Dark Matter, what do you know of it?

Discussion in 'Astronomy, Exobiology, & Cosmology' started by Electro522, Dec 14, 2011.

  1. Electro522 Registered Senior Member

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    I have seen numerous articles and television shows that simply discuss Dark Matter, but none of them try to explain it. So far, the only explanation I have seen is it is the "glue" of galaxies, and without it, the expansion of the universe would tear all matter, even atoms, apart (aka "The Big Rip"). I know that we do not know much (or anything, for that matter) about Dark Matter, so I was hoping if all you could possibly post some of your own ideas about it just to get some clarification on what it might be.
     
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  3. AlexG Like nailing Jello to a tree Valued Senior Member

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    We know from observation that there is a so far undetected gravitational source surrounding and permeating galaxies. While we can't detect the cause, we can observe the effects. The high velocity of stars at the outer edges of the rotating galaxy can only be explained by this gravitational field.

    It is hypothesized that the gravity is produced by some form of matter which does not interact electromagnetically. This is what is called Dark Matter.
     
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  5. D-9 Registered Member

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    If you look at galaxy collisions, you can see dark matter separating from normal matter, and from what scientists see they've concluded that dark matter has no electrical charge, meaning that it doesn't interact electromagnetically. Also, its noted to not be influenced by friction, either by normal matter or other dark matter. And as the name suggests, it neither emits nor absorbs radiation/light.


    I found this at nasa.gov but I don't have enough posts to post the link yet

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  7. D-9 Registered Member

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    Since I can't post links yet, and that NASA site has a good overview of dark matter candidates in one of their links, I thought I'd just copy and paste some of the material, hope everyone is okay with that.

    When I get a few more posts in and can link to the site I'll do so.
     
  8. arauca Banned Banned

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    However, at this point, there are still a few dark matter possibilities that are viable. Baryonic matter could still make up the dark matter if it were all tied up in brown dwarfs or in small, dense chunks of heavy elements. These possibilities are known as massive compact halo objects, or "MACHOs". But the most common view is that dark matter is not baryonic at all, but that it is made up of other, more exotic particles like axions or WIMPS (Weakly Interacting Massive Particles).

    I found this at nasa.gov but I don't have enough posts to post the link yet

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    [/QUOTE]

    Wow give me some more fudges I am sure there will be some more .
    Can you guy scrap and stat all over ?
     
  9. D-9 Registered Member

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    It's pretty conclusive that dark matter exists, we unequivocally see its gravitational effects where there is no visible matter in any spectrum range. The question is 'what is it?' No one really knows, but there are viable candidates as you can read about above.

    Of course, we could all just throw up our hands and give up, attributing the mystery to God and whatnot, but that isn't doing science nor is it going to get us anywhere in further understanding the world we live in.

    What do you think of dark matter beyond it's all "fudges"?
     
  10. mathman Valued Senior Member

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    It can't be baryonic matter. The amount of deuterium in the universe is an independent check on the amount of baryonic matter in the universe, which is consistent with the current estimate of ~ 5%.
     
    Last edited: Dec 14, 2011
  11. arauca Banned Banned

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    # 1 Can you measure it , Does it have a mass.
    # 2 Does emit or reflect light
    Note I am not bringing God into the discussion .
    The force that holds the galaxy , Why not the gravity from the Black Hole ? could not that account for lensing ?
     
  12. D-9 Registered Member

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    Yes. Well, not me personally, but scientists yes.
    I think all evidence points to yes.
    Not that I know of, same with absorption (does a black hole do that?).
    I have noticed. I met someone before who didn't accept dark matter because he/she believed that scientists were making it up to disprove God. So I just threw it out there, didn't mean anything by it.
    I don't think so. The details of the lensing are properties of the mass of the object, so I think you can tell where and how massive said object is through lensing. Scientists can measure where the mass is, and it is in a halo around galaxies. If you're talking about the black holes in the center of the galaxy I think it is in the wrong place.

