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  #1  
Old October 24th 17, 09:25 PM posted to sci.astro.research
jacobnavia
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Posts: 105
Default Dark matter is:

As I read in the press, we have found a great percentage of dark matter.
Astronomers have suceeded in seeing the shadows of filaments in the
light of the CMB.

https://www.sciencealert.com/astrono...visible-matter
quote
So both teams of researchers relied on something called the
Sunyaev-Zel'dovich effect, a phenomenon that causes photons left over
from the glow of the Big Bang to scatter into slightly higher energies
as they pass through the electrons in the gases surrounding galaxy
clusters
end quote

This cosmic web becomes thicker. That is good news, maybe all of it is
just that:

"Dark matter" that we just doesn't seem able to see easily. But not
anything exotic. Just that: normal matter.

There are also filaments between the stars, this time detected by
gravitational effects in the light of background stars.

The whole thing looks like a connected web. And that web could be very
massive.

jacob

  #2  
Old October 25th 17, 07:06 AM posted to sci.astro.research
Phillip Helbig (undress to reply)[_2_]
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Posts: 273
Default Dark matter is:

In article , jacobnavia
writes:

As I read in the press, we have found a great percentage of dark matter.


Yes, as in matter which is dark. Not in the sense in which "dark
matter" is most often used, namely as shorthand for "non-luminous and
transparent non-baryonic matter other than neutrinos".

This cosmic web becomes thicker. That is good news, maybe all of it is
just that:

"Dark matter" that we just doesn't seem able to see easily. But not
anything exotic. Just that: normal matter.


There are many arguments against this hypothesis, the main ones being
big-bang nucleosynthesis and CMB observations, which both agree that
most of the "missing matter" (i.e. "dark matter" as the term is normally
used) cannot be baryonic.

The whole thing looks like a connected web. And that web could be very
massive.


It could be significantly massive in a cosmological sense only if
non-baryonic matter is associated with it. (This might well be the
case, but we have no evidence one way or the other.)
  #3  
Old October 25th 17, 10:34 PM posted to sci.astro.research
Richard D. Saam
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Posts: 240
Default Dark matter is:

On 10/25/17 1:06 AM, Phillip Helbig (undress to reply) wrote:

"Dark matter" that we just doesn't seem able to see easily. But not
anything exotic. Just that: normal matter.


There are many arguments against this hypothesis, the main ones being
big-bang nucleosynthesis and CMB observations, which both agree that
most of the "missing matter" (i.e. "dark matter" as the term is normally
used) cannot be baryonic.


With what certainty should the 'cannot be' assertion be made. In
science, such absolute assertions are very rare. Current big-bang
nucleosynthesis calculations and CMB observation dark matter
correlations should not exclude a complementary dark matter contribution
by some other mechanism.

  #4  
Old October 26th 17, 08:35 AM posted to sci.astro.research
John Heath
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Posts: 13
Default Dark matter is:

On Wednesday, October 25, 2017 at 2:06:07 AM UTC-4, Phillip Helbig (undress to reply) wrote:
In article , jacobnavia
writes:

As I read in the press, we have found a great percentage of dark matter.


Yes, as in matter which is dark. Not in the sense in which "dark
matter" is most often used, namely as shorthand for "non-luminous and
transparent non-baryonic matter other than neutrinos".

This cosmic web becomes thicker. That is good news, maybe all of it is
just that:

"Dark matter" that we just doesn't seem able to see easily. But not
anything exotic. Just that: normal matter.


There are many arguments against this hypothesis, the main ones being
big-bang nucleosynthesis and CMB observations, which both agree that
most of the "missing matter" (i.e. "dark matter" as the term is normally
used) cannot be baryonic.

The whole thing looks like a connected web. And that web could be very
massive.


It could be significantly massive in a cosmological sense only if
non-baryonic matter is associated with it. (This might well be the
case, but we have no evidence one way or the other.)


The axion is a possibility that is being looked for. If this particle
is found it could be a nice fit for dark matter.

https://www.youtube.com/watch?v=nYAplw_VbnE
  #5  
Old October 26th 17, 08:36 AM posted to sci.astro.research
Phillip Helbig (undress to reply)[_2_]
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Posts: 273
Default Dark matter is:

In article , "Richard D.
Saam" writes:

On 10/25/17 1:06 AM, Phillip Helbig (undress to reply) wrote:

"Dark matter" that we just doesn't seem able to see easily. But not
anything exotic. Just that: normal matter.


