Plasma Theory of Galactic Redshifts and 'Gravitational Lensing' of Light

I have suggested on my web page
http://www.plasmaphysics.org.uk/research/redshift.htm that the Hubble
redshift of galaxies is due to the 'stretching' of the light wave by
the electric 'micro'field associated with the intergalactic plasma.
This mechanism could also explain in a straightforward way both the
microwave background (as a saturation effect) as well as Olbers'
paradox for an infinite steady state universe (due to a progressive
incoherency and thus indetectability of the light). It also can account
for the apparent delay of supernova light curves.
The same theory can also be applied to the redshift and deflection
(lensing) of light by the sun and, using the galactic redshift as a
reference value, one obtains good numerical agreement with the observed
values ( see http://www.plasmaphysics.org.uk/research/lensing.htm )

Note that unlike some other plasma theories which have been suggested
for the redshift, this mechanism has nothing to do with scattering but
may be compared to refraction (albeit one independent of wavelength) as
the electric field affects the light wave in a continuous and gradual
manner. The redshifted object will therefore not also be simultaneously
blurred (the absence of blurring of redshifted objects pretty much
rules out any theory based on scattering (e.g. through the Compton
effect)).

It is also worth noting that the effect is essentially so weak that it
would take electric field strengths of the order of the inner-atomic
field in order to observe it over scales short enough to fit into a
lab. It is therefore not further surprising that both the redshift and
deflection of light have not been noticed yet in the lab but only
become apparent over astronomical distances.

Although the suggested mechanism is, like with any new theory, to a
certain degree still somewhat speculative , I feel it is an encouraging
sign that it manages to explain two such different phenomena like the
galactic redshifts and lensing of light by the sun.

Any comments on this are welcome.

Thomas

In message , Thomas Smid
writes
I have suggested on my web page
http://www.plasmaphysics.org.uk/research/redshift.htm that the Hubble
redshift of galaxies is due to the 'stretching' of the light wave by
the electric 'micro'field associated with the intergalactic plasma.


Although the suggested mechanism is, like with any new theory, to a
certain degree still somewhat speculative , I feel it is an encouraging
sign that it manages to explain two such different phenomena like the
galactic redshifts and lensing of light by the sun.


There's already a thread running here about Paul Marmet's theory, and
both have to explain how an effect involving interaction with charged
particles can be independent of wavelength.
Despite your claim that "Hubble law appears to be based on rather
limited data sets, and in particular has not been examined for its
strict validity throughout the whole of the electromagnetic spectrum (in
fact, it is known that the redshift factor for certain spectral lines
from the same object differs by up to 10% even within the visible part
of the spectrum itself). [Reference ?]
similar red shifts are seen for radio, visible, and X-ray wavelengths in
various sources.

Jonathan Silverlight wrote:
In message , Thomas Smid
writes
I have suggested on my web page
http://www.plasmaphysics.org.uk/research/redshift.htm that the Hubble
redshift of galaxies is due to the 'stretching' of the light wave by
the electric 'micro'field associated with the intergalactic plasma.


Although the suggested mechanism is, like with any new theory, to a
certain degree still somewhat speculative , I feel it is an encouraging
sign that it manages to explain two such different phenomena like the
galactic redshifts and lensing of light by the sun.


There's already a thread running here about Paul Marmet's theory, and
both have to explain how an effect involving interaction with charged
particles can be independent of wavelength.

The theory of Paul Marmet (and also of some other people) assumes
scattering processes to be responsible for the redshift. The point is
that scattering consists of localized discrete events where the
particles absorb and re-emit the radiation essentially over the whole
sphere. This would lead thus to a very substantial blurring of the
redshifted object here. The analogon that Paul Marmet uses by
considering the propagation of light through air can not be applied
here because the density of air is such that the distance between two
molecules is much smaller than the wavelength of the radiation. In air
the scattering is therefore coherent i.e. the light is scattered merely
in the forward direction (analogously to specular reflection from a
surface) and the scattering effects are then not apparent. In order to
have this coherent scattering one needs at least a density of about
10^18 m^-3, which can with certainty be ruled out for the intergalactic
medium (even our interplanetary medium has at best a density of 10^8
m^-3).

