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Space Science

Computer Model Points To the Missing Matter 97

eldavojohn writes "There exists a little-known problem of missing regular matter that has perhaps been overshadowed by the mysteries of dark matter and dark energy. Computer models show that there should be about 40% more regular matter than we see... so where is it? From the article: 'The study indicated a significant portion of the gas is in the filaments — which connect galaxy clusters — hidden from direct observation in enormous gas clouds in intergalactic space known as the Warm-Hot Intergalactic Medium, or WHIM, said CU-Boulder Professor Jack Burns... The team performed one of the largest cosmological supercomputer simulations ever, cramming 2.5 percent of the visible universe inside a computer to model a region more than 1.5 billion light-years across.' This hypothesis will be investigated and hopefully proved/disproved when telescopes are completed in Chile and the Antarctic. The paper will be up for review in this week's edition of the the Astrophysical Journal."
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Computer Model Points To the Missing Matter

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  • Bad name. (Score:4, Funny)

    by morgan_greywolf ( 835522 ) on Tuesday December 11, 2007 @03:45PM (#21660795) Homepage Journal
    Warm-Hot Intergalactic Matter? WHIM? The WHIM Hypothesis? I mean, it just SOUNDS like he made it up on whim!
    • Not Dark Matter (Score:5, Informative)

      by iamlucky13 ( 795185 ) on Tuesday December 11, 2007 @04:00PM (#21661079)
      Since I'm sure the question will be asked, no this missing mass is not dark matter, as both the summary and the article are clear to emphasize. I wanted to repeat that. The primary evidence for dark matter is the galactic rotation curves. The article is talking about gaseous normal matter that we believe exists, but hasn't spotted yet. This missing gaseous matter is nowhere near sufficient in mass to explain the gravitational effect of dark matter and is being looked for on a scale larger than galaxies. The missing mass is an estimate 2% of the mass of the universe, whereas dark matter is an estimate 25%.

      Also, I though it interesting that the is a very interesting rendition of the nearby universe. It's not related to the article, but it does show the filamentary structure the article talks about. []
      • Re: (Score:3, Informative)

        Right on, the matter the article discusses matter that should be there as pointed out in the Dirac equation. The universe should, based on theory, be made up of a certain percentage of baryons (three quark particles).
      • Re: (Score:2, Funny)

        no this missing mass is not dark matter
        You can say that again. It's mostly a transparent green haze from what I can see of it. The guy sitting in the next cubicle just found a good amount of that Warm-Hot gas and has released it into the workplace.
      • Re: (Score:3, Insightful)

        by scapermoya ( 769847 )
        very true. this dark matter does not need to be special in any way, it can be dust. but it has to be right around galaxies for the rotation curves to work out. there simply aren't enough stars to account for the way our (and every other) spiral galaxy behaves relatively far from its center. dark energy on the other hand is a different (and unrelated) story.
        • Actually, if it was dust, we'd be able to see it with radio telescopes, since it emit very low frequency radiation. The dark matter can't emit any radiation whatsoever.
          • Re: (Score:3, Interesting)

            by scapermoya ( 769847 )
            i think with the current evidence, it is safe to say that most dark matter is strictly non-baryonic (the mass we are used to). there is no doubt, however, that dust and other baryonic matter in all kinds of forms (clouds of gas, dwarf stars, planets, you name it) contribute to dark matter. what we must quibble about now is the amounts, the proportions.

            by the way, dust doesn't just spontaneously emit radio waves. if that were true, all the dust on our planet would likely make radio stations impossible. the
            • Re: (Score:3, Informative)

              by fnordboy ( 206021 )
              Ok, fair point - there are a lot of little, dense things like brown dwarfs and planets that we can't currently observe. However, these can only be a tiny component of the "dark" stuff that we don't see. If brown dwarfs or planets comprised a significant chunk of the dark matter, it would be detected by gravitational microlensing events, and those observations suggest that dense baryonic objects (such as stars, brown dwarves, etc.) aren't a big (which is to say, dynamically important) component of the gala
        • Re: (Score:3, Informative)

          by iamlucky13 ( 795185 )
          Sorry if I'm misreading your post, but what I was saying in my original post is that the matter the article is dealing with is a completely separate issue in astronomy from dark matter. You seem to be interpreting it as saying dark matter is probably actually normal matter. I won't get into that debate here but just want to clarify that this is not what either the paper or I was suggesting.

