SR time dilation on remote objects ?

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

In that "snip", there was my argument which showed that the speed
of light is c for the observer, not c-v. Interesting that you choose
to ignore it.



Your argument is irrelevant.

No, not at all.


The observer can claim that light moves at c-v wrt him.

1) He has no reason to claim that. Such a claim would be complete
nonsense and would have nothing to do with what actually happens.
2) It is irrelevant what the observer *claims*. Red shift is determined
by whart the speed of light *is*, not by what the observer *claims*.


But the point is that my formula is right, what you denied
till now.

*sigh*


I *never* denied that it is right *in a certain situation, using
certain assumptions*.
In a situation and using assumptions which have *nothing at all*
to do with cosmology!!!


Because, as the observer considers that his distance from the source
(or the source considers that its distance from the observer)
remains d, he/it can assume that light moves at c-v. This is
logically and mathematically right.

This is nonsense. Red shift is determined by what actually *happens*,
not by what the observer "considers" to happen!



Here is a less "synthetic" derivation:

Imagine that a crest has just reached an observer.
The wavelength of the emitted light is lambda, and its frequency Nu
corresponds of course to c/lambda.
If the observer is at rest wrt the source, he will get the next crest
after 1/Nu = lambda/c seconds.

Agreed.



The question is now, after what time will an observer moving away
at v from the source will get the next crest?

Stop right here. In your original scenario, the observer was resting,
and the source was moving.

And no, as long as one uses Galilean relativity (as you keep doing)
and a medium for light, those two situations are *not* equivalent.



Both situations are strictly equivalent.

As long as one uses Galilean relativity (as you keep doing)
and a medium for light, those two situations are *not* equivalent.


They would be equivalent in SR and LET - but you use neither of
those two theories here!!!!!


The answer is straightforward, after lambda/(c-v) seconds.

Only right if Galilean relativity applies and if light moves with
c in a medium.



Why not?

I explained that about 10 times now. You are *really* unteachable.


And (c-v) proves that the observer could claim that, mathematically,
light moves at such velocity.

Light does not move mathematically. Light moves *only* physically.

You make no sense.


Of course, he knows perfectly well that
light moves "physically" at c.

Red shift is determined by the *physical* speed of light,
not by an entirely hypothetical, totally nonsensical and unrealistic
so-called "mathematical" speed of light.



IOW, the number of crests got by the moving observer is (c-v)/lambda
crests/sec, which can be written Nu(o) = (c-v)/lambda.
Then we have Nu(o)/Nu = (c-v)/c, and lambda(o)/lambda = c/(c-v), or
1 + z = c/(c-v), thus
z = v/(c-v) = (v/c)/(1-v/c).

BFD. That's the standard Doppler result for sound. If one makes
the same assumption for light propagation as for sound propagation,
it's no wonder that the result is the same.



Why didn't you said this before?

I did. Read again my posts from the last week.


And why would not the same formula apply to light?

*sigh*

Because for light, Galilean relativity does not apply. This works
*only* for sound because the speed of sound is so much smaller than c.


In fact, it is the formula used to interpret the
data obtained by the radar systems used by the police to determine
the speed of cars, whether the system is at rest along the road, or moving
(see http://copradar.com/preview/chapt2/ch2d1.html#example ).

Huh? What are you talking about? That formula appears nowhere on that
page! Not even c-v appears there!


The formula z = (v/c) / (1-(v/c) can as well be used for light emitters/
receivers subject to space expansion.

Nonsense.



This formula is valid, whether the observer is moving away from
the light source, or the light source is moving away from the
observer.

Wrong. If you think so, *prove* that these situations are equivalent,
given the assumptions used above (Galileian relativity and light moving
with c in a medium). Hint: they aren't.



See the above reference.

Which in no way supports you.


Let's note that in an expanding universe, the observer and the
source are *simultaneously* moving away from each other,

More correct: the space between them is expanding.



This is the GR interpretation.

Yes. And since cosmology is *described* by GR, it makes no sense
to use any other interpretation.


But space carries galaxies, etc...,
along. How? GRT has no explanation at all.

GR *has* such an explanation. It is called "inertia".

Are you familiar with the Robertson-Walker metric and the geodesic equation?




hence time
on the observer's clock and the source's clock are both dilated
by the same amount, and neither the observer nor the source can
observe a relativistic time dilation

*sigh* For the 100th time: cosmological time dilation has nothing
to do with the time dilation of SR.



