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What could dark matter be?

  1. Nov 1, 2013 #1
    Hi all,

    I was wondering, could the dark matter just be the particles that actually pop in and out of existence inside the protons and neutrons and all other matter or anti-matter?

    Please enlighten me if my assumption is wrong somewhere.
     
  2. jcsd
  3. Nov 1, 2013 #2

    Simon Bridge

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    If I have understood what you are getting at:
    That's already accounted for as binding energy and mass for the protons and neutrons and etc.
     
  4. Nov 1, 2013 #3
    I don't think so, I do understand the binding force, but that's not what I am thinking about, I am thinking about the empty space between the quarks, and everywhere else for that matter. Maybe even outside of atoms. I am not so convinced about outside of atoms as yet
     
  5. Nov 1, 2013 #4

    Simon Bridge

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    The particles popping in and our of existence in the "empty space" between quarks is taken into account as vacuum energy... it's one of the suggested constituents of dark energy.

    According to the Planck mission team, and based on the standard model of cosmology, the total mass–energy of the known universe contains 4.9% ordinary matter, 26.8% dark matter and 68.3% dark energy.

    http://arstechnica.com/science/2013...-the-universe-is-still-weird-and-interesting/
    http://arxiv.org/abs/1303.5062

    If you are referring to some other mechanism for particles popping in and out of existence inside nucleons ... then I'll need to see a reference.
     
  6. Nov 2, 2013 #5

    PAllen

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    Dark matter has a distribution derived very directly from gravitational lensing observations and indirectly from the paths of stars in galaxies, galaxies in clusters. These imply most of it is where there are very few atoms or ordinary particles.
     
  7. Nov 2, 2013 #6
    Right now the leading theory is WIMPS although I heard something about LUX getting negative results on that?
     
  8. Nov 2, 2013 #7

    PAllen

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  9. Nov 2, 2013 #8

    Chalnoth

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    Such particles wouldn't cluster like dark matter does. Clustering requires them to be persistent.
     
  10. Nov 3, 2013 #9
    I was thinking that dark matter even isn't matter, its a force because apparently it might be interacting with gravity and gravity is a force.
     
  11. Nov 3, 2013 #10

    phinds

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    That is unsupportable personal speculation and as such it is not appropriate for this forum.
     
  12. Nov 3, 2013 #11
    Dryogeshd it self has given his/her idea, you are allowed to discuss and give your own reference to the question.
     
  13. Nov 3, 2013 #12

    phinds

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    Not when your idea is unsupportable personal speculation. Read the forum rules
     
  14. Nov 3, 2013 #13
    Is the question by itself supportable?
    Are all theories SUPPORTABLE?
     
  15. Nov 3, 2013 #14

    phinds

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    The original question was just that ... a QUESTION. The OP did not make unsupportable personal speculation, he asked a question. You made a statement.
     
  16. Nov 3, 2013 #15
    Comment on the statement
     
  17. Nov 3, 2013 #16

    phinds

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    The statement is unsupportable personal speculation, as I have already said.
     
  18. Nov 3, 2013 #17

    Drakkith

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    Forces act upon particles, so no, dark matter itself is not a force. Realize that there are no forces that act upon other forces. None of the 4 fundamental forces of nature interact with each other in any way. They act solely upon the particles themselves.
     
  19. Nov 4, 2013 #18
    So how about gravity, thats not a particle, is it? Its the curvature of space-time which acts on particles and other matters.
     
  20. Nov 4, 2013 #19

    phinds

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    Yes, dark matter is known to interact gravitationally both with normal matter and with itself. What does that have to do with your statement that
    If it isn't matter how does it interact gravitationally? You seem to be really confused about this. There are numerous articles available about dark matter. Why don't you study up on it a bit?
     
  21. Nov 4, 2013 #20

    Drakkith

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    No, gravity is not a particle.
     
  22. Nov 4, 2013 #21

    Chalnoth

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    Well, that's not quite true. The strong nuclear force acts on itself (in a sense: gluons carry strong force charges). This is why the strong nuclear force is a short-range force. Obviously a similar thing can't really be happening with dark matter for its impact to stretch across millions of light years.

    But regardless, the idea that somehow dark matter might be a modification of gravity, or something else that acts sorta like gravity, is very hard to support these days. Ryanuser, I recommend checking out this blog post that posts one rather striking piece of evidence for dark matter:
    http://www.preposterousuniverse.com/blog/2006/08/21/dark-matter-exists/
     
  23. Nov 4, 2013 #22

    Simon Bridge

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    ... so you are thinking that either 1. there is something else out there that puts an additional curvature to space-time, or 2. that gravity just does not behave the way we think over long distances?

    Both those would still be pretty much the same as "dark matter" though.
    At least with thinking of the stuff as "matter" we don't have to suppose a, hitherto undiscovered, fifth force that otherwise acts exactly like gravity from mass we cannot see.

    The idea that gravity is just different at long ranges has already been thought of and looked into...
    +1 :)

    Most of the suggestions in this thread have amounted to: "Hey, isn't dark matter actually something we already know about?" - insert specific personal favorite "stuff we already know about".

    The answer is that, with the current state of knowledge, the closest thing we already know about that deals with the phenomena we need to explain is "matter". The "dark" part of the name is an attempt to label how it seems to be different from the regular matter we know about.

    Don't get me wrong - these ideas are constantly being tested.
    The mainstream models are the way they are for a reason.
    Part of what PF exists for is to help people understand this.
     
  24. Nov 5, 2013 #23
    Hi all, Thank you so much for participating, Essentially, what I understand till now is that, dark matter is thought to be clumped in some places causing gravitational lensing, are these gravitational lenses located precisely around galaxies/black holes? or are they also distributed in the intergalactic space as well? If they are in the same positions as the galaxies, then it is probable that unaccounted for mass is within the matter that we measure in these galaxies.... That implies we are missing a rather important particle/s that is contributing to the mass on the universe.
     
  25. Nov 5, 2013 #24

    PAllen

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    I thought someone already linked to the bullet cluster. Here, you had two galaxies that collided, and the result is that the dark matter is displaced from both galaxies (as located by gravitational lensing). In the normal state of a galaxy, the COM for visible matter matches the gravitational COM sensitive to all matter (including dark matter).

    In the present day universe, there is believed to be little dark matter between galaxies.
     
  26. Nov 5, 2013 #25

    Chalnoth

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    There is a relationship with normal matter, but it isn't perfect. Read the blog post I linked above, as it highlights a case where the normal matter was separated from the dark matter due to a collision.
     
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