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Guru
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NASA Announces Dark Matter

08/21/2006 2:38 PM

NASA's Monday news release on the dark matter issue did not turn up anything not covered in the 'leaked' press beforehand. (See this previous thread).

The main feature is that a collision between two galactic clusters managed to separate the normal matter from the dark matter. The normal matter is radiating copious amounts of x-rays and the dark matter acts as a gravitational lens for more distant objects. And the two types of matter are no longer in the same spot.

If all of this is confirmed above reasonable doubt, the alternative theories attempting to explain the universe and cosmology are in for a tough time... Read more in Spaceflight Now.

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The Engineer
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#1

The article is a bit short on details

08/21/2006 3:02 PM

I would like to read more before I make more conclusions, but thats only natural since I've not really been very supportive of the theory in the past.

I'd like to know why the regular matter is holding together after losing the dark matter (maybe it isn't, I don't know). I'd like to know if the gravitational lensing they are attributing to the dark matter is in the proportion predicted by the theory. If they are publishing a paper, can you post the link so we can give it a read?

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#2
In reply to #1

Re:The article is a bit short on details

08/22/2006 3:42 AM

No papers that I know of yet, but this Sean Carroll post in Cosmic Variance is very well stated, linked and illustrated. His closing remarks somewhat support my view that dark matter is more plausible than dark energy at the moment ;-)

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#3
In reply to #1

Re:The article is a bit short on details

08/22/2006 7:22 AM

Found a draft paper from Harvard (pdf) here. I haven't read it yet, but it seams like in "Physics Letters" style and not too complex.

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The Engineer
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#4
In reply to #3

Re:The article is a bit short on details

08/22/2006 9:25 AM

Great link, thanks. I gave it a read. Basically two cluster galaxies collided 100 MYA and the center of mass as determined by gravitational lensing of the combined galaxies was significantly different than the COM as determined from the X-ray data. This is explained by dark matter seperating from the visual matter in the collision. The proportion seems to be 85% to 15%, right in line with theory for dark matter.

It is certainly strong evidence for the Dark Matter theory, however I'm not convinced it's proven. Why is there no correction for the blackholes in each of the colliding the galaxies? Certainly we all accept now that galaxies have supermassive black holes at their center and blackholes sprinkled through them. Couldn't these account for a part of the unseen mass? I don't think they would be slowed in the collision.

I look forward to the follow up research on this system. If the evidence builds up in several papers, I may have to rethink my stance on dark matter. I'm not convinced yet, but I can't deny this paper is convincing.

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The Engineer
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#5
In reply to #4

Re:The article is a bit short on details

08/22/2006 9:31 AM

With further reading I realize this is the collision of two clusters of galaxies, not cluster galaxies, my bad. I still want to wait on more evidence. Perhaps this is actually a discovery of Super-Super-Massive black holes in the center of galaxy clusters (unlikely I'll grant you).

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Guru
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#6
In reply to #5

Re:The article is a bit short on details

08/22/2006 10:13 AM

I do not think black holes count as part of the bulk of CDM, because BHs are mainly baryonic, while CDM is not. And BHs that collide are slowed down. They form one hole, so they can't just 'move thru' each other, I think!

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The Engineer
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#7
In reply to #6

Re:The article is a bit short on details

08/22/2006 10:25 AM

The paper spoke only of the visible mass that it says accounts for the vast majority of the baryonic mass. However a blackhole wouldn't be visible and therfore not counted in that mass. As for collisions, a blackhole would merge with other blackholes it collided with.

I'm just interested in the idea of a super super massive black hole at the center of a galactic cluster, though there is no evidence for that whatsoever. Like I said before, the paper is pretty strong evidence for Dark Matter, I just think we should hold off on the parade until others have had a chance to investigate the cluster and publish their results.

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#8
In reply to #7

Re:The article is a bit short on details

08/22/2006 11:24 AM

My wild guess is that a super massive black hole (SMBH) is still going to act as a gravitational point source even with a large Schwarzschild radius and you get a signature fast Keplerian motion of baryonic matter around it.

I thought that CDM is more equi-spaced and I would expect that the two could be differentiated by their lensing effects and any mass rotating around/within it.

I would also expect distributed CDN and a SMBH would have two different effects on the intersecting masses of the two clusters.

The prospect of a SMBH is an interesting one. Kind of like the Universe's version of a huge tidy land fill. However, you would expect a huge signature of radiation and x-rays would you not?

You are right that more information from independent researchers is needed, so a lot of this is speculation.

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The Engineer
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#9
In reply to #8

Re:The article is a bit short on details

08/22/2006 12:16 PM

Not too much speculation though, there is definitely something going on there and the data matches dark matter well. You raised an interesting point when you mentioned the black hole would behave like a point charge. Here's a question that you probably know the answer to. At large distances, how would the gravitational lensing of a massive point source (SMBH) compared to matter spread out evenly over a wide area. Should there a difference?