In contrast to this, my theory assumes that the light pulse is affected
by the electric field in the plasma in a continuous and gradual way
(the charges merely produce the field but the light does not directly
interact with them). Consequently, even if the distance between the
charges is larger than the wavelength, the object will not appear to be
blurred like for scattering (or at least, as shown on my page
http://www.plasmaphysics.org.uk/research/redshift.htm , the blurring is
only so small that it is practically undetectable).
Admittedly, the assumption of the effect being effectively independent
of wavelength is not further justified by me, but since the suggested
effect is not based on any other known theory, there is really nothing
that would force me to make the opposite assumption.


Despite your claim that "Hubble law appears to be based on rather
limited data sets, and in particular has not been examined for its
strict validity throughout the whole of the electromagnetic spectrum (in
fact, it is known that the redshift factor for certain spectral lines
from the same object differs by up to 10% even within the visible part
of the spectrum itself). [Reference ?]
similar red shifts are seen for radio, visible, and X-ray wavelengths in
various sources.

First of all, as far as I am aware, redshifts of spectral lines have
only been measured up to a few cm wavelength in the radio region. This
is already associated with atomic transitions involving Rydberg states
near about n=100. Even longer wavelengths would involve even higher
states and the lines would be very difficult if not impossible to
measure exactly. Hence my suggestion that actually the redshift
mechanism may break down for wavelengths longer than 1m (as this is
probably about the average distance of charges in the intergalactic
plasma).
Secondly, with the 10% redshift difference between certain lines I was
referring to the quasar OQ208 where the H(alpha) and H(beta) emission
lines are not only substantially broadened compared to the other lines
but also redshifted (Osterbrock and Cohen, MNRAS 187,61P (1979); for a
more recent analysis see also http://arxiv.org/pdf/astro-ph/9301001 ).
The reason for the redshift still seems to be a subject of debate, and
my idea here was that this might be due to the different coherency of
the lines (broad lines are less coherent than sharp lines). Again, in
comparison to the scale of the electric field variations in the
intergalactic plasma, this might produce an effect (even though only a
threshold effect).

But these are already complications to my theory which really don't
need to be considered for its discussion. I mentioned this merely on my
webpage in order to quote evidence that a velocity related redshift
theory would have problems with to explain. Thus my theory would be
somewhat more than just an alternative.

Thomas

Thomas Smid wrote:
The theory of Paul Marmet (and also of some other people) assumes
scattering processes to be responsible for the redshift. The point is
that scattering consists of localized discrete events where the
particles absorb and re-emit the radiation essentially over the whole
sphere. This would lead thus to a very substantial blurring of the
redshifted object here. The analogon that Paul Marmet uses by
considering the propagation of light through air can not be applied
here because the density of air is such that the distance between two
molecules is much smaller than the wavelength of the radiation. In air
the scattering is therefore coherent i.e. the light is scattered merely
in the forward direction (analogously to specular reflection from a
surface) and the scattering effects are then not apparent. In order to
have this coherent scattering one needs at least a density of about
10^18 m^-3, which can with certainty be ruled out for the intergalactic
medium (even our interplanetary medium has at best a density of 10^8
m^-3).

The reason that I started the thread "Redshift of solar limb and in
cosmology" recently was related to this issue of redshifting, scattering
and blurring. I think that the commonly accepted idea that redshifting
cannot result from scattering because that would result in noticeable
blurring might be wrong.

If it were true that a redshift related scattering resulted only from
absorption and re-emission then your argument might be right (although I
would still want to look at it because I think that it does not
recognise the large distances involved in the light paths). However at
the much lower densities that you describe then it seems logical that
the light path will have many very small scattering-angle events due to
missing most atoms by quite large distances relative to the wavelength
of light.

I would be interested to know if there is laboratory observational
evidence on scattering at extremely low gas densities, rather than just
using theory that has been derived at high density?

If very many small angle scattering events occurred then I see a
calculation that might look roughly like the following to justify large
redshifts and lack of noticeable blurring:

1. Let the density of the intergalactic medium be rho=1 m^-3

2. Then the typical atomic spacing is rho^(-1/3) = 1 m.

3. Consider a distance corresponding to the Hubble scale
d = c/H = 3x10^8 m/s * 4.3x10^17 s = 1.3x10^26 m

4. Over this distance there will therefore be about 10^26 scattering
events. We know that the redshift is of order 1 over this distance and
so if these events are the cause of the redshift, each event must cause
a redshift of z = 1x10^-26.

