Computer Model Points To the Missing Matter

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."

Comments

Bad name.

[morgan_greywolf]

Warm-Hot Intergalactic Matter? WHIM? The WHIM Hypothesis? I mean, it just SOUNDS like he made it up on whim!

Re:Bad name.

[sjaguar]

Actually, I read "Warm-Hot" as "Wal-Mart". I know they are expanding outside the US. I didn't know they were going intergalactic.

Re:Bad name.

[eclectro]

I mean, it just SOUNDS like he made it up on whim! Agreed. If he would have giving it any thought he would have named the large expanse of hot gas the O'Reilly Cloud.

Re:Bad name.

[SargentDU]

How about the Al Gore Cloud instead. It would be more appropriate.

Re:Bad name.

[eclectro]

How about the Al Gore Cloud instead.

Nah. In that case it would be the Al Gore Belt.

Re:Bad name.

[Yez70]

...you mean Belt(s).

Re:Bad name.

[networkBoy]

It's all moot anyway:

cramming 2.5 percent of the visible universe inside a computer In other news the computer coalesced into a black hole and devoured the solar system, Al Gore included. It then spit out his belt. News at 11.
-nB

Re:Bad name.

[vikstar]

I can cram almost 100% of the universe into my computer:
"".invert();

Obvious

[0racle]

Isn't the answer obvious?

Re:Obvious

[Anonymous Coward]

Mod parent up.

Another example of trying to change the universe because it doesn't match theory.

Re:Obvious

[Eternauta3k]

He made a semi-decent point, which is countered by saying we'll ever know what the universe is really like.

Check behind the couch.

[Anonymous Coward]

That's where my missing matter always turns up.

Does WHIM == ISM?

[explosivejared]

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?

Re:Does WHIM == ISM?

[Tejin]

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.

Re:Does WHIM == ISM?

[fnordboy]

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.

Re:Does WHIM == ISM?

[AikonMGB]

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,

Aikon-

Oh! Oh!

[Dr. Eggman]

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?

Re:Oh! Oh!

[zappepcs]

err... the answer is .... 42!

Re:Oh! Oh!

[Anonymous Coward]

well lets see, since the universe is infinite, and there is a finite amount of matter in it:

finite matter/(infinite volume (plus the other dimensions)) = 0 matter density

there is therefore no matter in any area in the universe.

Re:Oh! Oh!

[Anonymous Coward]

Why do you klaim universe as infinite? Is it not much more confortable to live in a finite universe?

Re:Oh! Oh!

[Anonymous Coward]

Only in an infinite universe will there be enough time for you to learn to spell properly.

Low Surface Brightness Galaxies

[Anonymous Coward]

http://en.wikipedia.org/wiki/Low_surface_brightness_galaxy

at great distances, this could add up to a considerable amount of unobservable real matter.

Packing Penuts

[jameskojiro]

The missing matter is in those Packing peanuts that the scientist's equipment was shipped with.

Not Dark Matter

[iamlucky13]

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:Not Dark Matter

[explosivejared]

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:Not Dark Matter

[Chosen Reject]

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:Not Dark Matter

[scapermoya]

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.

Re:Not Dark Matter

[ajs]

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.

Re:Not Dark Matter

[fnordboy]

That's not correct. The article discusses matter that should be there as pointed out by the http://en.wikipedia.org/wiki/Friedmann_equations/Friedmann equations and similar equations that describe the http://en.wikipedia.org/wiki/Cosmic_microwave_background_radiation cosmic microwave background. The Dirac equation doesn't say anything about the composition of the universe.

Re:Not Dark Matter

[fnordboy]

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:Not Dark Matter

[scapermoya]

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. there are plenty of places dust could be where it doesn't reflect light, or emit radiation due to absorption. in fact, dust contributes more to our inability to see our whole galaxy than anything else.

Re:Not Dark Matter

[fnordboy]

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 galactic halo.