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Guru
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#11
In reply to #9

Re:The article is a bit short on details

08/22/2006 2:18 PM

Roger, I think you meant a BHs acts like a point source of gravity and not like a point charge? ;-)

Spread out matter like galaxies and clusters produce different gravitational lensing than BHs (point source gravity). The galactic scale lensed images are much more messy than the clinical point source images, because galaxies and especially clusters are not homogeneous at all.

A point that is often overlooked is that even SMBHs are featherweights when it comes to galaxies or clusters – mass-wise, absolutely not in the same league.

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Guru
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#12
In reply to #11

Re:The article is a bit short on details

08/22/2006 2:25 PM

I should have added to my last statement: "A point that is often overlooked is that even SMBHs are featherweights when it comes to galaxies or clusters – mass-wise, absolutely not in the same league": The CDM, being the major contributor to cluster mass, would overshadow SMBHs at the centers of individual galaxies by orders of magnitude.

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The Engineer
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#13
In reply to #12

Re:The article is a bit short on details

08/22/2006 3:36 PM

I agree on the mass comment. That's why I was suggesting the possibility of perhaps a Super Super Massive Black Hole in the center of the cluster. Presumably it could form in a similair way SMBH form in the center of galaxies form, except instead of stars being consumed to form the black hole, galaxies nearby are consumed instead. If it were to scale, such a black hole might account for the extra mass, but that is pure conjecture. The more likely explanation is dark matter. I would like to see the data checked though.

Also Jorrie, as for my other question, I did mean point mass, not charge. Getting my fundamental properties mixed up ;)

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#10
In reply to #7

Re:The article is a bit short on details

08/22/2006 2:04 PM

Even S-SMBHs would not account for much of the mass of a galactic cluster. And then, as you said, no evidence for SSMBH at the center of galactic clusters - which is not surprising! One expects to find monster BHs at the center of galaxies, not clusters.

As for the idea that SMBHs are not visible - well, close at their centers, yes, but just outside of the event horizon, they radiate like crazy in X-rays. This is the way quasars are thought to work - the most luminous objects in the universe. So, I think any SSMBH just form part of the X-ray-visible ordinary matter, while in this case, the non-radiating cold dark matter (CDM) are some distance away.

There seems to be some confusion when cosmologists speak of 'dark matter'. They mostly refer to CDM as the non-baryonic part, which do not include ordinary matter like ordinary black holes. Then, to confuse things even more, there may actually be primordial black holes, which are classified as non-baryonic and thus part of CDM… Ouch!