There are many arguments against this hypothesis, the main ones being
big-bang nucleosynthesis and CMB observations, which both agree that
most of the "missing matter" (i.e. "dark matter" as the term is normally
used) cannot be baryonic.


With what certainty should the 'cannot be' assertion be made.


Relatively high certainty.

In
science, such absolute assertions are very rare.


True. Strictly speaking, there are no absolute certainties. However,
this doesn't mean that anything goes:

http://chem.tufts.edu/answersinscien...ityofwrong.htm

Current big-bang
nucleosynthesis calculations and CMB observation dark matter
correlations should not exclude a complementary dark matter contribution
by some other mechanism.


They exclude, to a high degree of certainty, most of the missing matter
being baryonic. Yes, that might be wrong, but one needs to show that it
is wrong; one can't claim that since there is no absolute certainty, we
might as well assume that an alternative claim---with zero evidence to
support it---is just as good.
  #6  
Old October 27th 17, 03:42 AM posted to sci.astro.research
Nicolaas Vroom
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Posts: 216
Default Dark matter is:

On Wednesday, 25 October 2017 23:34:51 UTC+2, Richard D. Saam wrote:
On 10/25/17 1:06 AM, Phillip Helbig (undress to reply) wrote:

"Dark matter" that we just doesn't seem able to see easily. But not
anything exotic. Just that: normal matter.


There are many arguments against this hypothesis, the main ones being
big-bang nucleosynthesis and CMB observations, which both agree that
most of the "missing matter" (i.e. "dark matter" as the term is normally
used) cannot be baryonic.


With what certainty should the 'cannot be' assertion be made. In
science, such absolute assertions are very rare. Current big-bang
nucleosynthesis calculations and CMB observation dark matter
correlations should not exclude a complementary dark matter contribution
by some other mechanism.


The whole issue is not dark matter because what is the definition?
The issue is the relation between baryonic versus nonbaryonic matter
in the universe and in our galaxy.

The Book the Big Bang by Joseph Silk defines the following events:
1) Big Bang
2) Particle Creation
3) Annihilation of proton-antiproton pairs
4) Annihilation of electron-positron pairs
5) Nucleosynthesis of helium and deuterium
6) (1 week) Radiation thermalizes prior to this epoch
7) (10 Years) Universe becomes matter dominated.
8) (300000 Y) Universe becomes transparant
9) (1-2 bil Y) Galaxy formation begins

My question is what is the percentage of baryonic matter in each
and which particular processes caused these changes. (roughly)

Suppose that all nonbaryonic matter in the universe (in outer space and
in our Galaxy Halo) are neutrino's when and how did they form?

An interesting article is:
https://arxiv.org/abs/astro-ph/9407006 1994
"Big-Bang Nucleosynthesis and the Baryon Density of the Universe"

See also: https://arxiv.org/abs/1505.01076
"Big Bang Nucleosynthesis: 2015"
In this article the word nonbaryonic is not mentioned.
The word dark matter is mentioned at the pages 3 and 16.

See also:
https://en.wikipedia.org/wiki/Big_Ba...esis#Deuterium
"This explanation is also consistent with calculations that show
that a universe made mostly of protons and neutrons would be far
more clumpy than is observed.[8]"
This raises the question how important is nonbaryonic matter
for the evolution of the Universe?

Nicolaas Vroom
  #7  
Old October 28th 17, 05:24 AM posted to sci.astro.research
Richard D. Saam
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Posts: 240
Default Dark matter is:

On 10/26/17 2:36 AM, Phillip Helbig (undress to reply) wrote:
In article , "Richard D.
Saam" writes:

On 10/25/17 1:06 AM, Phillip Helbig (undress to reply) wrote:

"Dark matter" that we just doesn't seem able to see easily. But not
anything exotic. Just that: normal matter.

There are many arguments against this hypothesis, the main ones being
big-bang nucleosynthesis and CMB observations, which both agree that
most of the "missing matter" (i.e. "dark matter" as the term is normally
used) cannot be baryonic.


With what certainty should the 'cannot be' assertion be made.


Relatively high certainty.

