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Dark Matter Particles May Have Been Detected
During two seminars at Stanford and Fermilab on Thursday, researchers described signals for two events detected deep in an old iron mine in Minnesota that might mark the first detection of dark matter — or not. The presenters said the chances that the signals they detected were caused by something other than "neutralino" dark matter particles was 23 percent. "One source indicates that we'd need less than 10 total detections within the CDMS' range in order to have a high degree of confidence in the results." The NY Times describes the Cryogenic Dark Matter Search methodology: "The cryogenic experiment is nearly half a mile underground in an old iron mine in Soudan, Minn., to shield it from cosmic rays. It consists of a stack of germanium and silicon detectors, cooled to one-hundredth of a degree Kelvin. When a particle hits one of the detectors, it produces an electrical charge and deposits a small bit of energy in the form of heat, each of which are independently measured. By comparing the amounts of charge and heat left behind, the collaboration’s physicists can tell so-called wimps from more mundane particles like neutrons, which are expected to flood the underground chamber from radioactivity in the rocks around it." Here are the research team's summary notes of the latest results (PDF).
As a 49 yo feminist grandmother, I reject these results, since they are done by an old boys network of grey haired caucasian scientists.
Something with no energy means it has no movement. No movement means it must radiate all of its energy as gravitation.
So, what you're saying is that something with no energy must lose all of its energy as gravitation. Anybody else see a problem with this explanation?
Modding "-1, Troll" is not a proper response if you disagree with me. Try reason.
You mean the cautious interpretation that it's only 77% or so likely to be a positive signal? What does it mean that such a forecast is never wrong? I think science feels more like religion when you decide that's how it works. Do you have an alternate suggestion for interpreting this dataset?
Their fiendishly clever plan to get more money hopefully flew under the radar of the other standing-room-only particle physicists and cosmologists in attendance at the seminar where the results were announced.
No, 1:4 is enough for a good argument. They need 1:1000 or lower to end the argument.
Rethinking email
Because scientist's interpretation of what they see is never wrong! When did science start to feel more like religion to me...
So tell me where they went fairy tale on us here?
Here is just a gross simplification, so I may not be completely accurate, but I fail to see where this is fairy-tale science.
Characterization: Isn't that where we are finding that galaxies aren't behaving as we expect them to, and that behavior is in the form of gravitational interactions which shouldn't happen given the amount of mass which we can see.
Hypothesis:
There is something there which for some reason has a lot of mass, but we can't see it. Literally: Dark Matter
Deduction: If Dark Matter is weakly interacting as is suggested by the fact that we can't currently see it. If we are able to detect an interaction which cannot be accounted for among known particles, you have either discovered dark matter, or some other particle altogether if that detected particle is not massive enough when combined with the rate of interaction and the mass of the detected particle.
Experimentation:
Stick a detector way down in a mine shaft which will help filter out a lot of things which could cause a false positive. Look for interactions which do not match any known possible interactions.
Again, that is grossly simplified, but I don't see the jump in logic you are looking for.
Out of modpoints but really liked a post? 1BDkF6TtmmeZ3yqXbz9yhdYVqRYnwFoXDj
All detected particles are due to abnormal solar activity.
The detected particles will melt the crust within the next three years. Buy tickets for the arch from me now! Just 1.000.000 Euro each... No checks
CU, Martin
P.S. Guess which movie i watched yesterday :-)
The country that falls behind in basic research is the country that falls behind in history.
It appears from a quick Google search that the University of Minnesota is funding it. I guess you're against NASA, too, but in favor of pouring trillions down the Iraqui quagmire?
WTF are you doing on slashdot? Trolling?
Free Martian Whores!
No, only ones that disagree with my worldview.
So by reducing the temperature of the sensor to half a degree Kelvin, they have reduced the energy level of the sensor to almost nothing. Yes, it interacts with incoming particles, but it also radiates gravitational waves that could be misinterpreted as external particles. In essence, the detector is detecting itself.
Of course, there is a 23% chance I am completely wrong.
