WTF is "information"

[Rye]

An apparently simple question to answer, I just recalled when Hawking said that information is not lost in a black hole, but what does this actually mena? What is this "information"?

[Darth RyanKCR]

An apparently simple question to answer, I just recalled when Hawking said that information is not lost in a black hole, but what does this actually mena? What is this "information"?

Mass, Velocity, ETC. The idea is that what every enters the black hole becomes part of the mass of the black hole and loses all of it's distinctive charecteristics. And since nothing can escape a black hole (well almost nothing ie Hawking's radiation) whatever it was is now lost.

[Sriad]

An apparently simple question to answer, I just recalled when Hawking said that information is not lost in a black hole, but what does this actually mena? What is this "information"?

Mass, Velocity, ETC. The idea is that what every enters the black hole becomes part of the mass of the black hole and loses all of it's distinctive charecteristics. And since nothing can escape a black hole (well almost nothing ie Hawking's radiation) whatever it was is now lost.

Or, if it is not lost as Hawking is suggesting, some ghost of the information continues and can be recovered (with arbitrarily advanced technology) by information on the black hole's own exact event horizon shape and emerging Hawking radiation.

And really who are we to argue? The stuff is named after him anyway.

[tharkûn]

Information is a measure of the number of distinguishable states "availible" to a system.

If a system S has N distinguishable states then:

I(S) = log N

The problem with black holes comes that the old theory, before Hawking recanted, was that you toss a system (say a crystal lattice) into a blackhole and it is infinitely compacted and there is only one state resulting; one which is completely described by the mass, charge, and spin of the black hole (as opposed to the quantum numbers, etc. of the original lattice).

Loss of information may be tantamount to violating thermo II and hence results in bad juju for theoretical blackhole physicists.

Recently Hawking has some new idea out that at some point in time a black hole opens up (I have no clue what this means) and the number of states coming back out is equivalent to those that went in. How this works, I can't follow, but current theory is that black holes do not destroy information.

[mr friendly guy]

I thought information was defined as the randomness of a system. I am not too clear how that necessarily applies to physical objects, but I can explain it in terms of words

For example

the set "aaaaa" has little information , ie randomness.

The set "The quick brown fox jumps over the lazy dog" has more information, which in this case is also meaningful

The set "abcdefhgheoatosygha'gh" has lots of information even though the set itself is meaningless as its just a random assortment of letters I typed up.

[Thinkmarble]

Specify the field you are woring in and you might get somewhere.
Shannons concept of information is distinct from the concept of entropy and information in physics, something which creationists never quite manage to understand.

[Molyneux]

Information is a measure of the number of distinguishable states "availible" to a system.

If a system S has N distinguishable states then:

I(S) = log N

The problem with black holes comes that the old theory, before Hawking recanted, was that you toss a system (say a crystal lattice) into a blackhole and it is infinitely compacted and there is only one state resulting; one which is completely described by the mass, charge, and spin of the black hole (as opposed to the quantum numbers, etc. of the original lattice).

Loss of information may be tantamount to violating thermo II and hence results in bad juju for theoretical blackhole physicists.

Recently Hawking has some new idea out that at some point in time a black hole opens up (I have no clue what this means) and the number of states coming back out is equivalent to those that went in. How this works, I can't follow, but current theory is that black holes do not destroy information.

Wait...so we're back to white holes again, just without the wormholes?

Nichelle Nichols: "It's about that rip in space-time that you saw!"
Stephen Hawking: "I call it a Hawking Hole."
Fry: "No fair! I saw it first!"
Stephen Hawking: "Who is the Journal of Quantum Physics going to believe?"

[tharkûn]

Wait...so we're back to white holes again, just without the wormholes?

Ehh what I can follow is that we now have hairy blackholes and that something screwy goes on with the wavefunctions inside the event horizon. Hawking did hand over the encyclopedia though.

[Kettch]

Rye, the quick dirty answer:

In physics you have to be able to run the clock backwards, at least in theory. I.e. blow something up, you can in theory find a the bits & pieces of an explosion you did not see & figure out exactly what was blown up & how, & what happened to the object before that, etc.

If something was dropped into a black hole, the question is, can you stop by at a later date & figure out, what was dropped in the BH? The only things that come out of a Black hole are Gravity, & Hawking radiation.

Hawking said, yes I can look at a BH & atleast in theory pull out the history of what went into the hole.