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.


1 Answer 1


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 http://jila.colorado.edu/~ajsh/insidebh/penrose_schw.html for graphic depiction.

  • $\begingroup$ 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. $\endgroup$
    – Dilaton
    Aug 25, 2014 at 23:18
  • $\begingroup$ @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. $\endgroup$ Aug 27, 2014 at 7:03

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