
Hologram Within a Hologram Hints at Solution to Black Hole Information Paradox - tambourine_man
https://www.quantamagazine.org/hologram-within-a-hologram-hints-at-solution-to-black-hole-information-paradox-20191119/
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parksy
Fascinating. I know the work these physicists are doing is vastly more complex
and involved, but I can't help but draw comparison to my own musings.

I've been chipping away at various angles of information theory as a hobby for
a few years now, conceptually for me a black hole in the traditional sense is
like compressing random bits to a single zero or one - there'd be no way of
getting information back out in the original order. Encoding a higher
dimensional representation holographically would be like having a side channel
of information I guess, so you could have the 0 or 1 as the 'black hole' but
still can reference external state data to reconstitute meaning from it.
Entropy is preserved, and laws of maths and physics are no longer being
broken.

Say, I can divide a sequence of bits by 2 if they're even, or add one then
divide by two if they're odd, repeatedly until the result is 1 (after which
the sequence repeats indefinitely, but we can stop at 1 - similar but
different to the collatz conjecture). If I know the sequence of operations I
can rebuild the original data, but encoding that sequence of operations is the
exact same amount of information as the original sequence (in my tests at
least).

I'm kind of comforted by the fact that it may turn out black holes aren't
destroying information, merely transforming it.

~~~
mjevans
The reduction of information aspect you suggest contradicts one of the key
elements outlined in the article (the QM view that information might be
transformed (combined/processed) but never removed).

I offer my own, within this realm of discussion, layman's perspective that a
black hole might be metaphorically similar to an above ground swimming pool
with a (small) hole in the side, within a still larger pool. If there is an
orderly structure within the small pool the flow will remove structured
information from within and spray it back out.

Following the above metaphore and the impression the article gave me: a black
hole does something similar but in a more fourth-dimensional hysteresis
format. Over time the energy and "information" contained within (or released
out as other forms of energy) is observation-ally constant. This would be a
lot more like the way a moon can create tides that pull water in and out of a
bay.

While I would also love for science fiction toys like the Portal Gun (or other
wormholes/gateways) to be a reality, I really doubt they're actually possible
and even if they are this would probably be as close to realizing them as
discovering the principles of electricity were to creating the microprocessor.

~~~
parksy
Can you point out specifically what I said that contradicts, not trying to be
obtuse but I want to reassess my thinking.

The reduction of information example I thought agreed with the article,
because traditionally (or in other words in layman's understanding) a black
hole seems to have been represented as thing that removes information from the
universe, which would be like taking a sequence of binary and reducing it to a
1 or 0 through some hidden methods. You'd never be able to get back the
original data - unless you had some encoding of the steps taken to reduce,
i.e. through a transformation.

Genuinely I'm just not quite sure which bit of my analogy contradicts the
article, and perhaps I've just not been clear enough in what I am writing, but
I appreciate your comment in any regards.

~~~
qubex
Basically quantum theory forbids hashing (because it’s an irreversible form of
information loss) — but what you are proposing is not a hash since it produces
a stream of bits which re-encode the original string (simply in a different
form).

------
throwaway_tech
This is sort of the basis of a visual model I have designed for a 4
cube/tesseract (what I call the "kaluza-klein cube" or "holocube") and a 5
cube (I call the "holofractal cube").

Holocube/Kaluza-Klein Cube:
[https://www.dropbox.com/s/3o0ovqe41j624wy/image4.jpeg?dl=0](https://www.dropbox.com/s/3o0ovqe41j624wy/image4.jpeg?dl=0)

Holo-Fractal Cube:
[https://www.dropbox.com/s/gmk375cgu2rylcu/image1.jpeg?dl=0](https://www.dropbox.com/s/gmk375cgu2rylcu/image1.jpeg?dl=0)

Although Kaluza-Klein theory has been disproven, I can't help but be amazed
that solving Einstein's equations in the higher dimensions independently
results the equations for electro-magnetism (light). I also can't help but
like the idea quatum mechanics is simply physics for higher dimensions, and
that all objects we believe are 3D extend both inward into 4D (particles) and
outward from the object in 4D (light/electro-magnetism).

Edit: May be more accurate to say solving Einstein equations in 5th dimension
independently yield the five-dimensional Einstein equations yield the four-
dimensional Einstein field equations, the Maxwell equations for the
electromagnetic field, and an equation for the scalar field.

~~~
Yajirobe
> solving Einstein's equations in the higher dimensions independently results
> the equations for electro-magnetism

Could you link a source to this? I would love to read about it.

~~~
snagglegaggle
That's a pretty big claim. It potentially means the theory got close to a
unified theory. Can a real physicist chime in?

