SR time dilation on remote objects ?

Dear Marcel Luttgens:

"Marcel Luttgens" wrote in message
om...
"N:dlzc D:aol T:com \(dlzc\)" N: dlzc1 D:cox wrote in
message news:jb01d.158753$4o.21393@fed1read01...
....
What would the velocity of light appear to an observer moving at
v wrt a light emitter, if the observer considered himself at rest
(using Galilean relativity)? Is not the answer c-v? What would then
be the observed frequency Nu(o) wrt the emitted frequency Nu?

Gallilean relativity holds that one cannot tell what speed one is
travelling based on measurements in the confines of a ship's cabin.
Gallileo, had he then been able with his lanterns and clocks to measure
c,
would have still measured c, since all measurements of c are TWLS
measurements.

An observer moving away from a light source at a velocity v
(along a straight line of course) can consider himself
at rest wrt the source, and that the light moves at c-v
relatively to him.

No. Gallilean, not Luttgensian, relativity was the question. Neither
Gallileo, Newton, Maxwell, nor Einstein (or most of the rest of the 20th
century's scientists) agree with your logic.

There is no evidence that light travels with c+v or c-v, and there are some
very strange requirements that must be met if it does. In order to have
TWLS = c, the light must reflect off a mirror with c-/+v after arriving at
c+/-v, which would violate conservation of momentum.

The razor cuts both ways. You have been shaved.

David A. Smith

"N:dlzc D:aol T:com \(dlzc\)" N: dlzc1 D:cox wrote in message news:Wvh1d.158901$4o.147134@fed1read01...
Dear Marcel Luttgens:

"Marcel Luttgens" wrote in message
om...
"N:dlzc D:aol T:com \(dlzc\)" N: dlzc1 D:cox wrote in
message news:jb01d.158753$4o.21393@fed1read01...
...
What would the velocity of light appear to an observer moving at
v wrt a light emitter, if the observer considered himself at rest
(using Galilean relativity)? Is not the answer c-v? What would then
be the observed frequency Nu(o) wrt the emitted frequency Nu?

Gallilean relativity holds that one cannot tell what speed one is
travelling based on measurements in the confines of a ship's cabin.
Gallileo, had he then been able with his lanterns and clocks to measure
c,
would have still measured c, since all measurements of c are TWLS
measurements.

An observer moving away from a light source at a velocity v
(along a straight line of course) can consider himself
at rest wrt the source, and that the light moves at c-v
relatively to him.

No. Gallilean, not Luttgensian, relativity was the question. Neither
Gallileo, Newton, Maxwell, nor Einstein (or most of the rest of the 20th
century's scientists) agree with your logic.

There is no evidence that light travels with c+v or c-v, and there are some
very strange requirements that must be met if it does. In order to have
TWLS = c, the light must reflect off a mirror with c-/+v after arriving at
c+/-v, which would violate conservation of momentum.


Remember how the Michelson/Morley experiment was first interpreted?
By assuming c-v and c+v! But this was according to some observer.
Nobody ever claimed that c itself changed.

The razor cuts both ways. You have been shaved.

Not at all.


David A. Smith

Marcel Luttgens

Bjoern Feuerbacher wrote in message ...
Marcel Luttgens wrote:
[snip]



An observer moving away from a light source at a velocity v
(along a straight line of course) can consider himself
at rest wrt the source, and that the light moves at c-v
relatively to him.

No, he can't. That would only make sense if the velocity c of light
were always relative to the source. And we know quite well that that
is not true.


I never claimed the contrary.


Let's call Nu the frequency of the emitted light.
If the observer is at rest wrt the light source, he considers
that light moves at c wrt him, and that he receives Nu waves/sec,
where Nu = c/lambda (c is expressed in cm/sec, and the wavelength
lambda is expressed in cm).
If the observer moves away at v wrt the source (or if the source moves
away from him at v, which is the case in an expanding universe),

How often do I need to tell you that the cosmological red shift should
not be interpreted as being due to a Doppler effect? Perhaps this link
will help:
http://www.astronomycafe.net/cosm/expan.html

Assuming a GR universe, you are right. But my universe is Euclidian.


he considers that light moves at c-v wrt him,

No, he doesn't. See above.