I didn't speak of SR.

You talked about a time dilation "caused" by the motion above. And the
cosmological time dilation has nothing to do with the motion.




How often do I need to tell you that? How many links to pages written by
professional cosmologists do I have to give to you which say that?



By "cosmological time dilation", you mean GRT time dilation.

A very special time dilation effect of GR. Not gravitational
time dilation, if you meant that.


GRT is the theory used today, this doesn't mean that it is right.

If you have evidence that it is wrong, feel free to provide it.

If you have a logical argument why we should not use it, feel free
to provide it.


If you don't understand this derivation, you really have big
"reading" problems.

The derivation you gave above is perfectly valid for Galileian
relativity, light moving with c in a medium, the source resting and
the observer moving.



No, the source can be moving,

No - then your derivation above doesn ot work.


and the observer can be at rest, or
both can be moving wrt each other, which is the case in an expanding
universe. See http://copradar.com/preview/chapt2/ch2d1.html#example.

Again: that page does not support you.



However, that situation has nothing at all to do with the actual
cosmological red shift.



How do you know that the GRT formulae for the cosmological red shift
gives results that correspond to reality?

Err, because it had been checked countless times?


From the above, I retain that you now accept my formula when the
observer is moving, the source being considered at rest.

*sigh*

You *really* have severe reading comprehension problems!

I pointed out *repeatedly* that your formula is *only* correct if
one uses *Galileian* relativity. It is *incorrect* in both SR and LET!


Read carefully the reference I gave you, and you will conclude that
the formula is also valid when the source is moving.

Please show why you think that page says anything like that.


Acknowledge that your previous arguments against it were wrong.

Pot. Kettle. Black.


Of course, you still could claim that even it it applies on Earth,
it cannot be used for the cosmological redshift. But this would be
the claim of a GRT partisan, nothing more.

Hint: learn some basic reading comprehension, and then look at my
arguments again. Especially at the ones you keep ignoring.


Bye,
Bjoern

Dear Marcel Luttgens:

"Marcel Luttgens" wrote in message
om...
Bjoern Feuerbacher wrote in message
...
Marcel Luttgens wrote:
Bjoern Feuerbacher wrote in
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But the point is that my formula is right, what you denied
till now.
....
In a situation and using assumptions which have *nothing at all*
to do with cosmology!!!


According to GRists.

Perhaps you are not being clear with your cosmology. Here is what you are
saying:
1) the Earth is at the periphery of all the matter in the Universe.
2) space is infinite, unbounded.
3) the Earth is everywhere on the periphery.

1 is your model of the "illusion" of expansion. 2 is the basis for your
mathematics. 3 is required since expansion is observed in all directions.
Because your model is similar to one used when "climbing out" of the core
of the Earth. And this is definitely not uniform in all directions.

David A. Smith

"George Dishman" wrote in message ...
"Marcel Luttgens" wrote in message
om...
Bjoern Feuerbacher wrote in message
...
And no, as long as one uses Galilean relativity (as you keep doing)
and a medium for light, those two situations are *not* equivalent.

Both situations are strictly equivalent.

Bjoern is right, they are not equivalent. The difference
is the speed of the medium relative to the observer. Look
up the standard formulae for Doppler shift of sound in any
text book.


Bjoern is right, according to the textbooks, but the formula for
sound Doppler is not valid for light, because of the limit c.

BFD. That's the standard Doppler result for sound. If one makes
the same assumption for light propagation as for sound propagation,
it's no wonder that the result is the same.

Why didn't you said this before? And why would not the same formula
apply to light?

In LET both the moving source and moving observer formulae
would apply (they are not the same - see above) but you
then need to also take clock slowing into account. For a
moving observer and a source at rest in the medium, clock
slowing applies to the observer but not the source so they
do not cancel. For a moving source and an observer at rest
in the medium, clock slowing applies to the source but not
the observer and again they do not cancel. [1]

You are right, clock slowing has to be taken into account in the situations
you cite, but not when the source and the observer are both receding
at the same opposite velocity, which is the case in an expanding universe.


I now return you to your regularly scheduled flames.


Ha ha!

George

[1] Hint: note that clock slowing of the source will reduce
the frequency measured by the observer but slowing of _his_
clocks makes the frequency _seem_ higher in comparison.