          Dark matter was detected gravitationally and generally believed to be non-baryonic. The matter in question has not b
      • by ajs ( 35943 )
        What I find interesting is that both dark matter and this missing matter exist only as the result of comparing our mathematical extrapolations with observation. When we finally learn the truth (will we?) of what makes up our universe, I have to wonder if it will have any resemblance to our guesses over the last 50 years or so... Personally, I doubt it.

  • by Anonymous Coward
    That's where my missing matter always turns up.
  • Not a Physicist

    Is the WHIM the same as the interstellar medium? [] From what I've read they sound a very similar.Does this mean that the missing baryonic matter has been staring us right in the face the whole time in the expanses between stars?
    • by Tejin ( 818001 )
      This is more an intergalactic medium [], thought to be even more tenuous than interstellar medium, which is in turn more tenuous than interplanetary space.

      What I think they're talking about (RTFA? Me? no time for that!) is the slightly-less-vaccuumy-than-total-vaccuum filaments that link galactic clusters. There could be a lot of matter hidden there where we can't see well because it's far from light sources like stars, and is thus cold and dark just like empty space.

      • You are mostly correct - what we're talking about are the filaments that link galaxy groups and clusters. However, this gas isn't actually all that cold - its temperature is generally between 100,000 and 1,000,000 Kelvin, making it emit in the ultraviolet. That particular waveband is very hard to observe, and the filaments are also quite diffuse - so it hasn't been seen because it emits in an inconvenient energy band (that can only be seen by orbital telescopes), and is also very, very dim.
    • I am also not a physicist (Aerospace Engineer), but here's my understanding for what its worth: "Interstellar Medium" comprises the gases etc. that exist between stars within a galaxy, while WHIM stands for "Warm-Hot Intergalactic Medium", meaning the gases etc. that exist between galaxies.

      Hope that helps,


  • What is "what lies outside of the visible universe, lies the unseen," Alex. Or maybe the vast interstellar distances is enough for the missing matter to be spread so thinly across it as to be practically undetectable. Quick! Somebody with math skills, how big is the known universe, how many atoms of missing matter would 40% be, and then from that how many atoms per cubic something-or-other is that?
  • by jameskojiro ( 705701 ) on Tuesday December 11, 2007 @04:00PM (#21661067) Journal
    The missing matter is in those Packing peanuts that the scientist's equipment was shipped with.

  • by hyades1 ( 1149581 ) <> on Tuesday December 11, 2007 @04:02PM (#21661135)

    "...hidden from direct observation in enormous gas clouds in intergalactic space..." >p>

    If all that missing matter is contained in gas clouds, I think I know where to find it. There's an election coming up, right?

  • by Anonymous Coward
    ...of left socks and you'll find all the missing matter in the universe.
    • by PPH ( 736903 )
      Left socks?! Now you tell us!

      We got the sign wrong again. Fix the model and get ready for another run.

  • by Hatta ( 162192 ) on Tuesday December 11, 2007 @04:17PM (#21661409) Journal
    I was under the impression that dark matter was, by definition, matter we can not detect. So I don't understand how there can be "regular" matter that's hidden. If you can't see it, how do you know it's there? Well you can detect its gravity, but that's how we detect dark matter. So how do you distinguish this stuff from the dark matter? What's the difference?
    • by belthize ( 990217 ) on Tuesday December 11, 2007 @04:23PM (#21661527)

          Dark Matter is matter that's not made up of normal baryonic material. As a matter of fact you can detect it but not enough to matter.

          Over and above the missing 'dark matter' there's the matter of the missing regular matter.

          It's the missing regular matter that matters in this case.

      • by Hatta ( 162192 )
        Ok, how do you know it's not made up of baryonic material if you can't see it? How do we know that this missing matter is made up of baryonic material if we can't see it?
        • I'll probably get this wrong but ...

          You don't really know, but you can infer.