5. If the scattering is of the same order as the redshift then there
will be 10^26 events of scatter 10^-26 each. Such an effect does not
cause blurring of order 1 because the scattering events are independant
and statistically n events will combine to give a mean proportional to
sqrt(n). That means that the blurring will only be of order
sqrt(10^26) x 10^-26 or 10^-13. That is such a small factor as to be
undetectable.

I know that the above argument is a bit loose. The important point that
I don't think has been recognised in the past is that a very large
number of very small events can result in one large effect - the
redshift, because the effects are additive, and one very small effect -
the blurring, because the effects are randomly combined.

--
Ray Tomes
http://ray.tomes.biz/
http://www.cyclesresearchinstitute.org/

Thomas Smid wrote:
In order to
have this coherent scattering one needs at least a density of about
10^18 m^-3, which can with certainty be ruled out for the intergalactic
medium

Just a clarification on this:

With 'coherent' I meant 'phase-coherent' here, not 'frequency-coherent'
as in my later statement regarding the coherency of spectral lines.
'Phase-coherent' has nothing to do with the spectral coherency as it
merely affects the spatial redistribution of the radiation but not the
frequency spectrum. Even an infinitely sharp (i.e. frequency-coherent)
line will be scattered phase-incoherently by randomly distributed
individual scatterers (but still maintains its spectral coherency).
Radiation will only be scattered phase-coherently by a random medium if
the scattering is not due to individual particles but a collective
process. The latter is the case if the average distance between two
scattering particles is less than the wavelength (in this case one has
a 'continuous' medium and the random nature disappears in this
respect). As mentioned above, this happens only at particle densities
higher than about 10^18 m^-3 for the visible region of the spectrum.
For shorter wavelengths the required density would even be higher
(~wavelength^-3).

Thomas

Ray Tomes wrote:

The reason that I started the thread "Redshift of solar limb and in
cosmology" recently was related to this issue of redshifting, scattering
and blurring. I think that the commonly accepted idea that redshifting
cannot result from scattering because that would result in noticeable
blurring might be wrong.

If it were true that a redshift related scattering resulted only from
absorption and re-emission then your argument might be right (although I
would still want to look at it because I think that it does not
recognise the large distances involved in the light paths). However at
the much lower densities that you describe then it seems logical that
the light path will have many very small scattering-angle events due to
missing most atoms by quite large distances relative to the wavelength
of light.

The point is that there are no exclusive small angle scatterings of
light. If an electromagnetic plane wave is scattered by an atom, then
the scattered light propagates into all directions (for unpolarized
light, the scattering phase function is the Rayleigh scattering
function 3/4(1+cos^2(theta)) where theta is the scattering angle). Of
course, not all of the incident wave will be scattered in one event,
but since only the scattered component could possibly be redshifted,
this is the only one of interest here. Therefore, any frequency shift
due to scattering would go hand in hand with a spatial blurring, unless
the density is so high that the scattering becomes phase-coherent
(which is the case if the average distance between the scattering atoms
is less than the wavelength).


I would be interested to know if there is laboratory observational
evidence on scattering at extremely low gas densities, rather than just
using theory that has been derived at high density?

As should be evident from what I said above, the usual scattering
theory does in fact only apply for small densities (i.e. if the average
distance between the scattering atoms is greater than the wavelength).
Otherwise, the usual effects of scattering vanish and the light is
merely scattered in the forward direction. One then would rather have a
refraction effect and the blurring problem would not occur, but in
intergalactic space such a high density is simply impossible.


If very many small angle scattering events occurred then I see a
calculation that might look roughly like the following to justify large
redshifts and lack of noticeable blurring:

1. Let the density of the intergalactic medium be rho=1 m^-3

2. Then the typical atomic spacing is rho^(-1/3) = 1 m.

3. Consider a distance corresponding to the Hubble scale
d = c/H = 3x10^8 m/s * 4.3x10^17 s = 1.3x10^26 m

4. Over this distance there will therefore be about 10^26 scattering
events. We know that the redshift is of order 1 over this distance and
so if these events are the cause of the redshift, each event must cause
a redshift of z = 1x10^-26.

