On May 7, 3:43Â*pm, " wrote:
On 7 mayo, 15:32, kenseto wrote:





On May 7, 11:42 am, " wrote:

On 7 mayo, 10:28, rbwinn wrote:

On May 7, 6:48�am, YBM wrote:

kenseto a �crit :

ROTFLOL....you are not responding because you don't have a valid
argument. I am not going to respond the rest of your post until you
admit that Einstein did stipulate that the lightning strikes occur
simultaneously and that:
1. the track observer sees them to be simultaneous because he is not
moving wrt the light fronts.
2. the train observer sees them to be not simultaneous because he is
moving wrt the light fronts.

In SR, "not moving with respect to a light front" makes no sense.

I have a question, YBM. Â*Whether you talk about photons or light
fronts, in the frame of reference of the train, the light is traveling
at a speed of c from the two points where light was emitted in the
frame of reference of the train. Â*Those two points remain exactly
where they were relative to the frame of reference of the train, and
the movement of the track relative to the train changes nothing. Â*How
do you get that the observer on the train is moving wrt the light
fronts in his frame of reference?

Your mistake is treating the points where the information (light) was
generated the same as the information.
They are quite different!

Â* Â* The observer on the train is not moving in his frame of
reference. Â*The train is not moving in the frame of reference of the
train, and the observer is at the middle of the train the entire
time. Â*The two light fronts are moving with a speed of c toward the
observer. Â*The track is moving toward the rear of the train. Â*What the
track does is irrelevant because the light travels with a speed of c
in the frame of reference of the train, regardless of the motion of
the source of light. Â*Since the track is moving toward the rear of the
train at a speed less than the speed of light, any photons emitted in
the frame of reference of the train after the first photons emitted
will still reach the observer at the middle of the train after the
first ones emitted.

The light carrying the information is moving isotropically from the
points where it was generated. So the train observer will receive
first the front light signal and later the back light signal.

This bogus assertion is based on the bogus assumption that the speed
of light is anisotropic in the train.

Ken Seto

Â* Â* Â*What you and Einstein and all other believers in relativity of
simultaneity are doing is clinging to some beliefs that pertain to
absolute time by making the frame of reference of the track a
preferred frame of reference as far as transmission of light is
concerned. Â*According to you, the train moves toward the source of
light at the front of the train, so that light reaches the observer
first. Â*Wrong. Â*The train is not moving in its own frame of
reference. Â*The track is moving toward the rear of the train. Â*That is
entirely irrelevant as far as when the light will reach the observer
at the middle of the train. Â*You scientists have faithfully copied
Einstein's mistake for more than 100 years. Â*Don't you think it might
be time to think about it?
Robert B. Winn

Nonsense

Miguel Rios- Hide quoted text -

- Show quoted text -

The only person making bogus assertions here is you.
Check your dictionary for the meaning of isotropy.
If you do not have one, here is the definition:
Isotropy is uniformity in all directions. The word is made up from
Greek iso (equal) and tropos (direction).


Right....so when Einstein asserted that the train observer rush toward
the light front from the front and receding from the light front from
the rear he is describing a scenario that destroys the isotropy of the
speed of light in the train.
So I guess it is you runt of the SRians failed to comprehend this
simple fact.

Ken Seto

On 7 mayo, 16:27, kenseto wrote:
On May 7, 3:43 pm, " wrote:



On 7 mayo, 15:32, kenseto wrote:

On May 7, 11:42 am, " wrote:

On 7 mayo, 10:28, rbwinn wrote:

On May 7, 6:48�am, YBM wrote:

kenseto a �crit :

ROTFLOL....you are not responding because you don't have a valid
argument. I am not going to respond the rest of your post until you
admit that Einstein did stipulate that the lightning strikes occur
simultaneously and that:
1. the track observer sees them to be simultaneous because he is not
moving wrt the light fronts.
2. the train observer sees them to be not simultaneous because he is
moving wrt the light fronts.

