Until today, the understanding I had of black holes was as a spherical “event horizon” with a singularity at the centre. The event horizon is the surface of no return – anything which goes past it can never escape. The singularity is where quantum gravity kicks in, and is very handy for evading the speed-of-light limit in science fiction plots, where it functions as a gateway to a wormhole which can take the protagonists wherever they need to be.
All this changed during a talk by Samir Mathur of Ohio State University just now, here at the Lepton Photon meeting in Mumbai. It’s all to do with entropy.