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by pino999
585 days ago
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It goes like this: We have two observers with a computer. A is outside a black hole. B goes over the event horizon. B is infinitely time dilated seen from A. It takes forever for B to reach the singularity from A standpoint. B reaches the middle in a finite time. A starts computation. If it halts A sends a result, otherwise it won't. B sees the result in a finite time. If it doesn't, the program didn't halt. If time is discrete, it won't fly I think. This works because there is no smallest time unit in gr. We are working with different types of infinities. A's computational steps take, the further B goes in, less time. Sort of Zeno's paradox. It is easy to map all natural numbers between 0 and 1 on the real line. Just not 1 to 1. There are more problems. How to get the information out and how to survive the divergent blue shift, it is somewhat unclear. B cannot talk back. But still a cool find. |
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For the usual meaning of the term, you certainly can construct a 1-to-1 (that is, injective) map N \to [0, 1] (for example, n \mapsto 10^(-n)); the natural numbers just can't be mapped onto [0, 1] (that is, the map can't be surjective). That's the opposite of the problem we have: it's saying you can losslessly encode a countable amount of information in an uncountable amount of space; but I'm saying conversely that you can't perform an uncountable number of steps in a countably infinite amount of time.