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I know someone or something sucked into a black hole could not survive, but is the bending of light so immense that an observer falling into a black hole will be able to witness any future events in the universe? That would definitely be cool :D I have a feeling this won't work though... so could you explain in detail why? Thanks.

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up vote 9 down vote accepted

The normal presentation of these gravitational time dilation effects can lead one to a mistaken conclusion. It is true that if an observer (A) is stationary near the event horizon of a black hole, and a second observer (B) is stationary at great distance from the event horizon, then B will see A's clock to be ticking slow, and A will see B's clock to be ticking fast. But if A falls down toward the event horizon (eventually crossing it) while B remains stationary, then what each sees is not as straight forward as the above situation suggests. As B sees things: A falls toward the event horizon, photons from A take longer and longer to climb out of the "gravtiational well" leading to the apparent slowing down of A's clock as seen by B, and when A is at the horizon, any photon emitted by A's clock takes (formally) an infinite time to get out to B. Imagine that each person's clock emits one photon for each tick of the clock, to make it easy to think about. Thus, A appears to freeze, as seen by B, just as you say. However, A has crossed the event horizon! It is only an illusion (literally an "optical" illusion) that makes B think A never crosses the horizon.

As A sees things: A falls, and crosses the horizon (in perhaps a very short time). A sees B's clock emitting photons, but A is rushing away from B, and so never gets to collect more than a finite number of those photons before crossing the event horizon. (If you wish, you can think of this as due to a cancellation of the gravitational time dilation by a doppler effect --- due to the motion of A away from B). After crossing the event horizon, the photons coming in from above are not easily sorted out by origin, so A cannot figure out how B's clock continued to tick.

A finite number of photons were emitted by A before A crossed the horizon, and a finite number of photons were emitted by B (and collected by A) before A crossed the horizon.

You might ask What if A were to be lowered ever so slowly toward the event horizon? Yes, then the doppler effect would not come into play, UNTIL, at some practical limit, A got too close to the horizon and would not be able to keep from falling in. Then A would only see a finite total of photons form B (but now a larger number --- covering more of B's time). Of course, if A "hung on" long enough before actually falling in, then A might see the future course of the universe.

Bottom line: simply falling into a black hole won't give you a view of the entire future of the universe. Black holes can exist without being part of the final big crunch, and matter can fall into black holes.

For a very nice discussion of black holes for non-scientists, see Kip Thorne's book: Black Holes and Time Warps.

From this source

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The confusion about finite or infinite time dilation at the Schwarzschild radius began since Karl Schwarzschild in 1915 used a space-time coordinate system where coordinate time went to +∞ when a falling object approached the Schwarzschild radius. But t → +∞ for a world line that approaches the horizon is a thing different from t → +∞ far from the black hole. An object that is about to cross the horizon is in no position to synchronize clocks with an outside world.

No, completely opposite situation to the OP’s expectations. If a falling observer will transmit a powerful beam of light out of the hole, then photons will reach increasingly far future of the exterior universe. But the future seen by the falling observer will be very limited; see for graphic depiction.

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The only people who are still confused about the difference between coordinate and true singularities are at most beginning students. So it is not clear about who s confusion the first sentence talkes about; working physicists can not be meant. – Dilaton Aug 25 '14 at 23:18
@Dilaton: some people trying to understand black holes become confused. And not necessarily about “coordinate singularity” in Schwarzschild’s coordinates, but generally about clock synchronization with a falling object. I do not see how your comment about supposed “working physicists” is helpful. – Incnis Mrsi Aug 27 '14 at 7:03

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