In SR, "not moving with respect to a light front" makes no sense..

I have a question, YBM. Whether you talk about photons or light
fronts, in the frame of reference of the train, the light is traveling
at a speed of c from the two points where light was emitted in the
frame of reference of the train. Those two points remain exactly
where they were relative to the frame of reference of the train, and
the movement of the track relative to the train changes nothing. How
do you get that the observer on the train is moving wrt the light
fronts in his frame of reference?

Your mistake is treating the points where the information (light) was
generated the same as the information.
They are quite different!

The observer on the train is not moving in his frame of
reference. The train is not moving in the frame of reference of the
train, and the observer is at the middle of the train the entire
time. The two light fronts are moving with a speed of c toward the
observer. The track is moving toward the rear of the train. What the
track does is irrelevant because the light travels with a speed of c
in the frame of reference of the train, regardless of the motion of
the source of light. Since the track is moving toward the rear of the
train at a speed less than the speed of light, any photons emitted in
the frame of reference of the train after the first photons emitted
will still reach the observer at the middle of the train after the
first ones emitted.

The light carrying the information is moving isotropically from the
points where it was generated. So the train observer will receive
first the front light signal and later the back light signal.

This bogus assertion is based on the bogus assumption that the speed
of light is anisotropic in the train.

Ken Seto

What you and Einstein and all other believers in relativity of
simultaneity are doing is clinging to some beliefs that pertain to
absolute time by making the frame of reference of the track a
preferred frame of reference as far as transmission of light is
concerned. According to you, the train moves toward the source of
light at the front of the train, so that light reaches the observer
first. Wrong. The train is not moving in its own frame of
reference. The track is moving toward the rear of the train. That is
entirely irrelevant as far as when the light will reach the observer
at the middle of the train. You scientists have faithfully copied
Einstein's mistake for more than 100 years. Don't you think it might
be time to think about it?
Robert B. Winn

Nonsense

Miguel Rios- Hide quoted text -

- Show quoted text -

The only person making bogus assertions here is you.
Check your dictionary for the meaning of isotropy.
If you do not have one, here is the definition:
Isotropy is uniformity in all directions. The word is made up from
Greek iso (equal) and tropos (direction).

Right....so when Einstein asserted that the train observer rush toward
the light front from the front and receding from the light front from
the rear he is describing a scenario that destroys the isotropy of the
speed of light in the train.
So I guess it is you runt of the SRians failed to comprehend this
simple fact.

Ken Seto

On the contrary, light signals from both strokes are precisely
isotropically propagating (in a spherical growing at c shape) from
their origin, which is exactly what isotropy propagation means. When
that sphere finds an eye (either the track or the train observer eyes)
the observers will say "hey I have detected a strike!".
So how you explain this nonsense of "destroying the isotropy of the
speed of light". Do you understand English at all?

Miguel Rios

On May 7, 3:27Â*pm, kenseto wrote:
On May 7, 3:43Â*pm, " wrote:



On 7 mayo, 15:32, kenseto wrote:

On May 7, 11:42 am, " wrote:

On 7 mayo, 10:28, rbwinn wrote:

On May 7, 6:48�am, YBM wrote:

kenseto a �crit :

ROTFLOL....you are not responding because you don't have a valid
argument. I am not going to respond the rest of your post until you
admit that Einstein did stipulate that the lightning strikes occur
simultaneously and that:
1. the track observer sees them to be simultaneous because he is not
moving wrt the light fronts.
2. the train observer sees them to be not simultaneous because he is
moving wrt the light fronts.

In SR, "not moving with respect to a light front" makes no sense..

I have a question, YBM. Â*Whether you talk about photons or light
fronts, in the frame of reference of the train, the light is traveling
at a speed of c from the two points where light was emitted in the
frame of reference of the train. Â*Those two points remain exactly
where they were relative to the frame of reference of the train, and
the movement of the track relative to the train changes nothing. Â*How
do you get that the observer on the train is moving wrt the light
fronts in his frame of reference?