He can.



and that he receives
Nu(o) waves/sec, where Nu(o) = (c-v)/lambda.
Hence, for him, Nu/Nu(o) = c / (c-v), or lambda(o) = lambda * c/(c-v).
Then 1 + z = lambda(o) / lambda = c/(c-v), and
z = c/(c-v) - 1 = v/(c-v), or
z = (v/c)/(1-v/c), which is my formula for an expanding universe.

It is irrelevant what the observer "considers". The only relevant thing
is what the observer *measures*. And it is simply not true that the
red shift from a source moving at v away from the observer is given
by your formula. The actual red shift for that situation is given
by the formula of special relativity:
z = sqrt((1+v/c)/(1-v/c)) - 1
For small v/c, this gives z = v/c, as it should.

http://hyperphysics.phy-astr.gsu.edu/hbase/relativ/reldop2.html


For small v/c, my formula also gives z = v/c.
And I already told you why SR doesn't apply.


[snip]

With 1/H = 15 Gy, the correlation coefficient between the results
obtained with this formula and those given by Ted Wright's calculator
(with H = 71 km/sec/Mpc (about 13.7 Gy), Omega M = 0.27 and a flat
universe) for the series z = 0.1, 0.5, 1, 2, 3, 5 and 6 is 0.999.

Err, why don't you compare the predictions of your formula to the actual
data? (astro-ph/0402512)


Are you implying that the GR formulae used by Ted Wright in his
calculator are wrong?


IOW, there is no statistically significative difference between
results obtained when assuming an Euclidean stable universe or
a GR expanding universe.
Using Occam's razor, one would consider that the universe is stable,
rather than expanding.

I already told you that red shifts are by far not the only piece of
evidence for an expanding universe.

All those pieces of evidence are far from being unequivocal.

And considering that your formula
above for red shift is nonsense, your situation becomes even worse.


And my formula is right.


Bye,
Bjoern

Marcel Luttgens

Bjoern Feuerbacher wrote in message ...
Marcel Luttgens wrote:
Bjoern Feuerbacher wrote in message ...


snip

Now that you have the answers,

No, I don't. See above.


and remembering the definition of frequency
and wavelength, you should easily find my formula z = (v/c)/(1 - v/c).

This is the formula one would get if the *emitter* is at rest, and the
*observer* is moving away from it with velocity v, in a medium in which
the wave travels with the velocity c.

Nice, you got my formula.


I don't know how you managed to get this formula for the situation in
which the observer is at rest, and the emitter is moving away from him.
Show your work, please.


Because both situations are equivalent. :-)

If you now say that both situations are equivalent, since velocity is
relative, then that does not help you: that is only true if there is no
medium in which the light travels, and then one has to use Special
Relativity to get the formula for the Doppler effect - which yet again
contradicts yours above.


Using SR is only justified if (according to the observer), there is time
dilation on the emitter.
But the emitter can as well claim that time is dilated on the observer's clock.
So, both dilations cancel each other.

[snip]



Bye,
Bjoern

Marcel Luttgens

Marcel Luttgens wrote:
Bjoern Feuerbacher wrote in message ...

Marcel Luttgens wrote:
[snip]




An observer moving away from a light source at a velocity v
(along a straight line of course) can consider himself
at rest wrt the source, and that the light moves at c-v
relatively to him.

No, he can't. That would only make sense if the velocity c of light
were always relative to the source. And we know quite well that that
is not true.



I never claimed the contrary.

Then the velocity of light is c, not c-v, and your argument below breaks
down.


Let's call Nu the frequency of the emitted light.
If the observer is at rest wrt the light source, he considers
that light moves at c wrt him, and that he receives Nu waves/sec,
where Nu = c/lambda (c is expressed in cm/sec, and the wavelength
lambda is expressed in cm).
If the observer moves away at v wrt the source (or if the source moves
away from him at v, which is the case in an expanding universe),

How often do I need to tell you that the cosmological red shift should
not be interpreted as being due to a Doppler effect? Perhaps this link
will help:
http://www.astronomycafe.net/cosm/expan.html


Assuming a GR universe, you are right.

Do you claim that GR is wrong, or that one should not apply it to the
whole universe?


But my universe is Euclidian.

Huh? In your universe, the signature of the metric is positive?


he considers that light moves at c-v wrt him,

No, he doesn't. See above.


