Dark Matter

[Jonathan Jarvis]

Can't quite get my head round this.

Dark matter is present in huge quantities in the universe. Matter has mass. Mass exerts a gravitational force.

So why no dark matter stars or galaxies?

Looked around Wiki but can't find the answer (or at least an answer I can understand)

 

[Chesterton]

So why no dark matter stars or galaxies?

I think the question is sort of a contradiction. Stars are matter we can see, dark matter is matter we can't see. If there were something like a star made of dark matter, it wouldn't be called a star, it'd have to be called something else.

 

[Golden Yak]

Can't quite get my head round this.

Dark matter is present in huge quantities in the universe. Matter has mass. Mass exerts a gravitational force.

So why no dark matter stars or galaxies?

Looked around Wiki but can't find the answer (or at least an answer I can understand)

I think the idea is that dark matter does not emit or reflect light. So you wouldn't see any great concentration of it.

Although to my knowledge it hasn't ever been observed obscuring anything - I've seen it described as 'diffuse' and 'transparent, almost invisible,' and is only detectable by looking for affects on gravity.

Dark matter has also been described as existing in a 'halo' around the galaxy, another explanation for it not being visible amongst the stars.

So it apparently has great mass, exists in tremendous quantities, is transparent and almost invisible, and exists mostly outside the galaxy.

Something tells me it might also be a code word for 'we really don't completely understand gravity yet.'

 

[AV1611VET]

I think dark matter is interesting, in light of ...

2 Peter 2:4 For if God spared not the angels that sinned, but cast them down to hell, and delivered them into chains of darkness, to be reserved unto judgment;

 

[Jonathan Jarvis]

I think dark matter is interesting, in light of ...

2 Peter 2:4 For if God spared not the angels that sinned, but cast them down to hell, and delivered them into chains of darkness, to be reserved unto judgment;

What a coincidence. I just started reading Milton's paradise lost today.

 

[MerlinJ]

What a coincidence. I just started reading Milton's paradise lost today.

Enjoy, it's quite the book, though not the easiest to follow. Try reading it aloud if you can. You get a really interesting kind of rhythmic effect that's less apparent otherwise.

 

[Michael]

Can't quite get my head round this.

Dark matter is present in huge quantities in the universe. Matter has mass. Mass exerts a gravitational force.

So why no dark matter stars or galaxies?

Looked around Wiki but can't find the answer (or at least an answer I can understand)

That's because "dark matter theory" (as in "exotic" matter theory) is a myth. It has taken three straight hits in row in the lab in just the past 18 months. It's quite literally become an exotic matter of the gaps theory because the mainstream astronomy community absolutely *refuses* to embrace the role of electrical current in movements of the plasmas of spacetime.

Up until last year SUSY theory and WIMP theory in particular were the "hottest topics" within the dark matter crowd, and they had 'high hopes' going into the LHC experiments. Unfortunately for them however, SUSY theory failed it's own 'golden test' in those experiments:

BBC News - Popular physics theory running out of hiding places

Some previous underground experiments had 'claimed' to have found some circumstantial evidence for WIMPS, but the most recent and most sensitive of such experiments at LUX found absolutely nothing:

LUX dark-matter search comes up empty - physicsworld.com

The "crowning blow" to SUSY theory, as well as to several other exotic matter concepts came at the hands of electron roundness experiments. Most exotic matter theories predict that the electron would not be perfectly round, but the most sensitive measurements run to date actually falsify that claim:

'Perfect' Electron Roundness Bruises Supersymmetry : Discovery News

On the other hand, it turns out that the mainstream has been *grossly* underestimating the number of actual stars in distant galaxies:

Galaxies Demand a Stellar Recount - NASA Jet Propulsion Laboratory

They also discovered that the various galaxies are actually considerably brighter and more massive than they had accounted for in their models:

New View: Universe Suddenly Twice as Bright | Space.com

And on top of all that, they just found more mass in the form of million degree plasma surrounding our galaxy than all the mass they had found in the whole history of astronomy prior to 2012:

NASA - NASA's Chandra Shows Milky Way is Surrounded by Halo of Hot Gas

Basically all the "missing mass" found thus far has all been found in ordinary plasma and there is no evidence that any other "missing mass' will be found in anything exotic.

