equations for the electric field suggest that the field lines should not be broken. When an electrical charge passes through a wormhole, the particle's charge field lines appear to emanate from the entry mouth and the exit mouth gains a charge density deficit due to Bernoulli's principle. (For mass, the entry mouth gains mass density and the exit mouth gets a mass density deficit.) Since a Kerr singularity has the same feature, it also allows this issue to be studied. Existence of ring singularities It is generally expected that since the usual collapse to a point singularity under general relativity involves arbitrarily dense conditions, quantum effects may become significant and prevent the singularity forming ("quantum fuzz"). Without quantum gravitational effects, there is good reason to suspect that the interior geometry of a rotating black hole is not the Kerr geometry. The inner event horizon of the Kerr geometry is probably not stable, due to the infinite blue-shifting of infalling radiation. This observation was supported by the investigation of charged black holes which exhibited similar "infinite blueshifting" behavior. While much work has been done, the realistic gravitational collapse of objects into rotating black holes, and the resultant geometry, continues to be an active research topic. See also Black hole Black hole electron Gravitational singularity Geon (physics) Further reading Thorne, Kip, Black Holes and Time Warps: Einstein's Outrageous Legacy, W. W. Norton & Company; Reprint edition, January 1, 1995, . Matt Visser, Lorentzian Wormholes: from Einstein to Hawking (AIP press, 1995) References Black holes Wormhole theory