Dark matter and Dark energy

[arthwollipot]

No, that's not what was confusing me.

 

[BeAChooser]

the little problem of reality

Seen any dark matter black holes lately? They should be possible, right?

 

[BeAChooser]

But if it's only interacting via gravity, it won't clump up the way ordinary matter does.

Why not? Why can't it form a dark matter dark hole that creates such incredible gravity that it bends space just like a black hole made from ordinary matter? And don't try to squirm out of this question by telling me that black holes are a form of dark matter. That's not answering my question.

 

[BeAChooser]

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.

Pointless only because YOU refuse to directly address the numerous highly unlikely "coincidences" between objects with highly different redshifts. You and the rest of the mainstream simply ignore them and that is quite telling. Of course, you have to ignore them because to do anything else will only lead to the demise of your many precious gnomes. And you know it.

 

[BeAChooser]

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

http://www.allaboutcircuits.com/vol_3/chpt_7/2.html "Neon lamps are nothing more than two metal electrodes inside a sealed glass bulb, separated by the neon gas inside. At room temperatures and with no applied voltage, the lamp has nearly infinite resistance. However, once a certain threshold voltage is exceeded (this voltage depends on the gas pressure and geometry of the lamp), the neon gas will become ionized (turned into a plasma) and its resistance dramatically reduced. In effect, the neon lamp exhibits the same characteristics as air in a lightning storm, complete with the emission of light as a result of the discharge, albeit on a much smaller scale."

 

[arthwollipot]

Why not? Why can't it form a dark matter dark hole that creates such incredible gravity that it bends space just like a black hole made from ordinary matter? And don't try to squirm out of this question by telling me that black holes are a form of dark matter. That's not answering my question.

As has been explained, ordinary matter clumps because it interacts through the electromagnetic force. Under the gravitational force alone, two hypothetical particles would simply pass straight through each other and fly off into space.

 

[BeAChooser]

As has been explained, ordinary matter clumps because it interacts through the electromagnetic force.

So not because of gravity? Finally, we get that cleared up.

Under the gravitational force alone, two hypothetical particles would simply pass straight through each other and fly off into space.

Never to return? Then is it electromagnetic force that keeps comets coming back?

 

[arthwollipot]

So not because of gravity? Finally, we get that cleared up.

I'm not too sure about "finally", because this was stated much earlier up in the thread.

Never to return? Then is it electromagnetic force that keeps comets coming back?

Did I say that? It is the electromagnetic force which keeps comets together, but it is gravity that keeps them on course around the sun.

The problem with any hypothetical dark matter acting only through gravity is that two particles will accelerate towards each other as they approach, and there will be nothing to stop them from passing through each other. In an ideal fictional universe where these two particles are the only matter present, I don't know whether this accelleration would be sufficient to overcome their mutual gravitational pull once they have passed each other. It would require some mathematics to determine, which is beyond my knowledge at this time. It is possible that such particles would simply continue orbiting each other. Many such particles would form a "cloud" which could in theory possess a significant gravitational pull.

However, in the real universe where there is lots of matter about, it is quite probable that after passing each other, they will be caught up in the gravitational fields of other particles, and will continue through the universe on a never-ending dance. They will be pulled in many directions by the gravitational field, and will never come to rest, since there will be no electromagnetic interactions which might stop the dance.

 

[Yllanes]

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?

The neon in a lamp is in a plasma state. It's not a matter of proving a claim, it simply meets the requirements of the definition of plasma.

 

[iantresman]

And i repeat you are a fool.

.

• "If one does not understand a person, one tends to regard him as a fool." -- Carl Gustav Jung

And I note:

• ".. the glow of a neon tube [.. is an] example of a low temperature plasma" (Ref)
• ".. the neon tube [..] produces a reddish orange plasma discharge (ref)
• "The neon inside the familiar neon tube is in the plasma state" (ref)

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

.
How about rather than slinging insults, you explain your point of view.

 

[edd]

Pointless only because YOU refuse to directly address the numerous highly unlikely "coincidences" between objects with highly different redshifts. You and the rest of the mainstream simply ignore them and that is quite telling. Of course, you have to ignore them because to do anything else will only lead to the demise of your many precious gnomes. And you know it.

Supposing I did spend time going through your 'numerous' examples and telling you what was going on with each - you'd still not be convinced and go off and find more. You're like an IDer who goes round saying "Look, the eye! Irreducibly complex!" and when someone tells you why it isn't you go "Look, the flagellum!"

I've no reason to chase after an endless stream of references when I've no reason to believe you'd change your mind on anything.

And as I've said before, I'd enjoy nothing more than to see what you call 'gnomes' be explained by something else, as that something else would have to be new and interesting physics. I don't know why you think we're irrationally attached to certain ideas, despite you being repeatedly told to the contrary.

