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Science

Dark Matter Filament Finally Found 190

Posted by samzenpus
from the there-it-is dept.
An anonymous reader writes "Everyone is talking about the recent Higgs boson announcement by the scientists at CERN, but another significant scientific discovery was revealed this week as well. In a study published online in the journal Nature on Wednesday, scientists show that they have successfully found the first dark matter filament."
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Dark Matter Filament Finally Found

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  • by slashmydots (2189826) on Thursday July 05, 2012 @08:35PM (#40559013)
    First of all, don't go to "page 2" and I use that term loosely. Secondly, it doesn't mention a single scientific detail about how they determined that the light was being bent around a filament-shaped object compared to the starts behind it actually being in the location the light suggests. It merely states "They used a model to subtract out the masses of the galaxy clusters and then fit the remaining mass with a model of what a filament might look like. They found that a filament must be present." So in other words, they didn't find anything other than a mathematical equation suggesting dark matter exists. Congratuations are in order indeed.
  • by slashmydots (2189826) on Thursday July 05, 2012 @08:43PM (#40559063)
    Aha, someone posted a hair bit of time ahead of me a much better article so let me ammend that with the short version:
    There are 2 galaxies kinda far apart but they're really overlapped from Earth's point of view. Like one is almost entirely behind the other. So the back galaxy's light passes along where the filament would be estimated to be between the galaxies. So the light travels through the dark matter's gravitational field for a really long time, running practically parallel to the filament. Even after that much light gravity tugging, it's barely perceptable by our current telescopes. So someone had some pics of this set of galaxies from 2001 but never did anything with them because they didn't realize the opportunity. This new team noticed it, compared it to background light to detect additional possible lensing, and discovered unmistakeable slight lensing. So something is obviously there and it has to be a particular shape, density, and reflect no light.
  • by Lukano (50323) on Thursday July 05, 2012 @08:45PM (#40559069)

    Yeah because 'real' scientists would have hopped in their VW wagon and drove out to the galaxy to test and take measurements and be 100% sure....

    The thing is bazillions of kilometers away, all they have to work with is mathemtical models to provide/disprove theories.

  • by rb12345 (1170423) on Thursday July 05, 2012 @08:46PM (#40559075)

    It would have helped if the summary had pointed at the actual Nature article [nature.com] or the ArXiv preprint [arxiv.org].

  • by jouassou (1854178) on Thursday July 05, 2012 @09:04PM (#40559161) Homepage
    This has already been considered [wikipedia.org], but the current cosmological models and experimental evidence requires that the majority of dark matter be non-baryonic, i.e. composed of particles that are incapable of forming atoms and thence stars and planets.
  • by nickersonm (1646933) on Thursday July 05, 2012 @09:09PM (#40559189)
    Strangely there's no citation of the paper in that article. Here's the arXiv preprint. [arxiv.org]
  • by Immerman (2627577) on Thursday July 05, 2012 @09:20PM (#40559235)

    Well, except that if 80% of the mass in our galaxy was simply non-luminous, we'd still see the "haze" from it, just as we can see evidence of the existing hydrogen haze by it's characteristic absorbtion spectra, especially when starlight passes through nebula where the diffuse matter density is extremely high. Perhaps the vast majority simply formed gas giants and the like that were two small to "ignite", recent evidence does suggest wandering planets may be far more common than star-bound ones, but to get the 5:1 ratio still we'd be talking about 5000 Jupiters for every sun, and the sun is actually pretty tiny as stars go - with that many dark planets whizzing around it seems likely we'd see some evidence of them, likely of the frequent "Gas giant zooms through solar system, multiple planetary orbits disrupted, news at 11" sort. If the planets were smaller the "invasions" would be even more frequent, and if they were much larger (we're not sure of the exact limit) they'd spontaneously ignite

    Then again - if using general relativity rather than Newtonian gravity actually does explain the odd rotational characteristics of our galaxy without reliance on massive amounts of additional matter then you may be right. There's still things like the Bullet Cluster that show evidence of something very weird going on though - the gravitational lensing seems to have become partially disconnected from the visible matter - if "dark matter" was simply non-luminous you would expect it to still have distribution and gravitational-collision properties similar to the glowing stuff, which is not the case there. Whatever is causing the lensing is behaving in a manner fundamentally different than the matter we can see, in fact it appears to be largely unaffected by the collision at all, which would seem to at odds with many "simple" dark matter theories as well (i.e. it's like normal matter, except light passes right through it).

  • by b4dc0d3r (1268512) on Friday July 06, 2012 @01:03AM (#40560485)

    Un-doing 7 well-deserved mod points to post this, so pay attention. Higgs was not a given. A particle in the same range without the ability to generate the Higgs field was also a possibility. The team explicitly stated that further confirmation is needed before they can say they found Higgs, or a Higgs-sized particle that does not do the things Higgs Boson is supposed to do.