He can.

It would make absolutely no sense for him to consider that. Why on
earth should he do that?

And, BTW, it is totally irrelevant what he "considers". What is
important is what he would *measure*. And he would measure c, not c-v.



and that he receives
Nu(o) waves/sec, where Nu(o) = (c-v)/lambda.
Hence, for him, Nu/Nu(o) = c / (c-v), or lambda(o) = lambda * c/(c-v).
Then 1 + z = lambda(o) / lambda = c/(c-v), and
z = c/(c-v) - 1 = v/(c-v), or
z = (v/c)/(1-v/c), which is my formula for an expanding universe.

It is irrelevant what the observer "considers". The only relevant thing
is what the observer *measures*. And it is simply not true that the
red shift from a source moving at v away from the observer is given
by your formula. The actual red shift for that situation is given
by the formula of special relativity:
z = sqrt((1+v/c)/(1-v/c)) - 1
For small v/c, this gives z = v/c, as it should.

http://hyperphysics.phy-astr.gsu.edu/hbase/relativ/reldop2.html


For small v/c, my formula also gives z = v/c.

BFD.

For larger v, your formula does not give sensible results anymore. If
you think it does, present some data to back this up. (hint: I am *not*
merely talking about cosmological data here - if your formula is right,
it should work for *all* phenomena where Doppler shifts occur)


And I already told you why SR doesn't apply.

No, you merely demonstrated that you don't understand it.




With 1/H = 15 Gy, the correlation coefficient between the results
obtained with this formula and those given by Ted Wright's calculator
(with H = 71 km/sec/Mpc (about 13.7 Gy), Omega M = 0.27 and a flat
universe) for the series z = 0.1, 0.5, 1, 2, 3, 5 and 6 is 0.999.

Err, why don't you compare the predictions of your formula to the actual
data? (astro-ph/0402512)



Are you implying that the GR formulae used by Ted Wright in his
calculator are wrong?

I am implying nothing like that. I merely ask you why you use
theoretically calculated numbers instead of the actual data.

Evasion noted.



IOW, there is no statistically significative difference between
results obtained when assuming an Euclidean stable universe or
a GR expanding universe.
Using Occam's razor, one would consider that the universe is stable,
rather than expanding.

I already told you that red shifts are by far not the only piece of
evidence for an expanding universe.


All those pieces of evidence are far from being unequivocal.

If you can explain all of them with your own model, feel free to do
so. So far, you have ignored most of them simply.



And considering that your formula
above for red shift is nonsense, your situation becomes even worse.



And my formula is right.

Provide evidence for that assertion, please.

And explain how one can derive it, in the light of the fact that
the speed of light for the observer is c, not c-v.


Bye,
Bjoern

Marcel Luttgens wrote:
"N:dlzc D:aol T:com \(dlzc\)" N: dlzc1 D:cox wrote in message news:Wvh1d.158901$4o.147134@fed1read01...

Dear Marcel Luttgens:

"Marcel Luttgens" wrote in message
.com...

"N:dlzc D:aol T:com \(dlzc\)" N: dlzc1 D:cox wrote in
message news:jb01d.158753$4o.21393@fed1read01...

...

What would the velocity of light appear to an observer moving at
v wrt a light emitter, if the observer considered himself at rest
(using Galilean relativity)? Is not the answer c-v? What would then
be the observed frequency Nu(o) wrt the emitted frequency Nu?

Gallilean relativity holds that one cannot tell what speed one is
travelling based on measurements in the confines of a ship's cabin.
Gallileo, had he then been able with his lanterns and clocks to measure
c,
would have still measured c, since all measurements of c are TWLS
measurements.

An observer moving away from a light source at a velocity v
(along a straight line of course) can consider himself
at rest wrt the source, and that the light moves at c-v
relatively to him.

No. Gallilean, not Luttgensian, relativity was the question. Neither
Gallileo, Newton, Maxwell, nor Einstein (or most of the rest of the 20th
century's scientists) agree with your logic.

There is no evidence that light travels with c+v or c-v, and there are some
very strange requirements that must be met if it does. In order to have
TWLS = c, the light must reflect off a mirror with c-/+v after arriving at
c+/-v, which would violate conservation of momentum.



