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The "core" of a neutron star is of debatable composition and is dependent on the highly uncertain equation of state of matter compressed to $10^{18}$ kg/m$^3$. It is possible that the core consists almost entirely of a solid neutron lattice with some protons that possibly form a superfluid. Other possibilities include new mesonic (pions or kaons) or ...

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Let's say you assume that the neutron star is spherically symmetric, e.g., ignore the effects of rotation. Then for a radial trajectory in the resulting Schwarzschild spacetime, the calculation is actually not quite wrong, although you must be careful in interpreting it. The reason is that orbits in a Schwarzschild spacetime have an effective potential that ...

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Having read John Rennie's answer above, I'm going to give an answer that's hopefully of the same sense, which hopefully makes sense, but which hopefully brings out an issue. 1. Is the free fall acceleration the same as the coordinate acceleration for a hypothetical observer at rest on the star surface? Yes and no. Yes because the falling body falls ...

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I'm guessing your questions all amount to whether general relativistic effects become important at the surface of a neutron star. To answer this we can compare the flat space metric (in polar coordinates): $$ds^2 = -c^2dt^2 + dr^2 + r^2 d\Omega^2 \tag{1}$$ with the Schwarzschild metric that describes the geometry outside a spherically symmetric mass:  ...

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The Pauli exclusion principle is being applied here to FREE neutrons. There are always free energy/momentum states for the neutrons to fill, even if they are compressed to ultra-high densities; these free states just have higher and higher energies (and momenta). One way of thiking about this is in terms of the uncertainty principle. Each quantum state ...

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The combined rest mass of a proton and an electron is less than that of a neutron. Fundamentally then, what you need to start turning a star into a neutron star is that the protons and electrons need kinetic energy as well as rest mass energy. How much energy: Well at a minimum (assuming the neutrino doesn't get much), then an electron interacting with a ...

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The minimum mass for one to form is 1.44 solar masses. Energy barrier: Neutron mass - 1 Proton mass - 0.99862349 Electron mass - 0.00054386734 $p+e→n+v_e$ Assuming that the neutrino mass is negligible, we get the difference between the neutron mass and the electron-proton mass to be 780 keV, meaning this is the energy barrier.

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How then, can they collapse, without violating the Pauli Exclusion Principle. At a certain point does it no longer apply? No. The Pauli Exclusion provides a "degeneracy pressure" as mentioned in the article. That degeneracy pressure is not great enough to stop the collapse in the case of a black hole. This isn't violating the Pauli Exclusion ...

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I don't know much about gravity, but, as far as I understand, collapse does not mean violation of the Pauli principle: I guess the radius of the black hole is still finite. Collapse just means that it becomes a black hole, that is, light cannot escape it.

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