Could Dark Matter Possibly Be . . .

[harry]

G'day Chris

You said

Dark matter is well defined, as the property or material responsible for a number of effects that are observable (so far) anomalous gravitational effects on visible matter.

What is it?

[Chris Peterson]

What is it?

Nobody knows for sure. Dark matter is currently defined in terms of its properties, particularly its mass. That definition doesn't require that much be known about its other physical properties.

Beyond its observable behavior, there are a number of theories about more specific properties. These are proper scientific theories, in that they present testable claims. As observations improve, some theories will fall, and others will be strengthened. Eventually, we'll have a high level of confidence that we deeply understand dark matter. The scientific process is very powerful.

[Martin]

There is also a good chance that we have gravity wrong once again and there is no "unkown matter".

[Chris Peterson]

There is also a good chance that we have gravity wrong once again and there is no "unkown matter". :oops:

I think there's only a very small chance we got gravity that wrong. We see many different types of evidence, both near and far, that gravity behaves the way GR predicts. Dark matter is very much more likely than a broken theory of gravity.

(As an aside, we've never gotten gravity wrong, so I don't know what you mean by "again". The first scientific theory of gravity was produced by Newton, and it remains substantially correct to this day. Einstein didn't show that Newton was wrong, but simply extended the theory to a wider range of conditions than Newton could have been aware of.)

[harry]

G'day

What about if all the dark matter and dark energy was in the form of degerate matter found in ultra dense plasma matter located in compact stars such as Neutron Stars, quark stars and dark stars (black holes).

[Chris Peterson]

What about if all the dark matter and dark energy was in the form of degerate matter found in ultra dense plasma matter located in compact stars such as Neutron Stars, quark stars and dark stars (black holes).

First of all, the only things dark matter and dark energy have in common are the word "dark". Otherwise, they are entirely different things, with entirely different properties, effects, and observations. So lets leave dark energy out of it completely.

As far as dark matter is concerned, there's no reason- either theoretically or experimentally- to think that degenerate matter magically becomes non-baryonic, or otherwise would not interact with EM radiation and therefore be invisible. Degenerate matter is either a baryonic solid (sometimes treated as a fluid), or a fermionic gas. In either case, there will be interaction with EM radiation. Also, degenerate matter is kept in that state by the force of gravity. Once removed from the strong gravitational field of a collapsed star, there's nothing to keep it in a degenerate state.

Strange matter may be considered degenerate, but it remains a theoretical concept, largely unsupported by observation (which is also the case for quark stars).

With respect to observations of degenerate matter, we should restrict ourselves to white dwarfs and neutron stars. Black hole (there's no such thing as a dark star) interiors are far enough outside current physical theory that to suggest they contain degenerate matter is nothing but speculation.

[harry]

G'day Chris

Your statement tells me that you need to read up.


Black holes or dark clusters in M31 and M32?
http://adsabs.harvard.edu/abs/1989ApJ...337...84G
Feb-89

http://adsabs.harvard.edu/abs/1998ApJ...500..591T
Dark Matter Concentration in the Galactic Center
Tsiklauri, David; Viollier, Raoul D.
Astrophysical Journal v.500, p.591 (ApJ Homepage)
Jun-98

http://adsabs.harvard.edu/abs/1991CQGra...8.1847B
Degenerate metrics and an empty black hole.
Bengtsson, I.
Classical Quantum Gravity, Vol. 8, No. 10, p. 1847 - 1857
Oct-91

Evolving, dynamical models for collapsed-core globular clusters - M15 and NGC 6624
Evolving, dynamical models for collapsed-core globular clusters - M15 and NGC 6624
Grabhorn, Robert P.; Cohn, Haldan N.; Lugger, Phyllis M.; Murphy, Brian W.
AA(Indiana University, Bloomington), AB(Indiana University, Bloomington), AC(Indiana University, Bloomington), AD(Utrecht, State University, Netherlands; Cornell University, Ithaca, NY)
Astrophysical Journal, Part 1 (ISSN 0004-637X), vol. 392, no. 1, June 10, 1992, p. 86-98. (ApJ Homepage)
Jun-92

