Galaxies without dark matter halos?

greywolf42 wrote:

Ulf Torkelsson wrote in message
..




This is simply incorrect. The cepheids can be, and have been, used
to calibrate other distance indicators such as the sizes of the
largest HII-regions of the galaxies, the brightnesses and sizes of the
brightest galaxies in clusters of galaxies, the Tully-Fisher relation
and so on. None of these distance scales will then depend on the value
of Hubble's constant as you have claimed.



At least the use of the Hubble constant is based on the assumption of known
physics -- the doppler shift.

No, it is not, though this is a common misconception. The cause of the
cosmological redshift is not a Doppler shift, it is due to the expansion
of the universe, which may sound like we are splitting hairs, but we
are not. In relativistic cosmology the galaxies are basically at rest in
the universe, but because the universe itself is expanding the distances
between the galaxies grow. The redshift is then the consequence of that
the universe has expanded with a certain factor between the emission and
reception of a light wave, and since the light wave is a part of the same
universe it expands with the same factor. The reason we, our planet, our
solar system and our galaxy are not expanding in the same way is because
we are held together by electromagnetic and gravitational forces that
are strong enough to overcome the expansion.

As of 2000 (according to the reference
provided by the moderator -- Sakai et al, 2000) there is still no "physical
basis for the TF relation." Despite decades of attempts. Even Sakai's 2000
TF calibration only used a sample of 21 galaxies (TF used 10 absolute
galaxies and 8 shifted). A smaller sample size than even Wirtz'
redshift-distance relation, in 1924 (or Hubble's 1929 version).

I believe the same goes for "largest HII regions" and "brightest in
clusters". Small Cepheid data samples and minimal theoretical support.


I would say that this is a slightly pessimistic, though largely correct,
description of the current state, but it does not matter. These methods
work in the sense that they give consistent distance estimates within
the bounds of their uncertainties. It does not matter much that we do
not yet know why they work, or why these relationships exist. As a
side note, medicine is still using many treatments that work, though
we do not understand why they work.

Ulf Torkelsson

Ulf Torkelsson wrote in message
...
greywolf42 wrote:


{snip}

At least the use of the Hubble constant is based on the assumption of
known physics -- the doppler shift.

No, it is not, though this is a common misconception. The cause of the
cosmological redshift is not a Doppler shift, it is due to the expansion
of the universe, which may sound like we are splitting hairs, but we
are not.

The original Hubble constant *is* a doppler shift. That modern cosmologists
have converted this into an expansion parameter (that works just like a
doppler shift, and has the same physics) is indeed splitting hairs.

In relativistic cosmology the galaxies are basically at rest in
the universe, but because the universe itself is expanding the distances
between the galaxies grow.

And this is needless hairsplitting, because the local regions of space --
with which the galaxies are assumed to be at 'rest' -- are physically moving
apart. Just like the galaxies are physically moving apart. This gives rise
to a doppler effect. Whether or not the galaxies drag 'space' along with
them (or vice versa). You'll only notice the difference if the rate of
expansion changes during time-of-flight.

The redshift is then the consequence of that
the universe has expanded with a certain factor between the emission and
reception of a light wave, and since the light wave is a part of the same
universe it expands with the same factor.

However, the motion is supposed to be real, as well. In addition to the
photon wavelength "expansion" during time-of-flight. The physical doppler
effect is never removed. Augmented or reduced, perhaps -- if the expansion
rate changes.

The reason we, our planet, our
solar system and our galaxy are not expanding in the same way is because
we are held together by electromagnetic and gravitational forces that
are strong enough to overcome the expansion.

I believe this is your own personal view. Which is fine. It is irrelevant
to the question at hand, though.

Do you believe that expansion of the universe exerts a force on matter?
That seems to be required if you need an EM or gravitational force to
overcome it. (Do photons in gravitational fields expand?)

As of 2000 (according to the reference
provided by the moderator -- Sakai et al, 2000) there is still no
"physical basis for the TF relation." Despite decades of attempts.
Even Sakai's 2000 TF calibration only used a sample of 21 galaxies
(TF used 10 absolute galaxies and 8 shifted). A smaller sample size
than even Wirtz' redshift-distance relation, in 1924 (or Hubble's 1929
version).

