Dark Matter Particles May Have Been Detected 156
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).
White male science (Score:5, Funny)
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Marie Jo, I told you to dust of my PC, not to surf the web.
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As a 49 yo feminist grandmother, I reject these results, since they are done by an old boys network of grey haired caucasian scientists.
http://www.fnal.gov/pub/presspass/press_releases/CDMS_Photos/cdms_2_collaboration.JPG
Yep, sure looks like an entire pack of grey haired Caucasian scientists to me -- if I squint really hard and cover up a few people in the photo.
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Now that's fame: to become a Slashdot meme.
Re:White male science (Score:5, Funny)
White male science has been looking in the wrong place for dark matter. They should try looking between the ears of politicians. Mod away... :p
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It's true that alot of politicians are corrupted, and not much gets done.
But have you worked in a large company yet, where in order to complete a project different seperated departments with different stakes are involved and all have an own opinion and different expertises?
Enlarging that to "projects in a country" or even on a larger scale, it amases me anything gets done at all, disregarding the intelligence of many trying to push their agenda, stakes
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1:4? (Score:2)
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The real fun happens at the open bar Christmas party.
Physicists Gone Wild!
Re:1:4? (Score:5, Insightful)
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Which is exactly what they specified in the article. They're not making any argument, they're reporting on their findings, and very specifically say:
...we can make no claim to have discovered WIMPs
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They need a 1:1000 to have a valid argument.
Well, the IPCC report into climate change only reported a 9:1 chance of global warming being due to humans [wikipedia.org]. I think most people would agree that climate change being anthropogenic is a valid arguement, even those who sceptical of the science.
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The chance that "nothing" (as in, no dark matter around here) would generate a signal as "big" as they saw (2 events) is 23%. If they had so many events that the chance of "nothing" generating that number of events was under 0.1% (they'd need 5 or more events on this analysis), they would be able to say the "null hypothesis", or the absence of dark matter, was proven wrong. With their current equipment, they can't do that, and now I'm sure this will be the same result when they analyse the full data set. It
Dark matter @ Home.org (Score:2)
Bring it on!
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Wouldn't this be something like Yeti@Home?
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Solar activity (Score:4, Funny)
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 :-)
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P.S. Guess which movie i watched yesterday :-)
Snakes on a plane?
Casablanca?
Dersu Uzala!
Re:Solar activity (Score:5, Funny)
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Or maybe you try to become rich-for-cheap and downloaded the spanish cam version: "Cómo hacerse rico en el 2013"?
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repeat after me
That movie doesnt exist
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10,000 arches (joined together with bricks an stuff), would make a hell of a bridge. And then you could sell that to someone, I'm sure.
Paper pre-print to appear on arxiv (Score:4, Informative)
The paper pre-print will appear on the arxiv as 0912.3592, but is already available as on the CDMS homepage [berkeley.edu]. 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...
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Pentaquarks went away after 50 events were discovered at more than 10 different labs...
The difference between pentaquarks and this experiment is that CDMS did their analysis blind. That is, they agreed on what a positive signal would look like before they looked at the data. There's much less chance of making a stupid systematic error when you do a blinded analysis. The pentaquark folk went wrong when they did hundreds of cuts on previously gathered data trying to find anomalies. When you look at a bunch of data and pick out blips, the chance that they're random fluctuations instead of real s
Tours available. (Score:3, Informative)
http://maps.google.com/maps?q=Soudan,+mn [google.com]
http://www.dnr.state.mn.us/state_parks/soudan_underground_mine/index.html [state.mn.us]
http://www.dnr.state.mn.us/soudan/physics_tour.html [state.mn.us]
(Generally open June-September -- check before you come.)
How to tell? (Score:3, Funny)
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.
Oh come on now. (Score:4, Informative)
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Antimatter -> explode.
He said implode, which is red matter.
Re:How to tell? (Score:5, Funny)
> I watched maybe too many star trek episodes...
You did.
