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Space Science

Scientists Expand Knowledge of Dark Matter 211

Posted by ScuttleMonkey from the lighter-shade-of-grey dept.
nife00 writes "BBC News is reporting that British scientists at Cambridge have expanded the current understanding of the mysterious particles known as dark matter." According to the article: "[The Cambridge Team] has at last been able to place limits on how it is packed in space and measure its "temperature". "It's the first clue of what this stuff might be," said Professor Gerry Gilmore. "For the first time ever, we're actually dealing with its physics," he told the BBC News website."
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Scientists Expand Knowledge of Dark Matter More

Scientists Expand Knowledge of Dark Matter

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  • How appropriate... (Score:5, Funny)

    by Jugalator ( 259273 ) on Monday February 06, 2006 @04:40AM (#14649266) Journal
    I just got this when first clicking on this article...

    Nothing for you to see here. Please move along.

    :-p

  • Uncertainty (Score:3, Insightful)

    by helioquake ( 841463 ) * on Monday February 06, 2006 @04:42AM (#14649272) Journal
    Give me the sensible error bar estimate on the mass, if they want to be scientific about it.

  • Just another point of view (Score:5, Insightful)

    by erroneus ( 253617 ) on Monday February 06, 2006 @04:46AM (#14649283) Homepage
    http://science.slashdot.org/article.pl?sid=06/01/2 5/1436243 [slashdot.org] -- This article points to the idea that there is no such thing as dark matter and explains everything with gravity. Now we're back to dark matter again? I still like science and all that but there are people who don't understand that "we don't really know everything" and that science as we know it today is merely an attempt at forming an understanding of our universe, not a definite mapping.

    • Re:Just another point of view (Score:5, Informative)

      by drgonzo59 ( 747139 ) on Monday February 06, 2006 @05:25AM (#14649382)
      I was actually wondering, could it be the case that we might not even be able to understand and explain some phonemena simply because our brain power is not adequate. For example the math works out for QM, but I don't think anyone can understand or conceptualize what is happening during entanglement (Einstein called it "spooky action at a distance" and never quite got to accept it).

      Or when someone is talking about multi-dimensional spaces, it is easy to express it in a mathemtical form (R^6 or C^6), but what does that mean in reality, how would you think about such a space?

      (Speaking of the 6 dimensions, there was an article on Slashdot about how the dark matter doesn't exist but instead we see what we do because "space has 6 dimensions".here [slashdot.org].)

      The point is that, just like dogs will never be able to solve integrals with the brain power they have now, so humans likewise might not be capable of understanding certain phenomena from the physical universe we live in.

      • Re:Just another point of view (Score:5, Informative)

        by meringuoid ( 568297 ) on Monday February 06, 2006 @05:37AM (#14649413)
        I was actually wondering, could it be the case that we might not even be able to understand and explain some phonemena simply because our brain power is not adequate. For example the math works out for QM, but I don't think anyone can understand or conceptualize what is happening during entanglement (Einstein called it "spooky action at a distance" and never quite got to accept it). Or when someone is talking about multi-dimensional spaces, it is easy to express it in a mathemtical form (R^6 or C^6), but what does that mean in reality, how would you think about such a space?

        You needn't go off with such physical exotica as QM and multidimensional spaces. Conceptually they're weird, but they're relatively simple mathematically. Indeed, that's the great value of such mathematics: it gives us the language with which to accurately describe the unimaginable.

        For a problem that seems to be truly beyond human intelligence, try turbulence. The mathematics to describe laminar fluid flows are well developed and understood, have been for centuries... but nobody has got the hang of turbulent flow. Even with supercomputer numerical simulations, you can only get so far. Proper modelling of turbulence has baffled the best minds for hundreds of years, and still we're not really any closer.

        • Proper modelling of turbulence has baffled the best minds for hundreds of years, and still we're not really any closer.