http://adsabs.harvard.edu/abs/1997RvMP...69..337A
A dying universe: the long-term fate and evolutionof astrophysical objects
Adams, Fred C.; Laughlin, Gregory
AA(Physics Department, University of Michigan, Ann Arbor, Michigan 48109), AB(Physics Department, University of Michigan, Ann Arbor, Michigan 48109)
Reviews of Modern Physics, Volume 69, Issue 2, April 1997, pp.337-372 (RvMP Homepage)
00/1997

http://adsabs.harvard.edu/abs/1999PhRvD..59d4026N
Quantum evolution of Schwarzschild-de Sitter (Nariai) black holes
Nojiri, Shin'ichi; Odintsov, Sergei D.
AA(Department of Mathematics and Physics, National Defence Academy, Hashirimizu Yokosuka 239, Japan), AB(Tomsk Pedagogical University, 634041 Tomsk, Russia)
Physical Review D (Particles, Fields, Gravitation, and Cosmology), Volume 59, Issue 4, 15 February 1999, id. 044026 (PhRvD Homepage)
Feb-99


http://adsabs.harvard.edu/abs/1998ApJ...509L.105M
Sagittarius A*: A Supermassive Black Hole or a Spatially Extended Object?
Munyaneza, F.; Tsiklauri, D.; Viollier, R. D.
The Astrophysical Journal, Volume 509, Issue 2, pp. L105-L108. (ApJ Homepage)
Dec-98

http://adsabs.harvard.edu/abs/1984jbp..bookQ....B
Astrophysics. Volume 1 - Stars
Bowers, R. L.; Deeming, T.
AA(Los Alamos National Laboratory, Los Alamos, NM)
Research supported by the University of Texas, Los Alamos National Laboratory, and Digicon Geophysical Corp. Boston, MA, Jones and Bartlett Publishers, Inc., 1984, 378 p.
00/1984

http://adsabs.harvard.edu/abs/1995ApJ...445L.129B
Observational constraints on the maximum neutron star mass
Bethe, H. A.; Brown, G. E.
AA(California Institute of Technology, Pasadena, California, US), AB(California Institute of Technology, Pasadena, California, US)
Astrophysical Journal, Part 2 - Letters (ISSN 0004-637X), vol. 445, no. 2, p. L129-L132 (ApJ Homepage)
Jun-95


http://adsabs.harvard.edu/abs/1994PhRvD..49.5080H
A cosmological constant limits the size of black holes
Hayward, Sean A.; Nakao, Ken-Ichi
AA(Department of Physics, Kyoto University, Kyoto 606-01, Japan), AB(Department of Physics, Kyoto University, Kyoto 606-01, Japan)
Physical Review D (Particles, Fields, Gravitation, and Cosmology), Volume 49, Issue 10, 15 May 1994, pp.5080-5085 (PhRvD Homepage)
May-94

http://adsabs.harvard.edu/abs/1997PhLB..403...12A
U-invariants, black-hole entropy and fixed scalars.
Andrianopoli, L.; D'Auria, R.; Ferrara, S.
Phys. Lett. B, Vol. 403, No. 1 - 2, p. 12 - 19
Jun-97


http://adsabs.harvard.edu/abs/1984GReGr..16..211M
Black hole uniqueness from a hidden symmetry of Einstein's gravity
Mazur, P. O.
AA(Krakow, Uniwersytet, Krakow, Poland)
General Relativity and Gravitation (ISSN 0001-7701), vol. 16, March 1984, p. 211-215. (GReGr Homepage)
Mar-84


http://adsabs.harvard.edu/abs/1980Sci...207..597P
Accreting neutron stars, black holes, and degenerate dwarf stars
Pines, D.
AA(Illinois, University, Urbana, Ill.)
Science, vol. 207, Feb. 8, 1980, p. 597-606. NSF-supported research.
Feb-80


http://adsabs.harvard.edu/abs/1999ApJ...526..744M
Dynamics of the Star S0-1 and the Nature of the Compact Dark Object at the Galactic Center

http://adsabs.harvard.edu/abs/2008ralc.conf...98N
Equilibrium Configurations of Degenerate Fermionic Dark Matter and the Black Hole Mass Hierarchy

http://adsabs.harvard.edu/abs/2006JPhCS..31..179N
Fully degenerate fermionic dark matter in the cluster-center and black hole


http://adsabs.harvard.edu/abs/2005astro.ph..6623N
Fully Degenerate Self-Gravitating Fermionic Dark Matter: Implications to the Density Profile of the Cluster of Galaxies A1689, and the Mass Hierarchy of Black Holes


http://adsabs.harvard.edu/abs/2007FoPh...37..632S
Condensates in the Cosmos: Quantum Stabilization of the Collapse of Relativistic Degenerate Stars to Black Holes

[Chris Peterson]

G'day Chris

Your statement tells me that you need to read up...