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dark matter is for pussies
real romulan men use only red matter
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Really, how would I know, how would you know, you never posted any info about
answering my question. I guess it's easier to just say someone doesn't know,
when we don't know ourselves!!!
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So what is dark matter then if it isn't anti matter?
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> So what is dark matter then if it isn't anti matter?
WIMPs.
One in two (Score:3, Funny)
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%.
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See, suppose there were a million doors...
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No, there are the following possibilities
1) both excess events are dark matter events
2) the first excess event is a dark matter event, the second isn't
3) the first excess event is not a dark matter event, the second is
4) both excess events aren't actually dark matter events
Hence, in one out of four cases there is no dark matter which gives their 23% after subtracting 2% since we actually know that there is dark matter.
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There are two possibilities: either the Earth is flat or it isn't. Therefore the probability is 50%.
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"There are two possibilities: either it is dark matter or it isn't. Therefore the probability is 50%."
Hidden assumption of equally likely events.
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And what about the events that they DIDN'T detect ? Just because they weren't detected doesn't mean they didn't happen, the scientists might have had their backs turned, or were looking the other way, or trying to find the spare detector batteries etc.
Perhaps dark matter deliberately avoids being detected, and the 23% that were could have been the one who didn't get the memo about "being dark", and were wearing spotted ties and green dinner jackets. Oh, and riding Segways.
In a universe of infinite possibili
1 Hundredth of a Degree Kevin (Score:3, Funny)
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.
Mod down (Score:4, Informative)
Copypasta
http://hardware.slashdot.org/comments.pl?sid=1429380&cid=29967482 [slashdot.org]
http://tech.slashdot.org/comments.pl?sid=1462774&cid=30288116 [slashdot.org]
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It's MY copypasta.
I wrote it.
I'll copypasta it whenever I see "Kelvin" used.
Mod up (Score:2, Funny)
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 righ
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The important question is... does the copypasta taste good?
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But everyone has Six Degrees of Kevin Bacon [wikipedia.org]!
Supersymmetry lives? (Score:3, Interesting)
If they have really found neutralinos [wikipedia.org] 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.
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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.
Pretty much. It would really only be a confirmation of one prediction of supersymetry, but it's a pretty damn impressive prediction to see born out, and smart money would be on the other particles predicted to eventually be discovered.
The only sad thing is that to really nail down the evidence for the neutralino will probably take years at CDMS. Oh w
No longer dark? (Score:3, Interesting)
If we can detect it, does that mean we have to stop calling it dark matter?
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No. The name has to do with the fact that it does not interact electromagnetically.
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Neutralino really sounds like the perfect name for a Hispanic Ferengi.
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If you can feel the shape of a dark statue in a dark room with your hands, does it stop being dark?
No? Then no.
Re:It's the lack of energy, stupid! (Score:5, Funny)
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?
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"If it has no movement, it's energy must be expressed otherwise, thus likely as gravitation."
Which is still wrong and silly.
When you cool an object, you are extracting heat energy from it and moving it somewhere else. To cool water enough to freeze, something else is going to get hotter. So it's not a matter of "if there's no movement, how is its energy expressed?" -- there simply is less energy to express, and whatever kinetic energy remains in the material (these detectors are not cooled to absolute zer
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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
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I believe you're talking about different things - the detector itself vs dark matter.
The OP was talking about the detector. He was saying that dark matter doesn't exist, and the detector was detecting itself giving of gravitational energy. Because it's cold, and must thus be emitting energy as something other than heat. This is nonsense. It just has less energy.
The known factors of (theoretical) dark matter is it has gravity but does not emit or reflect energy as heat or light. [snip] Now say we throw a
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That must explain why I get the weird feeling that days are somehow getting shorter.
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Technically, days on Earth get longer as the planet's rotation slows over time. A day was around 21 hours long when T. rex roamed the earth.
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Now THAT explains the Global Warming !
The earth is moving slower, hence those bits exposed to the sun are exposed for longer. Someone call Copenhagen and tell them they can go home.
