Dark matter and Dark energy

[GodMark2]

What happens when it comes into contact with matter?

Let's answer this by looking at what happens when normal matter 'comes into contact'. We'll use your hand, and the table it's resting on.

As your hand moves toward the table, several forces are acting on it. Mostly the force applied by your muscles. EM and Gravity are there, but so small that their effects can be ignored. Gravity because there's not enough mass to make much of it. EM because the difference in any attraction to protons and any repulsion to electrons in the table is very small.

As you get closer, however, things begin to change. Gravity is still minuscule, but the EM forces between the electrons in your hand begin to repel the electrons of the table. When the electrons in your hand are as far from the electrons in the table as the tables electrons are from their protons, you have four times as much force repelling the mutual electrons as you have attracting the protons to the electrons. Eventually, this force exceeds your muscles' ability to push the hand closer.

It's that transition from "very far away the net force is zero" to "close up the net force is huge" that we call 'contact with the table'. It all depends in electromagnetism. If dark matter doesn't interact with EM in any way, then it can never come 'in contact', with either itself, or 'ordinary' matter.

Summary: Dark Matter can never "come in contact" with anything, so asking "what happens when it does" doesn't make much sense.

 

[robinson]

Have the sun and the earth combined? I think that's not a very useful definition of the word "combine".

I asked about many things. Orbits was one of them. Does DM orbit matter? Does it attract itself? The earth and sun are both examples of how matter combines, due to gravity, to form objects. Does DM form objects? Is it a gas? Something else?

If it only interacts via gravity, then most of the time it'll just pass right through ordinary matter and even itself.

Are you trying to say it won't orbit? Change course? That DM somehow pulls on matter by gravity, but loses no energy doing so? Does not change direction, does not combine, somehow has mass, gravity, but can pass through matter with no effect? What?

This is starting to sound extremely woo woo.

 

[robinson]

It could be that the satellite galaxies are gravitationally attracted to these streams of dark matter and clumping around them, giving the appearance of being aligned along a single, wide plane.

Grebel stressed that at this point, both of these scenarios are just speculation.

"We have no proof whether any of these is actually true," she said.

http://www.space.com/scienceastronomy/060123_andromeda_plane.html

I think it is wise to remember the difference between speculation and fact.

 

[~enigma~]

This is starting to sound extremely woo woo.

You really don't have any place to call anyone or any idea about dark matter woo since you are under the impression that neon is not a gas since it glows and conducts electricity. Are you going to admit you were wrong? Honestly, there as a time that I thought you had some rationality within your posts but now I see I was mistaken.

 

[Ziggurat]

I asked about many things. Orbits was one of them. Does DM orbit matter?

Yes. That's why it's clustered around galaxies. Most of it's probably moving too fast to be in orbit around something like the earth or the sun, but it is in orbit about the galactic center.

Does it attract itself?

Yes. That's part of the whole point: it's got mass, it has a gravitational field, so it attracts and is attracted to anything else with mass, including both ordinary matter and other dark matter. But if it's only interacting via gravity, it won't clump up the way ordinary matter does.

The earth and sun are both examples of how matter combines, due to gravity, to form objects.

But that clumping requires more than just gravity. I already said: it requires that the matter lose energy so it doesn't just fly apart after getting attracted together. If there's no other interaction, then it can't lose energy, and it will not clump together like the earth.

Does DM form objects?

Not that we know of.

Is it a gas?

If it only interacts via gravity, it's probably like a diffuse gas.

Are you trying to say it won't orbit? Change course?

No, I'm not trying to say that at all.

can pass through matter with no effect?

No effect? I didn't say that. But if the effect is purely gravity, how exactly do you expect to notice it? If a semi drove through you but only interacted with you via gravity, what would happen. There would be an effect, but it's so tiny you'd never notice. And you don't notice all the neutrinos streaming through you right this second, but they interact with you too. But again, the interaction is too weak for you to notice.

