Re: Train gedanken pitfall

On Jun 18, 4:03 am, "Whoever" <no...@xxxxxxxxxxx> wrote:
"Bruce Richmond" <bsr3...@xxxxxxxxxxx> wrote in message

news:885e88c4-70b2-420b-b3d3-d2354a1038b1@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx

On Jun 17, 11:33 pm, "Whoever" <no...@xxxxxxxxxxx> wrote:
"Bruce Richmond" <bsr3...@xxxxxxxxxxx> wrote in message
We define the clocks sync so that it does.  Which is circular if we
intend
to then use those clocks to show the one-way speed of light is the same
in
all directions.

There is no need to prove it.  It is a given.

Only if we're accepting SR and its definition of clock sync.  If you are
accepting that as given, then the whole exercise is pointless.  Because we
are taking as given what we are trying experimentally to show !!!!

If you wish to test SR then the clock sync must be done in accordance
with SR or you are no longer testing SR but some other theory. Every
method of clock sync requires some assumptions. Using ones that are
different from SR does not prove those of SR incorrect.

BTW, your sync by slow transport assumes that moving the clock does
not affect its setting. It is generally accepted that SR agrees with
that assumption, but I can show otherwise. Put the clock on a moving
train Next to the clock at A' and sync it with that clock. Slowly
transport it along the train and place it next to the clock at B'.
According to SR the transported clock must now be in sync with the
clock at B'. From the tracks we see that the clock at B' is out of
sync with the clock at A', so the setting of the transported clock had
to change as it was transported to be in sync at its new location. We
are not talking about time dialation here. Transport the clock back
to A' and the setting reverts back so that it is in sync with the
clock at A'.

One test that could be done with two clocks that would not require
synchronization would be to see if one signal could be made to pass
another. Have the passage of signals M and N recorded at clock A and
a distant clock B. If signal M arrives at A 5 microseconds before
signal N does it also arrive at B 5 microseconds before. If signal N
somehow arrived at B first then the second postulate would be proven
incorrect. Does having signal N emitted from a moving source make any
difference?

Since there is no absolute time

There you go making assumptions again.  In SR there is no absolute time.
In
other theories there is.  But if we are trying to test if SR's postulate
of
a constant one-way speed of light is correct, we cant start with what SR
predicts.

We were discussing SR and in SR there is no absolute time.

We may be discussing SR, but we're not assuming it is correct .. seeing
we're taking about an experiment aimed at testing one the things SR says.

We are discussing here how one can show experimentally that the postulate of
SR of a uniform maximum speed of light is correct.  If the only way we can
prove it correct is to assume it is, then that is pointless.  Which is what
I've been saying.

Something you might find interesting.

http://www.mathpages.com/home/kmath229/kmath229.htm

One could
define an absolute time in some other theory, but that has no effect
on SR.  SR does not have to prove other theories wrong to be correct
itself.

I didn't claim it was .. you're making up things to argue with here.

You wrote, "That's if you follow the method and accept Einstein's
definition of synchronization. The method only synchronizes clocks if
it is true that the one-way speed of light IS the same in all
directions. If it isn't, then the clocks will actually be out-of-sync
and give a false result."

The SR clock sync method makes the speed of light the same in all
directions. The only way you will find that not to be true is if you
make assumptions that do not agree with SR. That in effect says the
other theory is correct and SR just gives the illusion of being
correct, or is wrong.

BTW, LET says that the speed of light is c in all directions only in
the ether frame. But in his 1904 paper Lorentz shows how all frames
end up measuring the speed of light to be c in all directions. In the
end the math becomes the same as that of SR.

If it provides observations that are consistant with what is
observed then it can stand on its own.

That's also what I've already said.  You're not arguing against me here ..
we're agreeing.

The point is we cannot independently test the one-way speed of light as
being uniform by using separate clocks and measuring the time it takes to
travel WITHOUT assuming that it already is.

That's the whole point.  To measuring time and distance for light to
travel
from A to B and calculating the speed makes lots of assumptions about SR
in
order to show the the speed is c.

there is no way to prove these agreements
faulty, so long as all signals travel at the same maximum speed.

But that is what we are trying to show .. that they all travel at the
same
maximum speed.

No, the argument here was about whether the speed of light was c in
both directions.

SR says it is .. but we don't have an experiment to show that.  Unless we
construct one on the assumption that it is .. one that forces it to be ..
and then, no surprise, we find that it is.  It's pointless

I agree, which is why I just say the clock sync method makes the speed
of light isotropic c.

If light travels at some costant speed as it does in
ether theory then we can make it travel at an inverient c.  If one ray
of light somehow manages to cover the distance AB quicker than another
no clock sync method will make it inverient c.

In LET there is an absolute ether frame, and the 'true' speed of light is
its speed in that frame.  In LET it is the physical distortion of our
measuring devices (clocks and rulers) that makes light APPEAR to travel at c
in other frames.  LET is an odd theory :)

Yes, an odd theory that uses the same math as SR and thus makes the
same predictions :)

We can't to and experiment to show that that only works if
we assume it is already true.

We can do the experiment if someone is stupid enough to want to see it
done.  We know it is circular.  If they don't see that it is their
problem.

It is only circular if we make it circular.

We can measure the two-way speed of light, because we don't need to worry
about clock sync, so we don't need to assume SR is correct.

SR clearly states that the one way speed of light is c. The two way
measurement doesn't tell you that.

The whole point here is that an experiment to measure the one-way speed of
light (using clocks at different locations) isn't possible t odo UNLESS we
assume SR is right and use SR's conventions for clock sync which are based
on stipulating the very thing we are trying to measure.





Someone can choose to sync the clocks differently and get different
results, but that does not make those results any more correct.

Nor any less.

There's no point in doing an
experiment to show a consistent one-way speed of light if that
experiment
assumes its own conclusion.  All it CAN do is calculate what the
one-way
speed WOULD be if it is indeed the same in all directions.

It IS the same because we MADE it the same.

Exactly .. only by arbitrary choice.  Ie we have assumed what SR says
about
one-way light speed and what clock sync means.  Different sync methods
could
lead to different results.

Those different results would lead to laws that are more complex than
those of SR.

I really don't care .. it doesn't matter.  The point is, that we need to
have agreement on clock sync, and that depends on us setting the clocks on
the assumption that the one-way speed of light is what SR says .. therefore
precluding by definition any other theories that may define clock sync in a
different way.  Its an experiment that cannot fail, which is no experiment
at all.

All we can say is that if we assume SR is correct about one-way speed of
light, and set up our experiment in a way that makes it so, then we will
get
a uniform one-way speed of light.  That really does nothing other than
waste
everyones time.  Absolute or not :):)

No, it will have established a sync that makes the laws the same for
all coordinate systems.  That is far better than having different laws
in every system.

Who is saying we need that?


Anyone that says the speed of light is not isotropic c. According to
them any law that assumed light traveled at isotropic c would be
incorrect.


Fortunately we don't NEED to show the one-way speed of light is the
same
in
all directions in order to test SR.  SR can make man predictions and
so
far
they are all supported (ie, not disproved) by experimental evidence..- Hide quoted text -

- Show quoted text -- Hide quoted text -

- Show quoted text -

.

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