It's just that statements like "an SR observer will claim that all
clocks moving wrt him are running slow" don't apply in cases of non-
inertial motion. You have this bonehead notion that SR makes this
claim unilaterally for all cases where SR is valid. That isn't the
case, though I can imagine how you might have gotten this notion by
reading coffee-table books. If you would start reading *real* books
about relativity, they would help dispel some of these bonehead
notions you've been laboring under for a decade.

But the math of SR certainly says that all the clocks moving wrt the
observer are running slow.

No, it doesn't. The math ONLY applies to inertial motion, NOT to all
motion. Understanding why the time dilation math formula should NOT be
used in the twin puzzle is one of the key points to the puzzle in the
first place.

This is not from a coffee table book. It is
from Einstein's book

Einstein's book is a coffee-table book. It is meant for lay public
consumption.

and from any text book.

This you claim, but you've only ever read one -- Fundamentals of
Physics, by Halliday and Resnick -- and you cannot properly quote what
that textbook says.

This makes your arguement
weak and bogus.

I know you'd like to think so, Ken, but it's plain that you do not
remember clearly what Einstein wrote and what Halliday and Resnick
wrote. You *claim* that this is what Einstein wrote, but when
confronted with what Einstein *actually* wrote, you then say, "Well,
then Einstein didn't know what he was talking about."

There is NO ONE that has ever written that SR means what you say it
means. Your memory is faulty and your understanding is simply wrong.

It is not a matter of argument being weak or bogus. It is a matter of
looking at the FACTS staring at you in the face. If you are unwilling
to accept FACTS staring at you in the face, then you have simply
detached from reality, Ken.




But it's not physically longer. The pole is physically shorter, which
is why it fits in the barn.

This is an assertion. No moving pole is measured directly to be
shorter.

Of course *it is. See the description of being "inside the barn"
below. If both ends of the pole are inside the barn at the same moment
in the barn frame, then this is a measurement that the pole is
physically shorter than the barn.

Sigh....your assertion that both ends of the poles are inside the barn
at the same moment is bogus and has not been proven experimentally.

Why, yes, yes it has, in an equivalent experiment.




Yes. This doesn't mean that something physical had to happen to the
pole to make it shorter.

Yes it does.

No, Ken, it does not. Nothing physical has to happen to a rock to have
its kinetic energy be different in two different reference frames.

No, Ken, it does not. Your inability to grasp this basic thing is a
severe stumbling block for you.

No it doesm't. If both ends of the longer poles are within the shorter
barn for an instant then the poles are really physically contracted.

Yes, it is really physically contracted. This does NOT mean that
something physical had to happen to the pole to make that happen. Note
that I didn't have to do ANYTHING to the rock to have its kinetic
energy be different in different reference frames. You seem to have
difficulty accepting this reality. You have an assumption that you
simply cannot let go of.


No problem.

Yes there is problem.

After all, I can record the kinetic energy of a rock from two
different reference frames and will have different answers for the
same rock, even though I never did anything physical to the rock to
add energy to it. The same thing is true for length.

Also, what about from the pole's
point of view? How can it fit into an already physically shorter barn
when the barn is under go further physical contraction?

The answer to this question has to do with what "being inside the
barn" means. What does it mean for the pole to be inside the barn for
an instant in the barn frame?

It means that the physical length of the pole is really shorter than
the physical length of the barn in the barn frame.

I think you can do better than that.
Here, let me give you a hint: The ends of the pole are both inside the
barn at the same moment. Right?

Right ....that's what you claimed and that's real physical
contraction.

Yes, that's right, it is. But nothing physical has to happen to the
pole to make that happen.
So where's the problem? Where's the contradiction?

Sure there is something physically happened to the pole....the fact
that both ends of the ;onger pole are within the shorter barn means
that the pole is really physically contracted

Yes, it is physically shorter. Nothing physical happened to the rod to
make that happen. See above.

due to relative motion.



Not so. Where are you reading such crap? Cite the reference.

The stipulation that the track observer are at equal distance and the
speed of light is isotropic automatically stipulates that the strikes
are simultaneous.

No, it certainly does not. Don't be an idiot.
I can have the speed of light be isotropic and an observer watching a
thunderstorm with a strike 3 miles away in one direction and another
strike 3 miles away in another direction, and this *certainly* doesn't
demand that the thunderstorm strikes all happen at the same time.

But if you said that you see the strikes occur simutlaneously then the
strikes must happen at the same time if the speed of light in your
frame is isotropic.

Yes, and in the frame where that happens, then the strikes are
simultaneous. However, in any other frame, where the strikes are NOT
seen to occur simultaneously (and this is seen in EXPERIMENT), then
the same two strikes are NOT simultaneous in that frame.

This is the experimental FACT:
1. Light speed is isotropic in both frames A and B.
2. The strikes are equidistant from the observer in both frames A and
B.

On May 6, 7:58*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. *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 a later picture showing the light fronts just reaching O1
simultaneously.