          If you know(1) there's some mass somewhere from say a gravitational lens but it doesn't emit radiation the way normal matter (proton, electron, neutron, typical neutrino's) would then it's presumably non-baryonic, ie dark matter(2). []

          On the other hand if you can detect the radiation (in line with e
        • (Non-baryonic) Dark Matter particles don't collide and don't lose energy through radiation (because then you would be able to see them). The consequence of this is that if you have a bunch of matter that is comprised of x% percent baryonic and y% non-baryonic matter it will evolve differently through time depending on the value of x and y. (baryonic matter tends to clump more for example) Now all you need is a snapshot of the universe at different times and you can calculate how much baryonic and non-baryon
        • Re: (Score:3, Informative)

          There's this story [] from a while back, which pointed to at least one case where the non-baryonic dark matter reacted differently from the baryonic matter. There was a galactic collision, and the non-baryonic matter sort of coasted on while much of the baryonic gas slammed together in the middle. Since non-baryonic dark matter reacts only to gravity, there are ways to distinguish between the two...
  • by butterwise ( 862336 ) <butterwise AT gmail> on Tuesday December 11, 2007 @04:20PM (#21661485)

    cramming 2.5 percent of the visible universe inside a computer
    That is one big-ass computer.
  • For a moment there, I was imagining some sexy blond showing off a computer system somewhere and then pointing to her head or something.
  • I hope the people who add up the matter also include all the energy too. IANAAP (Astro-Physicist) but doesn't the fact that we can see all the universe add up to a helluva lot of matter that has been converted to energy to enable us to see everything. If matter is energy and vice versa, wouldn't energy also have gravitational attraction?

    • Radiant energy (which is to say photons) is actually a very tiny fraction of the total energy density of the universe - something less than 0.1%. We ignore it in our simulations, but it's safe to do so.
      • by thewils ( 463314 )

        We ignore it in our simulations

        That's good, but whenever I do that it always bites me on the ass later.
      • by Yehooti ( 816574 )
        Do any of these models include a universe that is truly infinite and contains mass and energy that is also infinite? Wouldn't our known universe overpower observations of the effects this distant mass of energy and gravity have on us? Seems that we think in terms of our universe as being finite in terms of size and time. What's to say that our Big Bang was not just a local event in a much bigger scene?
  • Poll: Where will scientists find the missing matter?

    * It's not missing. Our measurements are wrong.
    * It's not missing. Our theories are wrong.
    * In filaments between the galaxies.
    * In an as-yet-undiscovered construct.
    * In CowboyNeal's sock drawer.
  • Computer model? (Score:3, Interesting)

    by phatvw ( 996438 ) on Tuesday December 11, 2007 @04:52PM (#21662029)
    I reckon this is a wee bit offtopic, but it struck me - are there any scientific models that are not "computer models"? It used to be the case that if it was a computer model, you'd think, "Ooooh they are using computers, they must be smart". But now?

    This stuff is absolutely fascinating. Good stuff from Colorado as always.
    • Sure, there are a lot of analytic models out there even today. Also, you can construct a physical model to study many phenomena (e.g., river formation in a lab).
  • to give to the Iraqis.

    It's now in the Cayman Islands.
  • Is this missing matter stuff that matters or is the matter of the missing matter merely a nerdy matter?

    Inquiring minds want to know!
  • "cramming 2.5 percent of the visible universe inside a computer to model a region more than 1.5 billion light-years across." "CU-Boulder" ""Warm-Hot Intergalactic Medium" From scientific clowns in a car to how they come up with those names to how they take their coffee. On the next Astrophysical Journal.
  • by greg_barton ( 5551 ) * <> on Tuesday December 11, 2007 @05:19PM (#21662535) Homepage Journal

    ...there should be about 40% more regular matter than we see... so where is it?

    Behind you...
  • Forgive me, but I just don't see how this helps humanity blow up the universe. The universe is far too important for humanity not to blow it up.
    How we feel if someone else got there first? I think I would die of shame.
    I help people find cats - []
    • That would read better if it actually said, "How would we feel if someone else got there first? I think I would die of shame."

      When you're an idiot, 'Preview' looks like 'Submit'.
  • Why do we always have to wait for the new telescope to be completed before we can find out cool new things about the cosmos?

    Seriousely. Why don't we ever hear about cool new things that can be confirmed with existing technology, but they just haven't gotten around to it yet or something?

  • See, if they start a religion based on this new model, then people will feel uncomfortable criticizing it or attempting to disprove it, and it can stay a viable alternative theory forever!
  • Why is it that I keep on seeing things where I think that it should be painfully obvious to everyone involved that models will reflect the views of the people making the models, but no one seems to realize it? Studying robots to discover how children learn falls to that, and now this? It's like everyone thinks that, just because it has computers in it, it isn't being manipulated by the people programing it so that it is nudged towards a certain point of view!
  • Does anyone know what language they coded the model in?

%DCL-MEM-BAD, bad memory VMS-F-PDGERS, pudding between the ears