5. If the scattering is of the same order as the redshift then there
will be 10^26 events of scatter 10^-26 each. Such an effect does not
cause blurring of order 1 because the scattering events are independant
and statistically n events will combine to give a mean proportional to
sqrt(n). That means that the blurring will only be of order
sqrt(10^26) x 10^-26 or 10^-13. That is such a small factor as to be
undetectable.


Yes, that's the calculation I made on my page
http://www.plasmaphysics.org.uk/research/redshift.htm , but, following
my argument above, the assumption of many very small deviations simply
rules out any scattering to be responsible for this. It must be a
continuous gradual effect which affects the light wave as such (i.e. a
kind of refraction effect). The obvious cause for this in my opinion
the small scale electric field due to the free charges in intergalactic
space.

Thomas

Dear moderators, Thanks for moderating this newsgroup!
Sorry to bug you, but here is a version of a post I just submitted,
with two spelling mistakes corrected.

Thomas, I have linked to your page
http://www.plasmaphysics.org.uk/research/redshift.htm as a
plasma redshift theory along with Ari Brynjolfsson's and mine.

The basis of your theory, as I understand it, is that a
wavefront of light (or microwaves etc.) which has a coherence length
shorter than the average inter-particle spacing will be stretched by
the electric field between those particles. I can't see exactly how
that would occur, but I think it warrants consideration.

Lets think of a left-to-right travelling wavefront as having energy
and momentum - and therefore mass - distributed along it. (With a
short enough wavelength the wavefront can congeal into an electron-
positron pair. Likewise, a flashlight in a spaceship loses mass to
the light beam it creates and the light beam deposits energy and
therefore mass on whatever part of the spaceship absorbs it, but the
total mass of the spaceship remains the same.)

The question is whether the electric field between a particle A, to
the left, which the wavefront is receding from and particle B, which
is is moving towards, can stretch the wavefront. Particle A has more
of an effect on the trailing end of the wavefront and B has more of
an effect on the leading edge. All we need is a mechanism by which
individual parts of the wavefront are attracted to a charged particle
of either polarity. Not much of an effect is required to explain the
cosmological redshift - one part in 13 billion or so per year the
light travels in the inter-cluster medium.

Maybe it is not an electrical attraction, but a gravitational one.

Whatever the nature of the stretching process, it would need to be
shown that the wavefront wasn't similarly compressed to the same
degree when it has one or more particles in its middle.

Such a stretching, redshifting, process would be subject to various
challenges, such as whether it would predict sideways scattering of
the light to a degree greater than that which is observed.

I disagree with your statement that the coherence length of the light
from stars is 100 microns. I estimate that an impulse which has the
spectral characteristics of the Sun's black body light would have
most (say 90%) of its energy in about 2 to 4 microns. The peak
energy is at about 0.5 microns. The coherence length of the
emission and absorption lines would be much longer than this.

I agree in broad principle with the notion of emr being redshifted
pervasively in the inter-galactic or inter-cluster medium by some
kind of plasma redshift process until it attains a wavelength or
coherence length which prevents further redshifting. How well that
would explain the CMB, I am not sure. When thinking about the CMB
and plasma redshift, the the Sunyaev-Zeldovich Effect may be worth
bearing in mind. This involves the CMB seeming to be slightly
shorter wavelength when looking towards galaxy clusters, supposedly
due to CMB being altered by the inter-cluster medium.
(http://www.astro.ucla.edu/~wright/distance.htm#SZ). I tentatively
suggest that this could be explained by the CMB emanating from the
cluster (by whatever mechanism) being not plasma redshifted at that
point compared to the CMB from more distant galaxies having been
plasma redshifted by its passage through a greater distance of
inter-cluster medium.

- Robin http://astroneu.com

Robin Whittle wrote:

The basis of your theory, as I understand it, is that a
wavefront of light (or microwaves etc.) which has a coherence length
shorter than the average inter-particle spacing will be stretched by
the electric field between those particles. I can't see exactly how
that would occur, but I think it warrants consideration.

Well, as I am suggesting this as an altogether new mechanism, you
shouldn't really try to see it in terms of known physics. At this
stage, you should better ask whether you can see a reason why it should
*not* occur.