 

[PsychoSarah]

I think the question is sort of a contradiction. Stars are matter we can see, dark matter is matter we can't see. If there were something like a star made of dark matter, it wouldn't be called a star, it'd have to be called something else.

Dark matter can be seen in one sense: it warps light that passes through it.

 

[Seipai]

Aside from all of the gravitational evidence, there is also this:

Particle physicists discover strongest ever evidence of dark matter | ExtremeTech

Then there is the fact that the theory that dark matter is part of predicts various observations of the universe better than any other model proposed to date.

 

[Michael]

Dark matter can be seen in one sense: it warps light that passes through it.

You are correct, but all normal forms of matter would have exactly the same lensing effect.

 

[Michael]

Aside from all of the gravitational evidence, there is also this:

Particle physicists discover strongest ever evidence of dark matter | ExtremeTech

Then there is the fact that the theory that dark matter is part of predicts various observations of the universe better than any other model proposed to date.

Apparently you didn't read the LUX article.

LUX dark-matter search comes up empty - physicsworld.com

Earlier this year, the US-based CDMS dark-matter experiment – located deep underground in the Soudan Mine in northern Minnesota – reported the detection of three WIMPs with masses of about 8.6 GeV/c2. While this mass is much lower than most conventional theories predict, it seems to agree with somewhat weaker observations in several other experiments. The CDMS detection has a statistical significance of about 3σ: well below the gold standard of 5σ, which is considered a discovery in particle physics. As a result some physicists doubt the CDMS result, while others have tried to explain it by developing new theories of WIMPs.
Expected 1600 events

However, the CDMS WIMPs should have produced more than 1600 events in LUX. No such signals were seen, making it much less likely that low-mass WIMPs exist.

If the Minnesota results had been "real", the LUX equipment should have registered 1600 events. It saw exactly none!

 

[Seipai]

Michael, apparently you did not read my post. I said that the amount of surety was only 3 sigma. Or don't you recognize the lower case symbol for sigma? You were almost going nuts over a finding of that you linked that was 3.5 sigma, only slightly better (which I also admitted) than the one I linked.

It seems that you don't understand the articles that either you or I link.

 

[Justatruthseeker]

Michael, apparently you did not read my post. I said that the amount of surety was only 3 sigma. Or don't you recognize the lower case symbol for sigma? You were almost going nuts over a finding of that you linked that was 3.5 sigma, only slightly better (which I also admitted) than the one I linked.

It seems that you don't understand the articles that either you or I link.

Apparently you didn't read the report.

Yes, I already dealt with this. Two separate experiments. One claims that they should have seen evidence that they were not set up for. Perhaps they would have, perhaps not.

Once again, you were going nuts over an experiment that was only 3.5 sigma, compared to this ones 3 sigma. They are fairly sure from the results in the Minnesota mine experiment, they are just not 5 sigma sure.

That's funny, that's not what the scientists themselves think.

Another dark-matter sign from a Minnesota mine : Nature News Blog

"Two other possible detections from the CDMS search, reported in 2010, turned out to be indistinguishable from background collisions from other, non-WIMP, sources. The same may yet hold true for the latest findings...

“We do not believe this result rises to the level of a discovery, but it does call for further investigation,” said Kevin McCarthy, a CDMS team member from the Massachusetts Institute of Technology in Cambridge"

In other words it is time to ask for more funding.

Why do you misrepresent the actual facts?

"The CDMS tries to get around that by shielding its detectors as much as possible and by precisely calculating the rate of expected collisions from other, background sources. The three possible WIMP events popped out of data in which 0.7 similar events would be expected from background, McCarthy said. Two of them occurred in the same detector.


He reported the signal at a 99.81% confidence level, or around three sigma in statistical language. “We favor the WIMP plus background hypothesis,” he said."