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

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 question:

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

- Show quoted text -

Ken Seto is right about this. A photon in S is traveling at 186,000
miles per second as measured by a cesium clock in that frame of
reference. A photon in S' is traveling at 186,000 miles per second as
measured by a cesium clock in that frame of reference. What is
occuring is called relativity of time.
With regard to your little diagrams, suppose that the bolts of
lightning strike the front and rear of a train, leaving marks on the
train and on the railroad track. In the frame of reference of the
track, photons are emitted at the two marks on the track and proceed
to the observer midway between them, reaching him in a time of .5L/c,
where L is the length of the train. In the frame of reference of the
train photons are emitted at the points where lightning struck in that
frame of reference, the two marks left on the train. The photons
proceed to the observer in the middle of the train, reaching him in a
time of .5L/c as measured by the cesium clock on the train.
Now you want us to consider what photons emitted at the two
points on the track are doing, and how one reaches the observer on the
train before the other. It does not happen. In the frame of
reference of the train, the first photons emitted are emitted at the
points where the lightning left marks on the train. Any marks left on
the track where made afterward. Consequently, any photons emitted
from the two marks on the track will reach the observer at the middle
of the train after the photons emitted at the points where the
lightning struck the train. What about the track moving relative to
the train?
Any photons emitted after the marks on the track move away from
the front and rear of the train will reach the observer at the middle
of the train after the photons emitted where the lightning struck the
front and rear of the train. The train is traveling slower than the
speed of light. The observer on the train sees the two flashes of
lightning at the same time, the same as the observer on the ground.
He sees them after the observer on the ground sees them because his
clock is slower.
Robert B. Winn

On May 6, 11:00*am, rbwinn wrote:
On May 6, 7:58*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. *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 a later picture showing the light fronts just reaching O1
simultaneously.

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

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 question:

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

- Show quoted text -

Ken Seto is right about this. *A photon in S is traveling at 186,000
miles per second as measured by a cesium clock in that frame of
reference. *A photon in S' is traveling at 186,000 miles per second as
measured by a cesium clock in that frame of reference. *What is
occuring is called relativity of time.
With regard to your little diagrams, suppose that the bolts of
lightning strike the front and rear of a train, leaving marks on the
train and on the railroad track. *In the frame of reference of the
track, photons are emitted at the two marks on the track and proceed
to the observer midway between them, reaching him in a time of .5L/c,
where L is the length of the train. *In the frame of reference of the
train photons are emitted at the points where lightning struck in that
frame of reference, the two marks left on the train. *The photons
proceed to the observer in the middle of the train, reaching him in a
time of .5L/c as measured by the cesium clock on the train.

Everything you've said up until this point is fine.
So let's call the time the rear strike hits (and leaves marks on track
and train) Tr (in the track frame) and Tr' (in the train frame). The
time the front strike hits (and leaves marks on track and train) Tf
(in the track frame) and Tf' (in the train frame). We don't know
anything about those times just yet; we've just given them labels.

And given your prescription, then, the track observer can expect to
see flashes from the two strikes at times
(Tr + 0.5L/c) and (Tf + 0.5L/c)
and the train observer can expect to see flashes from the two strikes
at the times
(Tr' + 0.5L/c) and (Tf' + 0.5L/c).
Now, these times in parentheses are what the observers actually see,
and so we can then *deduce* something from those *observed* times
about the nature of the *unobserved* times Tr, Tf, Tr', Tf'.

Interestingly, what happens (in real life, as measured in experiment)
is that the times of the flashes the track observer sees are the same:
(Tr + 0.5L/c) = (Tf + 0.5L/c)
and that the times of the flashes the train observer sees are not the
same:
(Tr' + 0.5L/c) =/= (Tf' + 0.5L/c).

Now, what one naturally concludes from this observation is that
Tr = Tf, that is, the strikes themselves were simultaneous in the
track frame,
and
Tr' =/= Tf', that is, the strikes themselves were not simultaneous in
the train frame.

On the other hand, Seto is of the opinions that
a) Einstein wrote his example with the explicit set-up (he calls it a
stipulation) that Tr=Tf AND Tr' = Tf'. Of course, when shown what
Einstein really wrote, there is no such explicit set-up at all, and
this flummoxes Seto.
b) Even if Einstein didn't write down his example this way, if Tr =
Tf, then it MUST be that Tr' = Tf' (for whatever reason Seto thinks
this is so), and that to hell what the train observer *actually* sees,
one would *logically* demand that (Tr' + 0.5L/c) = (Tf' + 0.5L/c).
c) The truth, according to Seto, is determined by argument and not by
experiment, and so what the train observer *actually* sees is
irrelevant. Seto thinks that he can *logically conclude* what the
train observer MUST see, based on what he thinks is a superior
assumption (that Tr' = Tf' because Tr = Tf), and he further thinks
that the *conclusion* that the train observer sees (Tr' + 0.5L/c) =/=
(Tf' + 0.5L/c) is based on a circular assumption that Tr' =/= Tf' and
doesn't see why one would assume that to begin with. He doesn't get
that what the train observer sees is not a *conclusion* but an
observational *fact* from which we *start*, not where we end up.


