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Space Science

Dark Matter Discovered 386

sebFlyte writes "Wired is reporting that scientists have come up to a solution as to where all the matter in the universe actually is. Experiments being done with Chandra, NASA's X-ray telescope have shown up a likely candidate for the solution of the dark matter problem. There are massive quantities of Baryons in a super-heated gas cloud several hundred million light years away."
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Dark Matter Discovered

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  • Fascinating (Score:5, Funny)

    by ackthpt ( 218170 ) * on Thursday February 03, 2005 @08:04PM (#11568045) Homepage Journal
    I'd love to see the modeling on this stuff, as they have some super computer up the road at UCSC probably grinding away on massive simulations this very minute, but it'd probably look less like those beautiful Hubble shots and more like a stack of paper covered with numbers.

    There are massive quantities of Baryons in a super-heated gas gloud several hundred million light years away."

    Which, IMHO, is a damn fine place for them to be, rather than here.

    The absorption pattern, as detected by Chandra, is consistent with interference caused by carbon, neon, nitrogen and oxygen ions -- in other words, baryons.

    It's really a neon sign on Frogstar World B announcing the construction of a restaurant to be constructed on this location in several billion years and reservations are welcome.

    "Assuming that what we see is a standard portion of the universe, we extrapolated the data and derived the volume density (of baryons in all the clouds) -- and it's consistent with 50 percent," said astronomer Fabrizio Nicastro, of the Harvard-Smithsonian Center for Astrophysics and lead author of the study.

    Later a two-headed, three-armed man entered and ate a piece of fairycake and destroyed their model.

    Whereas baryons account for 4 percent of the total matter and energy in the universe, dark matter is thought to make up 23 percent. The remaining 73 percent of the so-called matter-energy budget consists of what scientists call "dark energy." This energy acts like an anti-gravitational force that, in theory, is causing the universe to expand rather than contract.

    And here I thought it all existed somewhere along Lucas Valley Road and explained the Jar Jar character and Episodes I-III...

  • Nibbler? (Score:5, Funny)

    by blackicye ( 760472 ) on Thursday February 03, 2005 @08:05PM (#11568048)
    And would this "superheated gas pocket" perchance reside in Nibbler's lower intestinal tract? ;D
    • Nope... (Score:2, Funny)

      by Anonymous Coward
      Its the hunters running away from the stench of Bloodnut the flatulent...
  • Baryons (Score:4, Informative)

    by Anonymous Coward on Thursday February 03, 2005 @08:05PM (#11568053)
    In case anyone's wondering what a baryon is...

    http://en.wikipedia.org/wiki/Baryon [wikipedia.org]
  • Hmm (Score:4, Funny)

    by Elecore ( 784561 ) on Thursday February 03, 2005 @08:05PM (#11568056) Homepage
    I don't see anything??
  • Picture (Score:5, Funny)

    by Anonymous Coward on Thursday February 03, 2005 @08:06PM (#11568067)
    Here's a picture [wustl.edu].
  • Ummm (Score:5, Informative)

    by christurkel ( 520220 ) on Thursday February 03, 2005 @08:06PM (#11568073) Homepage Journal
    They found some of the ordinary matter that has gone unaccounted for, not dark matter. Read the article.
    • Re:Ummm (Score:4, Insightful)

      by Tlosk ( 761023 ) on Thursday February 03, 2005 @08:20PM (#11568179)
      You seem to be under the impression that we know what dark matter is and isn't. Dark matter is postulated given gravitational effects that would arise from mass that we cannot detect, hence dark.

      If it turns out that it is normal matter after all, and we just had trouble seeing it, we have still "discovered dark matter."

      Another way of putting it would be, who killed the prime minister of Georgia? If it turns out later that it was an accident from a faulty space heater, did we find out who killed him? Just becuase we were expecting a who and got a what doesn't mean the question wasn't answered.
      • RTFA. It addresses this. The article explains that half of baryonic maass was unaccounted for, and if these clouds are typical of the whole universe, that explains the 50% of "missing" baryonic mass. Astrophysicists can explain 2% of the expected mass of the universe as visible baryons. These clouds would be another 2% of the expected mass. Dark matter is 23%, dark energy is the remaining 73%.

        For this to explain dark matter, the clouds they discovered would have to be less than ONE TENTH of the averag
        • You're assuming that this unknown matter is uniform. If you pull out an olive have you explained the salad? No, but you do know more about it then before you pulled it out.
    • Re:Ummm (Score:3, Informative)

      by Entropius ( 188861 )
      That's what dark matter is -- just ordinary matter that isn't part of luminous objects and, thus, is invisible.

