7 ms·

Totally uninformed here: Have we proved the Hawking radiation is without information (or enough of it), or is it just 'encrypted' at a level we can't distingui

Totally uninformed here: Have we proved the Hawking radiation is without information (or enough of it), or is it just 'encrypted' at a level we can't distinguish from noise?

mannykannot 4y ago
This seems to address it (from the article): "[Hawking] radiation is thermal which means it’s random except for its temperature, and the temperature is inversely proportional to the mass of the black hole. This means two things. First, there’s no new information which comes out in the Hawking radiation..." Its mass is one of the few things we know from the outside.
- phendrenad2 4y ago
  How do we know it's thermal? How do we know there aren't small fluctuations that are too small for us to detect millions of miles away?
  - mannykannot 4y ago
    AFAIK Hawking radiation has never been detected. It is hypothesized on the basis of current theories of quantum mechanics and gravity, and those assumptions imply a thermal distribution of energy. So, we have a reason to think that Hawking radiation occurs and has this property, while no-one so far has proposed a mechanism that would encode data on it.
  - tsimionescu 4y ago
    It's important to understand that Hawking radiation is not something we've observed and have noticed seems random. Instead, Hawking radiation is a prediction of a mathematical model. In that model, Hakwing radiation is purely random. If I remember correctly, Hawking radiation is postulated to arise because of fluctuations in the vacuum giving rise to virtual particle pairs. Normally, these would annihiliate back almost instantly. But, when such an event happens near the event horizon, one of them may fall into the black hole, leaving the other one to "escape", and appear as if the event horizon is emitting radiation. Since this radiation is caused by random fluctuations in the void outside the event horizon, it can't be correlated with anything past the even horizon, so it can't carry information about that.
- GTP 4y ago
  Probably for OP this isn't enough: if the radiation was carrying encrypted information then it would look random without knowing the "key", whatever a "key" could be in the context of a physical system. But I think that talking about encryption here without a solid preparation in the filed of physics it is just trying to apply something we know to try to solve some problem we have no idea how to approach.
- andrewflnr 4y ago
  Thermal radiation from a classical object looks "random" but still obeys (and in fact inspired) quantum theory. The information about the past of the object is there, it's just unfeasible to recover. I suspect Hawking radiation is the same way.
  - lupire 4y ago
    Why do you suspect that? Do you deny that quantum mechanics is a valid model of the universe? Or do you believe quantum mechanics is equivalent to relativistic mechanins? Either would unwrite a century of physics.
    - andrewflnr 4y ago
      I'm proposing that quantum mechanics is right and GR is wrong, particularly as regards the no-hair theorem. I really can't tell how you jumped to the opposite proposals from my comment.
GTP 4y ago
I'm also totally uninformed, but my gut feeling is that physical systems don't encrypt information, at least not in the way we assume when talking about encryption. Also if you go down that route you risk having something that can't be proven: how do you prove that black holes are not using a one time pad to encrypt information, with each black hole using a different and random key?
- deleted 4y ago
  [deleted]
grogers 4y ago
I mean, hawking radiation itself is unproven - we can't experimentally verify it because the temperature of the radiation from stellar mass black holes would be too small. For small black holes, nobody has seen one 'pop'. In theory it's testable but probably not in our lifetimes.
jfengel 4y ago
The theorems that derive it's existence don't use the underlying state. They come from the margins of a black hole, which completely hides what's in it. That's the No Hair Theorem. If information leaks out they'll have to figure out why the No Hair Theorem is wrong.
theptip 4y ago
A lot of complexity is hidden behind the term “information”. You should be careful not to just use your existing intuition/definition for this word, it’s extremely specific Quantum Mechanics jargon here. This is talking about quantum states and how they describe the world. Each state corresponds to physical (quantum) reality, conforming to the laws of physics. So it’s not like you can just twiddle bits to make new representations. I think this is an area where appealing to the lay reader’s intuition is counterproductive. If you haven’t solved the Schrodinger equation before then you definitely shouldn’t be trying to intuit things about quantum systems; they are just weird and kind of irreducibly complex from the mathematical representation. Let me attempt to go against my advice above and give you some intuition for why encryption doesn’t parse here. It would be like you have a program with some static types, some classes, and then say “what if we just encrypt the memory location for this object on the heap and run the program”. The program is the thing that is running (laws of physics), the variables on the stack/heap are the state for the current execution, and it has no concept of decryption, so it would just produce garbage and crash. In the same way, the quantum physics description of a system has superposed states that are all valid configurations of the physical system, and no notion of “encryption”. So there is nowhere in the model of physical reality (and therefore unless we are missing some new Physics, nowhere in the reality that is modeled) for this information to “hide”. Or taking a different tack, “thermal entropy” means it’s just a bunch of gas buzzing around randomly at the same temperature - there is no physical place for structure to be “encrypted”. Where is the “key” in your model of the world? It’s just a cloud of gas. What physical process performed the encryption? That would require a complex structure, yet we are talking about a cloud of particles emitted when one half of a particle-antiparticle pair is captured by the black hole’s event horizon. There is no place in a workable physical model of the world for an entity that performs encryption on the quantum states (whatever that might mean). All this just points to why you can’t encrypt states in this way, not why the black hole information paradox is a problem. For that you really do need the maths; eg see https://www.cs.umd.edu/class/fall2018/cmsc657/projects/group_2.pdf https://www.cs.umd.edu/class/fall2018/cmsc657/projects/group... for the Physics here; while that requires graduate-level understanding of QM, hopefully the intro will be useful.
- lupire 4y ago
  Obviously no idea if this is true, but, an object falling into a black hole maybe could emit some radiation containing the key before the majority of the mass "encrypted" into the black hole.

