Dark matter and Dark energy

[BeAChooser]

The only other possibility (in GR) is that they form a black hole, but that requires them to pass extremely close together, and hence is very unlikely.

Yet, mainstream astrophysicists claim there are literally hundreds of millions or must it be by now "billions and billions" (said in a Sagan like voice) of *ordinary matter* black holes in the universe. Is that really highly unlikely? And considering that dark matter is supposely 4 or 5 times as plentiful as ordinary matter, isn't it even more likely that dark matter has formed a black hole or two?

 

[BeAChooser]

Dark matter is not some weird magical fairy dust. It's probably just regular matter. It just doesn't shine.

http://www.msnbc.msn.com/id/23236991/from/id/17399245/ “We know [dark matter] exists by secondary methods,” says Peter Limon, a particle physicist from Fermilab, near Chicago. But “we don't know what it is. It's strange stuff. We know it's not regular matter in the sense of protons and neutrons and things like that.”

Heck, it might just be gigantic flocks of planet-sized chicken flying about

Nope. The above rules that out. And now everyone sees why I know the dark matter proponents are having trouble with their theory. After 30 years of searching, this is what they tell us dark matter might be?

Perhaps you should read up on it, then, before you make that willful ignorance apparent.

And ironic statement in light of the above. Don't you think.

Quote:
Does it move towards matter? Does it have an orbit? Does it obey the laws of physics? Does it clump up? Form structures? Planet sized ones? Star sized ones? Can it carry a charge? Ionize? Is it affected by magnetism? Does it form plasmas?

Probably, possibly, absolutely, presumably, perchance, alledgedly, statistically, maybe, apparently, most likely, presumably, plausibly.

So the hundreds of millions (billions?) of dollars spent the last 30 years looking for dark matter hasn't done much to pin down the answers? So why should we think a few billion more will?

 

[BeAChooser]

You know that there are already plenty of extremely difficult to detect particles in nature which we have only recently directly observed in laboratories and which have nearly all of the properties necessary to be dark matter (neutrinos, for example), so it is not terribly surprising if there turn out to be more.

But the existence of each and every one of those particles came to light from measurements in experiments conducted here on earth that showed something was missing. When we then looked for that something, we then found it ... usually fairly quickly. No such experiment has been done on earth where dark matter is concerned. The case for the existence of most dark matter rests entirely on the interpretation of observations of something or some event in the very, very distant universe where our ability to make measurements is very limited.

You know that there are no viable alternative theories to DM

This is utterly false, as this thread is clearly proving. Distortion of the crisis in astrophysics doesn't strengthen your case, sol. What would strengthen it would be to meet the evidence being presented against mainstream astrophysics head on. You can start by providing us with peer reviewed papers that show the conclusions made in the peer reviewed papers I linked about high redshift objects being associated with low redshift objects are wrong. But then you can't, can you. There don't seem to be any.

You agree that the hypothesis of dark matter (and yes, it's a hypothesis, one with lots of evidence in its favor) explains mathematically every one of those observations in a simple and concise way.*

*That's an extremely compelling fact - thousands and thousands of observations can all be explained by a simple addition to the theory involving only a few numbers.

This claim is false too. Dark matter does not explain every single observation. Otherwise I wouldn't have been able to post links in various threads to articles where mainstream astronomers are quoted saying that such and such an observation defies explanation under the current theory of dark matter. And to match what observations it has, it has been necessary to vary the amount of dark matter and the location of the dark matter, without much reason as to why those variations occur. Furthermore, even with dark matter (and we are talking about a LOT of dark matter), the mainstream has still found it necessary to add Dark Energy. And now some in the mainstream are even calling for addition of a Dark Force gnome in order to match the predictions. So your theory isn't quite as "simple" as you make it out to be sol.

 

[BeAChooser]

Because if it only interacts via gravity, it can't lose energy the way ordinary matter does. In order to stick together, ordinary matter has to be able to lose energy - otherwise it'll just fly apart after being attracted close together. If there's no mechanism to lose energy, it won't stick together.

Odd that none of the half a dozen references I linked in another post regarding accretion mentioned anything but gravity.

Why must the dark matter that is coalescing to form a black hole lose energy in order to form that black hole? Can you provide a link that says this, Ziggurat?

