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Space Science

Galaxies Twice As Bright As Previously Thought 139

Astronomers led by Simon Driver of Scotland's University of St. Andrews have discovered that interstellar dust shades us from as much as 50% of the light emitted by stars and galaxies. The scientists compared the number of galaxies we could see "edge-on" against the number which were "facing us," reasoning that dust would obscure more of the former, since we already receive less light from them. SPACE.com notes, "In fact, the researchers counted about 70 percent fewer edge-on galaxies than face-on galaxies." A NYTimes report provides some additional details: "Interstellar dust absorbs the visible light emitted by stars and then re-radiates it as infrared, or heat, radiation. But when astronomers measured this heat glow from distant galaxies, the dust appeared to be putting out more energy than the stars. 'You can't get more energy out than you put in, so we knew something was very wrong,' said Dr. Driver. The results also mean that there is about 20 percent more mass in stars than previously thought."
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Galaxies Twice As Bright As Previously Thought

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  • by Vectronic ( 1221470 ) on Sunday May 18, 2008 @11:33AM (#23453412)
    "except to bend the light through gravitious pull"

    hence, "obscure" ... :P
  • From Wikipedia: The dark matter component has vastly more mass than the "visible" component of the universe

    From the summary: there is about 20 percent more mass in stars than previously thought

    Even if we assume that "vastly more mass" means 51% of all mass in the universe, we still have the problem of a lot of missing mass even with the increased estimations of stellar mass and interstellar dust.

    This study may increase our precision in our calculations of universe mass, but it is by no means eliminating dark matter as a theory.
  • by BemoanAndMoan ( 1008829 ) on Sunday May 18, 2008 @12:17PM (#23453674)
    Wow, a simple, seemingly obvious (as always, in hindsight) observation that throws a lot of carefully balanced highly theoretical equations out of whack.

    Of course, it could prove to be equally inaccurate by failing to take into account some other grand unknown that in turn will prove to be obvious, but I can't help but feel sorry thinking of all those academics sitting around a table of hardly-touched pints and muttering "well, fuck..." to no one in particular.


    "You're only as smart as the guys you think are smarter than you."
  • by Falladir ( 1026636 ) <kingfalladir@yahoo.com> on Sunday May 18, 2008 @01:07PM (#23454030)
    I suspect that the theories you're speaking of aren't actually *that* carefully balanced. A factor of 2 might seem huge, but we currently think there's several times more dark matter than normal matter in the universe, so I don't think this will put *that* much of a dent in the status quo.
  • by Ravon Rodriguez ( 1074038 ) on Sunday May 18, 2008 @01:22PM (#23454140)
    Occam's tells us that we should select the theory that introduces the fewest assumptions. In this case, we can assume that the extra mass is accounted for by dark matter, or that the galaxies are emitting more light than we can see. Occam's doesn't appear to apply.
  • LOL. (Score:2, Insightful)

    by msauve ( 701917 ) on Sunday May 18, 2008 @01:42PM (#23454278)
    You ignored the HUGE ASSUMPTION, unsupported by any facts (except gravitational effects), that any exotic black matter exists, in any quantity. THE ONLY REASON it is theorized is because nothing else had been identified which could cause those gravitational effects. Now there is evidence of previously unknown mass.

    You obviously don't know how to apply Occam if you prefer an unproven hypothetical to something which is observably evident.
  • by msauve ( 701917 ) on Sunday May 18, 2008 @02:04PM (#23454468)
    Science is about explaining observations (evidence) with testable theory, not claiming a theory to be evidence.

    The emperor has no clothes.
  • Re:LOL. (Score:2, Insightful)

    by Ravon Rodriguez ( 1074038 ) on Sunday May 18, 2008 @02:20PM (#23454596)
    It is NOT observably evident. What is observably evident is a mass increase of 20 percent. That in no way accounts for all of the unobserved matter. And I'm not applying Occam's, I'm saying Occam's doesn't apply here. Both situations are hypothetical. Get a clue.
  • Wrong... (Score:4, Insightful)

    by msauve ( 701917 ) on Sunday May 18, 2008 @05:54PM (#23456130)

    ...We know that dark matter can't be accounted for by large mass objects (like planets, asteroids, dust, etc) because CMB measurements tell us that the total amount of baryonic matter ('normal' matter made up of protons and neutrons) is a small fraction of the total matter
    What you mean to say is that the theory of life, the universe and everything which you subscribe to breaks if there is no exotic dark matter. There is no proven "upper limit on the amount of baryonic mass in the universe," there are only theories and hypothesis which make that claim as part of their model. I won't try and prove a negative by saying that theory is necessarily wrong, but the onus is on you to prove that portion of it correct by finding some of this imaginary non-baryonic mass. Myself, I'll claim that the Flying Spaghetti Monster [venganza.org] plays with the gravitational "constant" to fool with us. Prove me wrong.

    Your circular logic fails to prove that dark matter exists.

Statistics are no substitute for judgement. -- Henry Clay