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If the day is longer, the night is also longer. You get warmer days, but then you get colder nights.
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That's okay, because after that embarassing "Global Cooling" scare in the 70's and then the "Global Warming" that doesn't actually warm us and makes winters worse than ever, we now call it "Climate Change" to cover ALL our bases, and stop Michael Fish looking silly after he fails to predict hurricanes etc.
Funny that weather is always "Theres a chance of changeable weather with sunny periods and frequent showers" ... nothing is ever dealt with in absolutes.
But AGW is always "it's going to happen, we are cert
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Re:It's the lack of energy, stupid! (Score:5, Interesting)
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 [wikipedia.org]). 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.
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Something with no energy means it has no movement.
Or no mass.
Relativity... (Score:2)
Something with no energy means it has no movement.
Or no mass.
You mean "AND no mass.": E^2=m^2c^4+p^2c^2 so both mass and momentum must be zero for zero energy.
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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
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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.
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<aha>So, you really can prove things with religion! I've been wrong all these years.</aha>
Re:It must be true! (Score:5, Informative)
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.
Re:It must be true! (Score:5, Funny)
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.
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Might have been better if they'd called it Dark Mass, as that seems to be the thing we're twigging to about it all.
Re:It must be true! (Score:5, Insightful)
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.
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If you read CDMS's paper or watch the talks, you'll see that they never said that "there's a 77% chance we are completely correct" or anything like that. All they said (and all they can say with their data) is that, assuming that DM doesn't exist, the probability for the background alone to generate two events is 23%. Or: their result is compatible with a "Dark Matter doesn't exist" hypothesis, within a bit more than one standard deviation; that means their result is absolutely compatible with the absence o
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Don't mistake "scientific" journalists for scientists.
Yeah, this is typical distorted reporting. The paper is an entirely conventional one putting limits on mass and interaction strength. Some lying idiot in the press decided to hype up the "possibility dark matter has been dectected!" angle, demonstrating once again that no one hates science quite as much as "science journalists", who clearly don't trust that the subject matter is sufficiently interesting to warrant readers paying attention to it unless
No wonder people here hate psychology on Slashdot (Score:2)
Particle Statistics (Score:2)
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".
That is not what they are saying. They are really saying "IF we are correct there is a 23% chance that this is just a background fluctuation.". In particle physics we usually have two unofficial rules regarding results. If you have a 3 sigma effect (~1% chance of it being background) then you can claim "evidence for ...." and if you have a 5 sigma variation you can claim discovery. This is because it is REALLY easy to make mistakes in a complex analysis and underestimate or be unaware of other possible sou
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Did you forget a sarcasm tag, because there's nothing in TFA about global warming or evolution that I could see.
Does this fucking troll apply to all science articles now?...
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Re:It must be true! (Score:5, Funny)
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?
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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.
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Just because you are incapable of understanding the factual backing doesn't mean there is none.
Re:Meanwhile, Rome burns (Score:4, Insightful)
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My gut agrees with you, but I can't say why... Maybe it's the language that falls behind in basic research falls behind in history... If that's the case then funding translation into your language of basic research should be cheaper and have the same effect.
Or else maybe it has to do with having the people doing basic research in your country... I dunno... Maybe the proposition is false or not..
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There haven't been any reports of success, but fire is rumored to work pretty well.
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Re:Meanwhile, Rome burns (Score:4, Insightful)
It appears from a quick Google search that the University of Minnesota [uppermidwestherc.org] 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?
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Angsting (look at the user name).
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So the country is 1.8 trillion (US) in the hole this year, yet someone, somewhere, is funding research half a mile underground, with superconductors, to find particles that might not exist, and if they do, don't mean anything? How do I get out of this chicken-shit outfit?
Just pack up and move elsewhere.
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So the country is 1.8 trillion (US) in the hole this year, yet someone, somewhere, is sitting on slashdot bitching about inane things.
How do I best communicate to you that not eating or using energy for a year, or two, or ever, would actually do infinitely more for humanity than your comment here?