Marcel Luttgens

"N:dlzc D:aol T:com \(dlzc\)" N: dlzc1 D:cox wrote in message news:yfB3d.207162$4o.59667@fed1read01...
Dear Marcel Luttgens:

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


But the point is that my formula is right, what you denied
till now.
...
In a situation and using assumptions which have *nothing at all*
to do with cosmology!!!


According to GRists.

Perhaps you are not being clear with your cosmology. Here is what you are
saying:
1) the Earth is at the periphery of all the matter in the Universe.
2) space is infinite, unbounded.
3) the Earth is everywhere on the periphery.

1 is your model of the "illusion" of expansion. 2 is the basis for your
mathematics. 3 is required since expansion is observed in all directions.
Because your model is similar to one used when "climbing out" of the core
of the Earth. And this is definitely not uniform in all directions.


Not exactly.

In my model, everything is *very* close to the center of the (stable) universe,
which is so big that a distance c/H is so much smaller than the universe
radius, that the universe could as well be considered as infinite.
If it were mathematically infinite, the Earth, and all of its points,
would of course coincide with its center. In particular, all points
of the trajectory of a light signal (emitted for instance by a galaxy)
would be at the center of a sphere of radius c/H centered on the universe's
center, and thus subject to an acceleration cH explaining its redshift.

David A. Smith

Marcel Luttgens

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

Marcel Luttgens wrote:

Bjoern Feuerbacher wrote in message ...



But the point is that my formula is right, what you denied
till now.

*sigh*

I *never* denied that it is right *in a certain situation, using
certain assumptions*.


Nice of you.

So, you retract your assertion above that I denied that till now?



In a situation and using assumptions which have *nothing at all*
to do with cosmology!!!



According to GRists.

No. Even according to LET.



The derivation you gave above is perfectly valid for Galileian
relativity, light moving with c in a medium, the source resting and
the observer moving.



No, the source can be moving,

No - then your derivation above does not work.


Then show yours.

Using what? Galilean relativity? LET? SR? GR?

Hint: LET and SR give the same results. And that result is *not* the
one *you* obtain.


I presume that *your* formula is Nu(o) = Nu sqrt((1-v/c)/(1+v/c)), but
it would be clearer to write Nu(o) = Nu sqrt(1-v^2/c^2)/(1+v/c),
where sqrt(1-v^2/c^2) corresponds to the time dilation.
If vc, one is left with Nu(o) = Nu / (1+v/c), which is the Doppler
formula for sound when the sound source is receding from the
observer.
But you should realize that light is not sound, because
of the speed limit c. I keep claiming that the right formula is
Nu(o) = Nu * (1-v/c), which leads to z = (v/c)/(1-v/c), and which is valid
whether the observer or the source is receding. No time dilation factor
is needed in an expanding universe, because the light source and the
observer are simultaneously receding wrt each other.

Nu(o) = Nu * (1-v/c) should also be used when the source is receding
from the observer, because light can be considered as a train of photons
of wavelength lambda emitted at c by the source. But as the source
is moving away at v, the frequency Nu(o) at which the photons are
emitted becomes Nu * (c-v)/c for the observer. Of course, the velocity
of the emitted light remains c.

You claimed that your formula is used by radar systems, and cited
that page as support. But your formula does not appear on that page.
A formula appears on the page which can be *derived* from your formula
for small velocities. But that same formula can *also* be derived
from SR and LET for small velocities! So the page is no support for your
claim. It's that simple.

You could as well say that it is no support for LET/SR.


Bye,
Bjoern

Marcel Luttgens

Marcel Luttgens wrote:
"George Dishman" wrote in message ...

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

Bjoern Feuerbacher wrote in message

...

And no, as long as one uses Galilean relativity (as you keep doing)
and a medium for light, those two situations are *not* equivalent.

Both situations are strictly equivalent.

Bjoern is right, they are not equivalent. The difference
is the speed of the medium relative to the observer. Look
up the standard formulae for Doppler shift of sound in any
text book.



Bjoern is right, according to the textbooks, but the formula for
sound Doppler is not valid for light, because of the limit c.

*sigh* That's exactly what I keep saying.

The formula z = (v/c)/(1 + v/c) is *not* valid for light. It is only
right for sound.