 

[edd]

Is it?
[snip big lot of pointers to papers]

Right, first off you have the bullet cluster. It's either explainable by cold dark matter, or by a relatively massive (but still within current limits) neutrino filling the role of hot dark matter, along with MOND, which is what some of your first references suggest as a possibility. This is a relatively mainstream perspective, MOND-like TeVeS theories get discussed all the time as alternative explanations although you persistently like to characterise cosmologists as insisting on dark matter and dark energy, whereas actually it's merely the consensus that they're the current best explanation... and people work hard on coming up with alternatives as that's a good way to do science - generate theories and test them.

It's known that you need some hot dark matter to explain galaxy clusters as mentioned in your list here

http://arxiv.org/abs/0706.1279 "The wedding of modified dynamics and non-exotic dark matter in galaxy clusters, B. FAMAEY, G. W. ANGUS, G. GENTILE, H. Y. SHAN, H. S. ZHAO, 2007 ... snip ... We summarize the status of Modified Newtonian Dynamics (MOND) in galaxy clusters. The observed acceleration is typically larger than the acceleration threshold of MOND in the central regions, implying that some dark matter is necessary to explain the mass discrepancy there. A plausible resolution of this issue is that the unseen mass in MOND is in the form of ordinary neutrinos with masses just below the experimentally detectable limit. In particular, we show that the lensing mass reconstructions of the rich clusters 1E0657-56 (the bullet cluster) and Cl0024+17 (the ring) do not pose a new challenge to this scenario."

So you have a choice. Raise the number of dark matter particles from one to two, possibly with some theoretical justification from particle physics with candidates to fill that role, or you alter general relativity, and add complexity to your model there. You can't win at not adding complexity to your model (I doubt many of the authors here lend much weight to your plasma universe)
Then you mention this

http://space.newscientist.com/article/dn13280-galaxy-without-dark-matter-puzzles-astronomers.html "Galaxy without dark matter puzzles astronomers, February 2008 ... snip ... According to their combined mathematical model, ordinary luminous stars and gas can indeed account for all the mass in NGC 4736. ... snip ... "If this paper is correct, then this galaxy contains very little or no dark matter," says astrophysicist Jürg Diemand of the University of California, Santa Cruz, US, who is not a member of the team. "That is surprising." ... snip ... "It is unclear how one would form a galaxy without a dark halo, or how one could remove the halo without destroying the galaxy," says Diemand. "A galaxy without dark matter really does not fit into our current understanding of cosmology and galaxy formation." Nor can galaxies with declining rotation curves be easily explained by MOND, says McGaugh. So for now, it seems that some of our missing mass is missing."

So it doesn't seem MOND works here... which leaves us what? Dark matter in a stronger position, because although it's unclear how you form a galaxy without a dark halo, it seems even harder to model a galaxy with a declining rotation curve as MOND was built up to explain galaxies with flat curves. Missing mass is more explicable in a one-off unusual case than an entirely different law of gravity.

And I've already mentioned what plasma cosmologists have to say about the Bullet Cluster. But here it is again. The dark matter explanation is based on a calculation full of assumptions. For one, it assumes that redshift always equates to distance.

You know what, the more I read what you write the more I realise it's pointless because every argument I'd give relies on the very well determined redshift distance relation, and if you're going to steadfastly refuse to accept it then it's pointless. We can discuss till the cows come home about all sorts of interesting and unanswered questions in astrophysics but if we can't even get you to accept a fundamental thing like the redshift distance relation we're a no go. I mean, what's the point in discussing the weak lensing maps in the bullet cluster if you don't think the mass estimates are right because the distance distributions of the lensed background sources aren't what we think from their redshifts? It's utterly pointless.

It really is on a par with trying to discuss evolutionary biology with a creationist who thinks you can't properly date the rocks you find your fossils in.

 

[JEROME DA GNOME]

Considering how much evidence we have for its existence, yes.

Why is that evidence is not presented and only mocks are given in return for the request?

 

[JEROME DA GNOME]

Considering the two hypothesis, dark matter at least has the gravitational observations to suggest it.

And the fact that life is here and we have no explanation as to how it got here suggests God.

See, they are both making up concepts to explain the unknown.

 

[sol invictus]

Why is that evidence not presented and only mocks are given in return for the request?

Why do you completely ignore it every time evidence is presented?