~~~
throwaway_tech
It was a unified theory, and Einstein approved (note, this was pre-weak and
strong force so it was a unification of gravity and electro-magnetism only).
It was eventually disproven, but the math serves as the basis for higher
dimensional theories (i.e. string theory)

~~~
snagglegaggle
How was it disproven (I see the erroneous electron mass part)? I suppose I am
interested in the quantum field theory section of the wiki, which is
unwritten.

It is my understanding EM is more or less directly relatable to more
fundamental forces (or rather derived from it) so even being able to fit EM in
it means that the others must fit.

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aurelian15
Related PBS Space Time episode about the "Black Hole Information Paradox" (in
general, not about the particular paper discussed in the article):

[https://www.youtube.com/watch?v=9XkHBmE-N34](https://www.youtube.com/watch?v=9XkHBmE-N34)

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Dylan16807
[dead comment that isn't exactly terrible but I don't particularly want to
vouch for]> Schizophrenic rants about black holes containing meaningful
coherent “information” are as sane and rational as flat earthers

It's not "coherent" information. It's the markings caused by a trillion
different impacts. And smoothing things out takes energy, so it would be
strange if all those marks dissolved away spontaneously.

The statement "the things that fell into a black hole affect the radiation
coming out of it" isn't even a weird thing to say!

~~~
millstone
It would be _very surprising_ if the things that fall into a black hole affect
the radiation coming out of it.

The reason is that "the things that come out of it" are reference frame
dependent. That is, you and I will disagree on what is emitted as Hawking
radiation. In fact a free-falling observer will observe NO Hawking radiation!

So Hawking radiation must be determined entirely by spacetime geometry, which
depends only on mass-energy-momentum and not things like baryon number.

Oh, and "smoothing things out takes energy" doesn't seem right. Consider the
heat equation: a solid with a temperature differential reaches equilibrium
while conserving energy.

~~~
Dylan16807
> It would be very surprising if the things that fall into a black hole affect
> the radiation coming out of it.

I mean absent all the exotic physics calculations, since that comment is
saying that people are too twisted up in theoretical math. In a very basic
sense it seems reasonable.

> So Hawking radiation must be determined entirely by spacetime geometry,
> which depends only on mass-energy-momentum and not things like baryon
> number.

I'm not really following that 'so'. Lots of things are reference frame
dependent but still depend on exact particles.

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Agebor
I wonder how this relates to Cosmological Natural Selection theory - the idea
is that the black hole 'bounces' into a child universe, which inherits some of
the parent characteristics. Perhaps the information finds its way there.

[https://blogs.scientificamerican.com/guest-blog/the-logic-
an...](https://blogs.scientificamerican.com/guest-blog/the-logic-and-beauty-
of-cosmological-natural-selection/)

------
nabla9
Popularizing the bleeding edge of theoretical physics like they do in IAS is
hard. The holographic principle is something you can grasp. It's also possible
to understand the general concept of duality. But how anti-de Sitter/conformal
field theory correspondence works and what follows would require more than
reading these articles can give.

You could test learning and understanding by making questions based on these
articles where answers are not given in text and I doubt that you could answer
any of them. Or they could write two articles where one is carefully crafted
nonsense and it would be hard to figure out witch one is true.

------
CuriouslyC
Maybe our understanding of black holes is woefully incomplete and the paradox
is a result of our own ignorance.

~~~
antonvs
That's more or less what the "paradox" is telling us, and research like the
the OP is attempting to address.

It's a conflict in predictions involving different theories - quantum
mechanics only, vs. quantum mechanics plus general relativity. It's a
"paradox" in the sense that the two approaches reach conclusions that
contradict each other - both can't be right.

The conflict implies that one or both theories are incomplete or incorrect in
some way - which we already knew, because quantum mechanics and general
relativity are known to be incompatible with each other in various ways.

Such conflicts are rich ground for discovering new physics, because they
highlight very specific weaknesses in existing theories. That's why people
like Hawking, Susskind, and many others have spent so much time on this.

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keyle
This could be a ground breaking change in our understanding of black holes,
right?

------
darkmighty
This appears to confirm a prediction of mine that black holes aren't really
black holes -- you can escape them just fine !

I think physicists will become more and more convinced of this fact -- there
can be no impassable communication barrier (no event horizon).

I believe black holes will be understood in the future as simply arbitrarily
massive stars with increasing time dilation. That's because historically it
was always assumed black holes do exist, and worked from there. Models of
collapse were never fully laid out, and most don't consider an external
observer as the correct reference. It's essentially analogue to thinking the
field of electrons would diverge when sufficiently close to them (and the
paradoxes this would bring).