Your mistake is treating the points where the information (light) was
generated the same as the information.
They are quite different!

Â* Â* The observer on the train is not moving in his frame of
reference. Â*The train is not moving in the frame of reference of the
train, and the observer is at the middle of the train the entire
time. Â*The two light fronts are moving with a speed of c toward the
observer. Â*The track is moving toward the rear of the train. Â*What the
track does is irrelevant because the light travels with a speed of c
in the frame of reference of the train, regardless of the motion of
the source of light. Â*Since the track is moving toward the rear of the
train at a speed less than the speed of light, any photons emitted in
the frame of reference of the train after the first photons emitted
will still reach the observer at the middle of the train after the
first ones emitted.

The light carrying the information is moving isotropically from the
points where it was generated. So the train observer will receive
first the front light signal and later the back light signal.

This bogus assertion is based on the bogus assumption that the speed
of light is anisotropic in the train.

Ken Seto

Â* Â* Â*What you and Einstein and all other believers in relativity of
simultaneity are doing is clinging to some beliefs that pertain to
absolute time by making the frame of reference of the track a
preferred frame of reference as far as transmission of light is
concerned. Â*According to you, the train moves toward the source of
light at the front of the train, so that light reaches the observer
first. Â*Wrong. Â*The train is not moving in its own frame of
reference. Â*The track is moving toward the rear of the train. Â*That is
entirely irrelevant as far as when the light will reach the observer
at the middle of the train. Â*You scientists have faithfully copied
Einstein's mistake for more than 100 years. Â*Don't you think it might
be time to think about it?
Robert B. Winn

Nonsense

Miguel Rios- Hide quoted text -

- Show quoted text -

The only person making bogus assertions here is you.
Check your dictionary for the meaning of isotropy.
If you do not have one, here is the definition:
Isotropy is uniformity in all directions. The word is made up from
Greek iso (equal) and tropos (direction).

Right....so when Einstein asserted that the train observer rush toward
the light front from the front and receding from the light front from
the rear he is describing a scenario that destroys the isotropy of the
speed of light in the train.

Why no, Ken, isotropy is still the same.

The track observer notes:
The light from the front of the train is heading backwards at c, while
the train observer rushes toward that light at v.
The light from the back of the train is heading forwards at c, while
the train observer is receding from it at v.
The speed of light is c in both cases. It is still isotropic in the
track frame.

The train observer notes:
The light from the front of the train is heading backwards at c.
The light from the back of the train is heading forwards at c.
The speed of light is c in both cases. It is still isotropic in the
train frame.

Perhaps you don't know what isotropic means.
After all, you don't know what "vector component" means.

So I guess it is you runt of the SRians failed to comprehend this
simple fact.

Ken Seto

On May 7, 12:54Â*pm, " wrote:
On 7 mayo, 14:34, rbwinn wrote:





On May 7, 10:40�am, " wrote:

On 7 mayo, 12:25, rbwinn wrote:

On May 7, 8:06 am, PD wrote:

Well, no, if lightining strikes the front and rear of a moving train,
leaving marks on the train and the track, the marks on the track will
be the length of the train apart, which relativity of simultaneity
cannot explain. �According to mathematics, if the bolts of lightning
are simultaneous in the frame of reference of the track, the marks on
the track will be closer together than the length of the train; if the
bolts of lightning are simultaneous in the frame of reference of the
train, the marks on the track are further apart than the length of the
train. �Reality shows that the marks on the track will be the length
of the train apart, disproving this false teaching of Einstein.
Robert B. Winn

Nonsense. That is a bunch of words salad. What in the world those
marks you mention have to do with relativity of simultaneity?
This shows you have not read anything about SR. What does it mean
"according to mathematics"? And where does Einstein say the nonsense
of the marks on the track?
There are two events (the strikes) and two observers. What these
observers see is the light signal information that tells them about
the occurrence of those strikes. That is the reason one of them can
certify "I saw both strikes to be simultaneous", while the second
certify "I saw the front strike occurring before the back strike".