I believe the same goes for "largest HII regions" and "brightest in
clusters". Small Cepheid data samples and minimal theoretical support.

I would say that this is a slightly pessimistic, though largely correct,
description of the current state, but it does not matter.

If you agree that it's correct, then it's not pessimistic. It's realistic.

These methods
work in the sense that they give consistent distance estimates within
the bounds of their uncertainties. It does not matter much that we do
not yet know why they work, or why these relationships exist.

I would say that this is an optimistic description of the situation. It is
also non-scientific. Correlations without known cause are accepted if they
tend to support the paradigm. But if it something doesn't support the
paradigm (i.e. quantized redshift patterns), proof of mechanism is required.

As a
side note, medicine is still using many treatments that work, though
we do not understand why they work.

We don't really understand the placebo effect, yet. We use them because
they appear to work. Just like "coining" appears to work in some medical
practices. Medicine isn't science (much as we'd like it to be).

greywolf42
ubi dubium ibi libertas

Ulf Torkelsson wrote in message
...
greywolf42 wrote:


{snip}

At least the use of the Hubble constant is based on the assumption of
known physics -- the doppler shift.

No, it is not, though this is a common misconception. The cause of the
cosmological redshift is not a Doppler shift, it is due to the expansion
of the universe, which may sound like we are splitting hairs, but we
are not.

The original Hubble constant *is* a doppler shift. That modern cosmologists
have converted this into an expansion parameter (that works just like a
doppler shift, and has the same physics) is indeed splitting hairs.

In relativistic cosmology the galaxies are basically at rest in
the universe, but because the universe itself is expanding the distances
between the galaxies grow.

And this is needless hairsplitting, because the local regions of space --
with which the galaxies are assumed to be at 'rest' -- are physically moving
apart. Just like the galaxies are physically moving apart. This gives rise
to a doppler effect. Whether or not the galaxies drag 'space' along with
them (or vice versa). You'll only notice the difference if the rate of
expansion changes during time-of-flight.

The redshift is then the consequence of that
the universe has expanded with a certain factor between the emission and
reception of a light wave, and since the light wave is a part of the same
universe it expands with the same factor.

However, the motion is supposed to be real, as well. In addition to the
photon wavelength "expansion" during time-of-flight. The physical doppler
effect is never removed. Augmented or reduced, perhaps -- if the expansion
rate changes.

The reason we, our planet, our
solar system and our galaxy are not expanding in the same way is because
we are held together by electromagnetic and gravitational forces that
are strong enough to overcome the expansion.

I believe this is your own personal view. Which is fine. It is irrelevant
to the question at hand, though.

Do you believe that expansion of the universe exerts a force on matter?
That seems to be required if you need an EM or gravitational force to
overcome it. (Do photons in gravitational fields expand?)

As of 2000 (according to the reference
provided by the moderator -- Sakai et al, 2000) there is still no
"physical basis for the TF relation." Despite decades of attempts.
Even Sakai's 2000 TF calibration only used a sample of 21 galaxies
(TF used 10 absolute galaxies and 8 shifted). A smaller sample size
than even Wirtz' redshift-distance relation, in 1924 (or Hubble's 1929
version).

I believe the same goes for "largest HII regions" and "brightest in
clusters". Small Cepheid data samples and minimal theoretical support.

I would say that this is a slightly pessimistic, though largely correct,
description of the current state, but it does not matter.

If you agree that it's correct, then it's not pessimistic. It's realistic.

These methods
work in the sense that they give consistent distance estimates within
the bounds of their uncertainties. It does not matter much that we do
not yet know why they work, or why these relationships exist.

I would say that this is an optimistic description of the situation. It is
also non-scientific. Correlations without known cause are accepted if they
tend to support the paradigm. But if it something doesn't support the
paradigm (i.e. quantized redshift patterns), proof of mechanism is required.

As a
side note, medicine is still using many treatments that work, though
we do not understand why they work.

