Dark Matter Hinted at Again at Cresst Experiment 80
physburn writes "The BBC is reporting recent results from the Cresst dark matter search in Italy. Between 2009 and 2011, Cresst have seen 67 events, a 4 sigma detection of dark matter particles with a mass of either around 15 GeV or 25 GeV. The results are near those previous results from DAMA and Cogent. So has dark matter finally been found, and if so what is it?"
Not yet. (Score:4, Informative)
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I spit out a solid half finger of good Scotch whisky at that.
Haven't laughed this hard in weeks.
Good work.
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She canna take much more Captain!
Dark matter always seemed like a cop out. (Score:3)
Dark matter always seemed like a convenient hand wave, but I'm thrilled if there's some concrete evidence of it. I do love being wrong!
Re:Dark matter always seemed like a cop out. (Score:5, Funny)
You're married, aren't you? Sounds like for some time, too.
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Dark matter was a convenient hand wave for the galaxy rotation problem, and just one of many hypotheses. But the the CMBR measurements also showed dark matter in the early universe, and in the same proportion predicted. That was as solid a confirmation as you ever get in cosmology.
What's interesting now is what it's made of - all we know is there's no interaction with photons, and no frictional clumping as you'd see in normal matter (or at least not in the wide range of energies involved in galaxy formati
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What's interesting now is what it's made of - all we know is there's no interaction with photons, and no frictional clumping as you'd see in normal matter (or at least not in the wide range of energies involved in galaxy formation).
Like neutrinos, only heavier. Perhaps the hypothetical neutralino. They only interact via the weak force and gravity, which would explain the apparent behavior. Or maybe something completely different, but then these detectors would probably not be able to find it at all, which would be a bummer.
Man, it's so painful waiting for sufficient data to show up in real-time. These tantalizing but inconclusive hints are like torture! I can only imagine what it must be like for those actually doing the work --
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Probably not a neutralino. SUSY is mostly dead.
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What happened to it?
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In simple terms, it had its life sucked out by a machine [bbc.co.uk] and would take a miracle to come back now.
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It's not dead, initial results from the LHC are inconsistent with the simplest model of SUSY [newscientist.com], but do not yet rule out other models which have higher energies for s-particles.
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no interaction with photons, and no frictional clumping
AFAIK this is one point not two as frictional clumping is mediated by photons, as at some point are all our observations. Not that I don't fully accept the evidence for dark matter, nor have any sympathy with DM deniers. From a history of science perspective, their kind have always been wrong.
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I hate to tell you, but modern physics has luminiferous aether deeply entrenched in it via BOTH relativity and quantum mechanics. Relativity calls it "the fabric of spacetime." QM calls it "vacuum."
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The original concept of luminiferous aether was a medium requisite for the propagation of lightwaves. I hate to tell you, but Einstein completely debunked it via special relativity. Of course, Einstein allowed for a concept of "relativistic aether", but it is nothing like the original luminiferous aether theory claimed and only shares the concept the presence of physical properties of space. In that sense, "aether" was a regrettable choice of term on his part.
If you wish to mentally substitute "an invisible
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But what if light works something like this https://hekla.ipgp.fr/IMG/pdf/Couder-Fort_PRL_2006.pdf [hekla.ipgp.fr] ?
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It's not even difficult to completely disprove aether by running an experiment to measure the speed of light and see if it various according to the direction of the earth's movement "through the aether". If light propagates using aether, then it's speed won't be constant.
I bet you think that phlogiston is still used in physics as well.
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You are mistaken. Your parent is right. The concept of aether is indeed comming back as Gedankenexperiement or as an analogy. If you had read your parents post till the end you had seen "space time" or "fabric of space time" or "vacuum" as modern variations of the same aether concepts our for fathers had. Why don't you google? You should find many modern publications that "use" the word aether ... but not in the old classical sense.
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Aether is used as a concept, but unfortunately, too many people confuse it with the old useless theory of luminiferous aether - yourself included.
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Myself certainly not included, insult to injustice, sigh.
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It's not even difficult to completely disprove aether by running an experiment to measure the speed of light and see if it various according to the direction of the earth's movement "through the aether". If light propagates using aether, then it's speed won't be constant.
Amusingly, the gravity wave detectors are basically the same as the Michelson Morley apparatus, and the opposite result is expected. But of course we won't call these "aether waves" when we find them- that's so 19th century!
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Amusingly, the gravity wave detectors are basically the same as the Michelson Morley apparatus, and the opposite result is expected. But of course we won't call these "aether waves" when we find them- that's so 19th century!