          We are considerably closer. The conceptual mechanism of turbulence is more understood now - it seems that turbulence is caused by finite-dimentional strange attractors [wikipedia.org] in phase space (good news because navier-stocks equations phase-space is infinetly-dimentional). The bad news is that strange attractors inherintly unstable in numeric simulations and amount of calculation grow exponenti
          • Sorry to be a stickler, but you're talking about one of my relatives :)

            That's Navier-Stokes [wikipedia.org]

          • I'm following you up to 'grows exponentially with computation time'. You mean that because of the exponential divergence of initial conditions? I suppose it depends on whether you want to extract an exact future system configuration or whether you want statistical information about turbulent flows. Throwing a smaller timestep at it won't make a difference anyhow if its the errorbars in your initial condition that are diverging with the chaotic dynamics, so really for long times the best you can hope for is
          • The conceptual mechanism of turbulence is more understood now - it seems that turbulence is caused by finite-dimentional strange attractors in phase space (good news because navier-stocks equations phase-space is infinetly-dimentional).

                Damnit! I follow every link to "strange attractor", because I figure that someday one is going to show Anjelina Jolie. Leave it to slashdot to disabuse me of that notion every damned time...
        • It is said that on his deathbed Neils Bohr said "when I die, I am going ask god about relativity and turbulence. I think he can tell me something about relativity".

        • If you mean turbulence, as in what planes experience when flying, wouldn't that be a case of too many variables? We're unable to predict the weather with 100% certainty because of the too many variable problem. Wouldn't turbulence be the same? Sure there'd be less variables, but surely there'd still be too many for current maths/computers at the present?
          • I don't think that weatherprediction is just an issue with the number of variables. More an issue with how each of the variables influences the others. You can't really apply a divide and conquer strategy on such systems without making a significant error. Take the ideal gas law. It started with a number of laws in which two parameters of a volume of gas were considered. (the others were kept constant). These laws were brought together as a single law (ideal gas law, which approximated the behaviour of hydr
          • In a sense, you are right, but It's worse than that. In all the other cases, we have models of the phenomenon that (in many cases) are partially derived from second principles (the gas laws, Navier-Stokes equations, etc.). Unfortunately, turbulence in a fluid flow is apparently unamenable to modeling with those laws - they pretend that a fluid is grainless and infinitely divisible (no atoms/molecules), and wrap up the more complex intermolecular forces under the viscosity term. Turbulence (apparently) i
          • Actually the problem with the Weather might not be just the number of variables, but the different local sensitivities to those variables -- it is a chaotic system. So even if you buy a billion dollar computer and account for as many variables as possible you might still not similate the weather in some part of the world, because it is very sensitive on the initial conditions. For example it is inherently harder to simulate and predict weather in England. There have always been jokes about un-predictability
        • Have you really understood anything if the best you can do is write down a huge, abstract equation? (and in General Relativty and Quantum Physics, these equations get very huge/abstract)
          • Does it matter if you can still derive predictions?
            • "Does it matter if you can still derive predictions?"

              Predictions allow you to check an existing hypothesis, but to make more progress requires a better understanding of what is actually happening.
              • If you're classing quantum mechanics as something that's insufficiently understood, I'd strongly disagree - we're currently way past that to quantum field theory.
                • "If you're classing quantum mechanics as something that's insufficiently understood, I'd strongly disagree - we're currently way past that to quantum field theory."

                  The phrase "quantum mechanics" refers to both non-relativistic and relativistic quantum mechanics (the latter being quantum field theory). If you can't even get the lingo straight, what's the point in replying?
          • Well, that was the point of my post. We are using QM to build things. The math seems to predict the phenomena. Quantum encryption works with entanglement and there has been experimental proof. But it seems that we cannot really understand it. Other phenomena are likewise. So I was wondering whether there is actually a limit as to how much our brains can understand. In other words some phenomena we will comprehend as the science progresses, but some we will never be able to wrap our head around.