We don't really understand the placebo effect, yet. We use them because
they appear to work. Just like "coining" appears to work in some medical
practices. Medicine isn't science (much as we'd like it to be).

greywolf42
ubi dubium ibi libertas

Phillip Helbig---remove CLOTHES to reply wrote:


The point is, you get different results if you use the Doppler formula
as compared to the correct one, which is actually quite simple: 1+z,
where z is the redshift, is the factor by which the universe has
expanded while the radiation was in transit. (And no, the answer is not
to use the relativistic Doppler formula if the redshifts are large; that
will give (different) wrong answers as well.)


Actually, in GR it is correct to apply the SR Doppler formula to any
spectral shift as long as it is done properly. See

J.V. Narlikar, American Journal of Physics 62,903-907 (1994).

It is recommended that you read this paper before posting any more
strong opinions on the issue.

Phillip Helbig---remove CLOTHES to reply wrote:


The point is, you get different results if you use the Doppler formula
as compared to the correct one, which is actually quite simple: 1+z,
where z is the redshift, is the factor by which the universe has
expanded while the radiation was in transit. (And no, the answer is not
to use the relativistic Doppler formula if the redshifts are large; that
will give (different) wrong answers as well.)


Actually, in GR it is correct to apply the SR Doppler formula to any
spectral shift as long as it is done properly. See

J.V. Narlikar, American Journal of Physics 62,903-907 (1994).

It is recommended that you read this paper before posting any more
strong opinions on the issue.

In article , Dag Oestvang
writes:

Actually, in GR it is correct to apply the SR Doppler formula to any
spectral shift as long as it is done properly. See

J.V. Narlikar, American Journal of Physics 62,903-907 (1994).

It is recommended that you read this paper before posting any more
strong opinions on the issue.

OK, I'll have a look. In the meantime, since not all readers have
access to the American Journal of Physics, could you post a summary of
Narlikar's arguments in this paper?

In article , Dag Oestvang
writes:

Actually, in GR it is correct to apply the SR Doppler formula to any
spectral shift as long as it is done properly. See

J.V. Narlikar, American Journal of Physics 62,903-907 (1994).

It is recommended that you read this paper before posting any more
strong opinions on the issue.

OK, I'll have a look. In the meantime, since not all readers have
access to the American Journal of Physics, could you post a summary of
Narlikar's arguments in this paper?

"UT" == Ulf Torkelsson writes:

[Referring to the Tully-Fisher relation and other steps in the cosmic
distance ladder,]
UT I would say that this is a slightly pessimistic, though largely
UT correct, description of the current state, but it does not matter.
UT These methods work in the sense that they give consistent distance
UT estimates within the bounds of their uncertainties. It does not
UT matter much that we do not yet know why they work, or why these
UT relationships exist. As a side note, medicine is still using many
UT treatments that work, though we do not understand why they work.

An astronomical example might be that astronomers could work out the
distances to stars well before they knew why stars shine.

--
Lt. Lazio, HTML police | e-mail:
No means no, stop rape. | http://patriot.net/%7Ejlazio/
sci.astro FAQ at http://sciastro.astronomy.net/sci.astro.html

"UT" == Ulf Torkelsson writes:

[Referring to the Tully-Fisher relation and other steps in the cosmic
distance ladder,]
UT I would say that this is a slightly pessimistic, though largely
UT correct, description of the current state, but it does not matter.
UT These methods work in the sense that they give consistent distance
UT estimates within the bounds of their uncertainties. It does not
UT matter much that we do not yet know why they work, or why these
UT relationships exist. As a side note, medicine is still using many
UT treatments that work, though we do not understand why they work.

An astronomical example might be that astronomers could work out the
distances to stars well before they knew why stars shine.

--
Lt. Lazio, HTML police | e-mail:
No means no, stop rape. | http://patriot.net/%7Ejlazio/
sci.astro FAQ at http://sciastro.astronomy.net/sci.astro.html

In article , greywolf42
writes:

The original Hubble constant *is* a doppler shift. That modern
cosmologists have converted this into an expansion parameter
(that works just like a doppler shift, and has the same physics)
is indeed splitting hairs.

The physics of the universe is independent of who on Earth observed
what when.

Yes. What was your point?

That you explain what you mean by "The original Hubble constant *is* a
doppler shift.".