      Wired Magazine seems to be getting their terms confused:

      Whereas baryons account for 4 percent of the total matter and energy in the universe, dark matter is thought to make up 23 percent. The remaining 73 percent of the so-called matter-energy budget consists of what scientists call "dark energy."

      But one candidate for the "dark matter" (everything we can't see) *is* "baryons" -- which is ju

      • Re:Ummm (Score:5, Informative)

        by dspeyer ( 531333 ) <dspeyer@wam.u[ ]edu ['md.' in gap]> on Thursday February 03, 2005 @09:45PM (#11568758) Homepage Journal
        whether the missing mass lurks in galaxies, in galactic halos, or between galaxies is (as I recall) an open question.
        Maybe there's more then one sort of dark matter, but the dark matter I've studied must be inside galaxies.

        Dark matter is the extra mass needed to explain the observed motion of astronomical bodies in terms of known forces (ie gravity) after all the known matter is accounted for. In particular, galaxies rotate like rigid bodies (the same angular velocity at all radii) whereas the distribution of known mass (eg stars) suggests they shouldn't. An enormous amount of extra mass must be within the galaxies in a specific distribution to make this happen. (The alternative, which astrophysicists dislike, is that our equations for gravity are wrong for large distances.) This cloud is outside of a galaxy, so it isn't the missing matter.

        Now, there may be other discrepancies between what we can see and what we can compute should be there, and this cloud could explain some of those.

      • by mattorb ( 109142 ) on Thursday February 03, 2005 @10:37PM (#11569045)
        Hi --

        Distinguishing between baryonic matter -- stuff that bears any resemblance to everything around you, whether it is visible or not -- and other "dark" matter that does not fall into that category, is actually pretty commonplace in astrophysics. This seems like semantics, but turns out to be an important distinction.

        The point is that the fraction of baryonic matter in the universe is, we think, reasonably well constrained (by both observations of light element abundances in conjunction with Big Bang nucleosynthesis models, and by measurements of fluctuations in the cosmic microwave background) to be only about 5% of the total mass/energy density. Yet there's an additional matter component (accounting for about 25% of the total density) that we know little about -- this is what most astronomers mean when they say "dark matter" these days.

        This article says nothing at all about that 25%. It does, however, provide some clues towards a more complete accounting of the 5% that is "normal" (i.e. baryonic) matter. This is a very significant result, but the slashdot writeup and most of the comments to this article are completely distorting it.

        The puzzle regarding the "normal" 5% was this: in the local universe (redshifts less than 2), only 10% or so of it is luminous matter, stars and galaxies and the like. More (40% or so) has been accounted for by studies of cool clouds of gas residing between stars, but this still left 50% in an unknown reservoir of baryons. Theory/simulation had suggested that one such reservoir might be the "warm/hot intergalactic medium" -- gas that is heated to millions of K.

        The problem is that detecting low-density gas at that temperature is quite difficult, partly since most bound electrons have been lost. Only the more massive elements retain any electrons, and so can be visible in absorption in the FUV or X-rays.

        What the paper discussed here (published today in Nature) does is to describe a plausible-looking detection of such filaments of "warm-hot" gas, through X-ray absorption. They use this detection to extrapolate a matter density of this WHIM component, and find that it could account for 30-50% of the baryonic mass, and so constitute the "missing" baryonic matter.

        Note that this says nothing at all new about the 25% of truly "dark" non-baryonic matter.

        One fairly large quibble is that the 30-50% number represents an extrapolation from just two absorbers, over a comparatively short distance, to infer the WHIM density in the whole universe. That's sort of a big jump, in case that part wasn't obvious. But you can't do this sort of analysis for very many sightlines -- you need a really bright emitting object on the other side of the WHIM clouds if you're going to see them, and such objects are few and far between -- so for right now that's what you get.

        If you happen to be somewhere that has a subscription to Nature (most universities do), you can check out the two articles related to this in today's edition:

        There's a "news and views" article [nature.com] by Mike Shull that's a nice summary of the issues involved. And there's the full research article [nature.com] by Nicastro et al.

        Hope that clears at least a few things up. If I have time later tonight, I'll try to come back and respond to some of your other points.

  • This discovery will bring back Enterprise!
  • Nope can't do it. =)

    Those giant gas clouds got a Baryon enima?

