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Neutron degeneracy pressure

  1. Aug 24, 2004 #1
    How can gravity overcome the degeneracy pressure of neutrons in a neutron star? Isn't such a thing the same as violating the uncertainty principle?
  2. jcsd
  3. Aug 24, 2004 #2


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    No violations occur. The neutrons decompose into quarks and the whole thing collapses to form a black hole... probably. It is possible, however, there is a such thing as a 'quark degeneracy pressure' [i.e., the quarks may put up some additional resistance to further collapse]. In this case, the next stop on the road to a black hole would be a quark star. This would be a pretty spooky critter and there is actually is at least one 'suspect' in the case. See
  4. Aug 24, 2004 #3
    Presumably if the quarks don't hold out then they have structure and form
    smaller particles or the quarks form heavier quarks pentaquarks etc?
    The photo on that link is great.
    Last edited: Aug 24, 2004
  5. Aug 26, 2004 #4


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    I'm not sure anyone has done the calculations to see if there's another plateau of stability below 'quark degeneracy'. Even if they have, my guess would be we'd be into a region where the Standard Model isn't a reliable guide any more ... it's in an energy (etc) regime that's not well explored in Earthly accelerators (or not explored at all), and 'beyond the SM' physics has essentially no observational basis today.
  6. Aug 26, 2004 #5
    If the casimir vacuum force for plates gave the opposite result to what it normally does
    then neutrons could be held apart by this force.Trouble with this idea is that
    the casimir would be expected to increase above its normal level (it's been tested over a plate separation of 10^-7 m) and push neutrons even closer together for the kind of distance that neutrons in a neutron star are separated by ( 10^ -15 metres).Perhaps dark energy is more concentrated than usual in the gaps between neutrons in a neutron star and pushes outward against gravity.If dark energy consisted of particles then according to the Heisenberg uncertainty principle if these were trapped between neutrons in a neutron star then the small uncertainty in their position would give them a large momentum and a large repulsive force and hence they would counter the gravitational force strongly.And perhaps dark energy behaving like this could stop singularities forming when stars become black holes.
    Last edited: Aug 26, 2004
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