BFD. That's the standard Doppler result for sound. If one makes
the same assumption for light propagation as for sound propagation,
it's no wonder that the result is the same.

Why didn't you said this before? And why would not the same formula
apply to light?

In LET both the moving source and moving observer formulae
would apply (they are not the same - see above) but you
then need to also take clock slowing into account. For a
moving observer and a source at rest in the medium, clock
slowing applies to the observer but not the source so they
do not cancel. For a moving source and an observer at rest
in the medium, clock slowing applies to the source but not
the observer and again they do not cancel. [1]


You are right, clock slowing has to be taken into account in the situations
you cite, but not when the source and the observer are both receding
at the same opposite velocity, which is the case in an expanding universe.

No, that is *not* the case in an expanding universe.


[snip]

Bye,
Bjoern

Marcel Luttgens wrote:
"N:dlzc D:aol T:com \(dlzc\)" N: dlzc1 D:cox wrote in message news:yfB3d.207162$4o.59667@fed1read01...

Dear Marcel Luttgens:

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

Bjoern Feuerbacher wrote in message
...

Marcel Luttgens wrote:

Bjoern Feuerbacher wrote in
message ...




But the point is that my formula is right, what you denied
till now.

...

In a situation and using assumptions which have *nothing at all*
to do with cosmology!!!


According to GRists.

Perhaps you are not being clear with your cosmology. Here is what you are
saying:
1) the Earth is at the periphery of all the matter in the Universe.
2) space is infinite, unbounded.
3) the Earth is everywhere on the periphery.

1 is your model of the "illusion" of expansion. 2 is the basis for your
mathematics. 3 is required since expansion is observed in all directions.
Because your model is similar to one used when "climbing out" of the core
of the Earth. And this is definitely not uniform in all directions.



Not exactly.

In my model, everything is *very* close to the center of the (stable)
universe,

How can *everything* be *very* close to the center? You are not making
sense.

And, BTW, if the Earth were near the center of a homogeneous sphere,
the light we receive from outside would be *blueshifted*, not
*redshifted*, since the light *gains* energy when it travels inwards
in such a sphere.



which is so big that a distance c/H is so much smaller than the universe
radius, that the universe could as well be considered as infinite.
If it were mathematically infinite, the Earth, and all of its points,
would of course coincide with its center.

No. In that case, it would have *no* uniquely defined center.


In particular, all points
of the trajectory of a light signal (emitted for instance by a galaxy)
would be at the center of a sphere of radius c/H centered on the universe's
center, and thus subject to an acceleration cH explaining its redshift.

See above. This would give a blueshift, not a redshift.


Bye,
Bjoern

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

Marcel Luttgens wrote:

Bjoern Feuerbacher wrote in message ...


[snip]


No - then your derivation above does not work.


Then show yours.

Using what? Galilean relativity? LET? SR? GR?

Hint: LET and SR give the same results. And that result is *not* the
one *you* obtain.



I presume that *your* formula is Nu(o) = Nu sqrt((1-v/c)/(1+v/c)),

Yes. Nice that you finally got this.

Hint: that formula has been *tested*. See e.g. he
http://www.mathpages.com/rr/s2-04/2-04.htm
For a more detailed description of that experiment, see he
http://spiff.rit.edu/classes/phys314/lectures/doppler/doppler.html

Care to compare the predictions of your formula to the results
obtained there?


See also section IV of this article:
http://arxiv.org/pdf/physics/0408047


Oh, and while you are at it, you could also explain the transverse
Doppler effect, which also was tested experimentally, and where also
agreement with the predictions of SR was found.


but
it would be clearer to write Nu(o) = Nu sqrt(1-v^2/c^2)/(1+v/c),
where sqrt(1-v^2/c^2) corresponds to the time dilation.

If you want, write it that way.


If vc, one is left with Nu(o) = Nu / (1+v/c), which is the Doppler
formula for sound when the sound source is receding from the
observer.

Yes, indeed. Hint: for v c, one can also write this as
Nu(o) = Nu (1 - v/c),
which is the Doppler formula for sound when the observer is moving wrt
the sound source.

It has to be *expected* that for v c, the sound formulas are reproduced!


But you should realize that light is not sound, because
of the speed limit c.

*sigh* Obviously. That's why one uses Nu(o) = Nu sqrt((1-v/c)/(1+v/c)),
not Nu(o) = Nu / (1+v/c), if you didn't notice.