There's a 100% chance you're wrong. Gravitational waves can't be absorbed by these detectors in any meaningful way. To notice the effects of even massive gravitational waves you need a huge detector (like LIGO). Also, gravitational waves happen when a gravitational field changes. They propagate this change through the universe. Objects at rest aren't emitting gravitational waves.
If you isolated these sensors from the universe and let them sit for a long time, they wouldn't lose their mass to gravitational radiation - they'd probably sit around until death by baryon decay in 10^33 years.
And no, they're not detecting baryon decay either.
"I zero-index my hamsters" - Willtor (147206)
The paper pre-print will appear on the arxiv as 0912.3592, but is already available as on the CDMS homepage. Two events or 23% seems a bit low for all the hysteria... Pentaquarks went away after 50 events were discovered at more than 10 different labs...
If you're ever in the neighborhood, a tour of the mine and the lab are well worth the visit.
http://maps.google.com/maps?q=Soudan,+mn
http://www.dnr.state.mn.us/state_parks/soudan_underground_mine/index.html
http://www.dnr.state.mn.us/soudan/physics_tour.html
(Generally open June-September -- check before you come.)
I watched maybe too many star trek episodes, but I thought this dark matter stuff was in outer space and that any item touching it would implode (sort of). I am not a science expert, but would not finding dark matter inside earth's core insinuate that it was partially made of the stuff and that what we know about dark matter makes no sense??? I am sure there are no real dark matter exerts per se, as it is something we never really had contact with, however, what science knows about it to me seems very limited, and for what I do know ....dark matter should not be something we can just mine and tap into, it should be something that has a lot more involvement environmentally then I see here.
Dark matter != anti-matter. Turn in your geek credentials.
I don't understand where they got 23% from. There are two possibilities: either it is dark matter or it isn't. Therefore the probability is 50%.
Slashdot: news for Apple. Stuff that Apple.
That's dangerously low!
My home town nearly went to zero Kevins back in 1978.
It was a particularly cold winter, and we were already down to 3 Kevins (due to their low popularity at the time).
Kevin Thomas had flown out to be with his son's family for a wedding and got stuck in Boston for a whole week due to the weather. 2 Kevins left.
Kevin Lemmer was rushed to the hospital during my shift. I still remember the call from the EMTs as the ambulance was rushing toward us. "It's Lemmer. He's in bad shape. Drove right into the fucking ditch." We called the time of death at 6:15 PM.
At 6:16, all eyes turned to room 2217. Kevin Spencer was 82 and on his death bed with leukemia. His family being Catholic, he had already been given his last rights. If he couldn't hold out until Kevin Thomas returned, we would be at zero Kevins. Sure, we had 4 perfectly healthy Calvins, but they're just not the same.
It was 7:15 when Carla Brooks and her husband James burst through the main entrance. "She's not due for 2 weeks!", James exclaimed. As the staff bustled around getting the Brookses settled, they exchanged darting glances with each other. This was their first child, and they wanted to keep the baby's sex a secret. Of course, in a small town, secrets don't get kept. Nearly all of the hospital staff new that the child about to rip open Mrs. Brooks was indeed a boy.
The delivery was routine, and Kevin Brooks was born healthy, if a tad underweight, at 10:52 PM. Kevin Spencer was pronounced dead at 10:54.
It was, as they say, a close one. Kevin Thomas arrived two days later, the weather having finally cleared up. To this day, we still rib him about it.
Cedar Falls is currently at 5 Kevins.
They never said that "it's only 77% or so likely to be a positive signal", or that "the chances that the signals they detected were caused by something other than 'neutralino' dark matter particles was 23 percent". What they said is that there is a 23% chance that, in the total absence of DM particles, the background would generate those two events they found. Or: If they did the same experiment, with the same exposure and analysis (and if DM doesn't exist) hundreds of times, 23% of those experiments would show two or more events.
The chance that you flip a coin three times and get the same side up all three times is 25%, if the coin is honest. This doesn't mean that if you flip a coin three times and get the same side up three times, there is a 75% chance that the coin is not honest.
