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Most Sensitive Detector Yet Fails To Find Any Signs of Dark Matter

timothy posted about 9 months ago | from the turn-on-the-light-and-the-dark-escapes dept.

Space 293

ananyo writes "A U.S. team that claims to have built the world's most sensitive dark matter detector has completed its first data run without seeing any sign of the stuff. In a webcast presentation today at the Sanford Underground Laboratory in Lead, South Dakota, physicists working on the Large Underground Xenon (LUX) experiment said they had seen nothing statistically compelling in 110 days of data-taking. 'We find absolutely no events consistent with any kind of dark matter,' says LUX co-spokesman Rick Gaitskell, a physicist at Brown University in Providence, Rhode Island. Physicists know from astronomical observations that 85% of the Universe's matter is dark, making itself known only through its gravitational pull on conventional matter. Some think it may also engage in weak but detectable collisions with ordinary matter, and several direct detection experiments have reported tantalizing hints of these candidate dark matter particles, known as WIMPs (Weakly Interacting Massive Particles). Gaitskell says that it is now overwhelmingly likely that earlier sightings were statistical fluctuations. Despite the no-shows at XENON-100 and LUX, Laura Baudis, a physicist on XENON-100 at the University of Zurich in Switzerland, says physicists are not ready to give up on the idea of detecting WIMPs. They may simply have a lower mass, or may be more weakly interacting than originally hoped. 'We have some way to go,' she says."

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293 comments

First dark matter post (5, Funny)

GameboyRMH (1153867) | about 9 months ago | (#45284175)

Pulling in other posts below it :D

Re:First dark matter post (2)

bob_super (3391281) | about 9 months ago | (#45284411)

You don't seem to perceive the gravity of the topic.

Neither are they, despite going to Lead to find heavy stuff.

Re:First dark matter post (1)

Gareth Iwan Fairclough (2831535) | about 9 months ago | (#45284923)

Heavy stuff man.

Did they remember to turn it on? (2, Funny)

Anonymous Coward | about 9 months ago | (#45284227)

Just sayin'...

Re:Did they remember to turn it on? (1)

UnknowingFool (672806) | about 9 months ago | (#45284287)

Maybe they missed a decimal point or something. . .

Re:Did they remember to turn it on? (1)

Sique (173459) | about 9 months ago | (#45284795)

Are you sure, it's the decimal point and not some weird imperial duodecimal one?

Re:Did they remember to turn it on? (1)

peon_a-z,A-Z,0-9$_+! (2743031) | about 9 months ago | (#45284295)

It seems like they forgot to power-cycle it before making a determined observation.

Re:Did they remember to turn it on? (0)

Anonymous Coward | about 9 months ago | (#45285221)

All of you are making a huge assumption.... What if it doesn't want to be found??

Wrong People Trying (0, Flamebait)

Anonymous Coward | about 9 months ago | (#45284283)

The problem is that they've got the wrong people trying to accomplish this. If they really want to find something they should just tell the NSA that "there exists the theoretical possibility that some type of unknown phenomenon is present that cannot be excluded from terrorist activities" and the NSA will not only find the dark matter, they'll find something on it so embarrassing that it will announce itself to the rest of the world.

they just need to eat more kimchi (0)

Anonymous Coward | about 9 months ago | (#45284303)

they won't need a very sensitive detector for that dark matter

Maybe (5, Insightful)

Anonymous Coward | about 9 months ago | (#45284307)

Maybe it's just not there.
Dark matter always reminds of the 18th century hypothesis of the aether.

http://en.m.wikipedia.org/wiki/Luminiferous_aether

Same principle. Same made up matter that no one can see or detect but somehow fills the entire universe.

Re:Maybe (1)

Anonymous Coward | about 9 months ago | (#45284481)

One of the big problems is that we can observe the effects of dark matter on galaxies and celestial bodies. It is entirely possible that dark matter is not made up of WIMPs that scientists have been looking for and is something entirely different. So overall it looks like dark matter is a thing that has measurable effects on the rest of the universe but we cannot observe the matter itself.

Re:Maybe (4, Interesting)

Anon-Admin (443764) | about 9 months ago | (#45284637)

What we have is a phenomenon that is not explained by the calculated mass of the universe. As a filler we have titled it "Dark Matter" and "Dark Energy" and given it a mathematical correction to the calculations.

The mass issue is fixed if we realize that the size of the universe is larger than the visible horizon. Meaning it is bigger than we can see. With that we can assume that we can only see 13% of the whole universe and that the reset of it is too far away to see. Now, run those numbers through the formula to calculate the expansion rate of the universe and you get some great results!

The energy issue disappears when you realize that the closer an object is to a gravity well the slower time moves. Thus there is a large time differential between the edge of a given galaxy and intergalactic space. This time differential accounts for the perceived added gravity.

Better yet, paint it hot pink and put an SEP field around it. It is a better solution.

Re:Maybe (2)

Waffle Iron (339739) | about 9 months ago | (#45284695)

Looks like you're a shoo-in for the Nobel prize in physics.

A hint (1)

Anonymous Coward | about 9 months ago | (#45284723)

Gravitational lensing.

(And I'm kidding here:) You can't explain that!

Re:Maybe (5, Informative)

Anonymous Coward | about 9 months ago | (#45285157)

Protip... that still doesn't explain the rotation curve problem observed in spiral galaxies.

Re:Maybe (1)

occasional_dabbler (1735162) | about 9 months ago | (#45285195)

Well, I'm not necessarily convinced by your arguments, or as the ACs have said, you'd be elbowing Steven Hawkins off the Stockholm stage, but I agree with the sentiment that 'dark matter/energy' is PRspeke for "we don't know WTF is going on" I've seen some interesting articles (even here on /,) with possible alternatives: our universe is the 3D event horizon of a 4-D universe black hole for example (or somesuch). I can possibly accept that Dirac's quantum foam vacuum shows up as a mass that might explain the matter side, but the gravity-expulsive dark energy? No, that's BS.