Sorry, I fail to see the relevance of any of these citations to your speculations about dark matter.

If you have a point to make, you need to present your argument and provide a specific citation that supports it. If you feel that something I said is in error, you need to explain why you think that, so we have something to discuss.

A quick scan of the titles you provide makes me think I'm not going to learn anything new (except details, of course), and I don't see anything that seems to support your suggestions about degenerate matter as a candidate for dark matter.

[harry]

G'day from the land of ozzzzz

My point is that you need to read up on the topic.

Thats up to you.

[Chris Peterson]

G'day from the land of ozzzzz

My point is that you need to read up on the topic.

Thats up to you.

Okay. I'm all read up. My previous observations remain unchanged.

[Martin]

:

[harry]

G'day Chris

Upto this date I have not seen one person, being all read up.

If you are, than please explain to me the formation of Neutron Stars and the transition to ultra dense plasma matter that has a trapping horizon.

[Chris Peterson]

G'day Chris

Upto this date I have not seen one person, being all read up.

If you are, than please explain to me the formation of Neutron Stars and the transition to ultra dense plasma matter that has a trapping horizon.

That's a separate discussion. All I asked is that if you disagree with something I say (which is fine), please tell me specifically what you disagree with, and why. It's unreasonable to simply provide a reading list and ask me to figure out what I said that might be wrong... especially if the only thing "wrong" is your interpretation of what I said!

[harry]

G'day Chris

Please explain the difference btween Dark Matter and dark energy.

[Chris Peterson]

Please explain the difference btween Dark Matter and dark energy.

Dark matter is material (matter <g>) that is invisible (has little or no interaction with electromagnetic radiation) but exhibits obvious gravitational effects on normal matter. Its existence is widely accepted due to close correspondence between observation and theory in multiple, independent measurements. It's actual composition is unknown, but the currently most favored theories assume it consists of non-baryonic particles.

Dark energy is a hypothetical form of energy that fills all of space and is responsible for the apparent increase in the expansion rate of the Universe. While its existence is rather well accepted, it remains only marginally supported by observation.

There is nothing in common between dark matter and dark energy. If you examine the energy budget of the Universe, they are completely different components (dark energy, dark matter, ordinary matter).

[harry]

G'day Chris

Now! don't you think that definition is a bit odd?

[Chris Peterson]

Now! don't you think that definition is a bit odd?

No. It seems quite reasonable, and is accepted by 100% of the scientific community. The definitions are based solidly on observation, not on theory.

[harry]

G'day Chris

This may be of interest, If you are interested in reading.

Trapping Horizons
http://arxiv.org/find/all/1/all:+AND+Tr ... /0/all/0/1

From the list above

http://arxiv.org/abs/0802.3422
Black Holes without Event Horizons

http://arxiv.org/abs/astro-ph/0408323
A new proof for non-occurrence of trapped surfaces and information paradox

http://arxiv.org/abs/gr-qc/0404022
Simulation of gravitational objects in Bose-Einstein condensates

http://arxiv.org/abs/astro-ph/0307438
Do Black Hole Candidates Have Magnetic Moments Instead of Event Horizons?


http://arxiv.org/abs/astro-ph/0111421
Does The Principle Of Equivalence Prevent Trapped Surfaces From Being Formed In The General Relativistic Collapse Process?


http://arxiv.org/abs/gr-qc/0005119
Modified Black Hole with Polar Jet and Vortex

[Martin]

To not have it completely correct or completely understood can be phrased as "wrong", since it fails to fully explain itself in its entirety.