    It is still up in the air as to whether we have a Higgs Boson, or a Higgs-less theory of mass. Obviously everyone is leaning towards Higgs because it matches predictions. But what if it is Higgs sized without having the correct properties? Then you're wrong, and also an idiot for assuming it is a given.

    If we indeed found it, then you're a lucky guess at best.

    I agree this is more important, but only because we have been zeroing in on a Higgs-sized particle for quite some time. Dark matter has been purely theoretical until now (and still this is only the first sighting, subject to review and revision as with all experimental results). More important because it's newer.

    In truth, we won't know for a hundred years which is more important. If dark matter has been theorized since 1930's and we just confirmed it, it is no more important than such ideas as gravitational lensing which have been around for decades before being confirmed. We have known it for a long time, in other words. To me, more important would be strong evidence that a 90 year old hypothesis was completely incorrect and in need of revision.

    Neither one of these, to me, beats a fat man finally seeing his toes after 30 years. He had a feeling they were there, and had been told as much, but to finally see them is a whole different ball game.

  • by Jane Q. Public (1010737) on Friday July 06, 2012 @03:09AM (#40561013)

    "For example, wouldn't a nebula-sized cloud of free electrons still collapse under their gravitational influence?"

    Hell, no. Gravity is orders of magnitude weaker than electrical repulsion. A cloud of electrons would disperse, not coalesce.

    Gravity is even weaker than the so-called "weak" force in quantum physics. It is the weakest of all.

  • by khayman80 (824400) * on Friday July 06, 2012 @03:52AM (#40561203) Homepage Journal
    String theory isn't testable using current technology, but it's largely unrelated to dark matter. On the other hand, we've already discussed [slashdot.org] some of the actual evidence for dark matter. This new paper [arxiv.org] seems (to my non-cosmologist eyes) to be very rigorous. Among other checks, they extensively searched parameter space to exclude the possibility that standard NFW dark matter halos were being mistaken as a filament. The nearly head-on alignment of these two galaxies is fortunate, and the authors deserve credit for noting that it improves the signal-to-noise ratio of the gravitational lensing signal.
  • by TapeCutter (624760) on Friday July 06, 2012 @06:53AM (#40561879) Journal

    wouldn't all matter collapse into a common gravitational center?

    Yes, assuming it's not ripped apart by the expansion of space and assuming there is enough mass in the cloud for gravity to eventually dominate the other forces. Note that some of these filiments are long enough that the two ends are not gavitationally bound (due to the exansion of space).

    As I understand it the reason that DM comes in filaments between galaxies rather than seperate blobs has something to do with quantum fluctuations when our observable universe was compresed into a point particle, it also appears that the bulk of the normal matter (galaxy clusters) occurs where these filaments meet (although I don't know of a explaination as to why), the rest of the normal matter (lone galaxies and primordial gas) coincides with the dark matter filaments. In simplistic terms the matter in the universe is arranged like swiss cheese but the space containing the cheese is expanding to rapidly for the cheese to sucumb to gravity and lump together at a central point. Supercomputer models of the 14Gyr evolution of the universe that include dark matter are consistent with observations, models that only use normal matter are not as skillfull in reproducing ALL the observations.

    And for all the metaphysics types out there it's been pointed out a map of the universe at the largest scale [sciencemag.org] looks remarkably like the nuron network in a brain [typepad.com]

  • by cowboy76Spain (815442) on Friday July 06, 2012 @10:02AM (#40563287)

    Dark matter is expected to be non-barionic, that means, amongst other things, that it is not formed by atoms (so, no elements as we know them).

  • by Chris Burke (6130) on Friday July 06, 2012 @12:22PM (#40565247) Homepage

    Maybe, but the gravity is also the only force which works beyond subatomic distances.

    Electromagnetism is not short-range. It only seems like it is normally because most materials are electrically neutral.

    It's effect is also additive so enough electrons held together would eventually be massive enough to overcome the electromagnetic repulsion (just like protons).

    Yes, it's being additive which is why gravity dominates the large-scale structure of the universe (not accounting for dark energy). Electromagnetism likes to cancel out, while gravity likes to build and build.

    Weather it's actually possible to condense a cloud of electrons in order for them to exhibit a strong enough gravitational pull, I have no idea.

    I don't think so, since the cloud wouldn't exist in the first place. It would disperse long before there was anything like a 'cloud'.

    However if you started with something else, like a cloud of hydrogen gas, that could condense, eventually creating a situation where gravity has overcome the electron's repulsion. Something like what our sun will become [wikipedia.org].

    These kinds of objects don't make good dark matter candidates. At least for the majority of the unseen mass, and the observations supporting its existence.

It is wrong always, everywhere and for everyone to believe anything upon insufficient evidence. - W. K. Clifford, British philosopher, circa 1876

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