Does the dark matter have to lose angular momentum? If so, how do you know it has angular momentum? Does a collection of dark matter have to be rotating about some point (bearing in mind that most rotation in ordinary matter is originally due to electromagnetic effects which black holes presumably don't experience under current theory)? And besides, black holes can spin. Wouldn't the dark matter just collapse retaining that dark spin?

And how do you know that the laws of physics for ordinary matter ... say in direct collisions ... even apply to dark matter? Is dark matter perfectly elastic? How do you know that linear momentum is conserved? You've already created a particle that can do anything you want ... have any property you need. Why not add one or more more cool features to this gnome?

And if I'm wrong about all that, how do you know there isn't a dark mechanism that causes dark matter to lose dark energy?

In fact, how do YOU explain that Abell 520 observation where astrophysicists enchanted by dark matter claim a whole bunch of dark matter appears to have come together and not flown apart? What made it "stick" together, Ziggurat?

 

[BeAChooser]

This is your last chance. Answer the question or go on ignore. You make the choice.

If I were you iantresman, I'd choose ignore.

 

[RecoveringYuppy]

Odd that none of the half a dozen references I linked in another post regarding accretion mentioned anything but gravity.

If you simply consult the wikipedia article on accreation disks you'll see friction, viscosity and EM radiation mentioned.

Why must the dark matter that is coalescing to form a black hole lose energy in order to form that black hole? Can you provide a link that says this, Ziggurat?

If, simply by chance, enough dark matter showed up in the same place at the same time it would form a black hole without requiring any energy to be lost.

But except for that one very implausible situation the answer to your question is because if it doesn't lose energy it will simply keep moving.

 

[BeAChooser]

chemical bonding is what makes comets solid.

It's not a question of what keeps them solid but what keeps the dirty, fluffy, talcum powder consistency snowball together. And as I pointed out above, most references still state it is "gravity".

And chemical bonding is electromagnetism.

Except I assumed we weren't talking about chemical bonding in this discussion. And I honestly don't believe arthwollipot meant chemical bonding either. He can correct me if I was mistaken.

Did you honestly not know this?

Did you honestly not know that the Death Star jet was plasma? Did you honestly not know that most of the matter observed in the universe is plasma? Did you honestly not know that plasma can exist under conditions other than "1) stars and 2) the VERY early stages of the universe"?

In order for the cloud to shrink, it needs to be able to lose energy.

But who says dark matter clouds have to have angular momentum? Why would they at the beginning of the universe? I can't think of any gravity process that creates angular momentum. But electromagnetic processes do. All the time. Unfortunately, you tell us that dark matter doesn't experience those forces.

 

[GodMark2]

That is a horrible example.

Really? What, specifically, is horrible about it? It's a succinct description of what "contact' means at a subatomic level.

So, DM can never be modified? Where are you getting this from?

What do you mean by 'modified'? I was talking about how the common definition of 'contact' cannot be applied to Dark Matter, as it does not interact through EM, like Normal Matter does. How did we get from "contact" to "modified"?

 

[BeAChooser]

It sure looks like a lot of what is there came from something like the Big band Event, then other stuff was fused in stars. ERGO the Big Band Event occured or at least does not contradict the observation.

Maybe I misunderstood what they meant by the "music of the spheres".

 

[BeAChooser]

If you simply consult the wikipedia article on accreation disks you'll see friction, viscosity and EM radiation mentioned.

Yeah ... but that was written by someone like you or I ... with more common sense than the folks who dream up dark matter and dark energy. I was linking things written by those in NASA and who interviewed astrophysicists in preparing their articles. Besides, how do you know there isn't dark friction, dark viscosity, and dark EM radiations (hey ... maybe that's what Dark Energy is)?

If, simply by chance, enough dark matter showed up in the same place at the same time it would form a black hole without requiring any energy to be lost.

Ahhhh ... we are getting somewhere.

But except for that one very implausible situation the answer to your question is because if it doesn't lose energy it will simply keep moving.

So why didn't it in Abell 520?

 

[edd]

I think you just demonstrated why I think that.

Matey, if you're going to be critical I'm going to need a bit more detail of what you're going to be critical about if you want a response.