Also, with respect to dust, it's actually quite easy to detect it in the interstellar medium, in both emission and absorption. It doesn't ALWAYS emit radiation, and doesn't do it spontaneously, but when dust is bombarded by light from nearby stars, it tends to re-emit in the infrared and radio. So it's incredibly easy to detect it in both of those bands, and use it to learn things about galaxies. It blocks optical light, of course, so you can see it in nearby (and not so nearby) gas-rich galaxies.

I see by the link below your name that you're from Berkeley, or at least probably have some berkeley ties. You should go talk to Chris McKee in the astronomy department if you think dust is more of a pain than it's worth - he'll set you straight!

Re:Not Dark Matter

[iamlucky13]

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 been detected at all, but is thought to exist based on the current models of how the universe was formed. Dark matter appears to make up 25% of the mass/energy in the universe. The matter the article discusses in only about 2%.

Also, from my interpretation of the article and prior reading, it shouldn't be dust, but simply vast clouds of mostly hydrogen and some helium gas. This stuff would reside in the huge volumes of space between the galaxies and would never have achieved sufficient densities to collapse into stars where it could be fused into the heavier atoms necessary to form space dust. At the distances, densities, and temperatures involved, it would be undetectable with our current technology.

And of course, there is free gas and dust that we are able to see in the Milky Way and neighboring galaxies, but this also is a separate issue.

Re:Not Dark Matter

[Anonymous Coward]

The primary evidence for dark matter is the galactic rotation curves.

I've been curious for a while now: Has relativity been properly accounted for in the galactic rotation curves? I.e., the gravity from a star on one side of a galaxy is not felt on the other side until a significant time later, after which there has already been some rotation.

Re:Not Dark Matter

[Anonymous Coward]

I honestly don't know, but with stars like the sun moving 220 km/s and the speed of light being 300,000 km/s, that's surely insufficient to explain the total gravity-generating mass of a galaxy being 6-7 times as much as the visible mass. By the time a gravity wave from the sun crossed the galaxy to a star exactly opposite it at the same radius (~53,000 years), the sun would have moved only 1/600 of a degree (assuming I didn't miss a unit conversion somewhere).

Also, that effect is continuous and wouldn't actually change the speed of rotation.

I think I know where it will be found

[hyades1]

"...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?

Follow the trail...

[Anonymous Coward]

...of left socks and you'll find all the missing matter in the universe.

Re:Follow the trail...

[PPH]

Left socks?! Now you tell us!

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

Answer

[Anonymous Coward]

So where is it? I think we all know the answer to this. It's obviously been Slashdotted.

missing matter != dark matter?

[Hatta]

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?

Re:missing matter != dark matter?

[belthize]

    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.

Belthize

Re:missing matter != dark matter?

[Anonymous Coward]

If you can't see it, how do you know it's there?

Because equations that you believe to be good models of the universe tell you that more matter ought to be around somewhere.

Re:missing matter != dark matter?

[Hatta]

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?

Re:missing matter != dark matter?

[Anonymous Coward]

but does it really matter?

Re:missing matter != dark matter?

[Intron]

I explained to my bank that my computer model showed 40% more money in my account than they listed. For some reason they refused to listen to me.

Re:missing matter != dark matter?

[pln2bz]

Because equations that you believe to be good models of the universe tell you that more matter ought to be around somewhere.

As this quote relates specifically to dark matter, I would go one step further ...

Because equations that you believe to be good models of the universe tell you that more matter ought to be around somewhere, based upon an observation that large-scale structures do not behave as we expected them to, and under the assumption that charged particles in space (plasmas) tend to behave as fluids unlike other plasmas we observe -- like lightning, neon lights and current-carrying copper wires.

They are important details that can add context to the problem.

Re:missing matter != dark matter?

