- #1

- 39

- 2

The solution of Einstein's field equations for a simple black hole show a slowing of time as you get close to the black hole. Time stops at the event horizon. An observer in flat spacetime far from the hole would see an astronaut fall slower and slower as he approaches the event horizon. It would take an infinite amount of time (as seen by the outside observer) for him to reach it. But a black hole will completely evaporate by Hawking radiation in a very long but finite time. So the observer will see that the astronaut never enters the black hole and he is in empty flat space again after the complete evaporation of the black hole trillions of years in the future. The astronaut could then go and shake hands with the outside observer.

From the astronaut's point of view, he will be in a free fall for only a short time during which he will see time running extremely fast for the outside universe. He will free fall through the event horizon, not noticing anything strange. Once inside the black hole, he will free fall for a short finite time until he is torn apart be tidal forces and his atoms get crushed at the singularity.

How can these two points of view be compatible? How can the astronaut be killed in the black hole but still survive, see the black hole evaporate, and meet the outside observer in the far future?

What am I interpreting wrong? Have I made an error in describing either the astronaut's experiences or the outside observer's point of view?

Jeff

From the astronaut's point of view, he will be in a free fall for only a short time during which he will see time running extremely fast for the outside universe. He will free fall through the event horizon, not noticing anything strange. Once inside the black hole, he will free fall for a short finite time until he is torn apart be tidal forces and his atoms get crushed at the singularity.

How can these two points of view be compatible? How can the astronaut be killed in the black hole but still survive, see the black hole evaporate, and meet the outside observer in the far future?

What am I interpreting wrong? Have I made an error in describing either the astronaut's experiences or the outside observer's point of view?

Jeff

Last edited by a moderator: