Basic Dark Matter Question

In article ,
Phillip Helbig---remove CLOTHES to reply wrote:

In the case of the solar system, well over 99% of the mass is in the
Sun, so the situation is not really comparable. Otherwise, I agree with
you: why should most matter shine for the convenience of the astronomer?

The puzzle is that we don't know what it is.

This is completely right, of course.

As others have suggested elsewhere in this thread, the other puzzling
thing is that evidence strongly suggests that a lot of the dark matter
is non-baryonic, which means that it's not made of atoms.

The evidence for this comes from estimating the total density of
matter in the universe, and estimating the total density of atoms.
The former is significantly greater than the latter. Both of these
estimates can now be done in multiple independent ways, with
quite robust results.

-Ted

--
[E-mail me at , as opposed to .]

In article ,
Max Keon wrote:
Bjoern Feuerbacher wrote:

According to modern measurements, the universe could even be
infinitely large!


You do of course have substantial evidence to back up that claim?

There is precisely no evidence that the universe is infinitely large.
There is also precisely no evidence that the universe is finite in
size. Existing data are consistent with both possibilities. Bjoern
Feuerbacher is therefore completely right on this: the phrase "could
be" expresses possibility, not certainty.

-Ted

--
[E-mail me at , as opposed to .]

Hans Aberg wrote:


Suppose a large amount of very young, hard to observe, galaxies exist out
there, which one has found a few of the last year or so, and they turn out
to have a lot of young stars, with a lot of more hydrogen proportion. How
would this affect this modelling?

Such galaxies do exist. They have a slightly lower helium abundance,
and dramatically lower abundances of heavier elements, what astronomers
call metals. This supports our general notion, that most of the helium
has a different origin from the heavier elements, and the only way we
can generate massive amounts of helium without producing metals is
through the big bang.

Ulf Torkelsson

In article , Ulf Torkelsson
wrote:

Suppose a large amount of very young, hard to observe, galaxies exist out
there, which one has found a few of the last year or so, and they turn out
to have a lot of young stars, with a lot of more hydrogen proportion. How
would this affect this modelling?

Such galaxies do exist. They have a slightly lower helium abundance,
and dramatically lower abundances of heavier elements, what astronomers
call metals. This supports our general notion, that most of the helium
has a different origin from the heavier elements, and the only way we
can generate massive amounts of helium without producing metals is
through the big bang.

So the key point is the portion of observed hydrogen and helium at
production stage?

I.e., if the helium/hydrogen ratio is sufficiently high, the Big Bang
model can be used to explain it. But if that ratio is lower, the Big Bang
model would be too hot, indicating a more continuous production line of
elements from hydrogen and up.

--
Hans Aberg

Hans Aberg wrote:
In article , Ulf Torkelsson
wrote:


Suppose a large amount of very young, hard to observe, galaxies exist out
there, which one has found a few of the last year or so, and they turn out
to have a lot of young stars, with a lot of more hydrogen proportion. How
would this affect this modelling?


Such galaxies do exist. They have a slightly lower helium abundance,
and dramatically lower abundances of heavier elements, what astronomers
call metals. This supports our general notion, that most of the helium
has a different origin from the heavier elements, and the only way we
can generate massive amounts of helium without producing metals is
through the big bang.


So the key point is the portion of observed hydrogen and helium at
production stage?

I.e., if the helium/hydrogen ratio is sufficiently high, the Big Bang
model can be used to explain it. But if that ratio is lower, the Big Bang
model would be too hot, indicating a more continuous production line of
elements from hydrogen and up.

The big bang model explains nicely the high helium abundance that we
observe everywhere in the universe, and in particular the fact that
the helium abundance is not proportional to the metal abundance in
the universe. The predicted helium abundance is rather insensitive
to the exact conditions at the big bang. A much lower helium abundance
would have been a strong argument against the big bang, or in favour
of some *very* exotic particle physics in the early universe.

Ulf Torkelsson

In article , Ulf Torkelsson
wrote:

So the key point is the portion of observed hydrogen and helium at
production stage?

I.e., if the helium/hydrogen ratio is sufficiently high, the Big Bang
model can be used to explain it. But if that ratio is lower, the Big Bang
model would be too hot, indicating a more continuous production line of
elements from hydrogen and up.

The big bang model explains nicely the high helium abundance that we
observe everywhere in the universe, and in particular the fact that
the helium abundance is not proportional to the metal abundance in
the universe. The predicted helium abundance is rather insensitive
to the exact conditions at the big bang. A much lower helium abundance
would have been a strong argument against the big bang, or in favour
of some *very* exotic particle physics in the early universe.

If there is such a high helium/hydrogen ratio, also in the youngest formed
stars in the youngest galaxies, with the absence of astronomic metals,
then that seems to be a fact to be dealt with. In addition, there must be
some QM process involved with, sufficiently hot to generate it, some form
of "nucleosynthesis". In addition, the absence of metals, in this youngest
formed starts, seem to tell us that the origin of this matter cannot be
from residues of other starts, as then one would have such metals in the
formation starts.

