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What is Dark Matter?

  1. Mar 2, 2010 #1

    FeDeX_LaTeX

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    Hello;

    What is dark matter? I have been told from numerous sources that it is simply an invisible form of matter that is undetectable by its electromagnetic radiation. However, that does not explain what it is, that just tells me that I can't see it.

    What particles does dark matter consist of? What properties does dark matter exhibit?

    Thanks
     
  2. jcsd
  3. Mar 2, 2010 #2
    No one knows exactly what dark matter is composed of yet (or more accurately if it even exists). They think it could be unaccounted for black holes, an undiscovered type of particle, neutrinos, etc. Its only even posited to exist because of an anomaly in the way galaxies revolve ( http://en.wikipedia.org/wiki/Vera_Rubin ) that does not mesh with our present scientific model of the universe .

    Here's a good documentary on dark matter:


    BBC also has a good documentary on the topic:
    http://www.youtube.com/watch?v=LRMdLO_My9A&feature=SeriesPlayList&p=49560DAA7B8CD529
     
    Last edited by a moderator: Sep 25, 2014
  4. Mar 10, 2010 #3
    Is it possible to ask a question here?
     
  5. Mar 10, 2010 #4
    you just asked one :).
     
  6. Mar 10, 2010 #5

    Char. Limit

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    All things are possible... And, in response to the question I believe you wanted to ask, yes, you are allowed to ask questions here.

    They must be relevant, though, I believe...
     
  7. Mar 11, 2010 #6
    Thanks for the encouragement.I was being disconnected before I could complete my messages.Here`s a question about Dark Matter. Is it possible that atoms existed before the Big Bang which were oriented like a disc.and they were damaged in the explosion?That would make them "visible".So we live in a universe made out of "bent"atoms. Think of a spinning bicycle wheel.It takes a lot of energy to turn with that.How much energy would it take to straighten out all the bent atoms.
     
  8. Mar 11, 2010 #7
    Add to the last question the idea of digital watches.The orientation of molecules in the number display will render invisibility possible with a small charge.Some spiders render themselves invisible by rapidly shaking themselves.They had never seen a propellor when they started doing that.
     
  9. Mar 11, 2010 #8
    One simple rule of thumb relating to explosions in a market place is that for every person killed there will be roughly 6 times more injured.That roughly fits the mismatch in the Dark Matter scenario.
     
  10. Mar 12, 2010 #9

    Chronos

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    Simply put, dark matter is the missing mass necessary to explain the observed gravitational attraction between galaxies. Zwicky first noticed this missing mass nearly a century ago. See virial theorem and the bullet cluster for more detail. Dark matter is also necessary to explain large scale structure in the universe [filaments].
     
  11. Mar 12, 2010 #10
    Chronos .This idea of mine is just something for others more expert to play with..The centre of my question is the idea of atoms (pre-Big Bang ) being similar in shape to Galaxies which have the familiar flat layout. Many planets which arrived late in some galaxies were stuck in odd angles to the rest.Most galaxies seem to be quite well aligned . Maybe gravity between flat atoms would be too strong for them to separate. If one wanted a disc shaped atom how much energy would be needed to reshape it ? Is this question just an old "chestnut"?
     
  12. Mar 13, 2010 #11

    qwe

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    no that's not the same thing. those molecules would be detectable like other molecules if they were in a nebula (if there was enough of it) it wouldn't be dark matter. those are "normal molecules" in the watches and in the spiders
    atoms don't have shapes, they are collections of particles in a stable equilibrium (aka like "orbit") due to their interactions (aka like gravity). the "shape of the atom" is determined by how the electrons interact with themselves mostly. but the "shape of the atom" is statistical/a "probability-cloud", aka, a picture of where the different components are more likely to be at any particular time

    so it doesn't make sense to think of atoms themselves as discs or balls

    i can tell you're confusing atoms with particles though. you can't have atoms that go through the big bang... the big bang came through a point too small for that, the atoms would break apart even if you could "have atoms before the big bang"

    so your question could be rephrased "do particles have a sort of shape, and did the big bang alter the shape of a large set of particles that came into the universe at the start of the universe?"

    that question is highly speculative... it's all over the place lol
    for this to be the case, the particles would have had to be interacting with eachother differently before the big bang, the big bang altering their properties. there is no particular reason to believe this. yeah there are probably a myriad of weird unkown particles in unknown multidimensional universes. but for this particular idea i think it's coming from a misconception of what particles and spacetime actually are (not that anyone knows for sure)
     
  13. Mar 17, 2010 #12

    FeDeX_LaTeX

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    Thanks for the discussion. I guess we'll have to wait a few more years to find more evidence for this phenomenon...
     
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