Current big-bang
nucleosynthesis calculations and CMB observation dark matter
correlations should not exclude a complementary dark matter contribution
by some other mechanism.


They exclude, to a high degree of certainty, most of the missing matter
being baryonic. Yes, that might be wrong, but one needs to show that it
is wrong; one can't claim that since there is no absolute certainty, we
might as well assume that an alternative claim---with zero evidence to
support it---is just as good.

It is not a matter of being wrong but incomplete.
For reference, CMB blackbody parameters
with associated redshifts(1+z)^n a

Temperature 2.729*(1+z)^1 kelvin
Frequency 1.60x10^11*(1+z)^1 Hz
Wave Length .106*(1+z)^-1 cm
Mass Density 4.67x10^-34*(1+z)^4 g/cm^3
Energy Density 4.20x10^-13*(1+z)^4 erg/cm^3
Photon Density 412*(1+z)^3 #/cm^3

Small variation of these numbers
as indicators of Dark Matter
represent a small segment of the universe parameter space.
Larger frequencies(energies) have been studied for the WIMP searches
but lower frequencies(down to the microHz level)
have not been adequately searched
(mostly due to instrumentation measurement inadequacies)
for other dark matter contributors.

As for nucleosynthesis mechanisms,
there is an ongoing LHC study of nuclear dynamics
simulating The Big Bang that may bring more certainty
in resolving incompleteness.


[[Mod. note -- Experiments at Brookhaven's RHIC (Relativistic Heavy
Ion Collider) are also relevant here. -- jt]]
  #8  
Old October 28th 17, 05:24 AM posted to sci.astro.research
Phillip Helbig (undress to reply)[_2_]
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Posts: 273
Default Dark matter is:

In article ,
Nicolaas Vroom writes:

On Wednesday, 25 October 2017 23:34:51 UTC+2, Richard D. Saam wrote:
On 10/25/17 1:06 AM, Phillip Helbig (undress to reply) wrote:

"Dark matter" that we just doesn't seem able to see easily. But not
anything exotic. Just that: normal matter.

There are many arguments against this hypothesis, the main ones being
big-bang nucleosynthesis and CMB observations, which both agree that
most of the "missing matter" (i.e. "dark matter" as the term is normally
used) cannot be baryonic.


With what certainty should the 'cannot be' assertion be made. In
science, such absolute assertions are very rare. Current big-bang
nucleosynthesis calculations and CMB observation dark matter
correlations should not exclude a complementary dark matter contribution
by some other mechanism.


The whole issue is not dark matter because what is the definition?
The issue is the relation between baryonic versus nonbaryonic matter
in the universe and in our galaxy.


Right.

The Book the Big Bang by Joseph Silk defines the following events:
1) Big Bang
2) Particle Creation
3) Annihilation of proton-antiproton pairs
4) Annihilation of electron-positron pairs
5) Nucleosynthesis of helium and deuterium
6) (1 week) Radiation thermalizes prior to this epoch
7) (10 Years) Universe becomes matter dominated.
8) (300000 Y) Universe becomes transparant
9) (1-2 bil Y) Galaxy formation begins

My question is what is the percentage of baryonic matter in each
and which particular processes caused these changes. (roughly)


After 3) and 4) the ratio is fixed. (Strictly speaking electrons are
not baryonic matter, but they are known matter and in any case, with
equal numbers of protons and electrons, the mass of electrons is
negligible.)

Suppose that all nonbaryonic matter in the universe (in outer space and
in our Galaxy Halo) are neutrino's


Doesn't seem to be possible, because neutrinos can't be heavy enough to
be cold dark matter, and warm dark matter is ruled out by structure
formation.

when and how did they form?


Like all the other particles. (Some neutrinos formed later, in
nucleosynthesis and so on, but, like photons, by far the most are from
the cosmic background.)

See also: https://arxiv.org/abs/1505.01076
"Big Bang Nucleosynthesis: 2015"
In this article the word nonbaryonic is not mentioned.


Non-baryonic matter is not really relevant for nucleosynthesis.

The word dark matter is mentioned at the pages 3 and 16.


These days, in a cosmological context, "dark matter" means
"non-luminous, transparent, non-baryonic matter apart from neutrinos".

https://en.wikipedia.org/wiki/Big_Ba...esis#Deuterium
"This explanation is also consistent with calculations that show
that a universe made mostly of protons and neutrons would be far
more clumpy than is observed.[8]"


Right.