Remember how the Michelson/Morley experiment was first interpreted?
By assuming c-v and c+v!

That's news to me. Please provide a reference for that assertion.

And even if that is right - so what? We know today from other
observations that this interpretation was wrong.


But this was according to some observer.
Nobody ever claimed that c itself changed.

According to SR, the speed of light measured by every observer is
*always* c. No matter how the observer is moving, no matter how the
emitter is moving.


The razor cuts both ways. You have been shaved.


Not at all.

Yes, you indeed have been.



Bye,
Bjoern

Marcel Luttgens wrote:
Bjoern Feuerbacher wrote in message ...

Marcel Luttgens wrote:

Bjoern Feuerbacher wrote in message ...


[snip]


and remembering the definition of frequency
and wavelength, you should easily find my formula z = (v/c)/(1 - v/c).

This is the formula one would get if the *emitter* is at rest, and the
*observer* is moving away from it with velocity v, in a medium in which
the wave travels with the velocity c.


Nice, you got my formula.

For a completely different situation than you presented it!!! Doesn't
that disturb you at all?

For the situation *you* presented, and which you need if you wish
to describe the red shift by the Doppler effect, this formula does
*not* hold! Additionally, the formula above does *only* hold if there
is a *medium* in which the waves travels!


I don't know how you managed to get this formula for the situation in
which the observer is at rest, and the emitter is moving away from him.
Show your work, please.



Because both situations are equivalent. :-)

No, they aren't. As soon as there is a medium in which the wave travels,
the situations "observer resting, emitter travelling" and "observer
travelling, emitter resting" are *not* equivalent anymore.

OTOH, if there is no medium, the formula does *not* apply.


If you now say that both situations are equivalent, since velocity is
relative, then that does not help you: that is only true if there is no
medium in which the light travels, and then one has to use Special
Relativity to get the formula for the Doppler effect - which yet again
contradicts yours above.



Using SR is only justified if (according to the observer), there is
time dilation on the emitter.

Absolute utter nonsense. SR *always* has to be used if there are
two different frames.


But the emitter can as well claim that time is dilated on the observer's clock.
So, both dilations cancel each other.

*sigh*

*That* utter nonsense again...



Bye,
Bjoern

Dear Marcel Luttgens:

"Marcel Luttgens" wrote in message
om...
"N:dlzc D:aol T:com \(dlzc\)" N: dlzc1 D:cox wrote in
message news:Wvh1d.158901$4o.147134@fed1read01...
....
An observer moving away from a light source at a velocity v
(along a straight line of course) can consider himself
at rest wrt the source, and that the light moves at c-v
relatively to him.

No. Gallilean, not Luttgensian, relativity was the question. Neither
Gallileo, Newton, Maxwell, nor Einstein (or most of the rest of the 20th
century's scientists) agree with your logic.

There is no evidence that light travels with c+v or c-v, and there are
some
very strange requirements that must be met if it does. In order to have
TWLS = c, the light must reflect off a mirror with c-/+v after arriving
at
c+/-v, which would violate conservation of momentum.


Remember how the Michelson/Morley experiment was first interpreted?
By assuming c-v and c+v!

Michelson's paper is on the internet. Care to review it, to substantiate
your claim?

But this was according to some observer.
Nobody ever claimed that c itself changed.

You have. You have said that light travels at 'c-v'.

The razor cuts both ways. You have been shaved.

Not at all.

Quite. And clean shaven you appear to be!

David A. Smith

Bjoern Feuerbacher wrote in message ...
Marcel Luttgens wrote:
Bjoern Feuerbacher wrote in message ...

Marcel Luttgens wrote:

Bjoern Feuerbacher wrote in message ...


[snip]


and remembering the definition of frequency
and wavelength, you should easily find my formula z = (v/c)/(1 - v/c).

This is the formula one would get if the *emitter* is at rest, and the
*observer* is moving away from it with velocity v, in a medium in which
the wave travels with the velocity c.


Nice, you got my formula.

For a completely different situation than you presented it!!! Doesn't
that disturb you at all?

For the situation *you* presented, and which you need if you wish
to describe the red shift by the Doppler effect, this formula does
*not* hold! Additionally, the formula above does *only* hold if there
is a *medium* in which the waves travels!


I use LET, which assumes a medium.