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#14
In reply to #1

Re:The article is a bit short on details

09/13/2006 12:24 AM

My View of the Universe. Marvin E. Frisbie Do you realize at the beginning of time there was a massive explosion that created a whole soup of hydrogen. The Hydrogen collected together from mutual attraction (gravity) until it was so compacted that the hydrogen lit off and the suns burst into the atomic reaction of burning hydrogen. They burned until they ran out of hydrogen. Then the suns collapsed, and compacted again, and another sun burst free from the residue, and the new collection of matter. About six successive suns created all the matter we have listed in the periodic table. We added some matter from Scientific Experiments with Super Colliders, fed by Large Linear Accelerators. (It wasn't just one sun collapsing, lighting off, collapsing, lighting off, Etc.) But a whole universe of suns. Some are still in the Collapsing, and lighting off stages. That doesn't seem like happenstance. How did all the matter, and energy in the universe get compacted into a point of singularity" about the size the point of a needle? Wait; I know: Happenstance. And the Finger of God. To have all the Matter, energy, and anti Matter, and anti-energy compacted into one point of singularity took massive force to hold it to a point of Singularity, in a micro-micro-micro Etc. second, until the anti-matter, and normal Matter annihilated them selves in a burst of monumental energy, as the restraint was released.. Science found anti matter in Radioactive decay. The anti-matter particle pops into existence and immediately unites with a normal matter particle, and both self destruct and convert their matter into pure energy. I think all the dark matter in the universe, which scientists do not know what it is, is really anti matter. Very small particles, which are unseen, but have repulsion, in place of attraction, just the opposite to the attraction of gravity. Not as strong as gravity. This explains a lot. The small anti-matter particles have the same Distance square loss of repulsion as does gravity's attraction. But the repulsion of the anti-matter to normal matter causes the anti matter to be compacted and thus the repulsion actually adds, so it builds great repulsion in the rifts of the universe. There is evidence of these particles, by the Motion of celestial bodies orbiting other celestial bodies. It works like this: Scientists see the orbiting bodies always accelerating, but never reach escape velocity, to break free of the celestial bodies they are orbiting. This is because we are looking from the rifts in the universe. As an orbiting Body comes into view from behind the Celestial body it is orbiting, the repulsion of the anti-matter in the rift causes the Orbiting body to slow down, and drop into a lower orbit, as it drops, it accelerates. We are at a distance such as we can note the acceleration, but do not see the Drop into a lower orbit from our angle of view. As the orbiting celestial body moves across the Orbited body, the centerline of our view; the speed is at maximum, and the lowest point in the orbit. At this point in the orbit, the repulsion starts to push the orbiting body to accelerate around the Orbited Celestial Body, and the orbiting body rises in orbital height, until it reaches original orbital height, and velocity as it hides behind the orbited body. Back there it stabilizes into the original orbit, because it has achieved the velocity to establish the original orbital height it started in the last round. This goes on and on, seemingly always accelerating, but never reaching escape velocity. At the start of each visible orbit we are looking at the orbiting body dead on. We do not see the drop in velocity from the repulsion from the rift, but we see the increase in velocity from the drop in orbit. The increase in velocity increases until it is in the lowest point in the orbit. It is there at the center of our view. We can not see the variation in orbital height, but we can see the increase in velocity. At this point the repulsion would increase the velocity of the orbiting body, and it would increase its orbital height from the increase in velocity. Then it hides behind the orbited body, and coasts at the original orbital height and velocity. There it would coast until it came back into view. This would explain the constant increase in velocity without ever obtaining escape velocity. Our angle of view allows us to recognize the acceleration, but it also causes us to miss the change in orbital height. One more thing: Stephen Hawking is correct in stating there is a wasting of matter in the Black Holes, as matter enters it. But it is not out the backside. It is visible from our view. The Black Holes have such a massive gravity, that it overcomes the additive repulsion of the small particles of Anti-matter. So the radiation of the event horizon of the black hole is the anti-matter and normal matter annihilating each other, the same we saw in radioactive decay. At the same time the anti matter is penetrating into the black hole, (because of the black hole's massive gravity Attraction) and annihilating some of the normal matter in the black hole. This is the wasting Stephen Hawking theorized, but just slightly different. Please bring the above theory to Steven Hawking, as soon as you can. He is the brain in this now Universe, in the stature of Leonardo De Vinci, Newton, and Einstein. A Very rare atmosphere. I would like his take on this. If I have a possible correct view of the universe, I would like a Nobel Prize in Physics, for a non scientist. I'm half kidding? A letter from Steven Hawking would be actually more important to me. Fris. One other theory. As light enters the Black Hole, it is charged particles, and as such do not travel in a straight line, gravity bends the Photon path, so I theorize that there is a very bright ball of light in the center of the black Hole. Fris. I don't see much use for the light in the center of a black hole, but it is interesting. Also I have a way to prove, or disprove the Anti-matter particles in the rifts in the universe, if anyone thinks this theory has any validity. It would seem to be the only theory that fits the CONSTANT Acceleration of orbiting bodies, and never gaining escape velocity. I think I have a way to validate the existence of Anti- matter in the riff. DO YOU HAVE A MORE VALID THEORY? I will be interested. Fris U. S. Citizens' Party We need Candidates For: States, Cities, Counties, Townships, in Boards, and Offices. Any Race Color or Creed. Just Honest citizens.

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Guru
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#15
In reply to #14

Re:The article is a bit short on details

09/15/2006 3:12 PM

Fris, I think politics may be a more rewarding career for you than theoretical physics!

Your "CONSTANT Acceleration of orbiting bodies, and never gaining escape velocity" is pretty 'provocative' - do you have observational evidence? If so, please give us the references.

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#16
In reply to #15

Re:The article is a bit short on details

10/07/2006 6:23 AM

Well Jorrie it's a perfect explanation that satisfies my continuing disillusionment about the constant (although elliptic) balance between the earth and the moon ( how otherwise have they constantly remained in their respective positions from before recorded time? and mentioning that antibodies have a effect opposite to gravity gives me more substance to my theory that UFO's (although a tad [UFO's] hypothetical) work on a principal of repulsion for their escape velocity from planetary bodies, as with the thread I started some days ago.

The UFO disscussion came from a discussion here at my house about the pendular type movement of a suppose sighting of a UFO in the Coromandel region of a UFO that was described is some detail (as to its pre takeoff movements also) before disappearing at great velocity from it's apparent parking spot over the shore adjacent to the Coromandel peninsular (very skeptical I'm sure especially from a learned engineer and mathematician like your self or others, but at least worthy of a few lonely brain cells spare milliseconds that it may inconvenience.

I'd further like to add that (about the said UFO) having parked over a source of saline solution there may be more to it than just a convenient place for the inhabitants of the UFO to picnic. Is there not? many theories coming to the fore about the constant flow of water (or possibly saline solutions or other) over materials that change or charge particles or that give off an electrical charge, that may be in use by these UFO occupants to re-generate their crafts in some manor.

I've constantly bumped into new sciences that use water flow over elements in even our known periodic tables that convert the flow to electrical charge, apart from the use of turbines, and there may always be others still undiscovered.

I must admit to all that I delve into is from the absurd and the sublime for my theory and in "design" constantly trip over solutions that others have hastily passed by, not noticing the real alternatives in all sciences and occults (the unknown). all with greatest respect to your learned self, Jorrie as my greater peer by far.

Robbie

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