I believe it is highly more probable than you are suggesting it is. Just because we can make accurate predictions does not automatically imply that we have a complete understanding. Chances are that our lack of knowledge is a greater suspect. Our history of science clearly supports this conclusion. However, it is highly presumptuous to speak with any real confidence on this subject until more evidence is observed.

Another unusual suspect could be empty space itself.

[Chris Peterson]

Chances are that our lack of knowledge is a greater suspect. Our history of science clearly supports this conclusion.

I would argue that our history of science, with respect to fundamental physical laws, shows that we have seldom been wrong. Once the process of understanding nature was approached scientifically, we rather quickly developed accurate descriptions of how things work. Very few of these theories have been thrown out; most have simply been refined with time.

There is really nothing to make me think we don't have a good, solid understanding of gravity. I'm sure we will learn more with time, and better integrate gravity into other theories, but I doubt very much that our current theory will change much.

[harry]

G'day from the land of ozzz

We know what gravity can do, but! we do not know what gravity is.

We do not even know what the speed of gravity is.

[Martin]

Chris wrote:

There is really nothing to make me think we don't have a good, solid understanding of gravity.

When was the last time "non-baryonic particles" were needed to explain an observed phenomenon? Has any non-baryonic matter ever been observed else where in our universe? And our current understanding of gravity cannot explain the expansion rate between observable galaxies.

These would be some of the reasons to make me think there is a good chance we lack solid understanding. As you suggested earlier we probably just need to expand upon GR so that our observations match our theories, eh?

Good point Harry. I think the currently accepted view is that Gravity was one part of 3 forces that were combined into one super force particle prior to the BB. Gravity being the 1st force to break away independently. This theory also attempts to explain the mystery of the evenly distributed temperature of space. Saying that the temperature was locked into the sphere of expansion following the BB.

[Chris Peterson]

When was the last time "non-baryonic particles" were needed to explain an observed phenomenon? Has any non-baryonic matter ever been observed else where in our universe?

That dark matter exists is virtually certain. And current theory (well supported by observation) strongly favors non-baryonic matter. And especially important, theories describing its nature are highly testable. So we simply accept that non-baryonic matter is currently the best candidate for dark matter, but far from the only one. I have little doubt that we will know much more about this within just a few years. But my comments about our understanding of cosmology being essentially correct hold no matter what dark matter turns out to be. The most important point is that it exists and interacts gravitationally with matter we can see. The details of its nature are still being discovered. Nobody has set into canon yet what dark matter is, so there is no fundamental science to be found wrong. I very much doubt we are going to discover that dark matter doesn't exist, and that the observations we record will turn out to be from something radically different, like a fundamental misunderstanding about the nature of gravity.

And our current understanding of gravity cannot explain the expansion rate between observable galaxies.

It does if we assume that there is such a thing as dark energy. Again, theories that require dark energy also explain with high accuracy many structural details we see in the Universe, going back to the Big Bang. We don't need to understand all the details to understand, in broad strokes, what physical laws underlie our observations.

[Chris Peterson]

We know what gravity can do, but! we do not know what gravity is.

What gravity is may be a meaningless question. It is defined by what it does, and that we understand very well. Indeed, under GR, what gravity actually is happens to be well understood as a distortion of spacetime. So it's very likely we do know "what" gravity is.

We do not even know what the speed of gravity is.

GR tells us that gravity waves propagate at the speed of light. That has been confirmed by several experiments. It would be fairer to say that there is still some debate about the exact speed of gravity than to say we do not know this at all.

[Qev]

When was the last time "non-baryonic particles" were needed to explain an observed phenomenon? Has any non-baryonic matter ever been observed else where in our universe?

Just thought I'd point out, leptons, photons, W and Z bosons, and neutrinos are all non-baryonic matter.

There doesn't seem to be anything that outrageous (to me at least) with the idea of dark matter; consider neutrinos, which only interact via the weak force and gravitation, and how difficult they are to detect. Take away that weak interaction, and imagine how difficult such a particle would be to observe in laboratory conditions.

I mean, heck, neutrinos themselves have already played a dark-matter-like role in physics. They were first proposed to exist because some small amount of momentum was vanishing undetected from various nuclear interactions. Pauli suggested a difficult-to-detect neutral particle was making off with the missing energy; the rest is history.