Structure of the black hole nucleus

Explores different possibilities for the nuclear structure of a black hole formed by a collapse with zero angular momentum. If the stress induced by vacuum polarisation along the axes of the 3-cylinders r=constant is a tension rather than a pressure, the spacetime geometry could be self-regulatory and describable semiclassically down to radii of a few Planck units. The nucleus would then appear as an open string of roughly constant sub-Planckian density, with a thickness of order (h(cross)G2M/c5)13/-about 10-20 cm for a solar-mass black hole.