Einstein was the one who thought of the train and two bolts of
lightning. Â*He did not fully consider the mathematics of the situation
he described. Â*Einstein did not say anything about marks on the track,
but I did. Â*The marks on the track prove that relativity of
simultaneity cannot exist in reality. Â*Lightning hits the front and
rear of the train simultaneously as seen by an observer by the track,
leaving marks on the front and rear of the train and marks on the
railroad track. Â*The distance between the marks on the train is the
length of the train. Â*The distance between the marks on the track is
the length of the train. Â*In order for relativity of simultaneity to
exist, the marks on the track would have to be closer together than
the length of the train. Â*Conversely, if the bolts of lightning are
seen simultaneously by the observer on the train, in order for
relativity of simultaneity to exist, the marks on the track would have
to be further apart than the length of the train. Â*Reality shows that
the marks on the track are the length of the train apart.
Robert B. Winn

That is complete nonsense. What Einstein wrote about this subject,
just for people like you, can be seen inhttp://www.bartleby.com/173/9.html
Observers do not have to measure any length (actually it would be very
tough to measure a 200000km train, not speaking of how to build it and
how to place the tracks). The only requirement is for the observers to
coincide at t=0 at x=0, that the strikes occurred at x=-X0 and at x=
+X0 and that the train with its observer is moving at a speed v into
the +x direction.
The observations consist of both observers receiving the light signals
that communicate them of the strikes occurrence. Where in the world
are you seeing something related to measuring lengths?

c=176,000 miles /sec. The mile is a unit of length. The velocity of
the train is also measured in units of length divided by time. In
addition to that, the train has a length that is measured in units of
length.
Robert B. Winn

On May 7, 1:11Â*pm, PD wrote:
On May 7, 1:45Â*pm, rbwinn wrote:





On May 7, 10:40�am, PD wrote:

On May 7, 11:25�am, rbwinn wrote:

Well, no, if lightining strikes the front and rear of a moving train,
leaving marks on the train and the track, the marks on the track will
be the length of the train apart, which relativity of simultaneity
cannot explain.

Sure, it explains it.

Here's how:
The track observer goes back after the train has passed and notes that
the marks on the track are 400 m apart. Remember that, for the track
observer, the strikes hit simultaneously. Since the marks are also on
the train, the track observer correctly notes that the train is 400 m
long. (This is what a length measurement entails anyway: marking the
locations of the ends of an object at the same time.)

Now the train observer goes back after the strikes have hit and notes
that the marks on the train are 500 m apart. But it's also true that
this observer saw the front strike happen before the rear strike ---
the strikes are not simultaneous in this frame. So it doesn't bother
this observer at all that the track observer sees the marks 400 m
apart. That's exactly what you'd expect if you marked the location of
the front of a moving object before you marked the location of the
rear of the moving object -- and that's exactly what the train
observer is sure happened.

The length of the train is frame-dependent. Whether the marks at the
end of the train were made at the same time, is also frame-dependent.

Does this help you understand?

The train has an actual length.

No, actually, it does not. Length is a frame-dependent quantity. The
value in one frame is no more "actual" than the value in another
frame. Now, there is a "rest length" which is the length measured in
the frame in which the train just happens to be at rest, but there is
nothing preferential about this frame.

Well, no, length is not a frame dependent quantity. Length is
length. There is no distance contraction.
Robert B. Winn

On 7 mayo, 18:46, rbwinn wrote:
On May 7, 1:11 pm, PD wrote:



On May 7, 1:45 pm, rbwinn wrote:

On May 7, 10:40�am, PD wrote:

On May 7, 11:25�am, rbwinn wrote:

Well, no, if lightining strikes the front and rear of a moving train,
leaving marks on the train and the track, the marks on the track will
be the length of the train apart, which relativity of simultaneity
cannot explain.