  • Gloud (Score:3, Funny)

    by rickst13 ( 723165 ) on Thursday February 03, 2005 @08:08PM (#11568092)
    "There are massive quantities of Baryons in a super-heated gas gloud"

    Google wants to know if you mean "gas cloud".
    • I was startign to think I was the only one who noticed the word 'gloud'... Though in my case I'm finding it hard to stop laughing over that word and I'm not sure why... 0_o
  • by Anonymous Coward on Thursday February 03, 2005 @08:09PM (#11568093)
    Wired is reporting that scientists have come up to a solution as to where all the matter in the universe actually is.

    WIRED also said that "Push is the next Big Thing."
  • Wrong Name (Score:4, Insightful)

    by unclem0nkey ( 741514 ) on Thursday February 03, 2005 @08:10PM (#11568101)
    In physics we don't call it dark matter. We call it "make the theory fit the data" matter.
    • At least they aren't "making the data fit the theory". Just imagine what gravity would work like if Newton wanted it to point away from the earth ;)
    • Re:Wrong Name (Score:4, Interesting)

      by cybergrue ( 696844 ) on Thursday February 03, 2005 @10:06PM (#11568900)
      Dark Matter isn't the only theory about why astronomical data doesn't fit theory. Another theory is called MOND, MOdified Newtonion Dynamics, and it postulates Newtons gravety theory might break down at astronomical distances (instead of inverse square it might be something else) A modified version of Newtons gravety creation have been created to fit the astronomical data, but there is no explanation about why the force of gravity should change over vast distances. There was an article in New Scientist [newscientist.com] magazine a few weeks back about how the guys behind the MOND theory think that there may be two types of gravity, and it might explain the discrepency in the location of the Pioneer probes.
      • Re:Wrong Name (Score:5, Interesting)

        by StarsAreAlsoFire ( 738726 ) on Thursday February 03, 2005 @11:27PM (#11569285)
        a, but there is no explanation about why the force of gravity should change over vast distances.

        YOu gotta admit, though... There really isn't a good explanation of why gravity SHOULDN'T change over vast distances. :~D

        F=ma = G*M*m/(r^2) -- 'G' is derived observationally. Only a few hundred years of observation tell us that it is a constant. Only a few dozen of those actually FROM SPACE -- Perhaps a few hundred years more will show that it is proportional to some (presumambly negative) exponent of 'r' (distance). Perhaps not.

        I admit to preferring MOND over imaginary matter. However, what I like the most is that the guys have open minds... unlike the typical 'scientist' favoring NB matter -- a bad hypothesis usually treated as sound theory. If NB matter were treated with the caution that MOND is, I would enjoy reading about it. Instead most authors treat it as assumed fact and build upon it. Bah. Excel can curve fit data; doesn't mean I assume a random scatter plot can be modeled by a 4th order equation.
  • Not quite... (Score:5, Informative)

    by Anonymous Coward on Thursday February 03, 2005 @08:11PM (#11568112)
    The summary is not correct (big surprise there) in that this is a confirmation of a long-suspected theory as to where the missing ordinary (baryonic) matter in the universe is. This does not solve the dark matter problem at all.

    Read more at the press release from the Chandra team at Marshall: http://www.spaceref.com/news/viewpr.html?pid=16049 [spaceref.com]

    Dark matter is yet another topic altogether, as is the even more elusive dark energy.
  • More Information (Score:4, Informative)

    by NEOtaku17 ( 679902 ) on Thursday February 03, 2005 @08:12PM (#11568120) Homepage
    Here [lanl.gov] is a link to some of the more recent papers written on dark matter kinematics.

    They are extremely interesting for anyone fascinated with physics.

  • With the massive quantity of Barry Whiteon gone, cool, heavy dark matter is ruled out, I guess.
  • by FalconZero ( 607567 ) * <[FalconZero] [at] [Gmail.com]> on Thursday February 03, 2005 @08:12PM (#11568126)
    This should be "Missing Matter Discovered" not "Dark Matter Discovered"
    They HAVE NOT found dark matter, they've found the 'missing matter' as the article says. They have found a clue as to the dark matter, as a result of the discovery.
    Although discovering the dark matter would be much cooler, (yeah I was excited when I read the title).