Re:Maybe (5, Informative)

boristhespider (1678416) | about 9 months ago | (#45285207)

"What we have is a phenomenon that is not explained by the calculated mass of the universe."

Vague statement. What we have are two phenomena, one which is not explained by the observed mass in galaxies or in clusters, and one not explained by the present (and currently only serious) model of the universe. Feel free to propose alternative models for the universe... but make sure that they fit the current observations *at least* as well as that model and fails to break the Solar System. That is hard to do.

"As a filler we have titled it "Dark Matter" and "Dark Energy" and given it a mathematical correction to the calculations."

True, with the correction above.

"The mass issue is fixed if we realize that the size of the universe is larger than the visible horizon."

No it isn't. That will do precisely nothing for the rotation curves of galaxies and will also basically do nothing for the cosmological problem either. Vague hand-waving and appeals to Mach's principle don't hold without a concrete model. Provide that model and people may be convinced, but at the minute what you're suggesting is startlingly acausal and, as a result, unacceptable.

"Meaning it is bigger than we can see."

Very true. No-one thinks that the entire universe is the observed universe.

"With that we can assume that we can only see 13% of the whole universe and that the reset of it is too far away to see. Now, run those numbers through the formula to calculate the expansion rate of the universe and you get some great results!"

Nope, you get precisely the same results that we currently get, because while it may startle you, that's what we currently do -- effectively. Thanks to causality, matter outside of our horizon cannot have an effect on us. Basically, something which is far enough away from us that light cannot have made the distance cannot possibly have influenced us. That, or you have to propose a new theory of gravity -- good luck with that one. It's a common game in cosmology, and one which precious few people since Einstein have had any luck at.

"The energy issue disappears when you realize that the closer an object is to a gravity well the slower time moves."

No it doesn't. Do you think that we're using non-relativistic models of cosmology? Relativity is at the heart of your statement that gravity wells dilate time, and relativity is at the heart of cosmological models.

"Thus there is a large time differential between the edge of a given galaxy and intergalactic space. This time differential accounts for the perceived added gravity."

Now this is a much more interesting statement. Dig out Wiltshire's attempts to use time dilations between galactic clusters and voids to explain the dark energy problem, firmly in the context of general relativity. The fundamentals are not well-studied, but it is promising. However, it goes the opposite direction from your surmise -- it tends towards providing a dark energy rather than a dark matter. It does drive home the point though that it is vital to actually try and calculate something based on an idea, properly rooted in a concrete theory. The answers might be rather different from what you expected...

Re:Maybe (4, Funny)

FatdogHaiku (978357) | about 9 months ago | (#45284673)

Or there could be some interference.
From Security Video:

Jedi WIMP: These aren't the WIMPs you were looking for!
Physicist: "These aren't the WIMPs we are looking for!"
Jedi WIMP:They can go about their business.
Physicist: "They can go about their business."
Jedi WIMP: Move along.
Physicist: "Move along... move along."
Physicist: "Damn, we still haven't found anything!"

Re:Maybe (4, Insightful)

TheCarp (96830) | about 9 months ago | (#45284553)

Yes but I could pick another example, the nutrino and say it sounds like that too:
"In 1930 Wolfgang Pauli proposed a solution to the missing energy in nuclear beta decays, namely that it was carried by a neutral particle " ( http://www.ps.uci.edu/physics/news/nuexpt.html [uci.edu] )

It makes perfect sense. You have theories that test to a high confidence in every way you can test them, then you find an anomaly in specific instances. Whats the response? Take those theories and attempt to narrow down the properties of what would cause the anomaly.

It obviously doesn't always produce a hypothesis that pans out as correct, but, can you really say that Aether theory was so bad? It was wrong, yes, but, it lead to the creation of experiments that answered new questions and ultimately, shaped the theories that came after it.

and...at the time... that is, after light was shown to be wave-like AND before we knew that there was no motion relative to its "medium", postulating Aether made a lot of sense.

Re:Maybe (5, Insightful)

icebike (68054) | about 9 months ago | (#45284947)

True, even failed theories advance science in some way or other.
However at some point you have to let them go.

The summary where it clearly states:

Physicists know from astronomical observations that 85% of the Universe's matter is dark,

I suggest they KNOW no such thing, and merely postulate dark matter to get their equations to balance. But how many such equation balancing inventions are laying in the dustbin of Physicists' revised theories over the years?

Unless or until the Physicists can find fault with the detectors, all of which have failed to find a trace of something allegedly composing 85% of the universe , it would seem that the whole "dark matter is known to exist" statement needs to taken down a notch. Detectors designed to their own specs fail to produce a single trace. It doesn't matter that there are very precise measurements of exactly how much the equations are out of balance.

Re:Maybe (3, Informative)

Sique (173459) | about 9 months ago | (#45284953)

That's what they are doing with the experiment. They know that there is a difference between the observed gravitation inside the galaxy and the expected gravitation from the visible matter. They know a lot of properties the missing matter has not: it doesn't interact with anything else than gravitation. Thus it does not interact for instance with the electromagnetic force, it is thus electrically neutral. It has no magnetic spin. It does not absorb photons. It does not interact with visible matter except by gravitational force.

This experiment tries to find some other interactions, but none so far were detected.

Re:Maybe (0)

Anonymous Coward | about 9 months ago | (#45285107)

The neutrino is a perfect example of this since much of what happens in modern physics comes down to realizing that there is a missing piece, determine what that piece would look like, then striking out to find it.

