Due to the curvature of space-time near the event horizon of a black hole, time is warped so severely that an observer would see events happening in the outside universe in the distant future. In other words, the black hole itself always "sees" the rest of the universe in the distant future. Or even simpler, the black hole itself is in the distant future of the universe. Now, let's assume that in 100 billion years the universe will end due to a change in vacuum energy. This means that for the black hole, this moment has already arrived. But the black hole is also part of the universe, since it is located in it. And since for the black hole the universe has already collapsed, then it should not exist either. But since we observe black holes, does this mean that the universe has no end?
2 Answers
If the universe collapses or anything else happens in the future, it cannot destroy the black hole we are seeing now. Because the black holes, either non-rotating (Schwarzschild) or rotating (Kerr with sufficiently small angular momentum $a<M$) don't have closed timelike curves. The information about future events can't escape the event horizon. The future can't influence the past, even if there are black holes.
Also, the black hole can't vanish instantly: if its mass was non-zero a moment ago and is zero now, this violates the law of energy conservation. The only way for a black hole to vanish is to evaporate slowly because of the Hawking radiation.
- 1,005
You have probably come to this conclusion because from our perspective, someone falling into a black hole will appear "frozen" on the horizon. So you assume that from their perspective, they will the see the rest of the universe being fast-forwarded infinitely into the future. But this is wrong. A simple way to understand this is that from our perspective, any light signal travelling into the black hole will also appear to freeze at the horizon. The light signals from future events will thus never actually reach the falling person. See also this similar question for more detailed explanations.
The apparent "slowing down" of time near the event horizon as seen by us is in many ways just an optical illusion. The proper time to reach the event horizon is finite, and an observer crossing the event horizon will not experience anything unusual (apart from possibly tidal forces if the black hole is not large enough).
So in short, black holes do not "live in the future" in any meaningful way.
- 2,680
- 1
- 6
- 15