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Dark matter and gravity

  1. Jun 28, 2012 #1
    I've heard that most of dark matter is located in the outer portions of galaxies. If that is so, wouldn't the gravity from the dark matter tend to pull the galaxies apart?
     
  2. jcsd
  3. Jun 28, 2012 #2

    Chronos

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    The center of mass is still within the galaxy.
     
  4. Jun 28, 2012 #3
    many thanks Chronos
     
  5. Jun 29, 2012 #4

    Chalnoth

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    Even if the dark matter wasn't more dense towards the center of the galaxy, the net gravitational force on the inside of a shell of matter is identically zero.
     
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