A neutron star collapses - where's pauli?

[fargoth]

neutrons are fermions, with half spin, as such the must not occupy the same quantum state (meaning the wave functions can't overlap - atleast not with a big probability density portion of each other).
so, if neutron star is in the most dense state it can get, meaning its degenerate and every level is taken - how can it collapse?

 

[WMGoBuffs]

That degeneracy pressure is what keeps the neutron star from collapsing in the first place. Only if there is enough mass to overcome this degeneracy pressure does the star collapse into a black hole.

 

[James R]

What happens to the matter when a neutron star collapses to become a black hole? Nobody really knows. I think that's why we need a quantum theory of gravity.

 

[humanino]

neutrons are fermions, with half spin, as such the must not occupy the same quantum state (meaning the wave functions can't overlap - atleast not with a big probability density portion of each other).
so, if neutron star is in the most dense state it can get, meaning its degenerate and every level is taken - how can it collapse?

It is very naive to just picture a neutron star as a huge stack of neutrons. This is a semi-classical point of view. Neutrons are not fundamental particles : at the energies, pressures, density scales involved in neutrons stars, the intermost layers (the core) of the star must be a real soup of mesons and quarks (quark and gluon plasma, if such a thing exists). My point is the following : sure before we can claim to understand black hole formation, we need quantum gravity. Yet even before we have that at disposal, we need to understand quark matter.

(Now I'm waiting for Kea who will claim we cannot understand QCD (and especially the mass gap and confinement) before we reach quantum gravity theory tools )

 

[fargoth]

i thought when a red quark is coupled with blue and green quarks they disable each other's fields almost complitely...
and even if this is like a crystal made of quarks.. it takes-up a deffinite space, quarks have half spin too, and they can't exist at the same place.
ok, so the bottom line is no one knows... is there any proof that neutron stars collapse? i mean, what's the diffrence between a massive neutron star and a black hole when we watch them? can't a neutron star be invisible and have lots of gravity?

 

[starfield]

I Must Say That Your Questions Was Genuinely A Beautiful One, Fargoth...it Has Start Me Thinking Too... :)

 

[Hans de Vries]

It is very naive to just picture a neutron star as a huge stack of neutrons. This is a semi-classical point of view. Neutrons are not fundamental particles : at the energies, pressures, density scales involved in neutrons stars, the intermost layers (the core) of the star must be a real soup of mesons and quarks (quark and gluon plasma, if such a thing exists). My point is the following : sure before we can claim to understand black hole formation, we need quantum gravity. Yet even before we have that at disposal, we need to understand quark matter.

(Now I'm waiting for Kea who will claim we cannot understand QCD (and especially the mass gap and confinement) before we reach quantum gravity theory tools )

Lattice QCD seems to get really rolling now.

A new determination of light quark masses:
http://latticeqcd.blogspot.com/2005/11/new-determination-of-light-quark.html

Most Precise Mass Calculation For Lattice QCD:
http://www.aip.org/pnu/2005/split/731-1.html

So, We probably may see this work extended in the not to far away
future to hypothetical "Quark-stars" or other interesting objects.


Regards, Hans