 

[edd]

Maybe I misunderstood what they meant by the "music of the spheres".

But I must confess that typo makes me chuckle too

 

[RecoveringYuppy]

So why didn't it in Abell 520?

Why do you think it didn't?

 

[BeAChooser]

Why do you think it didn't?

From one of my earlier posts:

http://chandra.harvard.edu/press/07_releases/press_081607.html "A popular theory of dark matter predicts that dark matter and galaxies should stay together, even during a violent collision, as observed in the case of the so-called Bullet Cluster. However, when the Chandra data of the galaxy cluster system known as Abell 520 was mapped along with the optical data from the Canada-France-Hawaii Telescope and Subaru Telescope atop Mauna Kea, HI, a puzzling picture emerged. A dark matter core was found, which also contained hot gas but no bright galaxies. "It blew us away that it looks like the galaxies are removed from the densest core of dark matter," said Dr. Hendrik Hoekstra, also of University of Victoria. "This would be the first time we've seen such a thing and could be a huge test of our knowledge of how dark matter behaves." ... snip ... In addition to the dark matter core, a corresponding "light region" containing a group of galaxies with little or no dark matter was also detected. The dark matter appears to have separated from the galaxies. "The observation of this group of galaxies that is almost devoid of dark matter flies in the face of our current understanding of the cosmos," said Dr. Arif Babul, University of Victoria. "Our standard model is that a bound group of galaxies like this should have a lot of dark matter. What does it mean that this one doesn't?" ... snip ... In Abell 520, it appears that the galaxies were unimpeded by the collision, as expected, while a significant amount of dark matter has remained in the middle of the cluster along with the hot gas."

 

[RecoveringYuppy]

What in that makes you think the dark matter isn't moving?

 

[Ziggurat]

Except I assumed we weren't talking about chemical bonding in this discussion.

Why would you assume that? And even bonding aside, what do you think makes gas molecules bounce off each other? Why can't ordinary matter just pass through itself? Why didn't Shoemaker-Levy just pass through Jupiter? It isn't gravity which did that.

Did you honestly not know that the Death Star jet was plasma?

I did not. But you see, I learn from my mistakes. You don't. You just bury your head ever deeper and deeper. Which is why, even now, you won't admit that electricity cannot power the sun. You've got no argument for how it's possible, I've demonstrated that it isn't, and yet you just won't let go of it. And you expect to be able to beat me over the head with a past mistake of mine? Please. That's just sad.

But who says dark matter clouds have to have angular momentum?

I'm not sure it needs any total angular momentum (though locally it certainly can, just from random fluctuations during the big bang). But each particle is likely to have angular momentum because it should have had some random spread of velocities/momentum from the beginning of the universe. And how will it lose that angular momentum? But it's more than just that. Consider two massive particles with no angular momentum, initially at rest some distance from each other. They attract each other, and move together. What happens when they reach each other? Well, if it's ordinary matter which can interact via electromagnetism, they will collide, possibly stick, or possibly bounce off (maybe even losing some energy in the process). But if they can't? Well, then they'll just pass right through each other. Gravity alone will not make them stick, it will not make them bounce off each other. They will continue to oscillate back and forth, until they radiate away that energy via gravitational waves. But that's such a weak process for small masses that they won't even slow down over the kind of time scales we're interested in.

 

[Ziggurat]

Odd that none of the half a dozen references I linked in another post regarding accretion mentioned anything but gravity.

I seriously doubt that is true. Perhaps you just didn't recognize the reference to such mechanisms, or perhaps they weren't made explicit in terms you could understand because it should have been bloody obvious (such as the fact that Shoemaker-Levy didn't pass through Jupiter because of electromagnetic forces).

And how do you know that the laws of physics for ordinary matter ... say in direct collisions ... even apply to dark matter? Is dark matter perfectly elastic?

That question doesn't even make sense. Is an electron perfectly elastic? Is it inelastic? The term doesn't work for single particles.

How do you know that linear momentum is conserved?

Are you suggesting it isn't?

 

[BeAChooser]

What in that makes you think the dark matter isn't moving?