            This is more

        • Speaking of turbulence, I am not an expert, but I remember reading about the problem of turbulence in Wolfram's "A New Kind Of Science" book about it. He approached the problem from a CA point of view and got some interesting results. here [wolframscience.com] is the chapter on it.

          At the same time, I have to say it is Wolfram, the self proclaimed pioneer and genius, who wrote a book full of proofs that start with "I am quite convinced..." or "It seems to me...". But nevertheless some of the stuff he did is quite interesting.

          • I think the way he would deal with turbulence is to say that it cannot be broken down into smaller calculations, the only way to find the actual outcome of a sufficiently turbulent system is to run the calculations in the real world, i.e just see what happens. It makes sense that there are some conditions that are not reducible to smaller equations, those equations are just models, and models are inherently inaccurate to some degree. Any degree of inaccuracy in modeling turbulence throws the whole result
            • What he did, is he set up a CA on a hex grid, with a certain set of rules, to be the medium (i.e. each mollecule is approximated by a cell). Then he simulated the movement of a plate through that medium and it turns out some interesting eddies form behind the plate that look very much like turbulence. The problem of course is that the CA "eddies" look like turbulence, but that doesn't mean that they somehow model the real world turbulent flow. But it is still an interesting picture to look at. Perhaps someo

      • Re:Just another point of view (Score:4, Interesting)

        by TapeCutter ( 624760 ) on Monday February 06, 2006 @07:37AM (#14649720) Journal
        "could it be the case that we might not even be able to understand and explain some phonemena simply because our brain power is not adequate."

        Godel [miskatonic.org] has already shown that no system of description is adequate, this is independant of of the amount of brain power on hand (or in head). People often wonder why maths is so good at describing the Universe, I belive it is because it is actually describing the model used by the brain to create the illusion of "I". ie: The simulated Universe containing the simulated self we all carry around in our heads. The "physical universe we live in" is an illusion.

        A favourite quote from the above link: Although this theorem can be stated and proved in a rigorously mathematical way, what it seems to say is that rational thought can never penetrate to the final ultimate truth ... But, paradoxically, to understand Gödel's proof is to find a sort of liberation. For many logic students, the final breakthrough to full understanding of the Incompleteness Theorem is practically a conversion experience. This is partly a by-product of the potent mystique Gödel's name carries. But, more profoundly, to understand the essentially labyrinthine nature of the castle is, somehow, to be free of it.

        I find the quote interesting because it relates a similar experience to religious conversion, ie: acceptance of the unknowable.

        • Re:Just another point of view (Score:5, Insightful)

          by Starker_Kull ( 896770 ) on Monday February 06, 2006 @09:42AM (#14650130)
          Actually, Godel did no such thing - he demonstrated that in any formal system of logic sufficiently complex to encapsulate basic arithmetic, there will be unprovable statements which are nonetheless true. Note that the reason we can say these unprovable statements are true is because that if they were false, there would exist a provable counterexample to the statement (i.e. an example of the falseness), and thus the statement would not be unprovable - but this knowledge comes from outside the logical system. In other words, he demonstrated that there will be true statements in a logical system that can never be proven within that system to be true; a hypothetical example might be Goldbach's conjecture, that any even number > 4 is the sum of two (not necessarily distinct) primes. If this was, in fact, true, but was somehow "unprovable", we would be left in the uncomfortable position of seeing billions of examples where it is true, not a single example where it was false, but of course there would always be an infinity of cases we didn't check yet. This is, in fact, the present state of our knowledge - and thus why I used it as an example. Of course, some clever egg might stumble upon a proof of Goldbach's conjecture tomorrow - people used to use Fermat's Last Theorem as a potential example of something that might be true but unprovable, until Wiles proved it. This is the problem, that we have no way of knowing what is unprovable in mathematics, because if we did have such a way of "knowing" (i.e. proving that a proposition is unprovable) for a specific proposition, we would have just proven it true, and thus it would not be unprovable! So we will never know what is not provable - we will only suspect that one of Godel's unprovable but true phantasms is staring us in the face.