Going a bit deeper in the statistics, the probability that A happens with the hypothesis B is NOT the same as the probability that hypothesis B is true given that A happened. To "flip" those 23% probability that the background gives you 2 events to a probability that the two events events are caused by the background, you need to apply Bayes' theorem. You can only do that if you use, as prior knowledge, the probability that a dark matter particle exists. This prior can't be defined precisely by anyone, each physicist would give you a different value; so you can't apply Bayes' theorem here without being heavily biased.
What you can infer is that there is a pretty good chance that this was just a background fluctuation, specially since their previous results had zero events (with a similar background expectation). The REAL point that physicists got from the talk was that CDMS reached its limit, and has to be upgraded to SuperCDMS to stay relevant.
The only comment I have to make in the other direction is that I am uncomfortable with the probabilities that scientists have suddenly started to give - "there's a 77% chance we are completely correct".
Except it's not even that.
There saying there's a 77% probability that the result was not due to random noise, and that they actually did detect particles that are within the range predicted for neutralinos by Supersymetric Theory. Does that means it's a neutralino? Not necessarily, but it is a pretty strong argument of the "hypothesis -> experimentation -> verification" variety. Does it mean that everything they predict for neutralinos is true, or that Supersymetric Theory is "completely correct"? No.
I wish for some good old scientific conservatism, and the need to put percentages on the proportion of 100% correct you are feels a bit dubious.
Again, they're only putting a percentage on this not being a null result. Your characterization is wrong.
They're being conservative. But they're excited. And when you take a theory as ridiculously successful at making predictions as the Standard Model, make a logic extension to it and then that theory quite possibly has had its first verified prediction, that's not unreasonable.
I remember when scientific skepticism on slashdot involved people taking issue with specific aspects of the experimental procedure. Not people complaining that they don't like the result or how snooty the scientists are using statistics to measure their success.
The enemies of Democracy are
If they have really found neutralinos then wouldn't that would mean supersymmetry is confirmed? It that case it is a whole new ballgame in particle physics. There are blogs out there that are saying that CERN is about to announce something big too.
Exactly! I keep telling people; Einstein was wrong! An absolute speed limit makes no sense because there's no way I can understand how that would work!
Do you have the email of the president of physics?
That's because your logic is fundamentally flawed. If you were really questioning, and not just accepting everything at face value, you would say this:
Characterization: Isn't that where we are finding that galaxies aren't behaving as we expect them to, and that behavior is in the form of gravitational interactions which shouldn't happen given the amount of mass which we can see.
Hypothe- err, fuck that, I mean PROOF:
It's God. Literally God!! He's got his hand in that galaxy like it was a Jeff Dunham puppet.
Deduction: If God is weakly interacting with the galaxies, all you heathen sciency evolution types are fucked! Richard Dawkins won't be able to save you from getting cornholed by fire demons for the rest of eternity.
Experimentation:
Invoke the spirit of Charles Darwin. Ask him how hot Hell is. Fall on your knees, and hear the Angels sing. Never question God or me again. Now I will call you saved, please deposit $200 into the jar.
That's how you really fight the dogma of science.
Well, who are you going to believe - a panel of experts with hundreds of years of combined knowledge of the specific subject, or your gut? This so called "intelligence" is just nothing but liberal elitism at it's best.
"But this one goes to 11!"
Science only feels like a religion because in both people with full knowledge of the arcana speak to the rest of us as though we are children.
The difference is in the veracity of the arcana.
So Science sometimes feels like a religion, while religion proves to be religion.
Copypasta
http://hardware.slashdot.org/comments.pl?sid=1429380&cid=29967482
http://tech.slashdot.org/comments.pl?sid=1462774&cid=30288116
Do what thou wilt shall be the whole of the Law
If we can detect it, does that mean we have to stop calling it dark matter?
William of Ockham had no beard. The most likely explanation is that it was chewed off by squirrels every morning.
I believe you're talking about different things - the detector itself vs dark matter.
