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Stephen Hawking Presents Theory On Getting Information Out of a Black Hole
An anonymous reader writes: Physicist Stephen Hawking claims to have figured out a way for information to leave a black hole. He presented his theory today at the KTH Royal Institute of Technology in Stockholm. Scientists have struggled with the black hole information paradox for years, and Hawking thinks this new theory could be a solution. He said, "I propose that the information is stored not in the interior of the black hole as one might expect, but in its boundary, the event horizon." Put in layman's terms, "this jumbled return of information was like burning an encyclopedia: You wouldn't technically lose any information if you kept all of the ashes in one place, but you'd have a hard time looking up the capital of Minnesota." Information can leave the black hole via Hawking radiation, though it will be functionally useless. Hawking worked with Cambridge's Malcolm Perry and Harvard's Andrew Stromberg on this theory.
A particle falling into a black hole never perceives itself as having moved past an event horizon, as an apparent event horizon recedes before it. The horizon keeps receding in the direction of the "singularity" until it's torn apart on the way in.
An external observer never perceives a particle falling past the so-called "true" horizon; it perceives the falling object's time as slowing down to a virtual stop at the event horizon.
Both of these views are logically consistent under a simple constraint: nothing ever passes an event horizon, and there's no such thing as a "true" horizon, only apparent horizons. The outside observer's view of "truth" should be given no more precedence as being reality than the infalling observer's perception.
The same nothing-moves-past-the-event-horizon rule must apply to particles falling into the black hole as it's forming: they never get to reach a "singularity" either. Meaning nothing is ever in a singularity state, even that which formed the black hole itself.
As a black hole evaporates, its mass drops and its event horizon moves inward. Hence, an outside observer will perceive more of an infalling particle's progress inward, as if time is slowly being released. The infalling particle perceives no wait, just a continuous fall. Since the outside observer is seeing the infalling particle's time as moving many, many orders of magnitude slower, then for the two reference frames to be logically consistent, the amount of black hole power output perceived by the outside observer must be perceived by the infalling particle to be many, many orders of magnitude more intense. Hence it's far from black to the infalling particle, rather an intense source of radiation, growing ever more violent as the particle falls further in.
In short, all of this implies that black holes, to an outside observer, are basically a spot where time slows to a near stop, slowly leaking it out as they radiate away. To an infalling observer, he's just falling into a collapsing star that grows ever more radiatively intense as it collapses. The infalling particle, like everything else that falls into the black hole in the collapse, is blown apart by the intense radiation. But no special rules occur, no loss of information - and no singularity.
Or whatever, what do I know ;)
Stale pastry is hollow succor to one who is bereft of ostrich.
I don't know if that is Suskind's view. Some physicists certainly hold the view that you do not see inside the black hole and what an external observer thinks of as the interior is really the surface.
That however is not the holographic principle. The holographic principle stats that there is an equivalence of certain 3 dimension gauges theories with four dimensional quantum gravity.
You're getting hung up on the word information. It's a term of art in this context. The physics is relying on an an equivalency between information content and energy. In many cases it's easier to model blackholes from an information-theoretic context. That is, bits go in, bits come out. It's like the word entropy--the same word is used to describe seemingly different phenomena regarding both information and energy, but really it's the same phenomenon.
Just replace "information" with "energy" and it will make more sense. By information coming out, they mean energy is coming out. And energy, of course, is that thing which allows us to perform useful work.
Why does this matter? Well remember that the laws of thermodynamics say that entropy is always increasing in a closed system. If blackholes sucked entropy out of the universe, the implications are problematic, for reasons I don't really understand, and that aren't resolved by simply stating the obvious--blackholes are part of the universe.
Rather than calling this the "entropy" paradox, though, it's called the "information paradox". It's just easier to reason about it when you think in terms of bits.
Also, your original assertion is incorrect. Imagine that we burn a tiny piece of paper with some secret information on it. Theoretically with enough cameras, recorders, and other equipment we could reconstitute the secret by tracking every scrap of carbon and every other molecule. But it requires tremendous resources. The resources needed scale as a high-order geometric function of the size (or complexity) of the thing we burned. If we thoroughly burnt a book, there wouldn't be enough resources on earth, perhaps the solar system, to build the machines needed to track and reconstitute the information.
Because the universe is finite, and the information released by a blackhole so "scrambled", there's not enough energy in the entire universe to unscramble it. As large as the universe is, it's no match for math. But we _know_ the information is there because the energy emitted can be used to perform work.
Being able to reassemble it is not the point, it's that you can re-wind time and get the information back out. With the normal idea of a blackhole, even if you could rewind time, you couldn't get the information back out.