          My point (longwindedly) is that this has little or nothing to do with the physical, mathematically modeled, problems at hand here; if you want a better idea of the type of barrier we are facing in this case, you would be better served by complexity and information theory; look up Shannon and Chaitin for more info - that is the type of problem involved in turbulence simulation, not logical issues of provability and incompleteness.
          • Don't you think there's an interesting little symmetry there though? We're trying to understand the complexity of the natural world, usually with formulae, but even divorced from the natural world our formulae are known to have limitations. Doesn't this imply that the very concept of description and understanding through formulae is limited? It cuts right through the idea that if we could only pin everything down to a number than it would all make sense (which seemed to be the prevailing theory before Go
          • "if you want a better idea of the type of barrier we are facing in this case, you would be better served by complexity and information theory....the type of problem involved in turbulence simulation, not logical issues of provability and incompleteness"

            I was going way OT, I was not talking about turbulence in particular I was agreeing with the GP who suggested there are things humans will never know.

            "but this knowledge comes from outside the logical system"

            ..and that is why I pointed to Godel.
        • I find the quote interesting because it relates a similar experience to religious conversion, ie: acceptance of the unknowable.

          Godel's theorem says nothing about "unknowability". It is about provability within a consistent axiomatic system.

          I know any amount of stuff by means other than proving it within a consistent axiomatic system. I know my name. I know my favourite colour. I know I'm wasting my time trying to explain something on Slashdot.

          Likewise, it is perfectly possible to know if a given theorem
        • Godel's theorem does not quite say what you suggest that it does. Rather, assume you have a logical system (built from axioms) which is consistent (the axioms don't contradict each other) and in which you can express enough different ideas (namely, you can formalize arithmetic in the system)). Then you can express certain ideas that cannot be proven or disproven.

          A fairly canonical example of this idea is the continuum hypothesis. If you look at the counting numbers, you can put them all into one infinite
          • "In any event, there is a difference between true and proveable and "knowable", just as there is a difference between a model, an axiomatic system, and reality. People like to throw around Godel's theorem a lot without fully appreciating its limits in scope. It is a powerful theorem of mathematical logic in that it shows that we cannot fully axiomatize the world. Still, it does not have the implications that you might suspect."

            Our mind is a model of reality, I belive (but cannot prove) that it is based o

      • I was actually wondering, could it be the case that we might not even be able to understand and explain some phonemena simply because our brain power is not adequate.

        Absolutely. To detect something one must have a tool of finer resolution than the thing itself. By corollary to understand something must one have a tool that has a "finer" resolution? I believe that one cannot understand things like entanglement with a lump of tissue (ones brain) that does not itself have the capacity to make use of entang

      • *Ahem* [sciencenews.org]. Dogs certainly do know calculus.
      • I was actually wondering, could it be the case that we might not even be able to understand and explain some phonemena simply because our brain power is not adequate.

        It sometimes strikes me that every model of the universe is an instance of lossy compression; it's small enough to fit into the human mind and gives you the gist of what's going on, but data is lost.

      • QM, but I don't think anyone can understand or conceptualize what is happening during entanglement (Einstein called it "spooky action at a distance" and never quite got to accept it).

        I think that's a good example. "Spooky" is a good word - things we don't understand are, historically, spooky. So, since it's spooky, we should accept that we don't understand it.

        The thing is, every so often a pretty simple theory comes along that explains these things rather elegantly. And then they're not spooky anymore.

        It

    • papers linked to (Score:3, Informative)

      by Falcon040 ( 915278 )
      Links here for related papers:

      Gravitational solution to the Pioneer 10/11 anomaly [arxiv.org]
      Galaxy Cluster Masses Without Non-Baryonic Dark Matter [arxiv.org]
      Galaxy Rotation Curves Without Non-Baryonic Dark Matter [arxiv.org]


      Other Interesting stuff:
      The Calphysics Institute [calphysics.org] and my earlier post [slashdot.org] about the Calphysics research.