Neutrinos _did_ turn out to be real.
Dark matter doesn't seem to be the answer (but, as they pointed out, it might just be a little different).
Higgs Boson _probably_ is real.

Science is the process of finding out which questions to ask and then trying to answer them, not just getting really good at guessing.

Re:Maybe (3, Informative)

lgw (121541) | about 9 months ago | (#45284557)

We can certainly detect dark matter. The CMBR studies have show it fairly directly (we've "observed" dark matter as much as we "observe" things with an electron microscope or radio telescope). The ratio of "normal" matter to "dark" matter in the early universe has been measured to 2 significant digits (perhaps more since last I looked into it).

The unknown part is what dark matter is made of. We know it's there, we just don't know what it is.

Re:Maybe (2, Insightful)

Anonymous Coward | about 9 months ago | (#45284757)

All we know is that there is something creating a gravity-like effect on large scales. We don't even really know how gravity works, so I don't think we can know dark matter 'exists' per se, as a type of matter, until we fully understand how gravity works at macro and quantum scales, the number of dimensions of the universe, the shape of the universe, etc... For all we know, the effect which we attribute to dark matter could just be a consequence of some other fundamental property of the universe that we know nothing about.

Re:Maybe (1)

cold fjord (826450) | about 9 months ago | (#45284959)

The unknown part is what dark matter is made of. We know it's there, we just don't know what it is.

I think it would be more correct to state that we can see the measured effect, but if it is matter or something else causing it is still uncertain. (That something else being a modified theory of gravity, or something else, for example.)

Re:Maybe (1)

lgw (121541) | about 9 months ago | (#45285109)

Well, science is about what the data points to, not just what sort of fun stories we can tell. The data points to some kind of matter that doesn't interact with electrons or photons, and that doesn't have some alternative way to clump due to friction (and I guess we know more about what it's not from TFA).

There were many explanations floated for galactic rotation rates, but one specific dark matter theory predicted the CMBR results with great accuracy, so the scientific method says we go with that until something make better predictions of newer data.

Re:Maybe (4, Insightful)

icebike (68054) | about 9 months ago | (#45285013)

We can certainly detect dark matter.

No, we can't.
We only know to what extent our speculation and our math fails to completely work to our satisfaction.
Se we invent a black-box term to get the math to work out. We are quite precise in our invention.
We design instruments to detect this stuff that the math predicts is there. Instruments fail, time after
time.

You always need to consider the fact that it might be something else in the math that is wrong.
Otherwise, you might just as well attribute it to unicorns.

Re:Maybe (1)

lgw (121541) | about 9 months ago | (#45285211)

The thing is: instruments did detect the presence of something that was
* Matter
* Not interacting with electrons or photons
* At the ratio to normal matter (quite accurately) predicted by a dark matter theory for galaxy rotation

Many theories were invented "to make the math work out" for galaxy rotation, and one of them made a quite accurate prediction of what we eventually measured about the early universe. Now we're trying to make additional measurements, because while we've measured dark matter at a large scale, that only tells us a little.

Re:Maybe (0)

JakeBurn (2731457) | about 9 months ago | (#45284667)

Too bad you took the coward's road AC. I would have modded you up instead of replying. I definitely feel that Dark Matter only exists because they want it to exist. It's always bothered me that we call something science that isn't really scientific at all. It's pseudo-science at best. The bigger issue is that religious people claim to have the answers. Believing they are all idiots and fools, (and saying as much to anyone that will listen), has left the scientific community in the position of NEEDING to show that they have all the answers. If one group says 'We have all of the answers' and another group responds 'you know, we really know jack shit compared to the totality of what's out there, we're just 99.99% certain that those other guys don't know what they're talking about' is the only honest answer. Instead people don't want to be perceived as lacking in knowledge when compared to someone they deem their enemy. This has lead to several areas of scientific research turning to theories that have little basis in reality except to cover that their previous theories were wrong when presented with new discoveries.

At what point did it become ok in the scientific community to keep on with a theory that evidence contradicts? Usually, when a theory is shown to be wrong its thrown out or at least revised, not magically shown to be correct overnight by making up something else to support it. I once read a book called The Road to Reality. Very long and fairly serious reading that started turning me against one of my favorite areas of science about 75% of the way through the book. The day I realized that the previous three chapters I had read were not science, but rather theories that were based on other theories based on yet other theories that only existed because the first theory was shown to be wrong at some point, was a real downer.

Re:Maybe (-1)

Anonymous Coward | about 9 months ago | (#45284961)

Like the THEORY of evolution. It's about as bone-headed as biblical creationism. Lots of evidence points to things changing too fast for it to have been caused by evolution. I think "evolution" had some help from a higher power. Or rather, smarter entities with the ability to engineer life starting with the DNA and "printing" the chicken that hatches the egg... Or just "enhancing" the DNA of native primates.

Hell, the fucking biblical book of Genesis supports this theory better than it supports the typical modern Christian view of creationism. Throw in technology that can terraform a planet and you've got a scientific explanation of everything written in Genesis without any sky fairies.

But you have to assume advanced intelligence exists outside of Earth. But most slashdotters already believe that while spouting off the virtues of not assuming anything without evidence...

Re: Maybe (0)

Anonymous Coward | about 9 months ago | (#45285129)

You don't know what a scientific theory is. Evolution has been proven. Over and over again.

A theory in science means something else than in everyday English.

What you think of a "theory" is called hypothesis. Evolution is no hypothesis. It's a scientific fact.

Re:Maybe (4, Informative)

Valdrax (32670) | about 9 months ago | (#45285003)

At what point did it become ok in the scientific community to keep on with a theory that evidence contradicts?

Where has it been contradicted here? The failure to observe WIMPs by this experiment doesn't mean that they don't exist -- just that they don't have certain properties that would make them detectable by this instrument.