    [rant] Why is it the only 3 times I've 'emailed the on duty editor' before publishing, I've been ignored and the mistakes gone through?? [/rant]
    • I though all of the missing matter was actually the the packaging in the boxes used to ship the scientists their equipment that they use to search for missing matter...

      but then again, some crazy girl with a bird hit me over the head with a rock, so I'm not thinking very clearly...

    • by StarsAreAlsoFire ( 738726 ) on Thursday February 03, 2005 @11:33PM (#11569315)
      Actually, you are wrong. Or you are right. Or you would be wrong if it were 5 years ago. Or.. OR AHHHHH

      Dark matter was originally used to refer to matter that was not yet accounted for. Non-baryonic matter being a subset of Dark Matter.

      The issue has been beaten to death so badly by poor authors that 'Dark Matter' is becoming assumed to refer to NB matter.

      It is hard to argue that you are wrong, but equally hard to win an argument saying you are correct.
  • ...Are we gonna find a something as cool as "dark matter" to toss into casual conversation to give the impression of superior intelligence.

    I mean really now, Baryons, oh come on nasa. Try something new and exciting like, antiquantafusitrons.

  • all those Water discovered on Mars stories. Astronomers invented dupes. Or maybe they were trying to give someone a hint.
  • by Electronik ( 821589 ) on Thursday February 03, 2005 @08:16PM (#11568153)
    "Baryons, along with mesons, belong to the family of particles known as hadrons, meaning they are composed of quarks. Baryons are fermions composed of three quarks, while mesons are bosons composed of a quark and an antiquark."

    Wikipedia cleared that one up nicely!
  • I thought Baryons and dark matter are two different things. It was my impression that the clouds of baryons mass they discovered were suppose to be "out there" and and we know what it's comprised of. Where as with dark matter, our scientists have no idea what it is or what it's made of. All we know is it's exerting gravitational forces and is holding back the expansion of the universe. As far as I'm concerned this discovery did nothing to shed light on dark matter... Can any astrophysists out there explai
  • Is how do these extremely difficult scientific questions get answered so quickly lately.

    It was just a couple days ago that slashdot reported that dark matter was being postulated as the reason for the extra mass of galaxies:

    Simulating the Universe with a zBox [slashdot.org].

    Now, in less than a week, we have proof for the existence of dark matter? Amazing!

    How can scientists go from hypothesis to proof in such a short time? Are we really progressing by such leaps and bounds? Or, is this an example of media ju

  • Every component of matter has an anti, correct? Light itself is a wave/matter combination, notably photons. However, what I read says that photos are their own anti. Does this mean I have no hope of making a flashlight which makes things darker? Is it possible for two photons moving in different directions to cancel eachother out (destructive interference)?
    • If you take two light bulbs and put them in the same room, do you get a dark spot in the middle?
    • by FalconZero ( 607567 ) * <[FalconZero] [at] [Gmail.com]> on Thursday February 03, 2005 @08:55PM (#11568437)
      (Assuming this is a serious question)
      Not correct, there are two classes of elementry particles (that we know about) Bosons [wikipedia.org] and Fermions [wikipedia.org].
      Bosons are things like :
      • Photons
      • Gluons
      • W and Z Bosons
      • Higgs Bosons
      Bosons don't have anti-particles, and are less likely to form stable structures.

      Fermions are things like :
      • Quarks
      • Electrons
      • Neutrons
      • Protons
      Fermions do have anti-particles, and form the everyday matter that you interact with.

      IANAP, but two photons cannot cancel each other out, however two beams can (assuming they are co-axial and anti-phased).
      As for the flashlight, general light is not regular so you certainly can't make one using interference.
  • by vought ( 160908 ) on Thursday February 03, 2005 @08:26PM (#11568231)
    I have it on good authority that all the dark matter is in Iraq, and that's why we had to invade.

  • As I understand it dark matter is a broad term for matter that equations tell us exists, we just can't see it. These Baryons, apparently very heavy, solve some of the problem, maybe all, because it's more mass that we didn't know was there before. It came out of the dark. Nobody knows if there is another class of matter but clouds of baryon fill the gap.
  • by fiannaFailMan ( 702447 ) on Thursday February 03, 2005 @08:31PM (#11568282) Journal
    They reversed the anti-proton to tachyon ratio in the main deflector array after flooding it with a plasma burst diverted from the warp core and then polarising it by reinforcing the nucleon field.
  • Google? (Score:3, Funny)

    by Saeed al-Sahaf ( 665390 ) on Thursday February 03, 2005 @08:32PM (#11568288) Homepage
    Wasn't Google looking to buy up all the Dark Matter, not too long ago? Sware I read it here...
  • I thought one of the sure indicators that showed the presence of unseen matter was that most galaxies behaved as though they were more massive. That the rotational energy of many/most/some galaxies should be ripping it apart, yet clearly there was some extra amount undetected mass in a galaxy that held it together.