* * *Now you want us to consider what photons emitted at the two
points on the track are doing, and how one reaches the observer on the
train before the other. *It does not happen. *In the frame of
reference of the train, the first photons emitted are emitted at the
points where the lightning left marks on the train. *Any marks left on
the track where made afterward. *Consequently, any photons emitted
from the two marks on the track will reach the observer at the middle
of the train after the photons emitted at the points where the
lightning struck the train. *What about the track moving relative to
the train?
* * Any photons emitted after the marks on the track move away from
the front and rear of the train will reach the observer at the middle
of the train after the photons emitted where the lightning struck the
front and rear of the train. *The train is traveling slower than the
speed of light. *The observer on the train sees the two flashes of
lightning at the same time, the same as the observer on the ground.
He sees them after the observer on the ground sees them because his
clock is slower.
Robert B. Winn

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

- Show quoted text -

On May 6, 12:55*pm, PD wrote:
On May 6, 11:00*am, rbwinn wrote:





On May 6, 7:58*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. *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 a later picture showing the light fronts just reaching O1
simultaneously.

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

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 question:

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

- Show quoted text -

Ken Seto is right about this. *A photon in S is traveling at 186,000
miles per second as measured by a cesium clock in that frame of
reference. *A photon in S' is traveling at 186,000 miles per second as
measured by a cesium clock in that frame of reference. *What is
occuring is called relativity of time.
With regard to your little diagrams, suppose that the bolts of
lightning strike the front and rear of a train, leaving marks on the
train and on the railroad track. *In the frame of reference of the
track, photons are emitted at the two marks on the track and proceed
to the observer midway between them, reaching him in a time of .5L/c,
where L is the length of the train. *In the frame of reference of the
train photons are emitted at the points where lightning struck in that
frame of reference, the two marks left on the train. *The photons
proceed to the observer in the middle of the train, reaching him in a
time of .5L/c as measured by the cesium clock on the train.

Everything you've said up until this point is fine.
So let's call the time the rear strike hits (and leaves marks on track
and train) Tr (in the track frame) and Tr' (in the train frame). The
time the front strike hits (and leaves marks on track and train) Tf
(in the track frame) and Tf' (in the train frame). We don't know
anything about those times just yet; we've just given them labels.

And given your prescription, then, the track observer can expect to
see flashes from the two strikes at times
(Tr + 0.5L/c) and (Tf + 0.5L/c)
and the train observer can expect to see flashes from the two strikes
at the times
(Tr' + 0.5L/c) and (Tf' + 0.5L/c).
Now, these times in parentheses are what the observers actually see,
and so we can then *deduce* something from those *observed* times
about the nature of the *unobserved* times Tr, Tf, Tr', Tf'.

Interestingly, what happens (in real life, as measured in experiment)
is that the times of the flashes the track observer sees are the same:
(Tr + 0.5L/c) = (Tf + 0.5L/c)
and that the times of the flashes the train observer sees are not the
same:
(Tr' + 0.5L/c) =/= (Tf' + 0.5L/c).

Now, what one naturally concludes from this observation is that
Tr = Tf, that is, the strikes themselves were simultaneous in the
track frame,
and
Tr' =/= Tf', that is, the strikes themselves were not simultaneous in
the train frame.

On the other hand, Seto is of the opinions that
a) Einstein wrote his example with the explicit set-up (he calls it a
stipulation) that Tr=Tf AND Tr' = Tf'. Of course, when shown what
Einstein really wrote, there is no such explicit set-up at all, and
this flummoxes Seto.
b) Even if Einstein didn't write down his example this way, if Tr =
Tf, then it MUST be that Tr' = Tf' (for whatever reason Seto thinks
this is so), and that to hell what the train observer *actually* sees,
one would *logically* demand that (Tr' + 0.5L/c) = (Tf' + 0.5L/c).
c) The truth, according to Seto, is determined by argument and not by
experiment, and so what the train observer *actually* sees is
irrelevant. Seto thinks that he can *logically conclude* what the
train observer MUST see, based on what he thinks is a superior
assumption (that Tr' = Tf' because Tr = Tf), and he further thinks
that the *conclusion* that the train observer sees (Tr' + 0.5L/c) =/=
(Tf' + 0.5L/c) is based on a circular assumption that Tr' =/= Tf' and
doesn't see why one would assume that to begin with. He doesn't get
that what the train observer sees is not a *conclusion* but an
observational *fact* from which we *start*, not where we end up.

What you wrote above is a bunch of bull you made up. I did not say any
of the thing you said above.

Ken Seto



* * *Now you want us to consider what photons emitted at the two
points on