It's like the search for the Higgs boson. There were theories that allowed for the Higgs to exist at lower energy levels than it was eventually found at. We tested them with the LEP and with Tevatron, in the 1990s. As we ruled out those lower (and some higher) energy levels, we got closer and closer to the truth. The Higgs boson exists are a mass somewhere around 125 GeV/c^2.

All this experiment has done is narrow the parameters a bit so far. Did you make a similar cry in 2011, when Tevatron shut down that we shouldn't have been wasting money on the LHC because the Higgs was contradicted? If so, then shame on you then. If not, then shame on you now.

The day I realized that the previous three chapters I had read were not science, but rather theories that were based on other theories based on yet other theories that only existed because the first theory was shown to be wrong at some point, was a real downer.

How is that not science? Science is all about filling in the gaps and trying to find explanations for what we don't know -- including the things we didn't previously know we didn't know. It's not some divine revelation that you either get right the first time or you disregard it as heresy and falsehood. It's a global learning process.

Re:Maybe (0)

Anonymous Coward | about 9 months ago | (#45284881)

^^ Nobel Prize winner!! Ding ding ding!!! ^^^

Of course, you'll have to share it with approx. 10 million others who thought of the same thing.

Re: Maybe (1)

umafuckit (2980809) | about 9 months ago | (#45285231)

Or the 20th century hypothesis of the neutrino.

Wimps? Wimps everywhere ! (1)

brunokummel (664267) | about 9 months ago | (#45284315)

from the article :
"... physicists are not ready to give up on the idea of detecting WIMPs. They may simply have a lower mass, or may be more weakly interacting than originally hoped....We have some way to go"

So former wimps are having a hard time finding WIMPs themselves? That's an interesting turn of events !!

the WIMPS are on your desks, sillies (1)

swschrad (312009) | about 9 months ago | (#45284539)

unless you are using DOS

Have they considiered... (2, Insightful)

0123456 (636235) | about 9 months ago | (#45284319)

...that maybe they're not seeing it because it's just not there?

Just a suggestion.

Re:Have they considiered... (0)

Anonymous Coward | about 9 months ago | (#45284391)

but it "has to" otherwise shit breaks apart

Re:Have they considiered... (1)

bob_super (3391281) | about 9 months ago | (#45284449)

Can you prove that?

According to our math based on our hypothesis, it does.
The universe doesn't have to agree with our puny hypothesis, despite how well it explains most of what we observe.

Re:Have they considiered... (1)

gewalker (57809) | about 9 months ago | (#45284583)

Not really, according to our math based on our hypothesis, our observations imply that we have missed something (dark matter and dark energy as well) -- however, good scientists also know that what we have missed might be that our current models may be slightly off, thus some scientists are investigating tweaks to our understanding of gravity -- see MOND [wikipedia.org] which seems to explains some thing betters thats dark matter, but has problems in other areas which is why most cosmologists are betting on dark matter or MOND. Either one is perfectly reasonable from a scientific basis, that's why researchers research.

Re:Have they considiered... (1)

bob_super (3391281) | about 9 months ago | (#45284651)

I'm pretty sure we both just said the same thing.

Re:Have they considiered... (1)

gewalker (57809) | about 9 months ago | (#45285239)

Maybe we did, hard to tell with all of the negatives in the stack :-)

Re:Have they considiered... (0)

Anonymous Coward | about 9 months ago | (#45284647)

I am not an astrophysicist or higher level scientist of any kind; however I do remember the basic scientific process. (details here: http://en.wikipedia.org/wiki/Scientific_method#Overview [wikipedia.org] )

Do not forget that everything is an observation. One part of the application of this methodology is to also question if we really are correct in our interpretation of what we are observing. The elimination of all currently proposed theories leaves two remaining possible alternatives.

Those alternatives are that our understanding of the observation is flawed, and/or something we have not yet evaluated is responsible for the results. In either case we are exploring the unknown; both cases should be pursued (as well as continuing existing operations, since there is also the chance that our sample period is insufficient).

Re:Have they considiered... (1)

bob_super (3391281) | about 9 months ago | (#45284739)

Ok, I'll spell it:
GP: "maybe it's just not there"
parent "but it "has to" otherwise shit breaks apart"
Me: "According to our math based on our hypothesis, it does."

Since the universe isn't breaking apart, and we can usually trust math before millions are spent on detectors, either we have a somewhat good hypothesis and there is dark matter preventing shit from breaking apart, but we're trying to detect it wrong, or we have a very bad hypothesis, and there isn't dark matter.
i'm questioning the statement that it "has to" be there.

I don't need to be reminded about scientific processes, you just didn't get my meaning.

Re:Have they considiered... (0)

Anonymous Coward | about 9 months ago | (#45285179)

Since the universe isn't breaking apart, and we can usually trust math before millions are spent on detectors

We can usually trust math since it is self contained within its axioms. Systems like that are always true as long as they are observed from within.

No one have been able to apply it to physics without simplifying the physics and even then the resulted calculations have shown errors. (Sometimes explained by measurement errors, sometimes explained by a flawed model.)
We have yet to prove that the universe actually follows the same axioms that are defined in math and until someone has actually found a model that works without things like the dark matter problem we can not know if it will ever work.

Re:Have they considiered... (1)

Gravis Zero (934156) | about 9 months ago | (#45284569)

the equations for our current theory "break" but one must remember that it is a theory. while it seems like a very solid theory, we do not know for a certainty if it's correct or not.

Dark matter fighting dark energy (2)

presidenteloco (659168) | about 9 months ago | (#45284409)

So undetected dark matter pulling stuff together more than expected and undetected dark energy pulling stuff apart more than expected.

