# How does a neutron star collapse into a black hole?

I don't think that's the case and think the collapse is entirely from relativistic effects because I think that Neutron stars have a bulk modulus that exceeds their density multiplied by $c^2$ because I once read that some neutron stars have a photon sphere. Another possible explanation is that by the time a neutron star is massive enough to collapse into a black hole, it's still predicted to have negligible gravitational contraction according to Newtonain physics because of its such extreme bulk modulus and as a neutron star slowly gets bigger, the gravitational field stops being in an equilibrium state and starts the runaway effect of getting further away from that state until space actually starts getting dragged in faster than light and the gravitational field outside the event horizon is a self sustaining gravitational field which controls the gravitational field beyond the event horizon.