Well of course, because the phenomenon and thus expected experimental results are completely different. The gravitational potential of the detector relative to the earth will be constant, ergo there would be no distortion based on the earth's movement -- consistent with the Michelson/Morely experimental results -- whereas you would expect a difference if there was a light-propagation medium through which the earth was moving.
It's the same reason why when they detect minute changes due to seismic vibrations
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Imagine if the 19th century test equipent had been accurate enough to find gravity waves - don't you think Michelson and Morley would have seen that as evidence of something aetheric going on? How confusing would that have been.
Ultimately, there is a light-propagating medium through which the Earth is moving - call it the vacuum, the "fabric of space time", or whatever - which can be distorted by the passage of objects, and which does act like a series of potential wells.
The nature of this medium is IMO o
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Imagine if the 19th century test equipent had been accurate enough to find gravity waves - don't you think Michelson and Morley would have seen that as evidence of something aetheric going on? How confusing would that have been.
Maybe, but they would have realised that it was very different than the theorised medium of the luminiferous aether. They expected a consistent difference between the arm of their device parallel to the motion of the earth versus the one perpendicular, showing the effect of the earth's motion through the medium. Transient effects not aligned with or related to the earth's motion would have indicated that their theory needed to be entirely re-worked.
Saying ultimate light propagates through the medium of s
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, but the aether was light's medium, not everything's.
But that's just it - that's the underpinning of modern physics right there - it's no that there's not an aether, it's that as goes light so goes the universe.
Amd this is /. - all snark is warrented, elsewise what would we read?
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But that's just it - that's the underpinning of modern physics right there - it's no that there's not an aether, it's that as goes light so goes the universe.
Not, that's not just it. The underpinning of modern physics is that there is no privileged reference frame, when the whole point of the aether was that it was such a frame. That frame -- the aether -- does not exist. That's the first major distinction between "modern" and the prior physics in which the aether was hypothesised. It is inherently contradictory to talk about modern physics and then say "it's not that there's not an aether" because it is an inherent consequence of the true underpinning of mod
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"I bet you think that phlogiston is still used in physics as well."
Sure. Phlogiston was believed to be a substance that was released when things burned or rusted (i.e. oxidized). The matter that was left afterward was believed to be in it's "base" state. If you extend the concept a little and postulate that phlogiston is released in any exothermic chemical reaction (oxidization being the most common and easily observable), you have... chemical energy. Extend it a little bit more to include all reactions
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I don't see how you can equate phlogiston with energy as they had the entire concept of combustion the wrong way round. They believed that phlogiston was a substance inside objects that got released during combustion. This in no way explains
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If you mean specifically classical Lorentzian luminiferous aether, then yes, it doesn't work. But the basic idea of a universal, all pervading "substance" is consistent with both relativity and QM. Given special relativistic properties, the concept of a medium though which electromagnetic disturbances propagate is essentially the same as the EM field from EM field theory.
Yes, phlogiston is a little more of a stretch, but you issued a challenge. However, my interpretation of phlogiston is completely compa
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Let's try it another way. The idea of luminiferous aether suggested an experiment to try and find the "aether wind." If you work out the speed of light propagating in a medium through which Earth is also moving, using Newton's equations you find that you should observe a difference in speed depending on the direction the light is travelling. Michaelson and Morely (and others) looked for that difference and didn't find it.
However, if you calculate the speed of light using special relativity instead of New
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AFAIK this is one point not two as frictional clumping is mediated by photons,
Frictional clumping in normal matter is about photons. There could be 17 additional fundamental forces that only interact with dark matter for all we know - but none of them can produce friction (exept perhaps at very low energy levels).
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What's interesting now is what it's made of - all we know is there's no interaction with photons, and no frictional clumping as you'd see in normal matter (or at least not in the wide range of energies involved in galaxy formation).
It's 4 space dimension matter rather than 3 space dimension. Since 'our' 3 space dimension matter has nil (0.0) 4d space volume, there is basically zero % chance of interaction*. Likewise with other lower or higher dimensional matter.
Additionally 4d photons don't interact directly with 3d matter, etc.etc.
The interesting thing is that spacetime curvature still occurs... which explains the gravitational effects of different dimensional matter.
* I can't recall
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i like to think of it as looking at a game of pool if you're sitting with your eye level aligned with the side of the table, and a whisky in your hand (that part is very important). the table is essentially reduced to 1 dimension instead of the 2 that are necessary to model it (excluding corner cases such as spin, and balls becoming airborne).
when a shot is taken, balls appear to either collide and bounce, or pass through each other. far more pass through each other than collide, and it's nigh on impossib
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Enjoy [gutenberg.org]
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That doesn't hold up. If dark matter had friction (regardless of why), the dark matter in galaxies would tend to form disks - it doesn't. Also, in a 4-spatial-diminsion universe, there are no stable orbits, and no large scale structures like galaxies could form if gravity fell off as R^3.
