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Dark matter detected?

Third Eye Open said:
I keep thinking about dark matter suns and planets moving through us at all times. Maybe even dark matter life forms trying to detect us in a similar way, wondering what this stuff is that makes up the unaccounted for 4% of their universe.
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You've really got the dark matter esque mindset down to a tee here. Dark matter aliens, dark matter galaxies, dark matter knomes and dark matter teapots are no doubt next to be proposed to have hugely significant effects in the precise areas current theories are incomplete. Soon everything in the universe will be explained with help from our good old hypothetical chum dark matter.

Creationists must be having a field day, a god thats made out of dark matter is going to be very hard for anyone to refute.

ben m said:
It's obviously the neutralino from a MSSM with m_1/2 = 400, m_0 = 90, and tan beta = 10, and mu > 0. Next question? ;)
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Which precise theory do these made up values and properties plug the hole in?

Dancing David said:
So where is the hyperbole, where is the overstatement, where is the equivalence?
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"mysterious and invisible substance that accounts for three-quarters of the matter in the universe"

Wrong.

"For 80 years, it has eluded the finest minds in science."

Wrong. Some of the finest minds have proposed alternative theories that dont need dark matter.

"The scale on which people are looking for dark matter is vast,"

True. So much funding has been invested in finding DM it would be extremely embaressing for the cosmologists that have to keep asking for the funding, and if not found definitively soon they run the real risk of far less grants, which would give more funding to people with 'rival' theories.

"Finding evidence for supersymmetry is one of the major goals of the Large Hadron Collider at Cern, in Switzerland."

True, and we all know how well that went :rolleyes:

"Dark matter particles are peculiar because they pass through objects as if they were not there."

Unprovable.

"published the first 3D map of dark matter"

misleading, publishing a map indicates its been found and plotted, whereas the map is actually just a map of areas the gaps in current gravitational theories infer there has to be dark matter, or else break down completely.

"a dark matter particle knocks into an atomic nucleus in the detector and makes it vibrate."

Seems awfully statistically unsound to say that something even smaller than an atom hitting a nucleus could be used as proof that the entire universe is now made primarily from invisible Dark Matter.

Also seems like a hell of a job shielding all the atoms in any given area from any sort of external interaction whether it be em radiation, em forces, temparature changes, geological movements, etc. Seems like a lot of room for an error to have crept in.

I do hope that there are a multitude of completely independant experiments using completely different techniques to independantly verify the results from this one. If they turn out to even be right.


Have the results been published in a journal yet?
 
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doh I really dont have the energy to continue this further, given the now inevitable replies will start mounting up. Shoulda thought this through.

Why did I have to get the top post of the page too, thats even worse.

Dammit.

Well whatever you say your all wrong and yes I have the proof.

But no you cant have it.

As I wrote it down on dark matter paper :p
 
Zeuzzz said:
"mysterious and invisible substance that accounts for three-quarters of the matter in the universe"

Wrong.
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That is what?

You account for the rotation of galaxies how?

Oh , I know dear one, now you will say you aren't up to it and run away.

darm matter is a hypothesis, it explains known observations and include things like nutrinos.

Is that the article or the researchers there as well.
 
Zeuzzz said:
doh I really dont have the energy to continue this further, given the now inevitable replies will start mounting up. Shoulda thought this through.

Why did I have to get the top post of the page too, thats even worse.

Dammit.

Well whatever you say your all wrong and yes I have the proof.

But no you cant have it.

As I wrote it down on dark matter paper :p
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Thats tight Zeuzzz, when it comes to backing your statements with evidence, you run away.

if you were any sort of real debater you would already know that nutrinos are part of dark matter and it would be very hard to make paper out of them.

But then you don't think nutrinos exist either.
 
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Fnord said:
Mneh ... I'm sure the check is already in the mail. After all, it is near year's end, and that means less than two weeks to make a donation that is deductable on the (U.S.) income tax.

They woman that taught me how to do 'psychic' readings to me that if there is one thing to rely on it is greed ... and gullibility.

No, make that two things; greed and gullibility ... and arrogance.
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Oh, I thought it was three things, ignorance, stupidity, and an inability to count.

