How can black holes have electrical charge, and spin?

AI Thread Summary
Black holes can possess electrical charge and spin due to the conservation of angular momentum and charge during their formation from collapsing stars. Although a black hole's singularity is often described as having zero volume, it does not mean that it lacks angular momentum; rather, the spacetime around it can be affected by this momentum. Kerr and Newman black holes, for instance, do not collapse into points but rather into structures with non-zero circumference, maintaining their properties. The laws of conservation still apply, ensuring that any angular momentum or charge from the original star is retained in the resulting black hole. Therefore, the assertion that black holes have "zero" volume is misleading, as they can still exhibit significant physical characteristics.
Lamdbaenergy
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If the star's mass supposedly collapses into a single point, and it ends up having "said" zero volume, then how can people say that the hole has a specific spin or that it can have an angular momentum?

Does it mean that the singularity is somehow still spinning, or maybe the spacetime around it is just being dragged for some reason?
This subject has been confusing me quite a bit whenever I think about it.
 
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Where would the charge and angular momentum of the star go otherwise?

On a related issue: Elementary particles are also modeled as point like, yet can carry both intrinsic charge and angular momentum.
 
Lamdbaenergy said:
If the star's mass supposedly collapses into a single point, and it ends up having "said" zero volume, then how can people say that the hole has a specific spin or that it can have an angular momentum?

Does it mean that the singularity is somehow still spinning, or maybe the spacetime around it is just being dragged for some reason?
This subject has been confusing me quite a bit whenever I think about it.

Sometimes the BH's gravity field is referred to as a 'fossil' field-

http://math.ucr.edu/home/baez/physics/Relativity/BlackHoles/black_gravity.html
 
Turns out Kerr and Newman black holes do NOT contract into points. They contract to circles... which still have zero volume, because zero thickness throughout their nonzero circumference.
Reissner black holes are point charges, just like Schwarzschild black holes.
 
In short: the laws of conservation (angular momentum, charge, mass-energy, etc.) still work during the process of creation of a black hole. So if a star had some angular momentum/charge before it collapsed, the resulting black hole will also have some (assuming the angular momentum/charge was not radiated away during the collapse).

Also, the claim that black holes have "zero" volume is simply incorrect.
 
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