    • Re:Just another point of view (Score:5, Informative)

      by Beryllium Sphere(tm) ( 193358 ) on Monday February 06, 2006 @05:26AM (#14649388) Journal
      That article dealt with only one kind of observation, namely how fast stars orbit the center of a galaxy.

      Dark matter theory would be on pretty tenuous ground if it only explained one kind of observation.

      There are features of the light from the Big Bang that are tough to explain without dark matter. The relative abundance of various nuclear isotopes is a sensitive gauge of conditions during the Big Bang, and again dark matter is the closest thing we have to an explanation.

      >science as we know it today is merely an attempt at forming an understanding of our universe, not a definite mapping.

      Isn't that the fun of it? My wife had a professor who always looked upward when he dropped a piece of chalk. He explained that we don't have real proof that gravity will always work, just an assumption that it will work like it always has, and if the chalk ever fell upward he sure didn't want to miss the event.

      Oh, and that paper about explaining orbital motions without dark matter may have been mistaken in its methods. People who know more than we at Slashdot do have pointed out what they consider fatal flaws.
    • Since there have been observations of galaxies consisting almost entirely of dark matter, it doesn't seem like a modification of the gravitational law is sufficient to account for the observations.

  • The Ministry of Silly Walks (Score:5, Funny)

    by malia8888 ( 646496 ) on Monday February 06, 2006 @05:03AM (#14649325)
    Using the biggest telescopes in the world, including the Very Large Telescope facility in Chile, the group has made detailed 3D maps of the galaxies, using the movement of their stars to "trace" the impression of the dark matter among them and weigh it very precisely.

    Doesn't the name "Very Large Telescope facility" sound like it is out of a Monty Python sketch, sort of like the "Ministry of Silly Walks"?

    Further, I am struck with the thought that dark matter is "Silly Putty" which has gone off a bit.

  • Ssshhhh... (Score:5, Funny)

    by Donut2099 ( 153459 ) on Monday February 06, 2006 @05:08AM (#14649342) Journal
    "For the first time ever, we're actually dealing with its physics,"

    Thats because we've secretly replaced the regular dark matter with Folger's Crystals!

  • Lots of it, and really damned hot? (Score:4, Interesting)

    by interiot ( 50685 ) on Monday February 06, 2006 @05:14AM (#14649361) Homepage
    The article mentions that there's quite a bit more of it than normal matter, and that it's about 10,000 degrees (... C?). Is that consistent? It just sounds odd for dark matter to have such a higher energy level than normal matter, weakly interacting or not.
    • I would have thought its temperature would have had to be much lower than that of normal matter. After all, it's only in equilibrium with the translational degrees of freedom of ordinary matter, because those are the only degrees of freedom that can couple gravitationally. I'm hard pressed to believe the average translational temperature of matter in the galaxy is that high -- it implies the average speed is at least several km/s. That seems very high.

      Maybe the dark matter has some kind of weird internal

      • Re:weird internal modes? (Score:5, Informative)

        by Stalyn ( 662 ) on Monday February 06, 2006 @06:56AM (#14649604) Homepage Journal
        What the findings suggest is that dark matter isn't exotic matter but a different kind of matter all together. The hierarchy of forces according to interaction goes gravity -> electroweak -> strong. This means all matter we know of interacts with gravity, all matter (until recently) interacts with the electroweak force and a subset of matter, quarks, interacts with the strong force. Note, quarks also interact with the electroweak force since protons and neutrons have electric charge and these particles are made of quarks. However leptons, like the electron do not interact with the strong force.

        Now it was possible that dark matter could interact with the electroweak force but very weakly and therefore undetectable at large scales. It was assumed that this meant they were very cold and at very low energy states. However if they are moving at 9km/s that would mean they have high energy states. Therefore if they did interact with the electroweak force, they would be absorbing or emitting photons. But they aren't.