Hmmm. Isn't it possible that the theory is just wrong about how gravity and spacetime works at really large scales?

Re:Dark matter fighting dark energy (1)

MrL0G1C (867445) | about 9 months ago | (#45284843)

Nice to hear some skepticism here on Slashdot. It certainly seems like scientists desperately want dark matter and dark energy to exist because their numbers are never adding up. It looks like bad science when they keep fiddling with the numbers to patch up their deficient theories.

Re:Dark matter fighting dark energy (5, Informative)

Zalbik (308903) | about 9 months ago | (#45284997)

It looks like bad science when they keep fiddling with the numbers to patch up their deficient theories.

Or to put it another way:
1. Scientists come up with theories to explain a phenomenon
2. Test to confirm
3. New observation breaks the theory
4. Theory refined to account for new measurements
5. Goto 2

That doesn't look like bad science at all.

The dark matter thing is stuck at step 2 as it may be either (a) the theory is wrong or (b) dark matter is really really hard to test for.

Science is a process, not a big book of answers. If you want a big book of answers there are any number of religions willing to accommodate you. Just be aware that the answers you get may be (1) vague, (2) contradictory and (3) of limited predictive use.

Re:Dark matter fighting dark energy (1)

i kan reed (749298) | about 9 months ago | (#45285161)

Yes, and the big problem is that a better, more testable #1 hasn't come along. We're stuck with dark matter at #2 until the variances seen can have another plausible explanation.

Re:Dark matter fighting dark energy (0)

Anonymous Coward | about 9 months ago | (#45285015)

Hmmm. Isn't it possible that the theory is just wrong about how gravity and spacetime works at really large scales?

Yes, that is possible. The problem is that any "solution" that has been suggested so far is more complicated and unlikely than just weaker dark matter.
Anyone who can find a simple solution that explains gravity and spacetime without the dark matter problem will probably get a Nobel prize and a chapter deticated to his/her theory in every physics book.

Re:Dark matter fighting dark energy (1)

lgw (121541) | about 9 months ago | (#45285053)

No for dark matter, because the strong evidence is from the early universe. Yes for "dark energy", because the term (like "cosmological constant") is just a placeholder for "there's something we don't know yet about how gravity and spacetime works at really large scales". Also, there's something we barely understand about it at very small scales - postulating "faster than light expansion of the early universe" explains a lot of data, but not much progress on a mechanism for it, or whether it's the same as "dark energy" or (more likely) unrelated.

Re:Dark matter fighting dark energy (1)

SEE (7681) | about 9 months ago | (#45285117)

Possible, yes, it just seems less likely than the existence of WIMPs.

The trouble is the Bullet Cluster lensing pretty much requires non-visible matter, even with the theories that assume relativity is wrong at large scales. It seems you can reconcile TeVeS with the Bullet Cluster using lots of neutrinos instead of WIMPs, but then when you plug that sort of neutrino abundance in TeVeS, you apparently get other inconsistencies elsewhere.

(Now, apparently STVG manages to handle the Bullet Cluster and galactic rotational curves without WIMPs . . . it'll be interesting to see what happens when people poke at that a bit more.)

Re:Dark matter fighting dark energy (1)

jmv (93421) | about 9 months ago | (#45285253)

At this point, the two are mostly equivalent. For example, Einstein's original "cosmological constant" in the general theory of relativity *is* a form of dark energy.

Re:Have they considiered... (3, Insightful)

wonkey_monkey (2592601) | about 9 months ago | (#45284485)

Hur hur, yeah, stupid scientists with their "degrees" and their "experiments."

What a bunch of losers.

Re:Have they considiered... (5, Interesting)

invid (163714) | about 9 months ago | (#45284505)

It's there. We've detected it from its gravity. They were just hoping that it wasn't completely dark. It's starting to look like it is. The trouble with it being completely dark is that would make it difficult to prove any theories about it. What they're doing is searching for their keys under the streetlight when they've probably fallen down the sewer.

Re:Have they considiered... (0)

Anonymous Coward | about 9 months ago | (#45284741)

You say "it's there, we've detected it" -- isn't that not strictly true? I mean, aren't their theories (MoND) that could potentially explain things w/o Dark Matter. Not saying they're likely, just that as I understand it they aren't completely ruled out....or am I wrong?

Re:Have they considiered... (2)

invid (163714) | about 9 months ago | (#45284905)

You say "it's there, we've detected it" -- isn't that not strictly true? I mean, aren't their theories (MoND) that could potentially explain things w/o Dark Matter. Not saying they're likely, just that as I understand it they aren't completely ruled out....or am I wrong?

You're technically correct. We've detected something or some phenomenon, and there are theories that can explain that something without dark matter, but like you said, they're not likely. Perhaps I was a little too dismissive of the fringe theories. Without direct evidence of what it is, all we really have is Occam's razor.

Re:Have they considiered... (1)

PolygamousRanchKid (1290638) | about 9 months ago | (#45285083)

Perhaps I was a little too dismissive of the fringe theories.

So are there theories that propose that there is something, that is not matter, but still creates the gravitational affect? Now that would be interesting.

I'm maybe not up to date, but I don't think that we've really managed to detect gravitational waves yet either. So maybe this gravity critter is just a little more complex than we have previously thought?

Only more experiments will give us more insight.

Re:Have they considiered... (2, Informative)

Antipater (2053064) | about 9 months ago | (#45285063)

MoND has problems, too. The most prominent is the Bullet cluster [wikipedia.org] . It's a group of colliding galaxies where the center of gravitational lensing and the center of observed mass don't line up, something that can't be explained by MoND but can be explained by dark matter: the collision "separated" the galaxies from their dark matter halos, causing the difference in CoG locations. Of course, this is also hotly debated, and IANAP.

oh, it's there, (4, Funny)

Thud457 (234763) | about 9 months ago | (#45285091)

it's spiders.
teeny-weeny black spiders.
hundreds of Quattuordecillions of teeny-weeny black spiders per cubic centimeter, crawling between the very fabric of creation.
crawling in your ear, in your eye.
SPIDERS.