Lets do some armchair physics, since I need to dumb it down to my level anyway (I've got a minor in physics...). The known factors of (theoretical) dark matter is it has gravity but does not emit or reflect energy as heat or light, and the reason we think it exists is because galaxies aren't spiraling apart fast enough given the amount of visible matter. I won't pretend to understand that, I'll take it as a given and that the real physicists know what they're talking about.
Now imagine you put up a "wall" and throw particles at it. When a visible particle hits the wall, it bounces off and release some energy such as heat, just like when you toss a ball at the garage door - it may not be much, but it certainly is there. Now say we throw a dark matter particle at that same wall - what form of energy would it release, assuming it doesn't retain all energy (perfect reflection)? Personally, I don't know, but gravity doesn't sound like a bad suggestion.
It's MY copypasta.
I wrote it.
I'll copypasta it whenever I see "sexconker" used.
Although I generally believe that the less said about sexconker, the better, I do feel obligated to say a few things about sexconker's scabrous maneuvers. First off, sexconker is the embodiment of everything petty in our lives. Every grievance, every envy, every tasteless ideology finds expression in sexconker. While you or I might find it natural to want to deliver him from his appalling ignorance, we must fight for what is right. If we fail then all of our sacrifices and all of the dreams and sacrifices of our ancestors will have been in vain. The key is to realize that even if one isn't completely conversant with current events, the evidence overwhelmingly indicates that sexconker's prognoses are silly to the core. If you don't believe me, see for yourself.
It is as if we were safely on the bank of a raging river, enjoying a picnic with our friends and family, when a bunch of lewd vulgarians came along and threw us into the river. Not only must we struggle to avoid drowning in the raging torrent of sexconker-sponsored mysticism, but we must crawl out of the river before we can call your attention to the problem of bumptious thieves. He is completely mistaken if he believes that all it takes to start a rabbit farm is a magician's magic hat. I would undoubtedly not have thought it possible that we must act against injustice, whether it concerns drunk driving, domestic violence, or even cannibalism, in such a way that there is nothing he can do about it except learn to live with the fait accompli, but it's true. Right is right and wrong is wrong. However true that is, people used to think I was exaggerating whenever I said that sexconker's love of demagogism and irrationalism gives a new, perverse dimension to the old adage, De gustibus non est disputandum. After seeing sexconker toss sops to the egos of the aberrant these same people now realize that I wasn't exaggerating at all. In fact, they even realize that if we set the record straight then the sea of sadism, on which sexconker so heavily relies, will begin to dry up.
Okay, I admit that sexconker's equivocations are made of the same spirit that accounts for the majority of the problems we face in this world. But sexconker says that all any child needs is a big dose of television every day. Yet he also wants to condone universal oppression. Am I the only one who sees the irony there? I ask because he is known for walking into crowded rooms and telling everyone there that superstition is no less credible than proven scientific principles. Try, if you can, to concoct a statement better calculated to show how lawless sexconker is. You can't do it. Not only that, but I am tired of hearing or reading that everything is happy and fine and good. You know that that is simply not true.
Who is sexconker to say that censorship could benefit us? Imagine people everywhere embracing his claim that he values our perspectives. The idea defies the imagination. In order to look at our situation realistically and from a viewpoint that takes in the whole picture we must put to rest the animosities that have kept various groups of people from enjoying anything other than superficial unity. And that's just the first step. Remember, if sexconker would abandon his name-calling and false dichotomies it would be much easier for me to force sexconker into early retirement.
This is not wild speculation. This is not a conspiracy theory. This is documented fact. The tone of sexconker's statements is so far removed from reality I find myself questioning what color the sky must be in sexconker's world. sexconker's irresponsible bons mots oppose the visceral views of 98 percent of the nation's citizens. News of this deviousness must spread like wildfire if we are ever to rally good-hearted people to the side of our cause. Does anybody else feel the way I do, or am I alone in my disgust with sexconker?
In the eighth grade, when I was told that an argument that could be summed up as "Respect my authority!" with no factual backing was a fallacy.
Do you like Japanese imports?
<aha>So, you really can prove things with religion! I've been wrong all these years.</aha>
I feel fantastic, and I'm still alive.