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> and with the proper key to decode it one could theoretically peer inside the black hole I've never seen anything asserting this, and this is not what standar

> and with the proper key to decode it one could theoretically peer inside the black hole I've never seen anything asserting this, and this is not what standard theories say. The idea is that with the right "key" you can recover the information that was encoded in the stuff that fell into the black hole. As far as I know there is no suggestion this gives you any information about what is going on inside it.

kromem 3y ago
Ah, then you might enjoy one of the more fun reads I had this past year: https://www.quantamagazine.org/new-calculations-show-how-to-escape-hawkings-black-hole-paradox-20230802/ https://www.quantamagazine.org/new-calculations-show-how-to-... I wouldn't put money on it being the case, but it's definitely "outside the event horizon" thinking and worth a read.
- eigenket 3y ago
  That is indeed a fun read, but nothing in it contradicts what I said.
  - gosub100 3y ago
    You made a malformed statement, implying that time and events continue on, like nothing is wrong and the only difference is we can't see it. But space and time switch places inside a black hole. All directions lead toward the singularity, where as in our world, all directions lead toward the future. The units are incompatible between the two worlds.
    - eigenket 3y ago
      Could you perhaps quote exactly what statement I made which is malformed? In any case the picture of time and space switching places inside a black hole is at best a rather deceptive simplification. The most important thing about the event horizon is that locally (i.e. to one falling in to it) nothing at all interesting happens at the event horizon. Edit: The "swapping" you are referring to is an artifact of coordinate systems, not of space-time. Thinking something wild happens to space-time as you pass through the event horizon is the same as thinking that something wild happens to the Earth's geometry as you reach the north pole. Sure at the north pole there is no longer any meaningful direction other than "south" but thats an artefact of the coordinate system you're using, the pole is a normal point just like any other.
      - gosub100 3y ago
        To any single observer that crosses, I agree with your statement, but it changes the moment you have two observers. I also agree that at the North Pole, "all directions are south", but the difference is you are free to move back and forth. If you picture us in an X-Y plane (which somehow represents all 3 spatial coords), and "up" is the time dimension, then a black hole would be the X-Y plane deformed into a 90-deg "pipe" facing straight down. Once you are in the pipe, your "X-Y" is our "up-down", this is probably the "artifact" you are referring to.
        eigenket 3y ago
        > If you picture us in an X-Y plane (which somehow represents all 3 spatial coords), and "up" is the time dimension, then a black hole would be the X-Y plane deformed into a 90-deg "pipe" facing straight down. This is not correct, there is no 90 degree bend. Space-time is locally Minkowskian ("flat") at the event horizon. It looks like a sharp 90 degrees turn in some coordinate system, just as when you walk in a "straight line" (a great circle if you prefer) over the north pole you go discontinuously from "walking north" to "walking south" even though your real motion is continuous.
  - kromem 3y ago
    Strange you think that. Care to explain why you came to that conclusion? The preprint linked to lays it out more technically if that's your jam: https://arxiv.org/pdf/2207.06536.pdf https://arxiv.org/pdf/2207.06536.pdf See section 6 on exterior vs interior measurements, and you can see the discussion in the FAQ about how measurements on the radiation after the Page time creates particles in the interior (which cites section 6 for more details). Then 8.2-3 goes more into what information about the interior can be known from observables in the fundamental description before and after the Page time. The "Previous attempts at an encoded interior" section in the discussion could help further clarify things. It's not saying that it's trivial to see inside a black hole from the Hawking radiation, but it would be incorrect to characterize their model as saying that nothing about the interior can be known in measuring the Hawking radiation.
    - eigenket 3y ago
      My understanding (which is highly limited, I am a researcher in quantum information but quantum gravity is very far out of my reach) is that this essentially gives you information about degrees of freedom of "stuff" (I guess quantum fields) that has been thrown into the black hole. I.e. you throw a diary with information in, and you can (theoretically) learn that information from the Hawking radiation if you absorb enough of it. This is quite different from being able to probe the space-time structure inside (i.e. ask questions like is there a real singularity in there). If you think about what you'd need there, you need the opposite of what they have in the FAQ, you would need operations in the interior to be able to create a particle on the exterior in order to build a "telescope" to look inside and I'm pretty sure this is ruled out even in this proposal.
      - kromem 3y ago
        Actually that's what their section 6.3 is all about, how if you sent an observer inside the event horizon measurements could influence the outside. It just admits that the feasibility of this is ridiculous with my favorite line of the paper: > Physically this seems absurd, as it allows a measurement inside a black hole to produce a record which stays outside, but we are not claiming that any effective-description observer could actually implement this unitary. But I agree that there's a big difference between the plausibility of measuring the 'stuff' vs it's spacetime configuration - that was a great point.

