QFT making leaky BH horizons?

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stargene

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Jun 2, 2021, 4:18:12 AMJun 2
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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

Jos Bergervoet

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Jun 2, 2021, 2:47:01 PMJun 2
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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

Gary Harnagel

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Jul 24, 2021, 5:23:56 AMJul 24
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[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
>> 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?
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