Sure, it explains it.

Here's how:
The track observer goes back after the train has passed and notes that
the marks on the track are 400 m apart. Remember that, for the track
observer, the strikes hit simultaneously. Since the marks are also on
the train, the track observer correctly notes that the train is 400 m
long. (This is what a length measurement entails anyway: marking the
locations of the ends of an object at the same time.)

Now the train observer goes back after the strikes have hit and notes
that the marks on the train are 500 m apart. But it's also true that
this observer saw the front strike happen before the rear strike ---
the strikes are not simultaneous in this frame. So it doesn't bother
this observer at all that the track observer sees the marks 400 m
apart. That's exactly what you'd expect if you marked the location of
the front of a moving object before you marked the location of the
rear of the moving object -- and that's exactly what the train
observer is sure happened.

The length of the train is frame-dependent. Whether the marks at the
end of the train were made at the same time, is also frame-dependent..

Does this help you understand?

The train has an actual length.

No, actually, it does not. Length is a frame-dependent quantity. The
value in one frame is no more "actual" than the value in another
frame. Now, there is a "rest length" which is the length measured in
the frame in which the train just happens to be at rest, but there is
nothing preferential about this frame.

Well, no, length is not a frame dependent quantity. Length is
length. There is no distance contraction.
Robert B. Winn

Says who?
And what does that have to do with relativity of simultaneity?
Einstein is quite specific in describing the situation in his book:

"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."

So you see, he is talking there about time relations of events, not
about length contraction. And sure enough length contraction is quite
real and measurable.

Miguel Rios

On 7 mayo, 18:38, rbwinn wrote:
On May 7, 12:54 pm, " wrote:

On 7 mayo, 14:34, rbwinn wrote:

On May 7, 10:40�am, " wrote:

On 7 mayo, 12:25, rbwinn wrote:

On May 7, 8:06 am, PD wrote:

Well, no, if lightining strikes the front and rear of a moving train,
leaving marks on the train and the track, the marks on the track will
be the length of the train apart, which relativity of simultaneity
cannot explain. �According to mathematics, if the bolts of lightning
are simultaneous in the frame of reference of the track, the marks on
the track will be closer together than the length of the train; if the
bolts of lightning are simultaneous in the frame of reference of the
train, the marks on the track are further apart than the length of the
train. �Reality shows that the marks on the track will be the length
of the train apart, disproving this false teaching of Einstein.
Robert B. Winn

Nonsense. That is a bunch of words salad. What in the world those
marks you mention have to do with relativity of simultaneity?
This shows you have not read anything about SR. What does it mean
"according to mathematics"? And where does Einstein say the nonsense
of the marks on the track?
There are two events (the strikes) and two observers. What these
observers see is the light signal information that tells them about
the occurrence of those strikes. That is the reason one of them can
certify "I saw both strikes to be simultaneous", while the second
certify "I saw the front strike occurring before the back strike".

Einstein was the one who thought of the train and two bolts of
lightning. He did not fully consider the mathematics of the situation
he described. Einstein did not say anything about marks on the track,
but I did. The marks on the track prove that relativity of
simultaneity cannot exist in reality. Lightning hits the front and
rear of the train simultaneously as seen by an observer by the track,
leaving marks on the front and rear of the train and marks on the
railroad track. The distance between the marks on the train is the
length of the train. The distance between the marks on the track is
the length of the train. In order for relativity of simultaneity to
exist, the marks on the track would have to be closer together than
the length of the train. Conversely, if the bolts of lightning are
seen simultaneously by the observer on the train, in order for
relativity of simultaneity to exist, the marks on the track would have
to be further apart than the length of the train. Reality shows that
the marks on the track are the length of the train apart.
Robert B. Winn