I keep claiming that the right formula is
Nu(o) = Nu * (1-v/c), which leads to z = (v/c)/(1-v/c), and which
is valid whether the observer or the source is receding.

With no supporting evidence, and with a calculation which is based
on "the distance changes, but let's consider that it it constant
anyway".


No time dilation factor
is needed in an expanding universe, because the light source and the
observer are simultaneously receding wrt each other.

Irrespective of a time dilation factor is needed or not, your
formula above is simply wrong. If you think otherwise, present
a derivation which is *not* based on "the distance changes, but let's
consider that it it constant anyway".




Nu(o) = Nu * (1-v/c) should also be used when the source is receding
from the observer, because light can be considered as a train of photons
of wavelength lambda emitted at c by the source. But as the source
is moving away at v, the frequency Nu(o) at which the photons are
emitted becomes Nu * (c-v)/c for the observer.

That claim is still utter nonsense.


Of course, the velocity of the emitted light remains c.

Finally something I can agree with.


You claimed that your formula is used by radar systems, and cited
that page as support. But your formula does not appear on that page.
A formula appears on the page which can be *derived* from your formula
for small velocities. But that same formula can *also* be derived
from SR and LET for small velocities! So the page is no support for your
claim. It's that simple.


You could as well say that it is no support for LET/SR.

Yes, I could say that. But: so what? *You* brought the page up as
support for *your* formula. I merely pointed out that what is written
on the page can't serve to distinguish between your formula and the one
of LET/SR.



Bye,
Bjoern

In message , Marcel
Luttgens writes

In my model, everything is *very* close to the center of the (stable)
universe,
which is so big that a distance c/H is so much smaller than the universe
radius, that the universe could as well be considered as infinite.
If it were mathematically infinite, the Earth, and all of its points,
would of course coincide with its center. In particular, all points
of the trajectory of a light signal (emitted for instance by a galaxy)
would be at the center of a sphere of radius c/H centered on the universe's
center, and thus subject to an acceleration cH explaining its redshift.


What acceleration? I thought your universe was static.
--
What have they got to hide? Release the ESA Beagle 2 report.
Remove spam and invalid from address to reply.

"Marcel Luttgens" wrote in message
om...
"George Dishman" wrote in message
...
"Marcel Luttgens" wrote in message
om...
Bjoern Feuerbacher wrote in message
...
And no, as long as one uses Galilean relativity (as you keep doing)
and a medium for light, those two situations are *not* equivalent.

Both situations are strictly equivalent.

Bjoern is right, they are not equivalent. The difference
is the speed of the medium relative to the observer. Look
up the standard formulae for Doppler shift of sound in any
text book.


Bjoern is right, according to the textbooks,

Bjoern is right that the situations are not equivalent,
however ...

but the formula for
sound Doppler is not valid for light, because of the limit c.

You are right, but you said you were using LET. The
formula for sound alone is not enough but if you
combine them (having replaced the speed of sound by
the speed of ligth) with time dilation then you get
the correct LET Doppler formula.

BFD. That's the standard Doppler result for sound. If one makes
the same assumption for light propagation as for sound propagation,
it's no wonder that the result is the same.

Why didn't you said this before? And why would not the same formula
apply to light?

In LET both the moving source and moving observer formulae
would apply (they are not the same - see above) but you
then need to also take clock slowing into account. For a
moving observer and a source at rest in the medium, clock
slowing applies to the observer but not the source so they
do not cancel. For a moving source and an observer at rest
in the medium, clock slowing applies to the source but not
the observer and again they do not cancel. [1]

You are right, clock slowing has to be taken into account in the situations
you cite, but not when the source and the observer are both receding
at the same opposite velocity, which is the case in an expanding universe.

You are almost right, that would be true if both source
and observer were moving at exactly the same speed
through the aether of LET. That need not be the case
just because the universe is expanding. For example if
the centre is at rest relative to the aether and source
and observer are equidistant from the centre and on
opposite sides, then the factors would cancel but in
general they will not.

However, I still think you should try doing the two
calculations I suggested. It should only take you a
few minutes and you will discover something useful.

[1] Hint: note that clock slowing of the source will reduce
the frequency measured by the observer but slowing of _his_
clocks makes the frequency _seem_ higher in comparison.

George