Editing Stellar evolution (section)

===Black holes===
{{Main|Black hole}}
If the mass of the stellar remnant is high enough, the neutron degeneracy pressure will be insufficient to prevent collapse below the [[Schwarzschild radius]]. The stellar remnant thus becomes a black hole. The mass at which this occurs is not known with certainty, but is currently estimated at between 2 and {{Solar mass|3}}.

Black holes are predicted by the theory of [[general relativity]]. According to classical general relativity, no matter or information can flow from the interior of a black hole to an outside observer, although [[quantum mechanics|quantum effect]]s may allow deviations from this strict rule. The existence of black holes in the universe is well supported, both theoretically and by astronomical observation.

Because the core-collapse mechanism of a supernova is, at present, only partially understood, it is still not known whether it is possible for a star to collapse directly to a black hole without producing a visible supernova, or whether some supernovae initially form unstable neutron stars which then collapse into black holes; the exact relation between the initial mass of the star and the final remnant is also not completely certain. Resolution of these uncertainties requires the analysis of more supernovae and supernova remnants.