        So we have a new type of matter with that only interacts with standard matter(leptons, quarks) via the gravitational force.
        • Neutrinos interact with the electroweak force, but they don't absorb or emit photons (except for higher-order effects, of course). That's the reason why you don't see the huge amounts of solar neutrinos which pass through earth all the time (you need large experiments to see the effects of their rare interaction with matter). Indeed, IIRC neutrinos were one candidate for dark matter (or maybe they still are?)

          Now there may be other reasons to assume that there's also no weak interaction between dark matter a
          • Neutrinos are considered a small percentage of hot dark matter. These findings suggest what we thought was cold dark matter is actually "hot". But the speed of 9km/s is way too slow for a neutrino. I guess there is the slim possibility of a massive neutrino or something like that. But I think we would have detected such by now.

            The SUSY partner of the neutrino, neutralino, is considered a WIMP and a dark matter candidate. But again this was before these findings so they might be cancelled out as well.
    • Yes, it's way odd. Expansion since the Big Bing should have chilled it to about 3 Kelvin. You could guess that something reheated it, but that is hard to do with something that doesn't like interacting with normal matter. If this is borne out (right now it's just an inference) it will be one of those "That's funny..." moments that lead to better understanding.
      • If something doesn't EMIT black body radiation (and doesn't absorb it), why would the temperature be related to the cosmological background radiation?
        • What a good question!

          The assumption is that at the dark matter can in principle interact with other things in the universe through non-gravitational means (most likely the weak force), so at some point in the early universe when reaction rates were much much much higher, it would have been in equilibrium with everything else (including the photons that would eventually become the cosmic microwave background (CMB)).

          At some point the reaction rates would become low enough that the average dark matter particle
    • I wondered this as well.

      Technically, shouldn't anything which doesn't emit light come under the banner Dark Matter?

      The Earth and Moon don't naturally emit light so would be difficult if impossible to see with a telescope.
      All of the asteriods and other rocky debris in our solar system is dark.

      All of this is moving at a lot more than a few centimeters a year.

      There can't be that much large fragments in the blackness of space because they would block our own view of the stars and lots more would appear to twink
      • The Earth and Moon don't naturally emit light so would be difficult if impossible to see with a telescope.
        All of the asteriods and other rocky debris in our solar system is dark.

        To my understanding dark matter is not defined as something that doesn't naturally give out light, but something that emits no light or radiation. The earth does emit light; that which is reflected off it from the sun, likewise for the moon. If I understand dark matter correctly, it wouldn't reflect the light from the sun, even i

        • That doesn't mean that the dark matter can block out the sun, does it? It means that the light passes through it? Would it cause the light to slow down though (I'm pretty sure glass causes it to slow down)?

          I thought the fact that dark matter has mass (and therefore substance?) was why galaxies hold together when they shouldn't. But how is that possible, if dark matter doesn't interact with normal matter in any observable way? And if it does interact with normal matter, where's it all hiding?
          • It interacts with normal matter through graviatation. It doesn't interact through electromagnetic interaction.

            Of course, light is affected indirectly through gravitation. However, normally gravitation doesn't shield light, it just bends it (the bending of light by the sun's gravitation was one of the first successful tests of General Relativity).

