Regarding the temperature of a black hole. There is a way it is calculated based on the predicted Hawking radiation correlated against standard black body radiation. The larger it is, the colder it is. Small black holes, like the ones feared to be produced by the LHC, would be quite hot, and evaporate in a burst of radiation.
I believe gravity would still be attractive under a reversal of time. The distance an object falls being proportional to 1/2 a t^2, if the time interval is negative, the direction of the motion does not change. After all, we know the Earth has been orbiting the sun for a long time so reversing the arrow of time we would expect to see it just orbit backward. If it flew out of orbit instead, the theory would be wrong. But I am all for anti-gravity, so I can finally get that hover board.
Perhaps in an antimatter universe, moving backward in time, entropy would increase as time progresses backward. But would we be able to tell the difference between that universe and our own if we were living in it?
I believe gravity would still be attractive under a reversal of time. The distance an object falls being proportional to 1/2 a t^2, if the time interval is negative, the direction of the motion does not change. After all, we know the Earth has been orbiting the sun for a long time so reversing the arrow of time we would expect to see it just orbit backward. If it flew out of orbit instead, the theory would be wrong. But I am all for anti-gravity, so I can finally get that hover board.
Perhaps in an antimatter universe, moving backward in time, entropy would increase as time progresses backward. But would we be able to tell the difference between that universe and our own if we were living in it?