    Because of things like looking at galaxy collisions, we know that dark matter must not interact with electromagnetism and has very little friction from either normal matter or other dark matter. From what I understand it is unlikely that dark matter collides with other dark matter or regular matter, and again I don't think that is a property of black holes.

    In case you missed it, the nasa page I found said that "Because [neutron stars and black holes] result from supernovae, they are not necessarily common objects. As a result of a supernova, a release of a massive amount of energy and heavy elements should occur. However, there is no such evidence that they occur in sufficient numbers in the halo of galaxies."

    Because of stuff like this most scientists have concluded that dark matter isn't the "MACHOs" which black holes are a part of. Rather part of the "WIMPs", which you can read about in my above post with the nasa quotes.
     
  13. joepistole Deacon Blues Valued Senior Member

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    In your honor D-9, and welcome to the forum.

    http://imagine.gsfc.nasa.gov/docs/teachers/galaxies/imagine/dark_matter.html
     
  14. convivial Registered Senior Member

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    I'm fairly sure you could get around the no-posting-links restriction by leaving out the http/www bit.
     
  15. AlexG Like nailing Jello to a tree Valued Senior Member

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    I think what Pincho is referring to is that there are stars at the outer edge of the galaxy, in orbit around the galactic center, which are moving faster than they should be in the absence of a greater gravatic field then can be accounted for by the visible matter in the galaxy.
     
  16. mathman Valued Senior Member

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  17. convivial Registered Senior Member

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    Wait. If dark matter has gravity, why wouldn't it tug stars out of galaxies? Because its force pushing galaxies apart and such is stronger?
     
  18. James R Just this guy, you know? Staff Member

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    Moderator note: "Alternative" theories of dark matter have been split to a separate thread.

    [thread=111722]Link[/thread]
     
  19. Gravage Registered Senior Member

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    Dark matter is detected for the first time:
    http://www.newscientist.com/article/dn21342-largest-dark-matter-map-holds-clues-to-dark-energy.html

    http://www.msnbc.msn.com/id/4592830...argest-map-yet-dark-matters-web/#.TxpsvYG0v48

    Here are number of photos:
    http://nanopatentsandinnovations.blogspot.com/2012/01/astronomers-reach-new-frontiers-of-dark.html (you should see this link)

    One more:
    http://www.scientificamerican.com/article.cfm?id=biggest-map-yet-of-universes
     
  20. wellwisher Banned Banned

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    One thing that needs to be taken into account, before we assume dark matter, is the Compton Effect. The Compton effect is when photons of energy interact with electrons. The result will be the electrons gaining energy and the photon losing energy and thereby red shifting. This can be demonstrated in the lab.

    The neccessity for dark matter is connected to the assumption of a pure doppler shift, in light of the amount of matter observed. But if part of this red shift is due to the Compton effect, the need for dark matter is less or not at all. This may be why we can't prove dark matter with hard data in the lab, but only through inference based on biased assumptions.

    The bottom line is we can't even predict weather on earth with perfect accuracy, so to assume we can pin point creation is naive. It comes down to opinion and traditions, with traditions having an advantage.
     
  21. origin Heading towards oblivion Valued Senior Member

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    Why are the assumptions biased? Why would someone be biased towards dark matter - it is silly. Dark matter arises from many observations. How do you explain rotation of the galaxies? How do you explain the lensing of the bullet galaxy cluster.

    You, my young fellow, are the one who appears biased, why you are biased against dark matter I cannot guess.:shrug:
     
  22. wlminex Banned Banned

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    Origin Post #18 "How do you explain rotation of the galaxies? How do you explain the lensing of the bullet galaxy cluster. "

    IMO (OOB) here) . . . Bullet galaxy looks strangely reminiscent to a 'bow' wave and 'wake' from an object moving rapidly through some spatial media.

    wlminex
     
  23. origin Heading towards oblivion Valued Senior Member

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    OOB thinking is fine, but 'looks like' from a nonprofessional, is not science, it is simply idle conjecture that is not worth considering.
     

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