Description
I shall first present some historical remarks, and then in the technical part focus on the physics of horizons.
The event horizons, and Cauchy horizons, of mathematical General Relativity are mathematical idealisations
that are not particularly well suited to questions that physicists and astronomers like to ask.
For very many purposes dynamical trapping horizons are much more suitable.
I shall give a brief overview of the current situation; with some (possibly controversial) hints for the future...