[Anonymous Coward]

That's because they poked a hole in your theory based on receipts, disbursements, and interest. If you can do the same authoratatively for this missing matter based on physics and cosmology, astronomers will likewise stop looking for the missing 40% of the baryonic mass in the universe.

Re:missing matter != dark matter?

[belthize]

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). http://www.nasa.gov/home/hqnews/2006/aug/HQ_06297_CHANDRA_Dark_Matter.html

      On the other hand if you can detect the radiation (in line with expected levels) and it's mass then you know it's baryonic.

      The normal baryonic matter in the article's case isn't detectable now due to instrument sensitivity,
not due to some abnormality in the material itself. Once the new instruments are built the
hope is the matter can be detected. The material itself isn't abnormal, just it's location and density is
abnormal.

1) For random definitions of know
2) This is more or less the meaning of dark matter.

Re:missing matter != dark matter?

[SquirrelsUnite]

(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-baryonic matter there should have been in order for the universe to evolve the way it did. The cosmic microwave background gives one such snapshot and by mapping the objects 1 Bn lightyears away you are getting a segment of the universe 1 billion years ago. Combining all these data and the laws of physics you get a best estimate for the amount of baryonic and non-baryonic dark matter.

Re:missing matter != dark matter?

[Anonymous Coward]

Taking a wild guess here, but why not?

I wonder if astrophysicists are taking into account the effects of magnetic fields between stars and even galactic structures. Gravity isn't the only force working on things at a distance. It'd probably take some tricky radioastronomy work to see if there's any electromagnetic structure phenomena (some kind of correlation thing happening between stars? Probably need years long data sets to see if there's any push-pull relationships, etc.) that aren't being accounted for with the current model. Maybe the missing matter wasn't there to begin with? (Just missing a big chunk of data instead?)

Re:missing matter != dark matter?

[Bryan K. Feir]

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...

Re:missing matter != dark matter?

[nih]

what, were they deaf?

IBM = Incredibly Big Machine

[butterwise]

cramming 2.5 percent of the visible universe inside a computer

That is one big-ass computer.

Re:IBM = Incredibly Big Machine

[jbeaupre]

As big as it was, it still kept saying the answer was 1.05. Luckily the solution scales well.

Re:IBM = Incredibly Big Machine

[jddj]

All you need is a suitable improbability generator - say, a nice hot cup of tea - and a piece of fairy cake...

Re:IBM = Incredibly Big Machine

[Oktober Sunset]

Shhhh... Never tell the femputer she has a big ass, seriously, she could have you snoo-snooed to death at any time

Re:IBM = Incredibly Big Machine

[Anonymous Coward]

But the fairy cake is needed for the Total Perspective Vortex. How can you use a Total Perspective Vortex if you don't have the fairy cake? ... then again, you can use anything else

Re:IBM = Incredibly Big Machine

[Anonymous Coward]

Yo' computer's so fat, when it starts to eat it bytes through whole solar systems!

Mental Image:

[erroneus]

For a moment there, I was imagining some sexy blond showing off a computer system somewhere and then pointing to her head or something.

Re:Mental Image:

[Anonymous Coward]

I didn't get it until I re-read the title, but now I'm supressing a workplace snicker.

*looks around to make sure no one is staring*

Does seeing matter?

[thewils]

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?

Re:Does seeing matter?

[fnordboy]

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.

Re:Does seeing matter?

[lowder]

Yes, the sum does include matter and energy. Yes, energy does indeed contribute to the total gravitation of the universe.

Your other point is kind of interesting, actually. At very early times, when the universe's mass/energy density was much higher than it is today, there was enough electromagnetic energy around to keep most matter fully ionized (charged) and therefore the universe was opaque to light. It's because we live in a time where the EM energy density is low that we can see across the universe!

-An astrophysicist

Re:Does seeing matter?

[thewils]

We ignore it in our simulations

That's good, but whenever I do that it always bites me on the ass later.

Re:Does seeing matter?

[Yehooti]

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?