Totally uninformed here: Have we proved the Hawking radiation is without information (or enough of it), or is it just 'encrypted' at a level we can't distinguish from noise?

mannykannot 4y ago

This seems to address it (from the article): "[Hawking] radiation is thermal which means it’s random except for its temperature, and the temperature is inversely proportional to the mass of the black hole. This means two things. First, there’s no new information which comes out in the Hawking radiation..." Its mass is one of the few things we know from the outside.

phendrenad2 4y ago
How do we know it's thermal? How do we know there aren't small fluctuations that are too small for us to detect millions of miles away?
- mannykannot 4y ago
  AFAIK Hawking radiation has never been detected. It is hypothesized on the basis of current theories of quantum mechanics and gravity, and those assumptions imply a thermal distribution of energy. So, we have a reason to think that Hawking radiation occurs and has this property, while no-one so far has proposed a mechanism that would encode data on it.
- tsimionescu 4y ago
  It's important to understand that Hawking radiation is not something we've observed and have noticed seems random. Instead, Hawking radiation is a prediction of a mathematical model. In that model, Hakwing radiation is purely random. If I remember correctly, Hawking radiation is postulated to arise because of fluctuations in the vacuum giving rise to virtual particle pairs. Normally, these would annihiliate back almost instantly. But, when such an event happens near the event horizon, one of them may fall into the black hole, leaving the other one to "escape", and appear as if the event horizon is emitting radiation. Since this radiation is caused by random fluctuations in the void outside the event horizon, it can't be correlated with anything past the even horizon, so it can't carry information about that.
GTP 4y ago
Probably for OP this isn't enough: if the radiation was carrying encrypted information then it would look random without knowing the "key", whatever a "key" could be in the context of a physical system. But I think that talking about encryption here without a solid preparation in the filed of physics it is just trying to apply something we know to try to solve some problem we have no idea how to approach.
andrewflnr 4y ago
Thermal radiation from a classical object looks "random" but still obeys (and in fact inspired) quantum theory. The information about the past of the object is there, it's just unfeasible to recover. I suspect Hawking radiation is the same way.
- lupire 4y ago
  Why do you suspect that? Do you deny that quantum mechanics is a valid model of the universe? Or do you believe quantum mechanics is equivalent to relativistic mechanins? Either would unwrite a century of physics.
  - andrewflnr 4y ago
    I'm proposing that quantum mechanics is right and GR is wrong, particularly as regards the no-hair theorem. I really can't tell how you jumped to the opposite proposals from my comment.

GTP 4y ago

I'm also totally uninformed, but my gut feeling is that physical systems don't encrypt information, at least not in the way we assume when talking about encryption. Also if you go down that route you risk having something that can't be proven: how do you prove that black holes are not using a one time pad to encrypt information, with each black hole using a different and random key?

deleted 4y ago
[deleted]

grogers 4y ago

I mean, hawking radiation itself is unproven - we can't experimentally verify it because the temperature of the radiation from stellar mass black holes would be too small. For small black holes, nobody has seen one 'pop'. In theory it's testable but probably not in our lifetimes.

jfengel 4y ago

The theorems that derive it's existence don't use the underlying state. They come from the margins of a black hole, which completely hides what's in it. That's the No Hair Theorem. If information leaks out they'll have to figure out why the No Hair Theorem is wrong.

theptip 4y ago

A lot of complexity is hidden behind the term “information”. You should be careful not to just use your existing intuition/definition for this word, it’s extremely specific Quantum Mechanics jargon here. This is talking about quantum states and how they describe the world. Each state corresponds to physical (quantum) reality, conforming to the laws of physics. So it’s not like you can just twiddle bits to make new representations. I think this is an area where appealing to the lay reader’s intuition is counterproductive. If you haven’t solved the Schrodinger equation before then you definitely shouldn’t be trying to intuit things about quantum systems; they are just weird and kind of irreducibly complex from the mathematical representation. Let me attempt to go against my advice above and give you some intuition for why encryption doesn’t parse here. It would be like you have a program with some static types, some classes, and then say “what if we just encrypt the memory location for this object on the heap and run the program”. The program is the thing that is running (laws of physics), the variables on the stack/heap are the state for the current execution, and it has no concept of decryption, so it would just produce garbage and crash. In the same way, the quantum physics description of a system has superposed states that are all valid configurations of the physical system, and no notion of “encryption”. So there is nowhere in the model of physical reality (and therefore unless we are missing some new Physics, nowhere in the reality that is modeled) for this information to “hide”. Or taking a different tack, “thermal entropy” means it’s just a bunch of gas buzzing around randomly at the same temperature - there is no physical place for structure to be “encrypted”. Where is the “key” in your model of the world? It’s just a cloud of gas. What physical process performed the encryption? That would require a complex structure, yet we are talking about a cloud of particles emitted when one half of a particle-antiparticle pair is captured by the black hole’s event horizon. There is no place in a workable physical model of the world for an entity that performs encryption on the quantum states (whatever that might mean). All this just points to why you can’t encrypt states in this way, not why the black hole information paradox is a problem. For that you really do need the maths; eg see https://www.cs.umd.edu/class/fall2018/cmsc657/projects/group_2.pdf https://www.cs.umd.edu/class/fall2018/cmsc657/projects/group... for the Physics here; while that requires graduate-level understanding of QM, hopefully the intro will be useful.

lupire 4y ago
Obviously no idea if this is true, but, an object falling into a black hole maybe could emit some radiation containing the key before the majority of the mass "encrypted" into the black hole.