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Collapsing stars

  1. Jun 27, 2007 #1
    White dwarfs and neutron stars have very low uncertainty in position (since the particles are practically on top of each other), but a lot of uncertainty in momentum, and thus the claustrophobic particles vibrate with great momentum creating an outward force to oppose gravity, but doesn't a singularity defy the uncertainty principle? All the stuff that used to be the star collapses to have a common position/time (a point of infinite density) and momentum/energy (all the mass-energy is infinitely compacted to that point)...
  2. jcsd
  3. Jun 27, 2007 #2


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    Your understanding of electron and neutron degeneracy is incorrect. These forms of degeneracy have nothing to do with small uncertainties in position. After all, even a tiny neutron star is still enormous compared to subatomic scales.

    Electron and neutron degeneracy are the result of all quantum mechanical states being filled. Since both electrons and neutrons are fermions, only one particle can occupy a particular quantum state.

    Singularities absolutely do violate the uncertainty principle, In fact, singularities are not permitted in quantum mechanics at all. Quantum mechanics forbids singularities, while general relativity predicts them -- this is one of the reasons why these two theories are incompatible, and one of the reasons physicists are seeking a more general theory that will correctly unify them.

    - Warren
  4. Jun 27, 2007 #3
    "only one particle can occupy a particular quantum state."
    This sounds like the Pauli-exclusion principle, but I thought the underpinning behind the principle was uncertainty, if the electrons fell into the same state in the atom they would be defying uncertainty, my wave interpretation is that the energy levels are the different harmonics of standing probability waves possible, and the reason there is nothing in between is that if two probability waves overlapped it would mean there was a probability of two electrons with common position and energy/momentum, is this all correct?

    I'm reading Feynman's lectures on physics and he tends to talk about electrons like little tennis balls bouncing around

    I'm assuming by quantum states you mean energy level, sub level, orbital, spin ect.

    thanks for replying =)
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