    These clouds are great for a macro-framework missing mass solution but unless they are found to exist in a somewhat smooth (or central) distribution in a galaxy how would massive clouds several
  • Assuming... (Score:5, Funny)

    by podperson ( 592944 ) on Thursday February 03, 2005 @08:38PM (#11568324) Homepage
    Assuming that what we see is a standard portion of the universe

    An astrophysicist, a physicist, and a mathematician are attending a conference in Scotland. During a break, they take a walk through some of the countryside, and come upon a black sheep.

    "Aha," exclaims the astrophysicist. "I had no idea that all sheep in Scotland are black."

    The physicist looks at her colleague in disbelief. "All sheep in Scotland are black? Are you nuts? We've only seen one sheep!"

    The mathematician interrupts. "And only one side of that sheep."
  • Who knew... (Score:5, Funny)

    by jpellino ( 202698 ) on Thursday February 03, 2005 @08:42PM (#11568357)
    Turns out it was behind the sofa cushions all along.
  • Duh... (Score:3, Funny)

    by PixelScuba ( 686633 ) on Thursday February 03, 2005 @08:42PM (#11568359)
    Obviously that's where the bulk of all the Univere's matter is. Each pound of the stuff weighs 10,000 pounds.
  • From TA: (yes I skipped the F)

    "If we are right, each single one of these filaments is connected to a cloud of dark matter," said Nicastro. "If there wasn't dark matter there, or something with strong gravity that pulled on the matter in these filaments, we wouldn't have galaxies or filaments." Rather, the baryons would be pulled into galaxies and the galaxies into each other.

    In other words, baryons in those clouds are the *EVIDENCE* of dark matter, but not the dark matter itself.

  • Just to add my two cents (I do cosmology research) to the chorus of complaints about this post, this research is NOT about discovering a new form of dark matter. This is about solving the "missing baryon" problem, which is a whole different kettle of fish. It's well known how many baryons (normal stuff) there should be according to big bang theory. However, if you look out at the universe and count observed gas and stars, you just don't see as much as you should. So people have assumed there are some hidden
  • by davie ( 191 ) on Thursday February 03, 2005 @08:55PM (#11568450) Journal
    There are massive quantities of Baryons in a super-heated gas gloud several hundred million light years away.

    At least there were, several hundred million years ago.

  • by jasno ( 124830 ) on Thursday February 03, 2005 @09:16PM (#11568593) Journal
    I've got a friend over at NASA who gave me a preview of some of the pictures [rr.com].

    Pretty fascinating if you ask me.
  • by Chatmag ( 646500 ) <editor@chatmag.com> on Thursday February 03, 2005 @10:22PM (#11568974) Homepage Journal
    At the bottom of the Wired story, there is a Google ad, "Buy Dark Matter on eBay".

    I just wonder if they throw in free shipping.
  • by mbrother ( 739193 ) <mbrother@uwy[ ]du ['o.e' in gap]> on Thursday February 03, 2005 @10:44PM (#11569090) Homepage
    First, this result only applies to BARYONIC dark matter, which is only a fraction of all the dark matter out there. Second, we already knew that a lot of it at the epochs in question was in the form of hot intercluster gas.

    The current work is an improvement over previous studies, and is good work. But the headline rather sucks. I thought we'd detected axions or something, even though I'd already read about this result.

    I teach techniques to estimate cluster masses based on X-ray emission, and have used the Chandra X-ray Observatory myself. A headline about such work shouldn't trick me.
  • by mindpixel ( 154865 ) on Friday February 04, 2005 @10:06AM (#11571380) Homepage Journal
    We understand nothing of gravitational dynamics on the galactic scale. For example, there was a paper in Nature on an ultra compact dwarf galaxy that predicted a dm/m ratio of 100/1, and when they did the measurement, instead of finding 100 dark matter masses for ever normal mass, they found ZERO!

    ZERO is what MOND [MOdified Newtonian Dynamics] predicts because if the compact nature of the galaxy in question, it is still in the Newtonian regime.

    It's time to reconsider Newton on large scales.

"If it's not loud, it doesn't work!" -- Blank Reg, from "Max Headroom"