Re:Have they considiered... (0)

Anonymous Coward | about 9 months ago | (#45284837)

Actually we haven't. There are even new theories dismissing [economist.com] dark matter

Re:Have they considiered... (1)

zdepthcharge (1792770) | about 9 months ago | (#45284983)

Take a fucking razor to this pile of shit. How about some serious money and effort gets put towards MOND? Stop chasing ghosts.

Re:Have they considiered... (1)

icebike (68054) | about 9 months ago | (#45285135)

We THINK we detected some anomaly in gravity. Even that isn't certain.

When you look into that, the Galaxy Rotation Curve [wikipedia.org] , (the source of much of the dark matter speculation), is itself pretty much of a huge kludge of assumptions and guesses.

Re:Have they considiered... (1)

UnknowingFool (672806) | about 9 months ago | (#45284513)

That is a possibility however it would conflict with known data so far. Seeing how it took almost 50 years to confirm Higgs boson after it was theorized, 110 days is not a long stretch of time.

Re:Have they considiered... (0)

Anonymous Coward | about 9 months ago | (#45284523)

I highly doubt it exists. Therefore, the parent hypothesis (let's stop calling unproven/tested science 'theory' ok?) is probably wrong.

Of course, no one seems willing to address this.

Re:Have they considiered... (0)

Anonymous Coward | about 9 months ago | (#45284883)

the parent hypothesis (let's stop calling unproven/tested science 'theory' ok?)

While I agree with your sentiment, as it stands it's a very easy way to determine at a glace who is clueless and talking out their ass, and who actually might have some kind of real insight or knowledge on a subject.

Re:Have they considiered... (1)

icebike (68054) | about 9 months ago | (#45285155)

Theory is exactly the right word.

Perhaps you were mistaking the word Theory for something else?

Re:Have they considiered... (5, Informative)

tylersoze (789256) | about 9 months ago | (#45284525)

Guess they should have given up on the Higgs boson search 10 years ago, too? A negative results is not a "failure", it just constrains things a little more.

The most compelling evidence for dark matter is http://en.wikipedia.org/wiki/Bullet_Cluster [wikipedia.org]

Obviously we should always be open to alternate hypotheses, but at the moment dark matter is still the most straightforward explanation.

Re:Have they considiered... (1)

MrL0G1C (867445) | about 9 months ago | (#45285081)

So, this dark matter, what is it? Because it seems to me that it hasn't been defined properly, it's just a massive kludge that scientists did when their observations didn't make scientific sense according to our current best theories of physics.

Dark matter is a theory without basis, it says oops, our measurements don't make sense. What is it, axions? - a type of particle that hasn't even been proved to exist. Dark matter is a theory shakily based on other unproven theories, proposed because the initial theories aren't working.

Re:Have they considiered... (1)

cold fjord (826450) | about 9 months ago | (#45284629)

...that maybe they're not seeing it because it's just not there?

Just a suggestion.

Although dark matter is a leading explanation for the universe we see, there are others. Modified theories of gravity are a contender. One of them that I find interesting is MoND and its TeVeS offshoot [wikipedia.org] . There aren't a lot of people working on it, so when a perceived roadblock appears it sometimes takes time to work around it.

Tensor-vector-scalar-modified gravity: from small scale to cosmology [arxiv.org]

Re:Have they considiered... (0)

Anonymous Coward | about 9 months ago | (#45284641)

Yes that is a consideration.

Since they don't have any widely accepted models that work with what we observe yet without it they aren't ready to say it doesn't exist, but if this and other experiments keep pointing to it not being there it will be come accepted that the dark matter stuff is either not there or even stranger than they thought such as only interacting via gravity but some how not interacting in any other way whatsoever.

Eventually someone may come along with a completely different thought that makes sense and can be proven. If that is the case dark matter can fall by the wayside like the geocentric solar system / universe.

The thing about science is even when you fail you succeed at gaining knowledge.

Re:Have they considiered... (0)

Anonymous Coward | about 9 months ago | (#45284715)

Or maybe the problem is that they're trying to detect it underground - suppose dark matter cannot penetrate a significant distance into solid matter or even gaseous matter?

captcha: unreal

No! Why didn't you mention this earlier? (2)

warrax_666 (144623) | about 9 months ago | (#45284791)

Of course they hadn't considered it earlier! What fools they've been shown to be!

(Hint: If you're a random commenter on Slashdot, then, yeah, the experts in the field have probably considered your idea before you suggested it.)

Dark Matter Location (1)

Anne_Nonymous (313852) | about 9 months ago | (#45284415)

Usually it is in and around the drumstick area.

God (0)

Anonymous Coward | about 9 months ago | (#45284435)

Finally some place where God may be hiding! We don't know what is attracting those particles, so clearly it is God! (Which god is an entirely other question.)

Re:God (0)

Anonymous Coward | about 9 months ago | (#45284615)

The particles don't have to be "held together" by God. Creation itself is naught but a figment of God's imagination... the belief that we are as real as God is about the same as characters in a book suggesting that they are as real as the author (that doesn't mean that what we do doesn't matter, however... for the consequences of our choices and actions are still inevitably experienced as perfectly "real" to us, and everyone around us). You won't find a flaw in this "matrix", because there isn't one.