            And yes, light would slow down a bit, since gravitation causes a slowdown of time (e.g. seen from space, the light on earth's surface is a bit slower, even when in
            • How can it only interact through gravitation? Is there ANY matter that does this, besides dark matter?
              • That's the amusing part; as far as I understand it, no. The whole dark matter thing is rather touchy because of this - it describes something that only interacts via gravity. Remember that our sense of "interaction" (touching, burning, etc.) are all based on electromagnetic forces, so this dark matter could be passing through us right now and we would not notice it (much like neutrinos, which pass through us by the billions per second). Of course, at least neutrinos have the decency to OCCASIONALLY inte
              • Well, it might also interact with normal matter through the weak force, at least I don't know any reason why it shouldn't.
                Of course, different matter takes place in different interactions (e.g. only quarks and gluons take place in the strong interaction, electrons etc. don't; gluon and neutrino don't interact electromagnetically, the gluon doesn't even interact through the weak interaction). Now there's a priori no reason why there shouldn't be a particle which only interacts through gravity. (I couldn't im
    • For something to lose energy, it needs to bump into a lot of stuff. If dark matter really is weakly interacting, then you would expect it to have a higher temperature than more interactive stuff at the same number density. As for why it is hotter to begin with, who knows...
    • Not all matter is cold. The gas in large clusters of galaxies is sufficiently hot that it emits X-rays, for instance. In fact, in some bits of astrophysics it's quite challenging to find ways for matter to cool down.

      I don't think that temperature is necessarily inconsistent with anything, but I've not read the papers yet.

  • No references (Score:5, Interesting)

    by Random Walk ( 252043 ) on Monday February 06, 2006 @05:18AM (#14649372)
    I'll probably never understand why newspapers are never able to quote any references for their news. Even in the absence of a published refereed paper, I would expect that there is at least a preprint or press release from the research group... apparently BBC news is convinced that their readers will drop dead on the floor if they encounter a hyperlink leading to something more than just random blurb from a journalist.

    Actually, they don't even say whether 'Professor Gerry Gilmore' is part of the group that did this research, or whether he is just someone they asked 'Hey guy, what do think about this stuff?'. I.e. they don't even identify clearly any member of this 'Institute of Astronomy, Cambridge, team'.

  • I thought measuring the temperature of dark matter was like measuring the distance to the celestial sphere.

    Or for more of a /. reference, like measuring the quantity in the bit bucket.

  • Obligatory (Score:5, Funny)

    by SeaFox ( 739806 ) on Monday February 06, 2006 @05:44AM (#14649428)
    So I guess you could say they're shedding some light on dark matter?

  • Dark Matter (Score:2, Funny)

    by ben_1432 ( 871549 )
    What's so hard to understand about it? It's the heaviest, densest matter available and it powers spaceships duh. Oh yeah, and Nibbler [gotfuturama.com] craps it.

  • "Scientists Expand Knowledge of Dark Matter" (Score:2, Funny)

    by Anonymous Coward
    ... they're making dark matter smarter?

  • AHAH... I got it!! (Score:4, Funny)

    by DaedalusHKX ( 660194 ) on Monday February 06, 2006 @06:18AM (#14649499) Journal
    Dark Matter == God.

    Yep... dark matter and he who cannot be seen are one and the same... see?

    Now, onward to forming a new religion.

    Dark Matterism.

    I wonder what country we'll butcher to spread THAT religion??

    Anyone??

    ~D
    • Well, a dark matter god would clearly be a materialistic god, therefore I'd try in the former communistic countries.

      However, beware of the followers of the dark energy god religion. They argue that only dark energy can be the real god, because unlike dark matter, it's everywhere in the universe. Also it's powerful enough to accelerate the universe as a whole, while dark matter only acts in a galactic range. Also, the fact that we can learn something about the dark matter, like its distribution, shows that i
    • Mmmm... that's *alot* of noodles.
  • I was hoping that this would provide some real evidence for Dark Matter. I have a problem with something so massive which, as far as I can see, is invented to explain a single fact: the anomalously fast rotation of galaxies.

    But this article doesn't do that. It says, as I understand it, if the rotation of galaxies is caused by dark matter then dark matter has these properties. If the unexpected rotation is caused by something else, then this is just a curious kind of meta-measurement,

    It is a bit like the phl

    • Re:Still assumes the answer (Score:4, Informative)

      by rknop ( 240417 ) on Monday February 06, 2006 @08:39AM (#14649893) Homepage
      I was hoping that this would provide some real evidence for Dark Matter. I have a problem with something so massive which, as far as I can see, is invented to explain a single fact: the anomalously fast rotation of galaxies. ...and the anomolously high velocity dispersion of clusters, and matter evolution models that go from the observed fluctuations in the Cosmic Microwave Background to the observed distribution of matter today, and the anomalous amount of gravitational lensing seen in various cluters...

