5 ms·

Do they destroy information? Last I checked they don't: https://physics.stackexchange.com/questions/29175/why-is-information-indestructible https://physics.stac

Do they destroy information? Last I checked they don't: https://physics.stackexchange.com/questions/29175/why-is-information-indestructible https://physics.stackexchange.com/questions/29175/why-is-inf... Maybe there is some recent development I am not aware of an Susskind is wrong though. More: - https://physics.stackexchange.com/questions/450326/why-is-the-information-paradox-restricted-to-black-holes https://physics.stackexchange.com/questions/450326/why-is-th...

ben_w 7y ago
That’s why it’s a problem — the two best tested laws of physics contradict each other.
- ailideex 7y ago
  Which law of physics say information must be lost in a black hole? AFAIK if information is lost in a black hole it will also violate the second law of thermodynamics - so really you have many many laws saying it cannot be lost - and Hawking temporarily claimed it will be lost in black holes before recanting and saying it won't. So ... I don't quite follow. I mean this title is as concerning to me as something that claims the earth is flat.
  - sohkamyung 7y ago
    I believe the 'No-hair theorem' is closest to a 'law' that says Black holes destroy information [1]. If it is true, then when you throw anything into a black hole, information about what you threw in (whether it is a chair, a star, a planet, etc.) is 'lost' as to the outside world they all yield the same observable parameters of the black hole. [1] https://en.wikipedia.org/wiki/No-hair_theorem https://en.wikipedia.org/wiki/No-hair_theorem
    - TeMPOraL 7y ago
      IANAPhysicist, but couldn't information be radiated away? When you have a particle and antiparticle annihilating, the information about what collided and when is carried away by the radiation from that annihilation event; nothing remains at ground zero to be inspected. As matter traverses the accretion disk and falls towards the event horizon, couldn't information about it be radiated away? As an observer, you could definitely tell whether somebody threw a planet or a planet-sized bunch of paperclips into a black hole by observing the accretion disk as it happened.
      - swebs 7y ago
        Outside the event horizon, sure. But imagine the (extremely) far future when the universe is dominated by black holes and even those photons have been absorbed. You would not be able to extract any information about the past universe aside from its mass.
        abakker 7y ago
        This may be a naive question, but, how do we know that the mass we measure for a black hole is equivalent to the things that went into the black Hole? We can’t have any observational data on what went into them in aggregate - is it not possible that the mass of black holes that we estimate is incorrect in some fundamental way? Or just that e.g. energy that enters them also becomes mass?
      - platz 7y ago
        As it stands, as far as we know, Hawking radiation is completely thermal and random, so as the article states, you can't tell the initial state from the final state even if you collect all the radiation. > observing the accretion disk Well that is not part of the black hole now, is it.
        posterboy 7y ago
        Kindly riddle me this. If a black hole was a closed system, then the premisses, that information inside will become lost, would be trivially true by the (2nd?) law of thermodynamics. There's energy going in, so it isn't hermetically sealed. Thus, the accretion disk is part of the system. But if there's no correlated information coming out, it's closed one-way. You say there is radiation coming out, theoreticly, and I know that radiation is information. It's information in one strict sense, but not in the other--what are the different scopes; Is the radiation not observable? Are the laws of thermodynamics seemingly violated, that is, is the theory not complete (rhethoric question); Thus your remark was in effect non-constructive, as you cannot prove one unknown with another, can you? Nevermind the kind of scary question whether any system in the grand scheme of things is closed at all. BTW another comment mentioned conservation of momentum and charge. I wonder, in the focal point of an ideal lense, in theory, can the image be reconstructed? Well, by looking at the flame quite trivially, at least, albeit not in the perspective of the focal point (not easily without ambiguity, surely). Is this what Tao's one-pixel-cam is about?
    - ailideex 7y ago
      IANAP but here is a physicist talking about no hair theorem and information loss paradox: https://www.youtube.com/watch?v=I55e6chHUs0 https://www.youtube.com/watch?v=I55e6chHUs0 TLDW: They probably do have hair.

ben_w 7y ago

That’s why it’s a problem — the two best tested laws of physics contradict each other.

ailideex 7y ago
Which law of physics say information must be lost in a black hole? AFAIK if information is lost in a black hole it will also violate the second law of thermodynamics - so really you have many many laws saying it cannot be lost - and Hawking temporarily claimed it will be lost in black holes before recanting and saying it won't. So ... I don't quite follow. I mean this title is as concerning to me as something that claims the earth is flat.
- sohkamyung 7y ago
  I believe the 'No-hair theorem' is closest to a 'law' that says Black holes destroy information [1]. If it is true, then when you throw anything into a black hole, information about what you threw in (whether it is a chair, a star, a planet, etc.) is 'lost' as to the outside world they all yield the same observable parameters of the black hole. [1] https://en.wikipedia.org/wiki/No-hair_theorem https://en.wikipedia.org/wiki/No-hair_theorem
  - TeMPOraL 7y ago
    IANAPhysicist, but couldn't information be radiated away? When you have a particle and antiparticle annihilating, the information about what collided and when is carried away by the radiation from that annihilation event; nothing remains at ground zero to be inspected. As matter traverses the accretion disk and falls towards the event horizon, couldn't information about it be radiated away? As an observer, you could definitely tell whether somebody threw a planet or a planet-sized bunch of paperclips into a black hole by observing the accretion disk as it happened.
    - swebs 7y ago
      Outside the event horizon, sure. But imagine the (extremely) far future when the universe is dominated by black holes and even those photons have been absorbed. You would not be able to extract any information about the past universe aside from its mass.
      - abakker 7y ago
        This may be a naive question, but, how do we know that the mass we measure for a black hole is equivalent to the things that went into the black Hole? We can’t have any observational data on what went into them in aggregate - is it not possible that the mass of black holes that we estimate is incorrect in some fundamental way? Or just that e.g. energy that enters them also becomes mass?
    - platz 7y ago
      As it stands, as far as we know, Hawking radiation is completely thermal and random, so as the article states, you can't tell the initial state from the final state even if you collect all the radiation. > observing the accretion disk Well that is not part of the black hole now, is it.
      - posterboy 7y ago
        Kindly riddle me this. If a black hole was a closed system, then the premisses, that information inside will become lost, would be trivially true by the (2nd?) law of thermodynamics. There's energy going in, so it isn't hermetically sealed. Thus, the accretion disk is part of the system. But if there's no correlated information coming out, it's closed one-way. You say there is radiation coming out, theoreticly, and I know that radiation is information. It's information in one strict sense, but not in the other--what are the different scopes; Is the radiation not observable? Are the laws of thermodynamics seemingly violated, that is, is the theory not complete (rhethoric question); Thus your remark was in effect non-constructive, as you cannot prove one unknown with another, can you? Nevermind the kind of scary question whether any system in the grand scheme of things is closed at all. BTW another comment mentioned conservation of momentum and charge. I wonder, in the focal point of an ideal lense, in theory, can the image be reconstructed? Well, by looking at the flame quite trivially, at least, albeit not in the perspective of the focal point (not easily without ambiguity, surely). Is this what Tao's one-pixel-cam is about?
  - ailideex 7y ago
    IANAP but here is a physicist talking about no hair theorem and information loss paradox: https://www.youtube.com/watch?v=I55e6chHUs0 https://www.youtube.com/watch?v=I55e6chHUs0 TLDW: They probably do have hair.