Of course they favor that hypothesis, their careers rely on it and so does future funding. So there is also a 99.81% confidence level that they are merely background noise, and 10 to 1 odds that's what they are and you will never hear of this again or they will finally come out and admit to it.


But then we find out the real actual statistical results.

http://cdms.berkeley.edu/CDMSII_Si_DM_Results.pdf

" We performed a profile likelihood analysis in which the background rates were treated as nuisance parameters and the WIMP mass and cross section were the parameters of interest. The highest likelihood is found for a WIMP mass of 8.6 GeV/c^2 and a WIMP-nucleon cross section of 1.9 10^41cm^2. The goodness-of-t test of this WIMP+background hypothesis results in a p-value of 68%, while the background-only hypothesis fits the data with a p-value of 4.5%. A profile likelihood ratio test including the event energies finds that the data favor the WIMP+background hypothesis over our background-only hypothesis with a p-value of 0.19%. Though this result favors a WIMP interpretation over the known-background-only hypothesis, we do not believe this result rises to the level of a discovery."

So the WIMP theory comes out .19% more favorable than just background, which is why they clearly state "we do not believe this result rises to the level of a discovery."

So you still have no discoveries of dark matter after 25 years of searching. And in 25 more years you will still have none. Fairie Dust can never be detected, because it is Fairie Dust.

 

[Justatruthseeker]

What is sad is that in science today a .19% probability over just background rises to the level of a press release and you can be sure a plea for more funding, since further investigations are clearly needed. I'd say a less than 1% probability calls for a declaration of a null result. But then they might not get that funding, so a <1% probability turns into a 99.81% confidence level. Man-o-man, the state of science today.

Correction: the state of astronomical so-called science.

 

[Seipai]

Wrong Justatrughtseeker. Read that article again. You misunderstood what it says. It says the odds of background only, in other words no WIMP's is 0.19%. The odds of WIMPS only is 68%, and the odds of WIMP's and background is 99.81%

 

[Michael]

Wrong Justatrughtseeker. Read that article again. You misunderstood what it says. It says the odds of background only, in other words no WIMP's is 0.19%. The odds of WIMPS only is 68%, and the odds of WIMP's and background is 99.81%

All those "odds" that you're talking about were made irrelevant by the much more sensitive LUX results. Had that 68% figure been correct or useful in the first place, LUX would have recorded around 1600 hits over the length of the run time of that *more sensitive* test. LUX recorded exactly none. It turns out that the .19% dark horse option was actually the "correct" answer according to LUX.

 

[Seipai]

All those "odds" that you're talking about were made irrelevant by the much more sensitive LUX results. Had that 68% figure been correct or useful in the first place, LUX would have recorded around 1600 hits over the length of the run time of that *more sensitive* test. LUX recorded exactly none. It turns out that the .19% dark horse option was actually the "correct" answer according to LUX.

There seems to be a difference of opinion about this. Since you are far from being an expert I will take any of your claims with a huge grain of salt.

 

[Michael]

There seems to be a difference of opinion about this. Since you are far from being an expert I will take any of your claims with a huge grain of salt.

Since you are far from willing to admit to the fact that your earlier 3 false positives were later falsified at LUX, I suppose all you can do now is attack the messenger. Yawn. The pattern of denial plays out almost identically, regardless of the topic in question.

 

[Seipai]

Since you are far from willing to admit to the fact that your earlier 3 false positives were later falsified at LUX, I suppose all you can do now is attack the messenger. Yawn. The pattern of denial plays out almost identically, regardless of the topic in question.

I said that they were possibly wrong. They did get a three sigma signal. You keep conveniently forgetting that 3.5 sigma event that you thought was "proof". The jury is still out on dark matter. The evidence for particles is still lacking. The observed evidence is still rather strong. Meanwhile you have nothing but old debunked ideas that you are not willing to let go.

 

[PsychoSarah]

You are correct, but all normal forms of matter would have exactly the same lensing effect.

It is probably the only normal property of dark matter. Perhaps dark matter doesn't have chemical reactions with itself, and thus why it doesn't seem to form stars? That is just conjecture of course, but it is something to consider.