2012, Authors A-M

Black Hole Horizons and How They Begin

By Dieter Brill   Thu, Jan 19, 2012

ABSTRACT
Properties of black holes are examined that follow from the definition of the horizon as the
boundary of the past of null infinity. The beginning of the black hole is defined as the set of
spacetime events at which the null geodesics that generate the horizon enter the horizon. This
set is spacelike and appears as a crease in the horizon because at least two generators cross at
each of its points. The relation between the crease set and future null infinity is that between
object and image produced by the gravitational lensing of the collapsing mass-energy. The
crease set is not a manifold but has the structure of a tree. Near a vertex the horizon is a cone
over a polyhedron.

By Dieter Brill