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So if enough matter feel into a black hole, we'd get an entangled parallel universe? Big question then it's what is the entanglement "key" and its properties.

So if enough matter feel into a black hole, we'd get an entangled parallel universe? Big question then it's what is the entanglement "key" and its properties. Or how to even brute force it.

FooBarBizBazz 6y ago
Blind leading blind: My impression was that parallel universes do not feature. Rather, it was that, contrary to appearances, Hawking radiation contains all the same information that went into the black hole. However, this information appears only in the joint distribution over those photons rather than in any of the marginal distributions. Broken metaphor: You throw a coin into a black hole. Was it heads or tails? Two photons escape the black hole, both spin-up* with 50% probability -- they each appear to carry no information about the coin. But suppose that if they are the /same/ spin, then the coin was heads, and if they are /different/ spin then the coin was tails. In this way the coin's information is not destroyed, but is also not carried by any individual photon. * I have no idea if spin is actually the property of the radiation that carries the information. I also get the impression that it is later photons that must somehow be entangled with earlier ones. That -- referring to that V-shaped curve -- the black hole is storing up information about what went in up to about the halfway point in time, which it later radiates away during the second half. Waiting for an actual physisict to chime in, as, disclaimer, I don't actually know anything about this.
- bryanrasmussen 6y ago
  >You throw a coin into a black hole. Was it heads or tails? being heads or tails is a property of landing with all of one side of the coin facing down. This does not seem possible in the situation described.
  - sudosysgen 6y ago
    Of course, but it doesn't matter. Any bit of information can do the trick here.
- minitoar 6y ago
  I read it as "every photon emitted carries information about everything that fell into the hole up until that point, but you don't get complete information about everything until the very last photon is emitted".
- andreareina 6y ago
  There's a Royal Institute video featuring Sean Carroll and Jen Ouelette[1] that more fully explains the problem, but as I understand it it comes down to a quantum mechanical principle called monogamy of entanglement---there's only so much entanglement to go around, and if two particles (e.g. the pair of Hawking radiation particles) are fully entangled then they cannot have any amount of entanglement with anything else (e.g. information about the black hole). The result in TFA breaks the entanglement between the Hawking pair, allowing the outgoing particles to encode the black hole's information. [1] https://www.youtube.com/watch?v=_8bhtEgB8Mo https://www.youtube.com/watch?v=_8bhtEgB8Mo

So if enough matter feel into a black hole, we'd get an entangled parallel universe? Big question then it's what is the entanglement "key" and its properties. Or how to even brute force it.

FooBarBizBazz 6y ago

Blind leading blind: My impression was that parallel universes do not feature. Rather, it was that, contrary to appearances, Hawking radiation contains all the same information that went into the black hole. However, this information appears only in the joint distribution over those photons rather than in any of the marginal distributions. Broken metaphor: You throw a coin into a black hole. Was it heads or tails? Two photons escape the black hole, both spin-up* with 50% probability -- they each appear to carry no information about the coin. But suppose that if they are the /same/ spin, then the coin was heads, and if they are /different/ spin then the coin was tails. In this way the coin's information is not destroyed, but is also not carried by any individual photon. * I have no idea if spin is actually the property of the radiation that carries the information. I also get the impression that it is later photons that must somehow be entangled with earlier ones. That -- referring to that V-shaped curve -- the black hole is storing up information about what went in up to about the halfway point in time, which it later radiates away during the second half. Waiting for an actual physisict to chime in, as, disclaimer, I don't actually know anything about this.

bryanrasmussen 6y ago
>You throw a coin into a black hole. Was it heads or tails? being heads or tails is a property of landing with all of one side of the coin facing down. This does not seem possible in the situation described.
- sudosysgen 6y ago
  Of course, but it doesn't matter. Any bit of information can do the trick here.
minitoar 6y ago
I read it as "every photon emitted carries information about everything that fell into the hole up until that point, but you don't get complete information about everything until the very last photon is emitted".
andreareina 6y ago
There's a Royal Institute video featuring Sean Carroll and Jen Ouelette[1] that more fully explains the problem, but as I understand it it comes down to a quantum mechanical principle called monogamy of entanglement---there's only so much entanglement to go around, and if two particles (e.g. the pair of Hawking radiation particles) are fully entangled then they cannot have any amount of entanglement with anything else (e.g. information about the black hole). The result in TFA breaks the entanglement between the Hawking pair, allowing the outgoing particles to encode the black hole's information. [1] https://www.youtube.com/watch?v=_8bhtEgB8Mo https://www.youtube.com/watch?v=_8bhtEgB8Mo