Luminiferous aether 2.0? (1)

Anonymous Coward | about 9 months ago | (#45284437)

Dark matter experiments sometimes remind me of the luminiferous aether theory experiments of the 19th century. After a certain number of tests fail to return a result you start to suspect that the experiment is working perfectly it's just that there's nothing to detect and something is fundamentally flawed with your theory.

obvious solution (1)

Gravis Zero (934156) | about 9 months ago | (#45284443)

clearly it's too dark to see so they should just use a flashlight.

in other breaking news... (1)

NikeHerc (694644) | about 9 months ago | (#45284453)

The SANTA and EASTER BUNNY teams are also reporting negative results today. Film at 11.

Physicists know (4, Interesting)

Spy Handler (822350) | about 9 months ago | (#45284457)

from astronomical observations that 85% of the Universe's matter is dark"

They don't *know*, they're deducing this from reconciling observed data with general relativity but it's far from certain.

However relativity is not infallible, maybe it's true only in a special case -- like how Newtonian mechanics works great but only in a special case (bigger size than quantum scale, less velocity than ~1/10 c, etc)

Maybe at very large size and mass such as galaxies, general relativity doesn't hold and there's a better theory for explaining motion and gravity. If so we wouldn't have to invent nonexistent dark matter to account for the faster-than-expected galactic rotation and other things.

Re:Physicists know (2)

TheRealMindChild (743925) | about 9 months ago | (#45284703)

However relativity is not infallible

EVERY SINGLE TIME someone says they have broken relativity, even with "proof", it is later shown to be wrong.

Re:Physicists know (0)

Anonymous Coward | about 9 months ago | (#45285275)

So far.

Re:Physicists know (1)

havexs (462346) | about 9 months ago | (#45284727)

There also used to be lots of evidence for the earth being flat......
And the sun orbiting the earth....
And...... you can fill in the rest.

They are just so fixed on the idea f dark matter that they can't see an alternative..... our great scientists...

Re:Physicists know (1)

SEE (7681) | about 9 months ago | (#45284969)

Maybe at very large size and mass such as galaxies, general relativity doesn't hold and there's a better theory for explaining motion and gravity. If so we wouldn't have to invent nonexistent dark matter to account for the faster-than-expected galactic rotation and other things.

Maybe. Physics does have people working that line (TeVeS with massive neutrinos to explain the Bullet Cluster, Moffat's STVG). But WIMPs still are considered the most likely candidate.

offtopic : annoying ads (0)

Anonymous Coward | about 9 months ago | (#45284507)

the fuck with the big-ass ad on the front page?!?!?

Direct dark matter detection is confusing (5, Informative)

amaurea (2900163) | about 9 months ago | (#45284517)

Several different experiments have tried to measure dark matter directly in the lab, and the experimental situation is pretty confusing. This plot [ggpht.com] shows the confidence intervals and exclusion limits for various experiments (but it does not include LUX yet). The shaded regions are confidence intervals, that basically say "we've seen dark matter, and its properties lie somewhere in this region. But the dotted lines say "we haven't seen it, and if it exists, it can't lie above these lines".

What is strange, then, is that all of the detections are in regions that have been excluded by other experiements. LUX just makes the situation even more strained by pulling those upper bounds even lower. Still, those bounds and intervals depend on assumptions about the properties of dark matter, and it may be possible to reconcile [blogspot.co.uk] the results.

It will be interesting to see what happens to those tentative detections when they get more data. My bet is that in the end some systematic effect will be found to be responsible for the apparent signal. Or (much less likely) that they were just flukes. But who knows?

Dark Matter and Dark Energy are not actual things (0)

Anonymous Coward | about 9 months ago | (#45284529)

Both Dark Matter and Dark energy are expressions of unknown variables that are required to make the Standard Model work. They do not represent actual things, but rather numbers on one side of a balanced formulae. While ther could be unobservable matter and energy, it is likely that most of these unknown variables result in our partial understanding of the matter that we do see.

I had a girlfriend who was hyper sensitive (1)

Steve_Ussler (2941703) | about 9 months ago | (#45284567)

I had a girlfriend who was hyper sensitive.she would be able to detect it.

General relativity (0)

Anonymous Coward | about 9 months ago | (#45284599)

When generally relativity is properly applied to the problem, dark matter will been seen as a mathematical illusion created by previously inadequate approximations.

There is no dark matter in the universe, really (1)

stevegee58 (1179505) | about 9 months ago | (#45284619)

Matter of fact, it's all dark.

Check the Phlogiston Compensators (1)

tempest69 (572798) | about 9 months ago | (#45284655)

The dark matter theory has always felt a bit contrived to me. But I don't have the background to make an cogent argument against it, nor have standing for my words to carry weight.

Re:Check the Phlogiston Compensators (3, Funny)

Anonymous Coward | about 9 months ago | (#45285057)

that was an awful lot of words to say "i should shut up"

Re:Check the Phlogiston Compensators (1)

TechyImmigrant (175943) | about 9 months ago | (#45285105)

>nor have standing for my words to carry weight

I see what you did there.

Four physical dimensions (0)

Anonymous Coward | about 9 months ago | (#45284761)

If dark matter happens to consist of four or more physical dimensions we would only be able to "see" what is the equivalent of a circle of a rod, or the roots of a tree. We cannot "see" more than 3 physical dimensions but could measure the gravitational effect of the 4th, etc. We are essentially Plato's "man in a cave", http://en.wikipedia.org/wiki/Allegory_of_the_Cave, when it comes to dark matter.

Plug (0)

Anonymous Coward | about 9 months ago | (#45284779)

Dis they remember to plug it in ?
My vast experience tells me that that is usually what is wrong

'Dark Matter' is NOT science (0)

Anonymous Coward | about 9 months ago | (#45285021)

At some point in the 20th Century, theoretical physics moved from science (where maths was simply the tool used to create MODELS, models that no-one ever thought were real, but offered a predictive mechanism) to maths, where idiots claims mathematical models are the SAME as reality. Beta class 'scientists' found this nonsense very easily to swallow. Better again was the fact that spewing unsubstantiated mathematical nonsense was a LOT easier than doing real scientific research.