I don't know how you managed to get this formula for the situation in
which the observer is at rest, and the emitter is moving away from him.
Show your work, please.



Because both situations are equivalent. :-)

No, they aren't. As soon as there is a medium in which the wave travels,
the situations "observer resting, emitter travelling" and "observer
travelling, emitter resting" are *not* equivalent anymore.


Wrong! For the observer, light travels at c-v in both cases.

OTOH, if there is no medium, the formula does *not* apply.


Of course, it doesn't apply in a GR universe. But why should our universe
obey GR rules?


If you now say that both situations are equivalent, since velocity is
relative, then that does not help you: that is only true if there is no
medium in which the light travels, and then one has to use Special
Relativity to get the formula for the Doppler effect - which yet again
contradicts yours above.



Using SR is only justified if (according to the observer), there is
time dilation on the emitter.

Absolute utter nonsense. SR *always* has to be used if there are
two different frames.


This is quibbling. GRists on this NG are notorious quibblers.
I meant that time dilation is mutual, hence that SR gives the same result
for the observer and the source, hence that its use is irrelevant in
this case.


But the emitter can as well claim that time is dilated on the observer's clock.
So, both dilations cancel each other.

*sigh*

*That* utter nonsense again...


Only for GRists. Are you unable to use or simply understand LET?



Bye,
Bjoern

Marcel Luttgens

Marcel Luttgens wrote:
Bjoern Feuerbacher wrote in message ...

Marcel Luttgens wrote:

Bjoern Feuerbacher wrote in message ...


Marcel Luttgens wrote:


Bjoern Feuerbacher wrote in message ...


[snip]



and remembering the definition of frequency
and wavelength, you should easily find my formula z = (v/c)/(1 - v/c).

This is the formula one would get if the *emitter* is at rest, and the
*observer* is moving away from it with velocity v, in a medium in which
the wave travels with the velocity c.


Nice, you got my formula.

For a completely different situation than you presented it!!! Doesn't
that disturb you at all?

Apparently not.


For the situation *you* presented, and which you need if you wish
to describe the red shift by the Doppler effect, this formula does
*not* hold! Additionally, the formula above does *only* hold if there
is a *medium* in which the waves travels!



I use LET, which assumes a medium.

Well, please show me how you derive your formula from LET.

So far, you have claimed that it follows from the observer "considering"
the light to move with a velocity c-v wrt him. But if light moves in
a medium, and the observer rests in that medium, that "consideration"
would be wrong!



I don't know how you managed to get this formula for the situation in
which the observer is at rest, and the emitter is moving away from him.
Show your work, please.



Because both situations are equivalent. :-)

No, they aren't. As soon as there is a medium in which the wave travels,
the situations "observer resting, emitter travelling" and "observer
travelling, emitter resting" are *not* equivalent anymore.



Wrong!

No, right.


For the observer, light travels at c-v in both cases.

Nonsense. Why should it? If light travels with c in a medium, and
the observer rests in that medium, light travels at c for him, not
at c-v.


OTOH, if there is no medium, the formula does *not* apply.



Of course, it doesn't apply in a GR universe.

GR is totally irrelevant for the argument here.


But why should our universe obey GR rules?

Do you claim that GR in general is not valid, or only that one shouldn't
it apply to the universe as a whole?



If you now say that both situations are equivalent, since velocity is
relative, then that does not help you: that is only true if there is no
medium in which the light travels, and then one has to use Special
Relativity to get the formula for the Doppler effect - which yet again
contradicts yours above.



Using SR is only justified if (according to the observer), there is
time dilation on the emitter.

Absolute utter nonsense. SR *always* has to be used if there are
two different frames.



This is quibbling.

No, not at all.


GRists on this NG are notorious quibblers.

Hint: if you actually understood Relativity, you would see that we are
not quibbling, but pointing out crucial points.


I meant that time dilation is mutual, hence that SR gives the same result
for the observer and the source, hence that its use is irrelevant in
this case.

Your usual nonsense.


But the emitter can as well claim that time is dilated on the observer's clock.
So, both dilations cancel each other.

*sigh*

*That* utter nonsense again...



Only for GRists. Are you unable to use or simply understand LET?

LET is claimed to give the same results as SR.


Bye,
Bjoern