• QFT making leaky BH horizons?

    From stargene@21:1/5 to All on Wed Jun 2 08:18:08 2021
    Profs. Susskind, ’t Hooft and others have occasionally referred
    to black hole event horizons as having tiny fluctuations in their
    locations at the smallest micro-scales, due to QFT.

    For me, this implies that a graviton, say, just inside the horizon,
    may find itself suddenly just outside of the horizon, due to such fluctuations…with the chance of then traveling outward.
    Two theorists confirmed that this could happen, but that more
    work needed to be done on the union between QFT and the
    BH horizon.

    But doesn’t this imply that information from inside the horizon
    can indeed propagate out into our universe, at least in principle?
    And if so, doesn’t QFT make it a whole new ball game regarding
    connectivity between the two realms?
    Thanks, Gene

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  • From Jos Bergervoet@21:1/5 to stargene on Wed Jun 2 19:46:59 2021
    On 21/06/02 10:18 AM, stargene wrote:
    Profs. Susskind, ’t Hooft and others have occasionally referred
    to black hole event horizons as having tiny fluctuations in their
    locations at the smallest micro-scales, due to QFT.

    For me, this implies that a graviton, say, just inside the horizon,
    may find itself suddenly just outside of the horizon,

    You are wrong. Gravitons do not have a position, they are
    spread out. Most of the relevant ones are even very much spread
    out, in wavelenght modes as big as the entire blak hole.

    In QFT the term "particle" has nothing to do with classical
    point particles anymore, it has gotten a totally different
    meaning, referring to the numbering of different sections of
    the Hilbert space.

    In contrast, the concept of "event horizon" still has its
    classical meaning: infinitely thin shell with precise position
    coordinates! (Probably this will have to change as well if the
    theories are worked out further and then people will keep
    using the old word with a new meaning also in that case,
    adding further to the confusion..)

    Two theorists confirmed that this could happen, but that more
    work needed to be done on the union between QFT and the
    BH horizon.

    Certainly! In particular we need to solve what happens if we
    describe a state as a superposition of states with different
    energy. The event horizon depends on this so it cannot be the
    classical concept based on exact position coordinates.

    The whole GR framework of classically describing the curvature
    of space-time based on the contained energy-momentum cannot
    work if there is a superposition of states with completely
    different energy-momentum values.

    But doesn’t this imply that information from inside the horizon
    can indeed propagate out into our universe,

    Well, if you first admit that there is "more work needed" then
    concluding things like that seems a bit premature..

    ... at least in principle?
    And if so, doesn’t QFT make it a whole new ball game regarding
    connectivity between the two realms?

    The basic question may remain the same: does everything leak
    out into our universe again in the end (after BH evaporation) or
    will a remnant be split off indefinitely?

    --
    Jos

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  • From Gary Harnagel@21:1/5 to Jos Bergervoet on Sun Jul 18 13:03:56 2021
    On Wednesday, June 2, 2021 at 12:47:01 PM UTC-6, Jos Bergervoet wrote:

    On 21/06/02 10:18 AM, stargene wrote:

    Profs. Susskind, ’t Hooft and others have occasionally referred
    to black hole event horizons as having tiny fluctuations in their
    locations at the smallest micro-scales, due to QFT.

    For me, this implies that a graviton, say, just inside the horizon,
    may find itself suddenly just outside of the horizon,

    You are wrong. Gravitons do not have a position, they are
    spread out. Most of the relevant ones are even very much spread
    out, in wavelenght modes as big as the entire blak hole.

    In QFT the term "particle" has nothing to do with classical
    point particles anymore, it has gotten a totally different
    meaning, referring to the numbering of different sections of
    the Hilbert space.

    In contrast, the concept of "event horizon" still has its
    classical meaning: infinitely thin shell with precise position
    coordinates! (Probably this will have to change as well if the
    theories are worked out further and then people will keep
    using the old word with a new meaning also in that case,
    adding further to the confusion..)

    Two theorists confirmed that this could happen, but that more
    work needed to be done on the union between QFT and the
    BH horizon.

    Certainly! In particular we need to solve what happens if we
    describe a state as a superposition of states with different
    energy. The event horizon depends on this so it cannot be the
    classical concept based on exact position coordinates.

    The whole GR framework of classically describing the curvature
    of space-time based on the contained energy-momentum cannot
    work if there is a superposition of states with completely
    different energy-momentum values.
    But doesn’t this imply that information from inside the horizon
    can indeed propagate out into our universe,
    Well, if you first admit that there is "more work needed" then
    concluding things like that seems a bit premature..

    ... at least in principle?
    And if so, doesn’t QFT make it a whole new ball game regarding
    connectivity between the two realms?

    The basic question may remain the same: does everything leak
    out into our universe again in the end (after BH evaporation) or
    will a remnant be split off indefinitely?

    --
    Jos

    Isn't it so that from our perspective (far outside the event horizon) it
    takes an infinite amount of time for an object falling into the BH to
    reach the EH? Thus, perhaps, shouldn't we think about the probability
    of a particle leaking INTO a BH in a finite time?

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    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Gary Harnagel@21:1/5 to Jos Bergervoet on Sat Jul 24 09:23:52 2021
    [Moderator's note: I forward this posting again since, according to the
    sender it hasn't appeared in the Newsgroup, also it definitely appeared
    via my news server.]

    On Wednesday, June 2, 2021 at 12:47:01 PM UTC-6, Jos Bergervoet wrote:

    On 21/06/02 10:18 AM, stargene wrote:

    Profs. Susskind, =E2=80=99t Hooft and others have occasionally referred
    to black hole event horizons as having tiny fluctuations in their
    locations at the smallest micro-scales, due to QFT.

    For me, this implies that a graviton, say, just inside the horizon,
    may find itself suddenly just outside of the horizon,

    You are wrong. Gravitons do not have a position, they are
    spread out. Most of the relevant ones are even very much spread
    out, in wavelenght modes as big as the entire blak hole.

    In QFT the term "particle" has nothing to do with classical
    point particles anymore, it has gotten a totally different
    meaning, referring to the numbering of different sections of
    the Hilbert space.

    In contrast, the concept of "event horizon" still has its
    classical meaning: infinitely thin shell with precise position
    coordinates! (Probably this will have to change as well if the
    theories are worked out further and then people will keep
    using the old word with a new meaning also in that case,
    adding further to the confusion..)

    Two theorists confirmed that this could happen, but that more
    work needed to be done on the union between QFT and the
    BH horizon.

    Certainly! In particular we need to solve what happens if we
    describe a state as a superposition of states with different
    energy. The event horizon depends on this so it cannot be the
    classical concept based on exact position coordinates.

    The whole GR framework of classically describing the curvature
    of space-time based on the contained energy-momentum cannot
    work if there is a superposition of states with completely
    different energy-momentum values.
    But doesn=E2=80=99t this imply that information from inside the horizon
    can indeed propagate out into our universe,
    Well, if you first admit that there is "more work needed" then
    concluding things like that seems a bit premature..

    ... at least in principle?
    And if so, doesn=E2=80=99t QFT make it a whole new ball game regarding
    connectivity between the two realms?

    The basic question may remain the same: does everything leak
    out into our universe again in the end (after BH evaporation) or
    will a remnant be split off indefinitely?

    --
    Jos

    Isn't it so that from our perspective (far outside the event horizon) it
    takes an infinite amount of time for an object falling into the BH to
    reach the EH? Thus, perhaps, shouldn't we think about the probability
    of a particle leaking INTO a BH in a finite time?

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)