# Can you communicate future information through the event horizon?

According to Hawking on "Particle Creation by Black Holes", there exists a relationship between the entropy outside of an event horizon, flux within the event horizon, and the area of that same event horizon.

Therefore a black hole can absorb a negatively charged -EDIT: negative energy- particle, and in exchange it's positive partner radiates off into infinity and in exchange contributes to an increase background radiation. In exchange its event horizon shrinks after eating the negative particle, balancing it out.

It must also be able to emit those particles too, according to Hawking.

http://www.itp.uni-hannover.de/~giulini/papers/BlackHoleSeminar/Hawking_CMP_1975.pdf

It then gets too math-heavy for me to understand.

You could conceivably just continue to expand and contract the event horizon by tunneling particles through the event horizon until it contracts down enough that you could tunnel your specific particle back.

So basically information cannot be lost in black holes, just stored until it radiates enough particles off that it collapses and releases the particle that tunneled in.

The particle that tunneled would have to get extremely close to the edge of the event horizon, with the distance from it dictating how long before the event horizon expands towards it and it tunnels through.

With this in mind, wouldn't you technically be pulling information out of the future, since the particle that did tunnel had experienced way more time than the observer looking at it, and then tunneled back to greet him, the same particle $\ P$ that went in, except 'older'?

If so, why the hell can a particle interact with the future? Is it interacting with another part of the universe that is further away from the black hole than time cannot propagate enough to 'catch up'? Is it in a different universe?

• I think you mean positive and negative energy, not charge, in the second paragraph. – Sheepman Apr 26 '15 at 23:11
• Where do you get the idea from that the particle that enters a black hole has some kind of independent existence from the other particles in there? That would require that you could distinguish it somehow, which is not possible. What you really need to do is count states of the black hole as a whole. – CuriousOne Apr 26 '15 at 23:11
• @CuriousOne Since information cannot be permanently lost in the black hole, collapsing the states into one, you just keep manipulating the energy levels within the event horizon, and your information particle would leak out. You would need to have returned the black hole to the excitement level it was in before injection. And no, you'd only need to track the state changes after the information injection, so that you could reverse it. The state it changes into would be a function of the energy input, so your one particle would change the state by x. – ARMATAV Apr 26 '15 at 23:28
• ARMATAV: For all practical purposes information is lost in nature all the time. I can pour a drop of milk in my coffee and it would be impossible for you or anyone else in the universe to collect the molecules of that drop of milk back the way they were. In reality you can't even keep two electrons separate unless you have a potential barrier, which requires, at least, a classical magnetic field (which is a non-existing construct). So the core of the black hole debate is really all about state counting. What is the number of quantum mechanical states of a black hole? – CuriousOne Apr 26 '15 at 23:38
• @ARMATAV: Analogies don't help you much in statistical mechanics. Either you know the symmetries and then you can count, or you don't. The truth is that we don't know what the internal microscopic structure of a black hole looks like. Moreover, we don't know what the quantum gravity vacuum looks like that they are connected to. You can't just drop something into a black hole and then not expect it to radiate gravitational waves, which you have to take into account if you want to talk about actual information. If you don't collect the gravitational waves, you lost something, already. – CuriousOne Apr 26 '15 at 23:59