 

[sol invictus]

The problem with any hypothetical dark matter acting only through gravity is that two particles will accelerate towards each other as they approach, and there will be nothing to stop them from passing through each other. In an ideal fictional universe where these two particles are the only matter present, I don't know whether this accelleration would be sufficient to overcome their mutual gravitational pull once they have passed each other. It would require some mathematics to determine, which is beyond my knowledge at this time. It is possible that such particles would simply continue orbiting each other.

If there are two particles, there are just two possibilities (in Newtonian gravity): either they start off in a bound state, in which case they orbit each other, or they don't, in which case they scatter off each other and then escape to infinity. 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.

Many such particles would form a "cloud" which could in theory possess a significant gravitational pull.

That's correct. Many simulations of this have been done, and the results match the observed distribution of dark matter. Those clouds of dark matter also have an extremely important influence on visible matter and the structures it forms.

 

[Belz...]

Robinson, I'm getting the impression that you have no idea what "dark matter" means.

Well, you would be correct then.

Then why the hell are you talking about it like you knew ?

You keep saying this and that about dark matter but it's obvious you have no idea what you're talking about.

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

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

It is supposed to explain Galaxies and rotation and other stuff, but when I ask a direct question about it, nobody seems to be able to answer. So of course I have no idea.

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

If you make something up, you are supposed to explain your invisible stuff, not expect others to.

It's called a hypothesis, Robinson. By definition, they are made up.

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.

Does that answer your questions ?

 

[Belz...]

How could it stay away from things it is gravitationally attracting?

http://en.wikipedia.org/wiki/Orbit

 

[Belz...]

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

Like everything else in science.

 

[robinson]

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

That isn't what other people say.

Some people speculate, based on the evidence, including galaxy rotation curves, gravitational lensing, structure formation, and the fraction of baryons in clusters and the cluster abundance combined with independent evidence for the baryon density, indicate that 80-90% of the mass in the universe does not interact with the electromagnetic force. This "dark matter" is evident through its gravitational effect. Several categories of dark matter have been postulated.

Baryonic dark matter One candidate for missing dark baryonic matter is Rydberg matter, which has spectroscopic signatures in agreement with the unidentified infrared bands.
S. Badiei, L. Holmlid. Mon. Not. R. Astron. Soc. 333, 360–364 (2002)

Non-baryonic dark matter which is divided into three different types:
o Hot dark matter - nonbaryonic particles that move ultrarelativistically
o Warm dark matter - nonbaryonic particles that move relativistically
o Cold dark matter - nonbaryonic particles that move non-relativistically

Wiki

Silk, Joseph. The Big Bang, 1989, chapter ix, page 182.
Umemura, Masayuki; Satoru Ikeuchi (1985). "Formation of Subgalactic Objects within Two-Component Dark Matter". Astrophysical Journal 299: 583—592.​
Vittorio, N.; J. Silk (1984). "Fine-scale anisotropy of the cosmic microwave background in a universe dominated by cold dark matter". Astrophysical Journal, Part 2 - Letters to the Editor 285: L39—L43.

Does that answer your questions ?

It is a start of course. Your answers sound like woo woo.

 

[JEROME DA GNOME]

Like everything else in science.

In reality much in science has been vetted through the scientific method. Dark matter has not, it is just an idea without evidence.

 

[sol invictus]

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

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

Dark matter has not, it is just an idea without evidence.

So what caused all the gravitational lensing in the blue parts of the image?

I do not know, but I am not going to WOO an answer.

You agree that there are a huge set of observations which you cannot explain, and which are inconsistent with our best understanding of the laws of nature and the visible matter content of the universe.

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.*

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.

You know that many of the theoretical extensions of the standard model have natural WIMP candidates.

You know that there are no viable alternative theories to DM, despite years and years of work by many theorists (there were some ideas, already a bit strained experimentally and theoretically problematic, but all were decisively ruled out by the bullet cluster observation).

And you know that the bullet cluster observation directly detected a large quantity of some kind of, well, non-luminous matter (gee, wouldn't it be nice if there was a more concise term meaning "non-luminous"!) around the two clusters, with a distribution and mass just as expected from the theory. This was a situation totally different from any that had ever been observed, and the prediction of the dark matter model for it was verified experimentally. Case closed.

You know (or at least have been told again and again) all of that, and yet you still have faith that dark matter is "woo" (whatever that even means for a scientific hypothesis which is being actively tested). Evidently you're a faith-based person.


*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. That's the definition of a good theory - whereas epicycles, for example, were by the same criterion a very bad theory. And it's very very hard to come up with theories that work and do not contradict something else, as the current total lack of any alternatives to DM illustrates.

 

[robinson]

Yeah, but a lot of time stuff that turns out to be valid starts out sounding woo woo.

 

[Belz...]

That isn't what other people say.

Followed by a link that says exactly what I said. How quaint.