Random832 <random...@fastmail.com>: > All objects, not just black holes, have those properties. The point > here is that we are in fact observing those properties of an object > that is not yet (and never will be) a black hole in our frame of > reference.
A physicist once clarified to me that an almost-black-hole is practically identical with a black hole because all information about anything falling in is very quickly red-shifted to oblivion. However, there is some information that (to my knowledge) is not affected by the red shift. Here's a thought experiment: ---------- / \ / (almost) \ N | black | | | hole | S \ / \ / ---------- We have a stationary, uncharged (almost) black hole in our vicinity and decide to send in a probe. We first align the probe so it is perfectly still wrt the black hole and let it fall in. Inside the probe, we have a powerful electrical magnet that our compass can detect from a safe distance away. The probe is also sending us a steady ping over the radio. As the probe approaches the event horizon, the ping frequency falls drastically and the signal frequency is red-shifted below our ability to receive. However, our compass still points to the magnet and notices that it "floats" on top of the event horizon: ---------- / \ / (almost) \ N | black || | hole |S \ / \ / ---------- / / compass needle / -- https://mail.python.org/mailman/listinfo/python-list