Proof that black holes do not destroy information

Join the discussion
Ask a follow-up here, or get your own question answered by working scientists, mathematicians and engineers — people, not an autocomplete.
Real named experts · corrections over time · the nuance an AI answer skips
2 replies · 1K views
Ipquarx
Messages
1
Reaction score
0
I have for you a simple proof that black holes do not destroy information, since wikipedia seems to be stating that it's an unsolved problem. http://en.wikipedia.org/wiki/List_of_unsolved_problems_in_physics

1. The second law of thermodynamics states that entropy must always increase.
2. If black holes destroyed information, that would lower the overall entropy of the universe.
Therefore, black holes cannot destroy information.

However I'm near certain it isn't that simple. What's wrong with this proof?
 
Astronomy news on Phys.org
Well, for a start, we say that black holes have entropy - see articles on Black Hole Thermodynamics.

But otherwise, what you've said isn't actually a proof, it's a restatement of the problem: Our understanding is that black holes destroy information, but that violates unitarity, and energy conservation, and all that fun stuff that we think has to be true in the universe. So something has to give. This is why it is an unsolved problem.
 
Welcome to PF;
You statement requires that (1) is true everywhere - even in black holes, and it equates "loss of information" with lower entropy.
So if both those things are true, the (2) must also be true.

But here's the thing - no information can travel faster than light.
Therefore, information cannot escape a black hole.
See the problem?

So your starting points are
(1) entropy must always increase
(2) information cannot escape a black hole
(3) information is entropy

For more um information...

Black holes, entropy and information (lecture)
http://web.physics.ucsb.edu/~gary/BH,Entropy,Info.pdf

information is not uncertainty
http://schneider.ncifcrf.gov/information.is.not.uncertainty.html

information cannot get out of a black hole
http://www.askamathematician.com/20...vity-then-how-does-the-gravity-itself-escape/

... but it is a popular topic so there's lots and lots about it.