Maybe it is not an electrical attraction, but a gravitational one.

How should gravity produce a systematic redshift with distance?
According to present theory, gravity can both lead to red- and
blue-shifts (depending on whether the light propagates against or with
gravity), so if you have a quasi-homogeneous medium with a merely
randomly fluctuating gravitational field, there would be on average no
frequency shift but merely a broadening of the line.

The point is that I am suggesting that an electric field leads in any
case to a redshift, which means that even a random medium will result
in a net redshift (corresponding to the average electric field in the
medium).


Such a stretching, redshifting, process would be subject to various
challenges, such as whether it would predict sideways scattering of
the light to a degree greater than that which is observed.

First of all, as mentioned before already, the suggested effect is not
a scattering mechanism. The direction of the wave front is only changed
by a very small amount over the scale of the electric field variations.
If you assume the latter to be 1m, then the fact that a galaxy at a
distance of 10^26 m (10^10 lightyears) has a redshift of the order of
z=3D1, tells you that the redshift changes within 1m by an amount
dz=3D10^-26. Assuming that the direction of propagation is changed by the
same relative amount (compared to 360 deg) within 1m, this results over
the total distance of 10^10 lightyears in a statistical angle of
deviation (i.e. a blurring) of =CE=94=CE=B1=3D10^-26*=E2=88=9A10^26 *360 de=
g =3D 4*10^-11
deg, which is negligibly small (for comparison, the angular width of
our own galaxy from a distance of 10^10 light years would be about
6*10^-4 deg , i.e. about 7 orders of magnitude larger; it would take a
distance of 7*10^14 lightyears until the blurring would become
comparable to the apparent size of the galaxy).


I disagree with your statement that the coherence length of the light
from stars is 100 microns. I estimate that an impulse which has the
spectral characteristics of the Sun's black body light would have
most (say 90%) of its energy in about 2 to 4 microns. The peak
energy is at about 0.5 microns. The coherence length of the
emission and absorption lines would be much longer than this.

Of course, any figure one gives here is somewhat debatable as it
depends on what one assumes for the collision frequency in the emitting
gas (which should usually be much shorter than the intrinsic coherence
length of an atomic transition). However, 1 micron or so would mean
that the coherence length is actually of the same order as the
wavelength itself (in the visible region), and I am not sure whether
this kind of radiation could still result in any physical effects (i.e.
whether it would be detectable at all).

Anyway, I am myself not quite sure yet whether it is the coherence
length or the wavelength which presents a threshold for the redshift
mechanism. On my page
http:/www.plasmaphysics.org.uk/research/redshift.htm , I suggested that
it is the former because the coherence length I assumed (10^-2 cm,
which I got from an estimate for the collision frequency in the
photosphere) would result in a redshift threshold of roughly z=3D10^4,
which would be consistent with the existence of the microwave
background radiation. However, it could well be that, as mentioned on
my webpage, the intergalactic plasma does not only stretch the waves,
but also 'scrambles' them to a random and thus eventually undetectable
signal. If the latter effect depends on the coherence length (which is
reasonable to assume), then this could actually explain the existence
of the microwave background threshold, i.e. in principle radiation is
being redshifted beyond z=3D10^4, but one simply can not see it anymore
as it has become completely incoherent. If however the *wavelength* of
the light becomes larger than the interparticle spacing, then surely
the redshift mechanism should vanish because with many positive and
negative charges within one wavelength there is simply no sufficiently
extended field anymore that could stretch the wave.=20

Thomas

Thomas Smid wrote:
The point is that I am suggesting that an electric field leads in any
case to a redshift, which means that even a random medium will result
in a net redshift (corresponding to the average electric field in the
medium).

Is this redshift supposed to be proportional to column density along
the line of sight? If so, why do we see the same redshift-distance
relation in different directions?

Steve Wilner wrote:

Is this redshift supposed to be proportional to column
density along the line of sight? If so, why do we see the
same redshift-distance relation in different directions?

Sorry this is long. I include references to papers which
argue that some of the observed redshift of galaxies cannot
be explained directly by Hubble Doppler redshift.

I can't speak about Thomas Smid's theory, which I don't
understand. Here is my response for a plasma redshift theory
in general, such as Ari Brynjolfsson's or my own tentative
theory.