Or was this just your subtle way of agreeing with me method actor style?
 
GreyICE said:
Oh, I thought it was three things, ignorance, stupidity, and an inability to count.

Or was this just your subtle way of agreeing with me method actor style?
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More like my subtle way of stating that I've lost all but a superficial interest in the topic of this thread ... whatever it may be.
 
Fnord said:
How much more likely was the announcement 'leaked' in order to finagle more funding for further research?
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Oh yeah. Tell me about. They're doing that with that stupid MS vein theory garbage. Argh.

Sorry, not trying to derail, just pointing out this is a common ploy with ridiculous unsubstantiated hypotheses made with unrealistic "evidence".
 
Zeuzzz said:
Originally Posted by ben m
It's obviously the neutralino from a MSSM with m_1/2 = 400, m_0 = 90, and tan beta = 10, and mu > 0. Next question? :wink:
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Which precise theory do these made up values and properties plug the hole in?
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Easy: MSSM. Next question? :wink:

Zeuzzz said:
"mysterious and invisible substance that accounts for three-quarters of the matter in the universe"

Wrong.
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Wrong.
It is an observed fact that three-quarters of the matter in the universe" is missing- WMAP tells us that the universe is flat, GR tells us that there missing mass & energy.

Zeuzzz said:
"For 80 years, it has eluded the finest minds in science."

Wrong. Some of the finest minds have proposed alternative theories that dont need dark matter.
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Wrong.
Some people have proposed alternative theories that don't need dark matter and do not account for all of the observations of dark matter. So these alternative theories are wrong.

Zeuzzz said:
"The scale on which people are looking for dark matter is vast,"

True. So much funding has been invested in finding DM it would be extremely embaressing for the cosmologists that have to keep asking for the funding, and if not found definitively soon they run the real risk of far less grants, which would give more funding to people with 'rival' theories.
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If the people with 'rival' theories had any credible theories then they would get funding. They do not and so they do not get funding.

Zeuzzz said:
"Dark matter particles are peculiar because they pass through objects as if they were not there."

Unprovable.
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Your ignorance is showing, Zeuzzz.
There are several observations of dark matter passing through "objects" (intracluster meduium) as if they were not there. Look up the Bullet Cluster some time.

Zeuzzz said:
"published the first 3D map of dark matter"

misleading, publishing a map indicates its been found and plotted, whereas the map is actually just a map of areas the gaps in current gravitational theories infer there has to be dark matter, or else break down completely.
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Wrong.
First 3D map of the Universe’s dark matter scaffolding
“To achieve this result, we extended gravitational lensing techniques - previously used to map the dark matter distribution in clusters of galaxies - and applied these in the COSMOS field to reveal a 3D dark matter” said co-investigator Jean-Paul Kneib of Observatoire Midi-Pyrénées.
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Now all you need to do is show that general relativity is wrong.

Zeuzzz said:
"a dark matter particle knocks into an atomic nucleus in the detector and makes it vibrate."

Seems awfully statistically unsound to say that something even smaller than an atom hitting a nucleus could be used as proof that the entire universe is now made primarily from invisible Dark Matter.
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Obviously you have never heard of neutrino observatories. Neutrinos are a bit smaller than an atom :D.
The results from this run of the CDMS experiment are awfully statistically sound. They are however statistically insignificant, i.e. have a 23% chance of being background events.

Zeuzzz said:
Also seems like a hell of a job shielding all the atoms in any given area from any sort of external interaction whether it be em radiation, em forces, temparature changes, geological movements, etc. Seems like a lot of room for an error to have crept in.
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It is a hard job. Luckily scientists have has decades of practice at doing this.


Your list is strange. None of these seem to be factors in the CDMS experiment.
  • "em radiation" = photons. So they switch off the lights at the bottom of the mine.
  • "em forces" - what is this?
  • "temparature changes" - AFAIK no effect on the experiment.
  • "geological movements" - definitely no effect on the experiment.
Zeuzzz said:
I do hope that there are a multitude of completely independant experiments using completely different techniques to independantly verify the results from this one. If they turn out to even be right.
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Yes there are: Dark matter detection.