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Dark matter does not appear to interact with itself any more than it does with normal matter. That's why in galactic collisions the dark matter of one galaxy will pass right through not just the dust clouds of the other galaxy, but its dark matter as well.
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Dark matter always seemed like a convenient hand wave, [...]
It might well seem that way, but I don't think it really is. In fact, it would be kind of strange if there was no dark matter because that would mean everything in the Universe glows. When you think about it a bit, you realize there's got to be a least some dark matter so the only question is: how much is there?
ISTM the dark matter hypothesis is completely reasonable. If anything, it is more humble than arrogant because it's not assuming that the only things that exist are the things we can directly s
and if so what is it? (Score:1)
Spiders.
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All the way down.
Don't bet your house on this result holding up (Score:5, Interesting)
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How I ruined Guiness for a friend: (Score:1)
(paraphrasing here, this was almost 20 years ago)
Friend: "Look at this! It's Guiness! Real. Live. Irish. Guiness! And I got it.... at the [insert early 90's supermarket chain here]."
Me: "Oh I've heard of that stuff. Is it really all that special?"
Friend: "What? Philistine! Look at this stuff. It's blacker than your soul. You could eat this for lunch. Many Irish do. It takes your girly American lager out back and beats it with a 2x4. Look, even the can has this automagical thingy inside it to reproduce the l
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Whoever told you guinness is supposed to be warm ...lied to you. It's served moderately chilled normally, and you can also ask for it "extra cold", at least in Ireland, officially served at 3.5ÂC. Also, Guinness doesn't taste like any soy sauce I've ever tasted *anyway*.
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Guinness tastes like soy sauce - I don't drink piss-warm "beer" so I wouldn't know.
Murphy's is better, is commonly available in the US, and also has the widget. Young's Double Chocolate Stout is even better than that. Rasputin's Imperial Stout is also not hard to find, and far better than Guinness. Australian Sheaf Stout is like heaven compared to any of those. But beware: Foster's makes a disappointing knockoff of the style and appears to have some kind of exclusive US distribution arrangement; I haven't seen a bottle of Tooth's Sheaf Stout in nearly 25 years.
The only thing that Guin
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Apparently Guinness tastes like soy sauce - I don't drink piss-warm "beer" so I wouldn't know.
You're lucky, then, that Guiness is served at as cold as 3.5C (unfortunately, for those of us who do like piss-warm beer).
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guinness and soy are both quite umami tastes.
in australia we'd say it tastes like vegemite, and we'd all rejoice and drink it all down.
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guinness and soy are both quite umami tastes.
Yeah. Saying Guinness tastes like Soy because both are "savory" is like saying potato chips taste like beef jerky because they're both salty.
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So do you think Cogent should move to New Jersey??
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From your own link, Cresst's 'M2' preferred mass region ranges from 9 to about 13 GeV, which is indeed 'near' both Cogent's 8 and Dama's 10.
At first glance it may look like this is ruled out by Xenon, but there is a lot of debate about the validity of Xenon's results in this low mass region, and just a small shift would make Cresst's results perfectly consistent with Xenon's.
Of course the Cresst signal could still disappear, but with three independent experiments claiming evidence in such a small region, th
Great introductions to dark matter (Score:4, Informative)
lots of these experiments running (Score:3)
There are lots of experiments of this type running right now. This team, CRESST-II, has announced that they have more events than can be explained by their background. However, that's not really the most convincing evidence you could ask for, since the background could have been underestimated. A more convincing thing to see is that some of the experiments are reporting signals that are modulated by the expected amount on a yearly basis by the earth's motion relative to the frame of the cosmic microwave background. Here [arxiv.org] is a paper that includes a survey of the the results as of June. There are some apparent contradictions between some groups' positive results and others' negative results.
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So I highly doubt a 30km/s rotation around our sun will impact our interaction with the CMB when our relative motion to it around the center of the milky way seams to be 390 KM/s.
You're right, it isn't the velocity relative to the CMB that's relevant, it's basically the velocity relative to the galactic halo. The dark matter particles they claim to be detecting would be gravitationally bound to the galaxy. I think the rest of what I wrote is correct. Check out the link I gave in the GP post, and also this paper http://arxiv.org/abs/1011.3076 [arxiv.org] , where they predicted the yearly modulation before they started the experiment. They measure a yearly modulation of about 16%, and that is app
I have proof of dark matter (Score:1)
I consistently see it every night after a drinking binge.
New unit (Score:2)
The abstract talks about "730 kg days". Huh?