But there is another possible, namely if matter is allowed to tunnel out
from a black hole. Tunneling can take place, wherever QM effects are
present, even though they can be highly unlikely. Particles tunneling out
of a black hole would not defy gravity in the normal GR sense, which is
impossible, but rather there would be a fuzzy GRQM event horizon, and
particle-fields sufficiently near this horizon would have states
simultaneously inside and out side it. There is a substantial problem,
producing equations admitting theoretical analysis. But in principle,
black holes could be observed, and the question settled empirically before
any theoretical equations arrives.

Now, thinking about this situation, I came to the conclusion that there is
another possibility: Matter can tunnel out of black hole, and some kind of
nucleosynthesis can take place in the process, generating the correct
observed infancy helium/hydrogen proportions. This would also explain the
absence of astronomic metals in the matter.

Now, suppose this, as a thought experiment. What happens then with the Big
Bang model?

--
Hans Aberg

"HA" == Hans Aberg writes:

HA In article , Ulf
HA Torkelsson wrote:

The big bang model explains nicely the high helium abundance that
we observe everywhere in the universe, and in particular the fact
that the helium abundance is not proportional to the metal
abundance in the universe. The predicted helium abundance is
rather insensitive to the exact conditions at the big bang. A much
lower helium abundance would have been a strong argument against
the big bang, or in favour of some *very* exotic particle physics
in the early universe.

HA If there is such a high helium/hydrogen ratio, also in the
HA youngest formed stars in the youngest galaxies, with the absence
HA of astronomic metals, then that seems to be a fact to be dealt
HA with. [...]

More than just the He/H ratio are light element abundance ratios
(including D/H, Li/H). What is seen, generally, is that there is a
"floor" value for these ratios, meaning that there is a minimum
value. (One has to be a bit careful in evaluating specific
observations because there are ways to destroy some of these
elements.) Generally, though, yes, there is a specific He/H ratio
that needs to be explained.

The Big Bang model does that. In the Big Bang model, the Universe was
hotter and denser in the past. Extrapolating into the past, there
would have been a time when the Universe had the temperature and
density of the interior of a star, and nucleosynthesis should have
occurred.


HA But there is another possible, namely if matter is allowed to
HA tunnel out from a black hole. [...]

O.k., this counts as speculation (recalling the post that started this
entire thread). One starts from a hypothesized process (black hole
evaporation) and proceeds to speculate, in a non-quantitative fashion,
about what might be able to happen.

Contrast that with BB nucleosynthesis. Nucleosynthesis experiments
have been conducted here on the Earth (they are known as thermonuclear
bomb tests), so we have a basic understanding of the physics involved.
We can explain the structure of stars, including our Sun, to
reasonable levels of precision. BB nucleosynthesis involving a hot
plasma early in the Universe's history involves extrapolation, but no
speculation.

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

In article , Joseph Lazio
wrote:

HA If there is such a high helium/hydrogen ratio, also in the
HA youngest formed stars in the youngest galaxies, with the absence
HA of astronomic metals, then that seems to be a fact to be dealt
HA with. [...]

More than just the He/H ratio are light element abundance ratios
(including D/H, Li/H). What is seen, generally, is that there is a
"floor" value for these ratios, meaning that there is a minimum
value. (One has to be a bit careful in evaluating specific
observations because there are ways to destroy some of these
elements.) Generally, though, yes, there is a specific He/H ratio
that needs to be explained.

The important thing is to isolate the element proportions in what might be
called "infancy material", the material that the youngest stars are formed
from, in regions with no heavier elements present, or as little thereof.

It seems one can get clues as to what this infancy material is composed of
by looking at some of these very young, nearby galaxies one has recently
discovered. By extrapolating back in time of stellar nucleosynthesis, of
these pristine stars, I gather, one should getter, even better minimum
values of these proportions, which then will tell the true proportions of
this infancy material.

An earlier post suggested that one indeed gets these proportions in this
infancy material, no matter how pristine star formation conditions one is
looking for.

So if this infancy material is formed by some elementary particle soup of
some kind, whatever its origin it now may be, and it has such minimal
element proportions, it must mean that there is some kind of
nucleosynthesis forming it.

The Big Bang model does that. In the Big Bang model, the Universe was
hotter and denser in the past. Extrapolating into the past, there
would have been a time when the Universe had the temperature and
density of the interior of a star, and nucleosynthesis should have
occurred.

We are aware of that Big Bang theories can be used to explain that.

HA But there is another possible, namely if matter is allowed to
HA tunnel out from a black hole. [...]

O.k., this counts as speculation (recalling the post that started this
entire thread).

[I have deliberately taken off-line the discussion of the meaning of the
word "speculation" in science theory and philosophy, though interesting
and important it may be, it does not seem to help forwarding the facts of
interest here.]