"In Abell 520, it appears that the galaxies were unimpeded by the collision, as expected, while a significant amount of dark matter has remained in the middle of the cluster along with the hot gas."

http://antwrp.gsfc.nasa.gov/apod//ap070820.html "Conventional wisdom holds that dark matter and normal matter are attracted the same gravitationally, and so should be distributed the same in Abell 520. Inspection of the above image, however, shows a surprising a lack of a concentration of visible galaxies along the dark matter. One hypothetical answer is that the discrepancy is caused by the large galaxies undergoing some sort of conventional gravitational slingshots. A more controversial hypothesis holds that the dark matter is colliding with itself in some non-gravitational way that has never been seen before. "

http://www.sciencenews.org/articles/20070825/fob5.asp "The Bullet cluster was a spectacular result, because it beautifully confirmed our assumptions about how dark matter, gas, and galaxies behave, [but] Abell 520 does the complete opposite," comments Julianne Dalcanton of the University of Washington in Seattle. One explanation for the new results is that dark matter is composed of particles that interact through forces other than gravity. However, such particles would cause a variety of other effects that have never been seen, such as making galaxy clusters spherical, notes Katherine Freese of the University of Michigan in Ann Arbor."

http://space.newscientist.com/article/dn12497-cosmic-train-wreck-defies-dark-matter-theories.html "Abell 520 turns out to hold a massive dark core, empty of bright galaxies. Some of the core is made up of hot gas, which the team detected from its emission of X-rays, but most of it has to be something else – presumably the same dark matter that astronomers detect elsewhere in the universe. ... snip ... One possibility is that the galaxies were once in the core, along with the dark matter, but then close encounters between the galaxies threw them out to the cluster's fringes. Unfortunately, the team can't get that to happen in their computer simulations, even if they tailor the initial conditions to encourage these gravitational slingshots. A more intriguing explanation is that when the original clusters collided, their dark matter was stripped out. Astronomers expect that to happen to gas clouds in colliding clusters, but dark matter is supposed to be more slippery, barely interacting with other matter or with itself. "We expect clouds of dark matter to flow right through each other," says team member Arif Babul at the University of Victoria in Canada. ... snip ... Could there be two types of dark matter, the conventional slippery form and another that interacts more strongly? Babul says it is possible, but dislikes the idea of invoking yet another invisible cosmic substance to explain these observations."

I'm sure they'll do it if they have to.

 

[robinson]

Babul says it is possible, but dislikes the idea of invoking yet another invisible cosmic substance to explain these observations."

Who wouldn't dislike the idea? The more stuff you make up, the harder it is to keep track.

 

[BeAChooser]

Originally Posted by BeAChooser
Except I assumed we weren't talking about chemical bonding in this discussion.

Why would you assume that?

Because in the last few weeks of discussion on various aspects of astrophysics, we haven't once been talking about chemical bonds when discussing electromagnetic forces.

And even bonding aside, what do you think makes gas molecules bounce off each other?

What makes you think you know every property of dark matter?

Quote:
Did you honestly not know that the Death Star jet was plasma?

I did not.

Well that's obvious.

But you see, I learn from my mistakes.

Well I certainly hope so. Maybe next time you'll think twice about so quickly acting like you know everything about a subject that you apparently know nothing about it.

But each particle is likely to have angular momentum because it should have had some random spread of velocities/momentum from the beginning of the universe.

Why should it? What in the Big Bang equations governs it? Was dark matter even mentioned in the formulation of inflation? Perhaps dark inflation is perfect in eliminating all dark fluxuations. Just admit you don't and can't possibly know what the initial conditions of something you can't even define or see at this point in time.

Consider two massive particles with no angular momentum, initially at rest some distance from each other. They attract each other, and move together. What happens when they reach each other? Well, if it's ordinary matter which can interact via electromagnetism, they will collide, possibly stick, or possibly bounce off (maybe even losing some energy in the process). But if they can't?

How do you know they can't? Explain Abell 520.

Well, then they'll just pass right through each other.

But they didn't in Abell 520.

They will continue to oscillate back and forth, until they radiate away that energy via gravitational waves.

How do you know that's the only way they radiate? Maybe they radiate dark energy? Maybe that's why Abell 520 stuck. Maybe that's why there is both dark matter and dark energy ... all that radiating going on.

But that's such a weak process

Maybe dark energy radiation isn't a weak process.