      The galaxy rotation curves are the cleanest and best piece of evidence, but there's a lot of evidence for dark matter. It's a major paradigm in astronomy, without which quite a number of things would be lacking an explanation.

      -Rob
    • It is a bit like the phlogiston theory.

      I like your analogy. I fear it's correct.

  • In other news... (Score:5, Funny)

    by jettoki ( 894493 ) on Monday February 06, 2006 @06:33AM (#14649538)
    British scientists at Cambridge have also placed limitations on the possible properties of the luminiferous aether. "We're pretty sure it's not yellow," says one researcher, "and we've also ruled out blue and pink. It's nice to know that we'll soon have figured out both this dark matter stuff and the luminiferous aether. Then we can start puzzling out those epicycles again."
    • Of course, dark matter and luminiferous aether are one and the same. Isn't that obvious? This explains immediatly why we cannot see it: It's not something in the way of light, but it's the medium of light itself!
      BTW, the dark energy is also solved. It's phlogiston. You know, phlogiston has negative weight, therefore it causes anti-gravitiaion. This neatly explains why dark energy causes acceleration of the universe expansion.
      The epicycle problem isn't yet completely solved, but it's likely that the enormous
  • IF dark matter exists, then it's like this...

    Reminds me Homer, author of Illiad and Odyssey. We don't know if he existed, but we know he was blind.

  • Here's what makes me unhappy (Score:5, Insightful)

    by rknop ( 240417 ) on Monday February 06, 2006 @08:47AM (#14649915) Homepage

    Here's what makes me unhappy:

    The Cambridge University team expects to submit the first of its results to a leading astrophysics journal in the next few weeks.

    I don't like this "press release before publication" mode of doing science. It's all about making sure that you get the attention and public recognition, and not about propery distributing the results so that others can understand and evaluate what you've done. Alas, it seems that Marketing Is All in the modern world, and not just in the USA any more. You can be sure that the institutions who house these scientists love to get the attention and so forth.

    I'd be happier if the paper had already been accepted by some real journal, with a preprint available on www.arxiv.org. As it is... we have a press release and a pop-sci article about an intersting result that's hard to truly evaluate. The article is mostly good and sounds reliable, but in my experience these pop-sci articles usually get something wrong. (For instance, even though 10,000 degrees sounds "hot", given the likely mass of the Dark Matter particle, it still is "cold" in the cosmological sense of "cold dark matter", which really means "nonrelativistic dark matter". I'm not sure how much of a surprise that temperature is, but it's probably not enough to make CDM wrong.)

    -Rob

  • If there is a "magic volume" of space a given amount of dark matter occupies, would this inflate the early universe until the dark matter fits?
  • "'It now looks as though the Milky Way is the biggest galaxy in the local Universe, bigger even than Andromeda. It was thought until just a few months ago that it was the other way around.'"

    Yeah, but it's like I was telling the Old Lady just the other night. It's really not so much the size, as how its used. I think Andromeda gets a whole lot more use out of itself than we do with the Milky Way. And, I find a hard time calling our galazy the Milky Way. I mean, Milky Ways have no nuts in them--and our galaxy
  • http://www.aas.org/publications/baas/v37n4/aas207 / 765.htm [aas.org]

    "... radial velocity measurements of red giants in the Galactic dwarf spheroidal (dSph) galaxy Leo I based on data taken with Gemini's Multiobject Spectrograph GMOS. These data, reaching out to the galaxy's nominal tidal radius, permit us to trace its velocity dispersion profile across the whole area of Leo I. By means of detailed dynamical modelling we discuss the implications on this dSph's dark matter halo and mass profile."

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