This raises the question how important is nonbaryonic matter
for the evolution of the Universe?


Very. Without dark matter, the fluctuations observed in the CMB would
not have had time to form the structure we see today. Although the book
is mainly about MOND, Bob Sanders's book DECONSTRUCTING COSMOLOGY gives
a good, unbiased overview of standard structure formation. (Bob is a
MOND enthusiast, but the evidence for MOND comes from galaxy-scale
physics. Even he admits that structure formation without the standard
dark-matter scenario doesn't seem to work.) Also, since most of the
matter is non-baryonic, without it the universe would not be nearly
flat (assuming that everything else stays the same).
  #9  
Old October 28th 17, 07:36 AM posted to sci.astro.research
jacobnavia
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Posts: 105
Default Dark matter is:

Yes, but after years of searches I think that is useless to go on
denying that we just have no idea how the universe works. No physical
counterpart of the supposed "dark matter" has been found in any lab.

There is no dark matter particle and hence exotic dark matter doesn't
exist. Normal matter could have unknown behaviour however, at big
scales. That is the logical conclusion.

Just one thing. Matter could be organized at big scales by forces that
at our level of being (1.8 meters, 5 watts brain freshly evolved from
some primate) are undetectable by our labs and particle accelerators.
Those forces acting at galactic or cluster scales could be determinant
for our understanding of the cosmic web.

Matter seems to be connected everywhere, and the size and forces that
make those connections and filaments are unknown to us but they exist,
since those filaments exist. There are filaments between the stars, and
filaments between the galaxies, and filaments between the clusters of
galaxies. Rivers of galaxies can be figured out, and astronomers have
followed those filaments to figure out the biggest being they have ever
seen, an incredible structure that you can see he

http://www.dailymail.co.uk/sciencete...Milky-Way.html

Its filamentary structure is evident in this drawing.

Sadly, our ideas about a big bang and the resulting explanations make
this hypothesis not so attractive for many people.

Since observations indicate that a sea of galaxies extends away and away
from us in all directions, I consider that the CMB doesn't really imply
a big bang.

It is just that: Cosmic Background. The sea of galaxies is bathed in the
relic light from all uncountable galaxies extending till who knows
where. This explains why is so uniform.

Ambient light.
  #10  
Old October 29th 17, 07:11 AM posted to sci.astro.research
Phillip Helbig (undress to reply)[_2_]
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Posts: 273
Default Dark matter is:

In article , jacobnavia
writes:

No physical
counterpart of the supposed "dark matter" has been found in any lab.


The same was true for neutrinos for a couple of decades, and we even
knew the sources and how many were produced. Not all experiments are
easy.

There is no dark matter particle and hence exotic dark matter doesn't
exist. Normal matter could have unknown behaviour however, at big
scales. That is the logical conclusion.


It is a possibility. But absence of evidence is not evidence of
absence. Yes, there are other possibilities for dark matter, but
particle dark matter is not completely ruled out yet.

Matter seems to be connected everywhere, and the size and forces that
make those connections and filaments are unknown to us but they exist,
since those filaments exist. There are filaments between the stars, and
filaments between the galaxies, and filaments between the clusters of
galaxies. Rivers of galaxies can be figured out, and astronomers have
followed those filaments to figure out the biggest being they have ever
seen, an incredible structure that you can see he


The filamentary structure is produced in numerical simulations, even
those which use only gravity. This is not a puzzle.

Sadly, our ideas about a big bang and the resulting explanations make
this hypothesis not so attractive for many people.


There is no need for another hypothesis since the filamentary structure
falls naturally out of numerical simulations.

Since observations indicate that a sea of galaxies extends away and away=


from us in all directions, I consider that the CMB doesn't really imply
a big bang.


Behind the galaxies is the CMB. We can't see any galaxies beyond the
CMB. Even if the universe is infinite, we can't see beyond the CMB, and
even if we could, we would see at best precursors of galaxies, since we
are seeing things far away as they were long ago.

It is just that: Cosmic Background. The sea of galaxies is bathed in the=


relic light from all uncountable galaxies extending till who knows
where. This explains why is so uniform.


Your hypothesis cannot explain the power spectrum of the CMB.
 




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