If it can be shown that the relationship between distance
and redshift is more even than the established differences
in overall column density of plasma in the various
directions, then this would favour the BBT over a theory of
a relatively static universe with most of the cosmological
redshift being explained by plasma redshift.

However, I am not sure that the distance / redshift ratio is
so clear and predictable. If it was, I would have expected
less variation in the various estimates than are evident in:

http://cfa-www.harvard.edu/~huchra/hubble/

Also, I think there are a lot of questions about the nature
of the Inter Cluster Medium (ICM) and the plasma between the
galaxies in the clusters - which I will call the Inter
Galactic Medium (IGM).

For the purposes of this discussion I will ignore various
challenges to the plasma redshift theory, and just
concentrate on how the redshift of visible lines might occur.

Here are some postulates:

1 - Most of the distance travelled by the light of objects
in which the cosmological redshift is clearly visible,
is in the ICM.

2 - While the IGM is denser (and therefore likely to create
more redshift per light year travelled), the distances
travelled are shorter, so the dominant source of the
cosmological redshift is still the ICM in the voids.

In my understanding of plasma redshift, short coherence
length light, such as black body starlight, is substantially
redshifted in relatively dense plasmas with inter-particle
spacings of more than 2 to 5 microns - such as anywhere
above the solar transition region (2,200 km above the
photosphere).

However, these plasmas only have a high column density for a
very short distance, and it is hard to observe the resultant
small shifts in the black body spectrum. If plasma redshift
explains the heating of the solar corona, then the redshift
is likely to be around 0.0001 which is the required fraction
of the Sun's radiant energy.

I expect these denser plasmas (such as in the coronae close
to stars) to redshift the emission or absorption lines to a
much lesser degree than for the black body signal - because
the coherence length of these signals is longer than the
average inter-particle spacing. (However, there may be
a very slight redshift because occasionally a wavefront
of X coherence length encounters a space between the
particles which is about as long, or longer than X, due to
the random spacing of plasma particles.)

I expect the particles of the ICM to be far enough apart to
redshift all visible light, black body and emission and
absorption lines, to the same degree - because I figure the
average inter-particle spacing is a metre or so, which is
longer than the coherence length of the lines. No-one
really knows the density or temperature of the ICM, but on
my page http://astroneu.com/plasma-redshift-1/ I point to a
paper which suggests a temperature of 440 mega-kelvin:

Field, G. B.; Perrenod, S. C. 1977
Constraints on a dense hot intergalactic medium.
ApJ vol. 215, 717-722. 1977ApJ...215..717F

I guess there is a lot of debate about this, but I just want
to suggest that such temperatures - and presumably densities
such as one particle per cubic metre or so - cannot be ruled
out.

Here is a third postulate, which I argue for at my site. This
is for a non-exploding Universe, with no obvious bounds, and
with an age much older than in the BBT. By "non-exploding",
I mean not expanding anywhere near as rapidly as the BBT
predicts. Maybe there was a "bang" in the far distant past -
maybe not. This model does not attempt to explain the
formation of matter or galaxies.

3 - The ICM in the voids is at about the same density and
temperature all over the Universe. This is due to ICM
being illuminated by about the same amount of starlight
(and AGN/quasar light, CMB, X-ray background etc.) at
all locations in the Universe, and this light being
redshifted to heat the ICM approximately uniformly. The
IGM over the billions of years (far longer than 13.7
etc.) has been heated and expanded, exerting a similar
pressure everywhere. The denser IGM, in the clusters,
is pushed around into the gaps between the voids, and
this is where we find the galaxies, which are lighter
than their surrounding clouds of intra-cluster medium
(IGM) and so are gravitationally bound* within these
squished blobs of IGM. The IGM is not so hot - and
therefore not as dense at the same pressure - as the
ICM, because it's greater density enables it to radiate
more heat via bremsstrahlung. In short, the galaxy
clusters are corralled by the pressure of the voids like
soapy water is formed into bubbles by the pressure of
the gas in the bubbles.
* (Actually, there needs to be a way of making the
galaxies aerodynamically stick in the cluster plasma,
but I won't pursue this further here.)

