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Evidence of Dark Matter within the Solar System?

  1. Mar 9, 2013 #1
  2. jcsd
  3. Mar 9, 2013 #2

    ZapperZ

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    Er... we are studying dark matter NOW! All the current possible candidates are being looked for!

    Zz.
     
  4. Mar 9, 2013 #3
    Hmm...I mean directly obtaining a sample from some location in our solar system and studying it. Possible?
     
  5. Mar 9, 2013 #4
    As an example, the AMS-02 experiment is running at the moment, and the first results are expected this month (hopefully). EDIT: this was not a reply to post #3.
     
    Last edited: Mar 9, 2013
  6. Mar 9, 2013 #5

    ZapperZ

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    Why are you putting in such restriction in studying this dark matter? Do we HAVE to go to some location in our solar system to study such a thing if we can find it in our underground detectors or even in our particle colliders?

    Zz.
     
  7. Mar 9, 2013 #6
    There are several projects currently underway to study dark matter. As pointed out. The results from the AMS are due for release this month. The other project is detectors far underground. Why underground has to do with how weakly interactive dark matter is considered to be. Similar in nature to neutrinos.
    Though dark matter is not considered to be a neutrino.

    LHC is also a possibility in creating dark matter thougj they have been unable to do so yet. Might be due to needing higher energy levels. However I'm not that familiar with that aspect to say for sure.
     
  8. Mar 9, 2013 #7

    Drakkith

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    Why do you believe this is possible? Perhaps our belief that dark matter doesn't interact through any other forces other than gravity is correct. This would mean that we couldn't obtain a sample, as it would pass through everything.
     
  9. Mar 9, 2013 #8

    Just a side note. This is one aspect thats always confused me.
    The statement dark matter only interacts via gravity leads me to ask how dark matter has mass. The Higgs field provides mass for quarks. So only accounts for a small percentage of mass. The strong nuclear force accounts for the remaining mass in baryonic particles. If dark matter does not interact or weakly interacts with the strong force. How do we account for its mass? Thats one
    question I've had for awhile but
    hadn't gotten around to asking.
    However I also have no interst in stealing this thread so if any answers are provided keep it short I' ll ask related questions on another thread
     
  10. Mar 9, 2013 #9

    Jonathan Scott

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    As far as I can see, both of those are not directly about dark matter, but rather about measuring whether the motion of local stars within the Milky Way galaxy seems to be accounted for by the gravitational effect of ordinary matter (according to GR, probably using Newtonian gravity as a reasonable approximation) and if not trying to estimate what distribution of "dark matter" would be needed to account for the motion.

    This tells us very little about the nature of the "dark matter" involved, and does not rule out alternative explanations such as modified gravity theories.
     
  11. Mar 9, 2013 #10

    ZapperZ

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    This is not correct. The Higgs field that we know of so far accounts for the mass in the leptonic sector. In fact, it accounts for the mass of the W and Z bosons.

    There are numerous models for the type of dark matter. Whether it will interact with the Higgs field or not is what needs to be tested. Whether is it WIMP, or sterile neutrinos, or some other species all will have different types and strength of interactions via the different mechanisms.

    Zz.
     
    Last edited: Mar 9, 2013
  12. Mar 9, 2013 #11
    Thanks Zapper both for the clarification on the Higgs interaction and the explaination on dark matter mass. Glad to see that it is one of the questions yet to be answered. I can see from your explaination that it would require more information on dark matter identity that makes sense. Thanks for pointing that out.
     
  13. Mar 10, 2013 #12

    Chalnoth

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    I would put a lot more than a "perhaps" on this. CMB observations guarantee that dark matter cannot have an electric charge. And without an electric charge, it most definitely passes straight through normal matter all the time. Rather like neutrinos.
     
  14. Mar 10, 2013 #13

    ZapperZ

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    Actually, just so those who are not familiar with the subject matter (no pun intended) do not get the wrong information, the lack of charge is not a necessary and sufficient criteria for something to "pass straight through normal matter all the time". A neutron, for example, is one of the most biologically ionizing particle and also causes damage to solids. So it interacts extremely strongly with matter. Yet it is also electrical neutral!

    So lack of charge is not the only criteria here for something such as a neutrino (and possibly dark matter candidates) to have such weak interactions (no pun intended here either).

    Zz.
     
  15. Mar 10, 2013 #14

    Chalnoth

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    Actually, neutrons do pass through matter pretty easily as well. You can't actually trap neutrons, except by joining them to atomic nuclei.

    That said, if dark matter interacted through the strong nuclear force, we would have detected it a long time ago.
     
  16. Mar 10, 2013 #15

    ZapperZ

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    If that is true, the shielding we have at neutron sources are useless, neutrons would not be considered as ionizing radiation, the walls around nuclear reactors would not suffer neutron damage as easily, and thermalizing neutrons in water for fission reaction would not happen.
     
  17. Mar 10, 2013 #16

    Drakkith

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    I look at a neutron kind of like I look like a neutral atom. Neither have a net electric charge, but both will interact with EM fields. It's not that Dark matter is just uncharged, it's that it doesn't interact through the EM force at all.
     
  18. Mar 10, 2013 #17

    ZapperZ

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    You seem to have completely ignored the evidence I presented on neutron interaction with stuff. Is there a reason why?

    Please note my original objection, that your characterization that it doesn't have any charge is the reason why it doesn't interact with matter. This is false because a neutron interacts quite well with matter. You would not want to stand in front of a neutron beam the way you would stand in front of a neutrino beam!

    We are not debating the mechanism of how neutrons interact with matter. We are debating the false and misleading claim that was made regarding neutrons and their interaction with matter.

    Zz.
     
  19. Mar 10, 2013 #18

    cepheid

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    It seems to me that Drakkith was totally agreeing with you in the post that you are responding to here, saying that having no electric charge is not a sufficient condition for not being able to interact with ordinary matter.
     
  20. Mar 10, 2013 #19

    ZapperZ

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    Ooops.. you're right. I thought I was responding to Chalnoth.

    My apologies, Drakkith.

    Zz.
     
  21. Mar 10, 2013 #20

    Drakkith

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    It's cool. I'll just go borrow Bannenstein, Evo's legendary Banhammer. I'll be back in a few...
     
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