One starts from a hypothesized process (black hole
evaporation) and proceeds to speculate, in a non-quantitative fashion,
about what might be able to happen.

As I pointed out, there are big problems in producing a quantitative
theory, simply because it is a serious problem of generating a
quantitative GRQM theory; if somebody had done the latter, we would just
have plugged in the values, and checked who was right, adjusting against
observations, in the usual fashion. Instead, we are faced with the problem
of identifying physical situations where such GRQM theory candidates can
be tested, once developed; the black hole conditions seems me might be a
candidate for that.

Otherwise, the unquantitative reasoning presented is sound and consistent
with well established principles of GR and QM. I should also both point
out that GR and QM taken as separate theories have each not yet been fully
mathematically formalized and thereby quantified (in the case of GR,
because of the absence of a unified matter model), but are making use of
largely empirical, unquantified reasoning. So the situation of making use
of unquantified reasoning is still something one cannot escape with,
making use of these well established theories.

Contrast that with BB nucleosynthesis. Nucleosynthesis experiments
have been conducted here on the Earth (they are known as thermonuclear
bomb tests), so we have a basic understanding of the physics involved.
We can explain the structure of stars, including our Sun, to
reasonable levels of precision. BB nucleosynthesis involving a hot
plasma early in the Universe's history involves extrapolation, but no
speculation.

According to one news report, one is even bickering over whether the first
experimental fusion reactor should be built in Europe, or Japan. If
particle and energy conditions are right, one gets nuclear fusion, that is
known. Nor is there any dispute that the Big Bang model can be used to
explain such a thing. But this does not constitute a proof that
nucleosynthesis producing infancy material cannot occur elsewhere.

Now thinking about it this way, I can not think of any other place
producing such infancy material than possibly the black holes, as first
high energies must be involved, at a level not occurring at many places in
our universe. Second, it cannot be stars or any such place, as then
astronomic metals would be a part of the infancy material.

In fact, by throwing this reasoning into the bag, I have given the
opportunity of strengthening the support for the Big Bang: Just show that
there cannot take place tunneling accompanied with suitable
nucleosynthesis out of a black hole. This is a very special condition,
because tunneling is in itself not enough; there has to be some additional
energy conditions producing the nucleosynthesis. In fact, this fact
confused me a lot at first while thinking about it. Then this demonstrated
exclusion will give further support for the Big Bang model, as the
presence of the infancy material cannot easily otherwise be explained.

--
Hans Aberg

Hans Aberg wrote:

But there is another possible, namely if matter is allowed to tunnel out
from a black hole. Tunneling can take place, wherever QM effects are
present, even though they can be highly unlikely. Particles tunneling out
of a black hole would not defy gravity in the normal GR sense, which is
impossible, but rather there would be a fuzzy GRQM event horizon, and
particle-fields sufficiently near this horizon would have states
simultaneously inside and out side it. There is a substantial problem,
producing equations admitting theoretical analysis. But in principle,
black holes could be observed, and the question settled empirically before
any theoretical equations arrives.

Actually, this analysis has been done, firstly by Hawking in 1974.
What you describe is nothing else than the Hawking radiation from
black holes. There is an extensive literature on this.

Now, thinking about this situation, I came to the conclusion that there is
another possibility: Matter can tunnel out of black hole, and some kind of
nucleosynthesis can take place in the process, generating the correct
observed infancy helium/hydrogen proportions. This would also explain the
absence of astronomic metals in the matter.



There is nothing in the theoretical studies of the Hawking radiation
that supports that the kind of nucleosynthesis that you suggest can
take place, and there have been some rather advanced QCD studies of
what particles can be produced at the event horizon.

Ulf Torkelsson

In article , Ulf Torkelsson
wrote:

But there is another possible, namely if matter is allowed to tunnel out
from a black hole.

Actually, this analysis has been done, firstly by Hawking in 1974.
What you describe is nothing else than the Hawking radiation from
black holes. There is an extensive literature on this.

No. Hawking assumed a classical, sharp GR event horizon, and he does not
make use of QM tunneling. From what I remember, he studies particle pairs,
one immediately inside the event horizon, and one immediately outside it,
and shows that under such circumstances, some energy can be transferred to
the one outside it via some QM processes. I do not recall that the
particle inside the actually leaving the black hole. But correct me, if I
am wrong.

There is nothing in the theoretical studies of the Hawking radiation
that supports that the kind of nucleosynthesis that you suggest can
take place, and there have been some rather advanced QCD studies of
what particles can be produced at the event horizon.

I know that the Hawking model is insufficient for the things I am asking
for; that is why I am asking about it. One has to combine GR and QM first
in a single theory, in order to arrive at the tunneling effects I am
thinking about. Hawking does not know anything about that, as far as I
know (correct me if I am wrong). (I have in the past given some hints on
the kind of mathematical theories I am playing around with, a Fock space
based on the manifold consisting of a Lorentz-manifold plus a copy of the
cotangent bundle for each particle.)

--
Hans Aberg