This would lead to most of the visible plasma redshift for
distant galaxies occurring in the ICM all over the Universe,
which has a reasonably consistent density and therefore
average inter-particle spacing. This is the answer to Steve
Wilner's question, but it does not predict an absolutely
direct relationship between distance and redshift. In order
for a plasma redshift theory to survive scrutiny, there
are quite a few implications of such a theory which can be
tested with existing observations. Please see the thread
"Redshift of solar limb and in cosmology" and my response to
some apparently successful critiques from Jonathan
Silverlight.

One difference from the direct distance - redshift
relationship I predict is that quasars have additional
redshift, due to them attracting a large amount of plasma
closer to themselves and/or for some other reason relating
to the nature of the plasma which surrounds them. I
predict that most of the Lyman alpha forest occurs close
to the quasar (or some other object such as a galaxy with
high "intrinsic" redshift).

In this scenario, we would also expect extra plasma
redshift, including detectable redshift of emission and
absorption lines, in the plasma closer to galaxies - in the
intra-cluster medium (IGM) and the plasma around each galaxy,
which may be known as the galaxy's corona.

This would result in excessive redshift for galaxies which
are at the back side of the cluster, from Earth, and so
which are viewed through a lot of cluster IGM compared to
galaxies which are on the Earthward edge of the cluster.
This would be observable as an always redward scatter of
galaxy redshifts in addition to the redshift of the cluster,
which is primarily caused by the intervening ICM, and any
actual velocity the cluster has with respect to Earth.

The "finger-of-god" effect is a scatter of redshifts for
galaxies in the same cluster. It is conventionally
attributed to relative motion of those galaxies, which
surely does occur to some extent, and would produce a
symmetrical scatter in both higher and lower redshifts.

In order for a plasma redshift theory to survive scrutiny, I
believe it would be necessary to show that such "finger of
god" effects have a redward bias - that they are the sum
of both plasma redshift effects in the cluster's IGM and of
the relative motions of the galaxies. I haven't tried to
investigate this in further detail. The CFA Redshift Catalog

http://cfa-www.harvard.edu/~huchra/zcat/zcom.htm

would be a good source of galaxy redshifts from several
surveys to do this work.

There is another effect which I think a plasma redshift
theory would predict about galaxy redshifts: To the extent
that different galaxies have different coronae - differing in
their extent and density, and perhaps in other ways such as
composition and temperature - then we would expect to see
different redshifts for those galaxies.

Assuming that different galaxy types (based on morphology
apparent size, spectral type etc.) have different types of
coronae, then in this plasma redshift scenario, we would
expect to see statistically different redshifts for
different types of galaxies in the same same cluster.

Some papers which finds such correlations a

Evidence for Intrinsic Redshifts in Normal Spiral Galaxies
David G. Russell
Astrophys.Space Sci. 298 (2005) 577-602
http://www.arxiv.org/abs/astro-ph/0408348

Further Evidence for Intrinsic Redshifts in Normal Spiral
Galaxies
David G. Russell
Astrophys.Space Sci. 299 (2005) 387-403
http://www.arxiv.org/abs/astro-ph/0503440

Intrinsic Redshifts and the Tully-Fisher Distance Scale
David G. Russell
Astrophys.Space Sci. 299 (2005) 405-418
http://www.arxiv.org/abs/astro-ph/0503432

Halton Arp, whose theories I do not support, wrote about
a similar effect with nearby hot blue stars having higher
than expected redshift.

Redshifts of high-luminosity stars - The K effect, the
Trumpler effect and mass-loss corrections
adsabs 1992MNRAS.258..800A

If such an effect could be demonstrated, a possible
explanation is that the hotter stars have a more extended
corona and that this causes more redshift of the light we
observe. In this case, it would have to be shown that the
absorption lines were redshifted by the plasma in the
stellar corona and wind and I suspect this would be a very
slight effect compared to the redshift of the black body
signal due to the stellar corona having a generally short
distance between its particles compared to the coherence
length of the absorption line signal. However, I haven't
tried to estimate the coherence length of those lines, or
the inter-particle distance in these stars' coronae. Nor
have I tried to verify the redshifts Arp discusses. I guess
there would still be a very slight redshift when the average
inter-particle distance was significantly less than the
coherence length of the light in question.

- Robin http://astroneu.com