That is complete nonsense. What Einstein wrote about this subject,
just for people like you, can be seen inhttp://www.bartleby.com/173/9.html
Observers do not have to measure any length (actually it would be very
tough to measure a 200000km train, not speaking of how to build it and
how to place the tracks). The only requirement is for the observers to
coincide at t=0 at x=0, that the strikes occurred at x=-X0 and at x=
+X0 and that the train with its observer is moving at a speed v into
the +x direction.
The observations consist of both observers receiving the light signals
that communicate them of the strikes occurrence. Where in the world
are you seeing something related to measuring lengths?

c=176,000 miles /sec. The mile is a unit of length. The velocity of
the train is also measured in units of length divided by time. In
addition to that, the train has a length that is measured in units of
length.
Robert B. Winn

And what are you trying to say with that?.
We are talking about the relativity of simultaneity, and that refers
to time relations, not to length contraction.
The whole point of this train thought experiment is to prove that time
is not absolute.

Miguel Rios

On May 7, 3:54Â*pm, " wrote:
On 7 mayo, 18:46, rbwinn wrote:





On May 7, 1:11 pm, PD wrote:

On May 7, 1:45 pm, rbwinn wrote:

On May 7, 10:40�am, PD wrote:

On May 7, 11:25�am, rbwinn wrote:

Well, no, if lightining strikes the front and rear of a moving train,
leaving marks on the train and the track, the marks on the track will
be the length of the train apart, which relativity of simultaneity
cannot explain.

Sure, it explains it.

Here's how:
The track observer goes back after the train has passed and notes that
the marks on the track are 400 m apart. Remember that, for the track
observer, the strikes hit simultaneously. Since the marks are also on
the train, the track observer correctly notes that the train is 400 m
long. (This is what a length measurement entails anyway: marking the
locations of the ends of an object at the same time.)

Now the train observer goes back after the strikes have hit and notes
that the marks on the train are 500 m apart. But it's also true that
this observer saw the front strike happen before the rear strike ---
the strikes are not simultaneous in this frame. So it doesn't bother
this observer at all that the track observer sees the marks 400 m
apart. That's exactly what you'd expect if you marked the location of
the front of a moving object before you marked the location of the
rear of the moving object -- and that's exactly what the train
observer is sure happened.

The length of the train is frame-dependent. Whether the marks at the
end of the train were made at the same time, is also frame-dependent.

On May 7, 3:57Â*pm, " wrote:
On 7 mayo, 18:38, rbwinn wrote:





On May 7, 12:54 pm, " wrote:

On 7 mayo, 14:34, rbwinn wrote:

On May 7, 10:40�am, " wrote:

On 7 mayo, 12:25, rbwinn wrote:

On May 7, 8:06 am, PD wrote:

Well, no, if lightining strikes the front and rear of a moving train,
leaving marks on the train and the track, the marks on the track will
be the length of the train apart, which relativity of simultaneity
cannot explain. �According to mathematics, if the bolts of lightning
are simultaneous in the frame of reference of the track, the marks on
the track will be closer together than the length of the train; if the
bolts of lightning are simultaneous in the frame of reference of the
train, the marks on the track are further apart than the length of the
train. �Reality shows that the marks on the track will be the length
of the train apart, disproving this false teaching of Einstein.
Robert B. Winn

Nonsense. That is a bunch of words salad. What in the world those
marks you mention have to do with relativity of simultaneity?
This shows you have not read anything about SR. What does it mean
"according to mathematics"? And where does Einstein say the nonsense
of the marks on the track?
There are two events (the strikes) and two observers. What these
observers see is the light signal information that tells them about
the occurrence of those strikes. That is the reason one of them can
certify "I saw both strikes to be simultaneous", while the second
certify "I saw the front strike occurring before the back strike".