 

[iantresman]

You really don't have any place to call anyone or any idea about dark matter woo since you are under the impression that neon is not a gas since it glows and conducts electricity. Are you going to admit you were wrong? Honestly, there as a time that I thought you had some rationality within your posts but now I see I was mistaken.

.
Neon gas does not glow. When you pass a current through it in a discharge tube, it becomes partly ionized and can be characterized as a weakly-ionized cold plasma, and it radiates light in "glow mode".

 

[~enigma~]

.
Neon gas does not glow. When you pass a current through it in a discharge tube, it becomes partly ionized and can be characterized as a weakly-ionized cold plasma, and it radiates light in "glow mode".

So the neon gas becomes not a gas? You are a fool

ETA - I will ask you the same thing I don't ecpect BAC to answer. What, if anything, would be sufficent to prove your claim false in your eyes?

 

[JEROME DA GNOME]

Why do you completely ignore it every time evidence is presented?

Because nothing is presented outside of observations and then it is stated that Dark matter is the cause.

Can you really not see that this a fallacious line of thought?

 

[sol invictus]

Because nothing is presented outside of observations and then it is stated that Dark matter is the cause.

Can you really not see that this a fallacious line of thought?

Dark matter is a mathematical model for the world. It's a model that explains a wide variety of observations and is inconsistent with none, and it's very very simple (that statement has a precise mathematical definition, which is related to how many parameters are necessary to specify it).

There are no other models with those properties. Therefore, dark matter is (correctly) the working hypothesis about the world, and people are looking for additional ways to test it.

Which part of that do you fail to understand?

 

[iantresman]

So the neon gas becomes not a gas? You are a fool

.
Correct. It becomes a weakly ionized plasma which includes a mixture of neon gas and ionized gas... which is called a plasma.

ETA - I will ask you the same thing I don't ecpect BAC to answer. What, if anything, would be sufficent to prove your claim false in your eyes?

I think Langmuir demonstrated beyond reasonable doubt that when you ionize a gas, it becomes a plasma. I'm not sure how you would disprove this.

 

[~enigma~]

.
Correct. It becomes a weakly ionized plasma which includes a mixture of neon gas and ionized gas... which is called a plasma.

And i repeat you are a fool. That is the exact same argument by bible thumpers that although it says that it really means something else. You demonstrate a MAJOR ignorance of chemistry.

I think Langmuir demonstrated beyond reasonable doubt that when you ionize a gas, it becomes a plasma. I'm not sure how you would disprove this.

The question is not about gas. It is about your ridiculous EU stupidity.

Do not attack other posters.

Replying to this modbox in thread will be off topic  Posted By: Cuddles

 

[JEROME DA GNOME]

Dark matter is a mathematical model for the world. It's a model that explains a wide variety of observations and is inconsistent with none, and it's very very simple (that statement has a precise mathematical definition, which is related to how many parameters are necessary to specify it).

There are no other models with those properties. Therefore, dark matter is (correctly) the working hypothesis about the world, and people are looking for additional ways to test it.

Which part of that do you fail to understand?

I am glad that you now admit Dark matter is nothing more than an idea presented to explain observations.

 

[sol invictus]

I am glad that you now admit Dark matter is nothing more than an idea presented to explain observations.

"Now admit"? Just what did you think it was?

Of course it's "an idea presented to explain observations" - just like gravity, electricity and magnetism, the standard model of particle physics, etc.

I think you need to learn a little bit about science.

 

[arthwollipot]

This thread is confusing me.

 

[JEROME DA GNOME]

This thread is confusing me.

That is because it is DARK and you can not measure it, it is only implied by otherwise unexplainable phenomenon.

The phenomenon is the evidence of the explanation of the cause.




I think you do understand.

 

[sol invictus]

This thread is confusing me.

Try this:

Dark matter is a mathematical model for the world. It's a model that explains a wide variety of observations and is inconsistent with none, and it's very very simple (that statement has a precise mathematical definition, which is related to how many parameters are necessary to specify it).

There are no other models with those properties. Therefore, dark matter is (correctly) the working hypothesis about the world, and people are looking for additional ways to test it.