kromem 3y ago

Ah, then you might enjoy one of the more fun reads I had this past year: https://www.quantamagazine.org/new-calculations-show-how-to-escape-hawkings-black-hole-paradox-20230802/ https://www.quantamagazine.org/new-calculations-show-how-to-... I wouldn't put money on it being the case, but it's definitely "outside the event horizon" thinking and worth a read.

eigenket 3y ago
That is indeed a fun read, but nothing in it contradicts what I said.
- gosub100 3y ago
  You made a malformed statement, implying that time and events continue on, like nothing is wrong and the only difference is we can't see it. But space and time switch places inside a black hole. All directions lead toward the singularity, where as in our world, all directions lead toward the future. The units are incompatible between the two worlds.
  - eigenket 3y ago
    Could you perhaps quote exactly what statement I made which is malformed? In any case the picture of time and space switching places inside a black hole is at best a rather deceptive simplification. The most important thing about the event horizon is that locally (i.e. to one falling in to it) nothing at all interesting happens at the event horizon. Edit: The "swapping" you are referring to is an artifact of coordinate systems, not of space-time. Thinking something wild happens to space-time as you pass through the event horizon is the same as thinking that something wild happens to the Earth's geometry as you reach the north pole. Sure at the north pole there is no longer any meaningful direction other than "south" but thats an artefact of the coordinate system you're using, the pole is a normal point just like any other.
    - gosub100 3y ago
      To any single observer that crosses, I agree with your statement, but it changes the moment you have two observers. I also agree that at the North Pole, "all directions are south", but the difference is you are free to move back and forth. If you picture us in an X-Y plane (which somehow represents all 3 spatial coords), and "up" is the time dimension, then a black hole would be the X-Y plane deformed into a 90-deg "pipe" facing straight down. Once you are in the pipe, your "X-Y" is our "up-down", this is probably the "artifact" you are referring to.
      - eigenket 3y ago
        > If you picture us in an X-Y plane (which somehow represents all 3 spatial coords), and "up" is the time dimension, then a black hole would be the X-Y plane deformed into a 90-deg "pipe" facing straight down. This is not correct, there is no 90 degree bend. Space-time is locally Minkowskian ("flat") at the event horizon. It looks like a sharp 90 degrees turn in some coordinate system, just as when you walk in a "straight line" (a great circle if you prefer) over the north pole you go discontinuously from "walking north" to "walking south" even though your real motion is continuous.
- kromem 3y ago
  Strange you think that. Care to explain why you came to that conclusion? The preprint linked to lays it out more technically if that's your jam: https://arxiv.org/pdf/2207.06536.pdf https://arxiv.org/pdf/2207.06536.pdf See section 6 on exterior vs interior measurements, and you can see the discussion in the FAQ about how measurements on the radiation after the Page time creates particles in the interior (which cites section 6 for more details). Then 8.2-3 goes more into what information about the interior can be known from observables in the fundamental description before and after the Page time. The "Previous attempts at an encoded interior" section in the discussion could help further clarify things. It's not saying that it's trivial to see inside a black hole from the Hawking radiation, but it would be incorrect to characterize their model as saying that nothing about the interior can be known in measuring the Hawking radiation.
  - eigenket 3y ago
    My understanding (which is highly limited, I am a researcher in quantum information but quantum gravity is very far out of my reach) is that this essentially gives you information about degrees of freedom of "stuff" (I guess quantum fields) that has been thrown into the black hole. I.e. you throw a diary with information in, and you can (theoretically) learn that information from the Hawking radiation if you absorb enough of it. This is quite different from being able to probe the space-time structure inside (i.e. ask questions like is there a real singularity in there). If you think about what you'd need there, you need the opposite of what they have in the FAQ, you would need operations in the interior to be able to create a particle on the exterior in order to build a "telescope" to look inside and I'm pretty sure this is ruled out even in this proposal.
    - kromem 3y ago
      Actually that's what their section 6.3 is all about, how if you sent an observer inside the event horizon measurements could influence the outside. It just admits that the feasibility of this is ridiculous with my favorite line of the paper: > Physically this seems absurd, as it allows a measurement inside a black hole to produce a record which stays outside, but we are not claiming that any effective-description observer could actually implement this unitary. But I agree that there's a big difference between the plausibility of measuring the 'stuff' vs it's spacetime configuration - that was a great point.