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Dark Matter

  1. Apr 28, 2013 #1
    Did The Dark Matter Really exist ? did we have an evidence ? and What is the compositions Of The Dark Matter ?
  2. jcsd
  3. Apr 28, 2013 #2


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    SOMETHING exists that causes galaxies to act in a way that they would not if that "stuff" were not there, so yes, SOMETHING unquestionably exists and since we can't see it, we call it "dark" matter.

    Actually, it's a bit more complex than that but you can find the details very easily with Google.

    The evidence for its existence is overwhelming, but WHAT it is is unknown. Again, you can find all the details you want with Google.
  4. Apr 29, 2013 #3


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    Well, precisely what it is is unknown. We do know a fair amount about it:
    1. It's probably made up of particles with some amount of mass.
    2. It interacts weakly both with itself and with normal matter. Having interactions comparable to the weak nuclear force, but not the electromagnetic or strong forces, would explain this. It may interact even more weakly, this is unknown.
    3. It had to have a low temperature in the early universe. This produces constraints on how they were produced, how strongly they interact, and how massive they are.
    4. It has to have been produced in sufficient quantities in the early universe to be about five times the quantity of normal matter (by mass).

    It's also worth noting that multiple dark matter search experiments are seeing excesses that have yet to be explained through other means that might be detections of the dark matter particles.
  5. Apr 29, 2013 #4
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