The light escape mechanism will _not_ turn out to be exotic -- it's simply
ordinary light being emitted by objects making its way out in an ordinary null
geodesic, which is possible since there is not event horizon :)

~~~
h4areh4er3
Sorry I don't think you should be downvoted. But I think the main criticism of
your post, is that yes, we do have an impassable communication barrier in the
sense of locality and the speed of light. A black hole's singularity, after
all, can be equally described as "light slowing down" or "space stretching".
So while there's no hard "information barrier", there is still no possible
means of communication.

~~~
LessDmesg
I think what he meant was that we have no proof that "singularity" even
exists. Cosmologists have a penchant for coming up with infinities: infinite
density in the moment of “Big Bang", infinite time dilation at an "event
horizon" etc, but in actual observation nothing infinite was ever seen. A
particle's field is represented with an 1/r2 function but somehow there are no
infinite fields in real matter - black holes may turn out to be something
similar too!

~~~
antonvs
Modern cosmologists don't generally believe the Big Bang involved infinite
density, nor do they believe that physical singularities of infinite density
exist.

Confusion arises because theories predict these things, but one has to be
careful to distinguish cases where the theory is being used in a regime beyond
its effective domain, from other cases where infinities are less problematic.
For example:

> in actual observation nothing infinite was ever seen.

"Real" infinities do show up in various places in physics and cosmology, not
in the sense of objects with infinite density, but in more abstract ways. For
example, it takes infinite energy to accelerate an object with mass to the
speed of light - which we interpret to mean that it is not possible to do
that.

A more relevant example is that beyond our cosmic event horizon, light that is
emitted "now" will never reach us, even if we wait an infinite time. That is
another kind of abstract infinity that doesn't pose any serious conceptual
problem.

One effective way to model this case is that the light is infinitely
redshifted, very much like light from the event horizon of a black hole. In
fact, some models equate the two cases.

You can argue that infinitely redshifted light doesn't actually exist, and in
a sense you'd be right - but the point is that very good models predict that
the light tends towards being infinitely redshifted, and the effect is that we
never see it, even after infinite time.

As such, talking about infinite redshift effectively means that the light in
question doesn't exist in the region in question, and "infinite redshift" is a
consistent way to model that. Infinite redshift also implies zero amplitude,
which again implies that the light in question doesn't exist in that region.

(As an aside, Heisenberg tells us there's no such thing as a consistently zero
amplitude quantum field, which gives us a direct link to Hawking radiation
from event horizons!)

> I think what he meant was that we have no proof that "singularity" even
> exists.

As I mentioned, that's not controversial. But what the original commenter
wrote was "you can escape [black holes] just fine !" That contradicts
everything we know about physics, including our observational evidence of
actual black holes.

Importantly, the infinities that arise at the event horizon are also observer-
dependent. The infalling observer doesn't see anything special at the event
horizon, it's only an external observer that observes time and redshift
tending towards infinity.

This is again analogous, if not equivalent to, the cosmic event horizon I
mentioned - the cosmic event horizon isn't common to all observers. If you
could travel to the location of the cosmic event horizon we observe from
Earth, you would find nothing special there, and you would observe another
cosmic event horizon 46.5 billion light years away. It's similar to the
ordinary visible horizon on Earth in this sense.

So there's no fundamental physical problem in this case with taking the
infinities literally, as long as you correctly understand what that means.
Besides, for the question of escaping a black hole, it doesn't really matter
whether these values actually "reach" infinity - you still aren't going to be
able to escape a black hole.

------
mjfl
I don’t understand why there is a black hole information paradox. Nothing ever
falls into a black hole in our frame of reference - it takes infinite time.

~~~
lostmsu
From my understanding, that is incorrect. As more stuff approaches "original"
event horizon, the mass of the black hole + mass of stuff near the horizon
grows, which extends the horizon outwards, effectively consuming stuff, that
got close to it.

~~~
lostmsu
Hopefully better explanation:

Imagine a black hole with mass M and radius R.

Let's assume to have radius R+1m, a black hole has to be of mass M+1kg.

Any falling matter trying to approach R will cross R+1m in finite time. At
some moment 1kg of matter will cross R+1m. At this moment, that 1kg will
effectively be inside the horizon.

~~~
millstone
"Effectively inside the horizon" isn't a good way to think about GR. Observers
have reference frames, and can only observe according to their own clocks and
rulers.

If you (a distant observer) watched your blinking probe approach a black hole,
you would see its blinks slow and red shift as the probe approaches the
horizon. You cannot see it enter the horizon, as light cannot escape from
inside the horizon. There would be a last blink, as the red shift approaches
infinity.

If the event horizon were to increase in radius, the effect would be to
further slow and red shift the blinks.

~~~
lostmsu
Can't you claim, that if probe reached R+0.5m (which you could potentially
see), and then subsequently BH grew to R+1m, that probe's last blink happened
in the area, that later became BH?

