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Space Science

Mysterious Dark Matter Blob Confounds Experts 151

Posted by Soulskill
from the dark-matter-needs-vacations-too dept.
mayberry42 writes "Astronomers using the Hubble Space Telescope are mystified by a merging galaxy cluster known as Abell 520 in which concentrations of visible matter and dark matter have apparently come unglued. A report on the Hubble observations, published in the Astrophysical Journal, raises more questions than answers about a cosmic pile-up that's occurring 2.4 billion light-years away. 'According to our current theory,' says Arif Babul, the study team's senior theorist, 'galaxies and dark matter are expected to stay together, even through a collision. But that's not what's happening in Abell 520. Here, the dark matter appears to have pooled to form the dark core, but most of the associated galaxies seem to have moved on.'"
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Mysterious Dark Matter Blob Confounds Experts

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  • by Tablizer (95088) on Saturday March 03, 2012 @07:06PM (#39234553) Homepage Journal

    We can't directly observe air either (in most cases), but can still measure its effects.

  • by JoshuaZ (1134087) on Saturday March 03, 2012 @07:13PM (#39234595) Homepage
    We can't. What we can observe is the gravitational pull of dark matter (which is the entire reason we know it is there). In this case, they can see where the dark matter is because of its gravitational effects.
  • by Daniel Dvorkin (106857) on Saturday March 03, 2012 @09:59PM (#39235467) Homepage Journal

    It's pretty conventional, when discussing astronomical observations, to use the present tense for "when we see it." Since it can't possibly have any effect on us before the light from the event gets here (assuming relativity is correct, yadda yadda) this makes sense. Also, having to say "2.4 billion years ago 2.4 billion light-years away" would just get annoyingly redundant after a while.

    There's pedantry which serves the useful purpose of correcting other people's mistakes, and then there's pedantry of the "look how clever I am" variety; posts like yours, which seem to get posted to every single story on any kind of astronomical event that takes place outside the solar system, are examples of the latter.

  • The Default (Score:4, Insightful)

    by rust627 (1072296) on Saturday March 03, 2012 @10:53PM (#39235677)

    The default position for scientists is "I don't know"
    everything else is trying to define and explain
    this is why nothing is set as a certainty but always as a theory
    a Theory (theory of gravity, theory of climate change etc.) is usually the best most simple hypothesis that explains experimentally verifiable data.
    you can create any theory you want from the incredibly convoluted to the overly simplistic (because god made it so strikes me as an overly simplistic theorem).
    Usually the simplest (but not most simplistic) theory will be the one that gains the most credence in the scientific community.
    the KISS rule applies very much in science too.

  • by hughJ (1343331) on Sunday March 04, 2012 @05:35AM (#39237517)
    "Dark matter" isn't simply regular matter/particles that we just can't see due to not emitting light. We may not know quite what it is, but we have a pretty good idea about what it is not, and that's regular matter as we know it.

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