Re:What a waste of money

[Leet0]

aaaaaaaaah... hahahahaha! I needed that. HiLLaRY '08! Y? Cuz she doesn't suck.. get it? get it?

And now to say on topic.. Actually the missing matter, just doesn't matter. Because we're looking back in time. It's here now, duh

Poll: Location of Missing Matter

[davidwr]

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?

[phatvw]

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.

Re:Computer model?

[CheshireCatCO]

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).

Mentally shift the hyphen...

[RockRampantly]

I'll leave it up to others to imagine what a big ass-computer does.

Re:What a waste of money

[Anonymous Coward]

heh, and you will be the first to say how cool it is when a massive discovery is made that changes our world as we know it do to these massive wastes of money. However, that discovery could be for better or worse. Who knows? Can't be any worse then wasting money on a war that a particular country will never win, nor admit to loosing...

It was given the Halibutrin

[gambolt]

to give to the Iraqis.

It's now in the Cayman Islands.

Does missing matter matter?

[phozz bare]

Is this missing matter stuff that matters or is the matter of the missing matter merely a nerdy matter?

Inquiring minds want to know!

Dee dee teelee tee

[ravensee]

"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.

Re:Poll: Location of Missing Matter

[phozz bare]

In the foam pellets the scientific equipment was packed in, of course.

The answer is obvious!

[greg_barton]

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

Behind you...

Well, clearly...

[Anonymous Coward]

Clearly the missing matter is being used to build bombs and computers in Iran. Duh.

eh..

[hotwatermusic]

Doesnt matter.

Re:OT: Jimmy Page announces 3 US concert dates on

[Anonymous Coward]

No YUO! Rick rolled! I even played it twice! Oh, what a world...

Wasted time.

[mtraskos35826]

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 - http://www.funnybutsad.com/Content/2007/10/17/LostCatFound.aspx/

Re:Wasted time.

[mtraskos35826]

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'.

Re:Wasted time.

[Anonymous Coward]

You should help yourself find your missing webpage.

Ninja Matter

[Shayneisgreat]

This matter must have crazy ninja skills. Thats why it can stealthfuly hide from the most powerful sensory technologies on the planet. I wonder when it will move in for the KILL.

Re:Ninja Matter

[ElizabethGreene]

Our solar system is safe. We have Chuck Norris AND Cowboy Neal.

2.5% of the visible universe?

[ElizabethGreene]

Only 2.5% of the visible universe? Seven of nine could do this in the turbolift on the way back to the astrometrics lab and still have time for solitaire. (I am a Star Trek Voyager fan. ....or more accurately, THE voyager fan.)

Re:2.5% of the visible universe?

[Anonymous Coward]

Certainly, imagining the performance of Seven of nine in the computation of astronomical simulations is a fantasy one doesn't encounter every day...

Re:2.5% of the visible universe?

[BiggerIsBetter]

Only 2.5% of the visible universe? Seven of nine could do this in the turbolift on the way back to the astrometrics lab and still have time for solitaire. (I am a Star Trek Voyager fan. ....or more accurately, THE voyager fan.)

Yes but to be fair, this simulation was actually done, and well, Seven Of Nine is fictional. It's not really an apples to apples comparison.

New Telescopes

[PatTheGreat]

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?

They should just start a religion

[Jim in Buffalo]

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!

Not mine

[davidwr]

My scientific instruments came packed in an energy matrix.

Computer Model = ?

[Aetuneo]

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!

Which language?

[vic.tz]

Does anyone know what language they coded the model in?

Just..

[Anonymous Coward]

bring back the idea of the Aether again. :D

That's probably why I'm not an astrophysicist

[Anonymous Coward]

[quote]Also, I though it interesting that the is a very interesting rendition of the nearby universe. [/quote]

I look at the image behind that link and I can't help thinking that if I'd been the one to create it, I would not have been able to stop myself substituting the words "you are here" for "Milky Way Center"