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Space

Physicists Theorize Out How To Retrieve Information From a Black Hole (sciencemag.org) 82

sciencehabit writes: Black holes earn their name because their gravity is so strong not even light can escape from them. Oddly, though, physicists have come up with a bit of theoretical sleight of hand to retrieve a speck of information that's been dropped into a black hole. The calculation touches on one of the biggest mysteries in physics: how all of the information trapped in a black hole leaks out as the black hole 'evaporates.' Many theorists think that must happen, but they don't know how.
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Physicists Theorize Out How To Retrieve Information From a Black Hole

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  • Easy (Score:5, Funny)

    by penguinoid ( 724646 ) on Thursday December 24, 2015 @01:45AM (#51176995) Homepage Journal

    Ask a politician or CEO or salesman. They routinely pull information out of a "black hole".

  • The radiation coming out of black hole will have lots of particles, normalising any information into practical randomness, hence increasing the entropy of universe. it'd take a hell of an effort to find out which photon will carry the information of electron.
  • for data compression.

  • by Black Parrot ( 19622 ) on Thursday December 24, 2015 @02:43AM (#51177097)

    Ignorant amateur here. ISTM that if a virtual pair appears straddling the event horizion, the one that gets away never was inside the black hole to begin with, and thus would not carry away any matter or energy. Isn't the black hole just working as an engine to extract matter/energy from the vacuum near the event horizon? Half of which goes in, making the BH bigger, and half of which escapes to the external universe.

    In the unlikely event that that conception is correct, it would be interesting to think about what happens to the vacuum near the event horizion. Does it get depleted of its vacuum energy, or is it an infinite source? If depleted, does vacuum energy flow in from other nearby vacuum to replenish it?

    Is the vacuum inside a black hole anything like the external vacuum?

    • Physics has an answer for how hawking radiation (the emissions caused by half of a virtual partial pair escaping from the event horizon) relates to energy of the local environment. Using thermodynamics, you can calculate the 'temperature' of a black hole, and by comparing this value with the temperature of the cosmic microwave background (3.3 kelvin, if I remember correctly) it predicts if the black hole is losing mass net energy to virtual particles over time. The math works out that larger black holes are
    • by maugle ( 1369813 ) on Thursday December 24, 2015 @03:16AM (#51177149)
      Not quite. The virtual pair has a net energy of 0, and therefore isn't really "extracting" anything from the vacuum. If the pair weren't straddling a black hole, they'd recombine and disappear and nothing would happen. However, when one member of the pair is sucked into a black hole while the other particle escapes, the escaping particle must have a greater-than-zero amount of energy. Because of that, and the requirement that the two particles balance each other out, the black hole has necessarily absorbed a negative-energy (not negatively-charged, mind you, actually negative energy) particle, causing the black hole to shrink ever so slightly. Basically, while the particles originally came from vacuum, the energy was taken from the black hole.

      Also, to an external observer this process looks exactly the same as if the black hole itself was slowly emitting particles and shrinking away. And if the black hole is emitting particles, we can use that to determine something about its internal state.
      • Not quite. The virtual pair has a net energy of 0, and therefore isn't really "extracting" anything from the vacuum. If the pair weren't straddling a black hole, they'd recombine and disappear and nothing would happen. However, when one member of the pair is sucked into a black hole while the other particle escapes, the escaping particle must have a greater-than-zero amount of energy. Because of that, and the requirement that the two particles balance each other out, the black hole has necessarily absorbed a negative-energy (not negatively-charged, mind you, actually negative energy) particle, causing the black hole to shrink ever so slightly. Basically, while the particles originally came from vacuum, the energy was taken from the black hole. Also, to an external observer this process looks exactly the same as if the black hole itself was slowly emitting particles and shrinking away. And if the black hole is emitting particles, we can use that to determine something about its internal state.

        This is correct. The article is specifically addressing a mechanism by which quantum teleportation could release this information across the horizon. Granted to tell exactly what this is you would need to know the instaneous spin to a ludicrous precision, understand how quantum gravity works, understand the exact structure within the black hole, and several other far off concepts. However it is an interesting approach to solving this problem and could further research efforts.

      • I was wondering about something related to this.
        Would the escaping particles be equal measures of matter and anti-matter?
        And if so, if the black hole was originally made up predominantly of matter, would the radiation process change the ratio of matter and antimatter in the universe (or at least locally)?
        Or is there some force or field that would only let same-charge particles to escape, allowing you to determine what it was originally made of?

    • by Anonymous Coward

      Half of which goes in, making the BH bigger, and half of which escapes to the external universe.

      It actually makes the BH smaller. The virtual particle at the event horizon has more energy than the same virtual particle inside the blackhole... so the blackhole loses mass when that virtual particle falls in (and the other `virtual' particle appears to be coming out of the horizon). It's weird, but you take a 5 solar mass star, collapse it into a black hole, and it will be much less than 5 solar masses...

      • by Mal-2 ( 675116 )

        It's weird, but you take a 5 solar mass star, collapse it into a black hole, and it will be much less than 5 solar masses...

        First, a 5 solar mass star will likely shed more than enough of it to survive as a neutron star, or possibly even a white dwarf like our Sun will end up. If it were to somehow collapse without blowing off any of its mass, it would just meet the mass of the smallest known stellar mass black hole, and in reality they typically shed the vast majority.

        Second, it's not strange at all that the object that remains has much less mass than the progenitor. Add the mass flung away in the explosion, and the kinetic ene

        • by maugle ( 1369813 )
          Very messy indeed. All the heavy elements we see around us, it's mind-boggling to think of the energy that must have been required to blast them out from the core of their collapsing star.
  • just go to blackhole.com

  • by mbone ( 558574 )

    It's not like there is a lot of experimental evidence here, one way or the other.

  • Does that get information, or just data?

  • Physicists Theorize Out

    Did they theorize the shit out of this thing?

  • Why don't they use water-boarding? It works so well, as we all know.

  • /dev/null earns its name because the device is so small nothing can be read from it. Oddly, though, physicists have come up with a bit of theoretical sleight of hand to retrieve a speck of information that's been sent to /dev/null. The calculation touches on one of the biggest mysteries in physics: how all of the information written to /dev/null hole leaks out as heat from the CPU and gets 'dispersed' by the heat sink. Many theorists think that happens, but they don't know how to put humpty dumpty together

  • dd if=/dev/blackhole of=/tmp/data ?
  • Call me when there is an experiment to back it up. Otherwise it is just speculation.

  • by peter303 ( 12292 ) on Thursday December 24, 2015 @06:26PM (#51180063)
    Of the information loss paradox and various fixes. The "holographic universe" is another fix. That is copy of information inside the BH exists imprinted on the event horizon.
  • The Akashic record has to be somewhere!
  • Or "guess". But not "theorize". Ah, the pain.

We can found no scientific discipline, nor a healthy profession on the technical mistakes of the Department of Defense and IBM. -- Edsger Dijkstra

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