Zeuzzz said:
Have the results been published in a journal yet?
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No. If you read the thread you will see that the results have been published in a preprint: "Results from the Final Exposure of the CDMS II Experiment"
 
Cryogenic Dark Matter Search
http://cdms.berkeley.edu/0912.3592v1.pdf

Perpetual Student asked me to get involved in this discussion. I'm still at work and I just started skimming through the paper. I can already see one problem with this "technique", namely it's not a "controlled experiment". There is no known source of DM, so unlike a neutrino detector, there seems to be no on/off switch to verify that yes indeed, we are seeing what we think we're seeing. I find that a bit disappointing frankly, but hey, unlike the dead inflation idea, there does seem to be a belief that "dark matter" can be 'detected' in a real lab.

I'm still reading through how they are calibrating the equipment and trying to figure out why they excluded so many of the detectors during this process. I'll let you know more once I've read through the rest of the paper, but so far my impression is that the paper is well written, and at least the detection method has some sound logic to it. The fact it lacks a controlled on/off switch limits my enthusiasm quite a bit, as it makes this claim of "detection" an "argument of the gaps" claim in the final analysis. Anything they can't "explain" becomes evidence that "exotic matter did it', but then why were so many of the detectors excluded in this process, and how would we really ever know that "dark matter did it" rather than there being some failure in one or two detectors, or some other real event that was triggered from some other "natural" source?
 
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http://www.timesonline.co.uk/tol/news/science/physics/article6961450.ece

The CDMS researchers emphasised, however, that they were not claiming to have discovered dark matter because there is a good chance that the events were caused by something else.

The probability that the signals were caused by ordinary radioactive decay or cosmic rays is about one in four, they said. A one in 1,000 chance of a random event would be needed to confirm that dark matter has finally been seen.

“In the new data set there are indeed two events seen with characteristics consistent with those expected from WIMPs,” the CDMS team said in a statement. “However, there is also a chance that both events could be due to background particles.

“Scientists have a strict set of criteria for determining whether a new discovery has been made, in essence that the ratio of signal to background events must be large enough that there is no reasonable doubt.

“Typically, there must be less than one chance in a thousand of the signal being due to background. In this case, a signal of about five events would have met those criteria. We estimate that there is about a one in four chance to have seen two background events, so we can make no claim to have discovered WIMPs.”
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FYI, as I understand it, they are not making the claim of having discovered WIMP's, just that they have two detection events that "could be" candidates.

I suppose their claim that there is only a 1 in 4 chance these two specific events 'could be" related to "dark matter" seems rather suspect to me, but I have not been through the whole paper yet, or done any investigating of the detectors. I don't have any idea how they intend to distinguish between a WIMP and an ordinary gamma ray for instance.
 
Michael Mozina said:
but I have not been through the whole paper yet, or done any investigating of the detectors. I don't have any idea how they intend to distinguish between a WIMP and an ordinary gamma ray for instance.
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You're "not through the whole paper yet"? The WIMP recoil vs. gamma ray discrimination is described in the third paragraph, and the first figure, and indeed is about half of the content of the entire paper.

(Hint: look for the words "electron recoil"; that's what you get from a gamma ray interaction.)
 
ben m said:
You're "not through the whole paper yet"? The WIMP recoil vs. gamma ray discrimination is described in the third paragraph, and the first figure, and indeed is about half of the content of the entire paper.

(Hint: look for the words "electron recoil"; that's what you get from a gamma ray interaction.)
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I meant "cosmic" ray and I still haven't had time to finish the paper. :)
 
Michael Mozina said:
I meant "cosmic" ray and I still haven't had time to finish the paper. :)
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Cosmic rays (by which I presume you mean "muons", the only relevant ones):

(a) are extremely rare this deep underground, and
(b) don't look the slightest bit like nuclear recoils. They deposit a huge amount of energy per event; if they enter the detector volume at all, they're visible on the way in and on the way out.

And still with the "haven't finished the paper"? It sounds like you haven't started---the muon shield and veto are mentioned in the 3rd paragraph.
 
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