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Why nuclei doesnt colapse?

  1. Mar 15, 2004 #1
    i was wondering this

    if the nuclear force overcomes the electromagnetic force in the nucleus, then what prevents the nuclei for colapse itself

    i read in somewhere this
    " the nuclear force has a repulsive core which prevents the nuclei from collapsing in on themselves"

    what is this "repulsive core"?
  2. jcsd
  3. Mar 19, 2004 #2
    The potential energy between two nucleons obeys the Yukawa potential. At small separation distances the potential energy is positive, and there is a strong repulsive force between the two nucleons. At larger distances, the potential energy is negative, and there is an attractive force. You can search for Yukawa potential and find out everything you want to know.
  4. Mar 20, 2004 #3

    many thanks for your reply, it seems that all forces are not always attractive or repulsive, but dependes of quarks spin orientation in the particles
    thats what i understood in some lecture i attend
  5. Mar 20, 2004 #4


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    Except gravity. As far as we can tell, gravity is always attractive.
  6. Mar 21, 2004 #5
    In some cases gravity is replusive. This happens because pressure is also a source of gravity and because a non-zero cosmological constant gives gravitational repulsion.

    When there is a negative pressure present in that source which is so large as to overcome the attractive source due to other sources like mass terms in Einstein's equations, then there can be a resulsive effect.

    A vacuum domain wall is a well-known example from cosmology.
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