Einstein was the one who thought of the train and two bolts of
lightning. Â*He did not fully consider the mathematics of the situation
he described. Â*Einstein did not say anything about marks on the track,
but I did. Â*The marks on the track prove that relativity of
simultaneity cannot exist in reality. Â*Lightning hits the front and
rear of the train simultaneously as seen by an observer by the track,
leaving marks on the front and rear of the train and marks on the
railroad track. Â*The distance between the marks on the train is the
length of the train. Â*The distance between the marks on the track is
the length of the train. Â*In order for relativity of simultaneity to
exist, the marks on the track would have to be closer together than
the length of the train. Â*Conversely, if the bolts of lightning are
seen simultaneously by the observer on the train, in order for
relativity of simultaneity to exist, the marks on the track would have
to be further apart than the length of the train. Â*Reality shows that
the marks on the track are the length of the train apart.
Robert B. Winn

That is complete nonsense. What Einstein wrote about this subject,
just for people like you, can be seen inhttp://www.bartleby.com/173/9.html
Observers do not have to measure any length (actually it would be very
tough to measure a 200000km train, not speaking of how to build it and
how to place the tracks). The only requirement is for the observers to
coincide at t=0 at x=0, that the strikes occurred at x=-X0 and at x=
+X0 and that the train with its observer is moving at a speed v into
the +x direction.
The observations consist of both observers receiving the light signals
that communicate them of the strikes occurrence. Where in the world
are you seeing something related to measuring lengths?

c=176,000 miles /sec. Â*The mile is a unit of length. Â*The velocity of
the train is also measured in units of length divided by time. Â*In
addition to that, the train has a length that is measured in units of
length.
Robert B. Winn

And what are you trying to say with that?.
We are talking about the relativity of simultaneity, and that refers
to time relations, not to length contraction.
The whole point of this train thought experiment is to prove that time
is not absolute.

Miguel Rios- Hide quoted text -

- Show quoted text -

Relativity of simultaneity, as explained by Einstein, is dependent on
length contraction. If lightning strikes both ends of a train,
leaving marks on the ends of the train and marks on the track, the
only way the marks can be closer together than the length of the
train, as is required if the lightning at the front strikes first, is
if there is a distance contraction, as seen from the frame of
reference of the track.
Robert B. Winn

On May 7, 5:46Â*pm, rbwinn wrote:
On May 7, 1:11Â*pm, PD wrote:



On May 7, 1:45Â*pm, rbwinn wrote:

On May 7, 10:40�am, PD wrote:

On May 7, 11:25�am, rbwinn wrote:

Well, no, if lightining strikes the front and rear of a moving train,
leaving marks on the train and the track, the marks on the track will
be the length of the train apart, which relativity of simultaneity
cannot explain.

Sure, it explains it.

Here's how:
The track observer goes back after the train has passed and notes that
the marks on the track are 400 m apart. Remember that, for the track
observer, the strikes hit simultaneously. Since the marks are also on
the train, the track observer correctly notes that the train is 400 m
long. (This is what a length measurement entails anyway: marking the
locations of the ends of an object at the same time.)

Now the train observer goes back after the strikes have hit and notes
that the marks on the train are 500 m apart. But it's also true that
this observer saw the front strike happen before the rear strike ---
the strikes are not simultaneous in this frame. So it doesn't bother
this observer at all that the track observer sees the marks 400 m
apart. That's exactly what you'd expect if you marked the location of
the front of a moving object before you marked the location of the
rear of the moving object -- and that's exactly what the train
observer is sure happened.

The length of the train is frame-dependent. Whether the marks at the
end of the train were made at the same time, is also frame-dependent..

Does this help you understand?

The train has an actual length.

No, actually, it does not. Length is a frame-dependent quantity. The
value in one frame is no more "actual" than the value in another
frame. Now, there is a "rest length" which is the length measured in
the frame in which the train just happens to be at rest, but there is
nothing preferential about this frame.

Well, no, length is not a frame dependent quantity.

That is at variance with experimental observation. Nice conjecture,
though.
How's that working for ya?

Â*Length is
length. Â*There is no distance contraction.
Robert B. Winn