Is information lost in a black hole?

  • Thread starter PRodQuanta
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Main Question or Discussion Point

Ok, so we know that black holes emit Hawking radiation. Knowing this, it is safe to say that over time, black holes will decrease in size until they disappear totally. After decreasing, everything should go back to normal, you'd think. My question is, does the "data", that had been sucked in by the black hole after crossing the event horizon and hurdled toward the singularity, just dissapear? Or does this "data" reappear?

Maybe a more laymen question is: Is there such a thing as conservation of data, according to a black hole? I'd surely think there would be.

Thoughts.

Paden Roder
 

Answers and Replies

  • #2
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If you burn a sheet of paper, can you recover whatever was written on it? I've heard of conservation of energy, not conservation of data.
 
  • #3
chroot
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Chen said:
If you burn a sheet of paper, can you recover whatever was written on it? I've heard of conservation of energy, not conservation of data.
In principle, yes, you could analyze the motion of every atom in the paper and recover what was originally there. In practice, no.

Black holes do indeed destroy information, and it is indeed a head-scratcher! Start here:

http://math.ucr.edu/home/baez/physics/Relativity/BlackHoles/info_loss.html

- Warren
 
  • #4
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chroot said:Black holes do indeed destroy information, and it is indeed a head-scratcher!
Is this factual. What I mean is: Could that be written in a physics textbook? Or is that just somebody's opinion?

I also see that they use quantum mechanics to describe it, which (I think) you need both QM and GR to explain a black hole. For quantum mechanics only works on the sub-macro scale (which, also, I think).

Once again, I say, I may be way off base here.

Thanks for the good read though. His hypothesis makes sense.

Chen said: I've heard of conservation of energy, not conservation of data
I have also heard of the 1st law of thermodynamics. I was just wondering if conservation of data (information) could really be something? Which I just found out (I think) is not.

Paden Roder
 
  • #5
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chroot said:
In principle, yes, you could analyze the motion of every atom in the paper and recover what was originally there. In practice, no.
Can it be proven that if I light the same piece of paper on fire over and over again, it would burn in the same way each and every time?
 
  • #6
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Chen said:Can it be proven that if I light the same piece of paper on fire over and over again, it would burn in the same way each and every time?
To answer for chroot, no. What he is saying is, if you were to observe the motion of every atom on that piece of paper, it is theoretically possible to reconstruct that paper atom by atom.

The probability of a paper burning the same way every time, would say no to your quesiton.

Paden Roder
 
  • #7
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But if the outcome of burning the same piece of paper changes every time we do it, isn't it possible that the outcome of burning two different papers can be the same? And then we face the problem of not knowing whether it was 2+2 or 16/4 that gave the answer of 4.

I'm not trying to challenge anyone, by the way. But it's 3AM and I'm bored. :wink:
 
  • #8
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Chen said: But if the outcome of burning the same piece of paper changes every time we do it, isn't it possible that the outcome of burning two different papers can be the same? And then we face the problem of not knowing whether it was 2+2 or 16/4 that gave the answer of 4.
All rightfully so, but what does this have to do with the constant or loss of information in a black hole?

Paden Roder
 
  • #9
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PRodQuanta said:
All rightfully so, but what does this have to do with the constant or loss of information in a black hole?
I am just wondering why you have to go as far as black holes to prove there is no such thing as conservation of information...
 
  • #10
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Chen said:I am just wondering why you have to go as far as black holes to prove there is no such thing as conservation of information...
And in come our first misconception :biggrin:

First off, my question was if black holes eliminate the infomation it sucks in, or if in conserves it.

Then, after that though, I wondered, if it didn't eliminate the information, if there would be such a thing as conservation of information. I wasn't trying to prove or disprove anything. I was just wondering?

I have no prejudice on if there is or isn't loss of information. Maybe that clears some things up.

Sorry for the misunderstanding,Chen!

Paden Roder
 
  • #11
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Why is it a problem if information is lost in a black hole?
Is this something to do with losing a wavefunction?
i.e the probability of a particle being in any state becomes zero-like the particle doesn't exist anymore and has vanished from the universe.
 
  • #12
To answer for chroot, no. What he is saying is, if you were to observe the motion of every atom on that piece of paper, it is theoretically possible to reconstruct that paper atom by atom.
I know I'm a little late with this, but there is one point about the burning paper that I'd like to discuss. If you know where each atom is at every moment in time, so that you can reassemble the piece of paper, surely you know the exact velocities and positions of every atom, which would violate the Uncertainty Principle.
 

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