Turn theoretical physics into a branch of maths, and writing speculative papers in what is CLAIMED to be theoretic physics becomes infinitely easier. In maths, nothing is SEMANTICALLY wrong, so long as the maths presented is SYNTACTICALLY correct. This is because, obviously, maths is ABSTRACT. By pretended theoretical physics is equally abstract (rather than describing reality), one can puke up endless nonsense in published papers, justified PURELY on the basis of 'correct' maths.

'Dark Matter' is a great example of this. Current models of the Universe hit a massive snag, when it became undeniable that the Universe is expanding, at an accelerating rate. That disgrace to physics, in his tedious coffee-table book, told the world that either the Universe was expanding forever, but forever slowing down, or that the Universe would eventually start to shrink back on itself. The one possibility that only a year or so later was proven to be TRUE was the one possibility the hilariously hopeless Hawking stated could never be true.

But Hawking is a mathematician PRETENDING to be a physicist, so it matters not to him (or his supporters) how hopeless his models prove to be, so long as the models themselves have an abstract mathematical 'correctness'. We see the same with 'climate science' where the worse the predictions of the models offered by Obama's approved scientists prove to be, the more the sheeple are told to trust these people. This isn't science- this is propaganda, social engineering (and in the case of much cosmology) and religion dressed in the clothes of 'science'.

'Dark Matter' is the name given to a block of maths that attempts to patch up certain current models of the Universe that otherwise fail in major, and testable predictions. It is as if the police arrest a 5 foot black man for a crime they KNOW was committed by a six foot white man, but invent an 'adjustment' called 'dark matter' to justify the 'correctness' of their arrest. It is nothing but an "after the event" fudge factor that has no place in science.

But such utter garbage provides well-paying and well praised careers for tens of thousands of theoretical physicists across the planet. And because no APPLIED physics is expected to result from their blue-sky flights of fancy, no-one cares. It would have been great if Hawking had resigned his chair AFTER the humiliation of the discovery that the Universe is expanding at an accelerating rate, but like all the worst and most aggressive idiots on Internet forums on ANY subject, after having been proven wrong he simply stated "I was RIGHT because I was wrong".

Dark Matter, Dark Energy, common cause? (1)

error_logic (1160341) | about 9 months ago | (#45285103)

This has been bugging me for years, but I don't understand enough to either substantiate or falsify my thoughts. I also don't want to try and convince people that it's right since it sounds crazy even to me, but please tell me if you can find something wrong with it... I know that there are some extensive theories and observations involved, and I'm very aware of the relevant xkcd... http://xkcd.com/675/ [xkcd.com]

All that said, it's very interesting to consider the possibility that there's a common cause of the observations that prompted dark matter/energy theories. I've read far too much about physics on Wikipedia trying to disprove the notion, with little success. All I've managed to do is find more and more curious aspects of things that would be *solved* by the idea.

I'd be very interested in someone finding evidence to falsify the possibility of dark matter and energy sharing a common anti-gravitational cause. I've been trying to find a contradiction for a very long time, and have found nothing conclusive.

If we consider that the anti-gravity could be caused by the missing antimatter purportedly absent due to baryogenesis, we might expect to find annihilation emissions in the spectra (Hmmm... http://en.wikipedia.org/wiki/Space_roar [wikipedia.org] ? Doubtful, but who knows?). However, such an observation could be absent for at least two possible reasons: It doesn't exist...or the bulk of the antimatter is something weakly interacting and low-mass, sharing the same problem as the standard dark matter model.

I don't mean that antimatter would fall up in such a changed model. Its inertial mass could behave as expected, and follow spacetime the same way as normal matter. It would just exert repulsive influence. Galaxies would be compressed by rings (or spheres, how dark matter is modeled?) of antimatter surrounding them and spread out somewhat in intergalactic space (dark matter), while being repelled from each other by the spherical gravitational dipole effect (dark energy).

If you model a binary system with one matter and one antimatter particle, they orbit a barycenter on the opposite side of the matter particle from the antimatter particle...in lock-step with each other. Put a black hole at that barycenter, add more particles of each type, and you get an orbiting system that goes much faster than it should from just the matter...just like dark matter's effects on galaxies.

There's some amazing symmetry if you think about this, and some weird implications. Inertial and gravitational mass would no longer be identical. Relativistic mass might be gravitationally neutral. An antimatter particle would chase a matter particle and require new interpretations of conservation of energy (Probably one of the biggest potential arguments against the whole concept, except it violates assumptions, not any evidence I'm aware of).

My most recent consideration from all this was the idea of applying CPT symmetry to the big bang (since it could be expected to involve both matter and antimatter), with some truly crazy implications. Unfortunately my understanding of it seems to be even more lacking than I thought, and I'm not sure how to mathematically formulate/test the possibility of the Universe sharing a common beginning and ending if you look at matter and antimatter versions in opposite time-space terms.

I don't know what I'm doing, and really wish someone could put this musing to rest one way or another. Unfortunately, I doubt we really have the experimental evidence either way. All of my musings amount to relaxation of assumptions--I haven't found a concrete contradiction, and all the predicted effects seem too subtle for current experiments to show.

If anyone could give good evidence for falsification of this common cause hypothesis, or point me in a direction for finding it, I'd be very appreciative. I've spent far too much time thinking about this with nothing to show for it, despite trying to break it.

Thanks for reading. Please get this out of my head. :P

Dark Matter is Anti gravity (0)

Anonymous Coward | about 9 months ago | (#45285143)

True story.. good luck finding it with your current methods.

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