
Black holes are like a hologram - atombender
https://earthsky.org/space/black-holes-are-like-a-hologram
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weswpg
Another summary of a press release based on a study that doesn't seem to
actually find anything new or 'surprising'. As the 'article' states, the
holographic principle is an idea that is 30 years old.

As I understand it, this paper is novel because it has found a scenario, a set
of rules, where the math shows that the universe could indeed work this
way...but this particular set of rules doesn't seem to be the ones we see in
this universe. (I'll get to the specifics in a moment)

Why is this still useful? Because it is a starting point, a model that
confirms the theory is workable. If the result had been negative, then some
parts of the theory could be ruled out.

Now to the specifics from the original paper's abstract:

> _We study this issue in the context of gravity with a negative cosmological
> constant. We exploit the most basic example of the holographic description
> of gravity (AdS /CFT): type IIB string theory on AdS5×S5, equivalent to
> maximally supersymmetric Yang-Mills theory in four dimensions. We thus
> resolve a long-standing question: Does the four-dimensional N=4 SU(N) Super-
> Yang-Mills theory on S3 at large N contain enough states to account for the
> entropy of rotating electrically charged supersymmetric black holes in 5D
> anti–de Sitter space? Our answer is positive._

Lots of words. A few things to take away is that this paper talks about a
universe with four spatial dimensions, not three, and it considers "anti-de
Sitter space", which would be a universe that loops back on itself instead of
being infinite and flat as our universe _appears_ to be. Last thing is that
because the rate of expansion of the universe is accelerating, the
cosmological constant is probably greater than zero but this theory only
considers a scenario where the cosmological constant is negative.

~~~
hankmccoy78
For anyone who wants to dive deeper into the science of this stuff I highly
recommend this playlist from PBS Spacetime:
[https://www.youtube.com/playlist?list=PLsPUh22kYmNCHVpiXDJyA...](https://www.youtube.com/playlist?list=PLsPUh22kYmNCHVpiXDJyAcRJ8gluQtOJR)

Also, quick note: I think you're confusing anti-de Sitter space w/ de Sitter
space? de Sitter has positive curvature (i.e. it curves back in on itself)
whereas _anti_ de Sitter space has negative curvature.

~~~
sophacles
I've really enjoyed PBS Spacetime - it's a great "more than layman" but "less
than physicist" channel. They aren't afraid to show math, and explain hard
concepts.

Additionally I've found this channel, from Anton Petrov, to be good in a
similar vein:

[https://www.youtube.com/user/whatdamath](https://www.youtube.com/user/whatdamath)

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techbio
Fascinating subject but the information density of this article falls short of
my event horizon.

~~~
weswpg
Same reaction.

[https://news.ycombinator.com/item?id=23431458](https://news.ycombinator.com/item?id=23431458)

This might be up your alley:

[https://www.youtube.com/playlist?list=PLsPUh22kYmNCHVpiXDJyA...](https://www.youtube.com/playlist?list=PLsPUh22kYmNCHVpiXDJyAcRJ8gluQtOJR)

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blueboo
> For scientists, black holes are a big question mark for many reasons.

The writing of this piece is so shockingly bad that I wonder if it was machine
translated.

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peter_d_sherman
>"Yet, according to new research by scientists in Italy, black holes could be
like a hologram, where all the information is amassed in a two-dimensional
surface able to reproduce a three-dimensional image. In this way, these cosmic
bodies, as affirmed by quantum theories, could be incredibly complex and
concentrate an enormous amount of information inside themselves, as

 _the largest hard disk that exists in nature, in two dimensions._ "

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AnotherGoodName
Somewhat irrelevant question but is the holographic universe theory a
reasonable hypothesis for the universe expanding at different rates in its
life since that could be explained by new material falling into the black hole
that the holographic universe lives on.

~~~
eipipuz
IANAP but black holes evaporate without losing information. So in your model,
how does that work?

Also, observation is that inflation has been ongoing for a long time, we don't
seem to have spikes of growth. Afaik we have basically 2 phases one where
inflation dominates and the one prior.

~~~
AnotherGoodName
There's lots of examples of the universe expanding at different rates. The
cosmic inflation early in the universe being one example and then the more
recent dark energy acceleration of the expansion.

As for evaporating without losing information that's the whole point. The
holographic universe theory states that a black hole doesn't destroy
information. The holographic universe is a consequence of no information being
destroyed in the formation or evaporation of a blackhole. It's literally the
entire basis for the theory. My theory above is just postulating that as a
block hole grows/shrinks due to information falling into it or evaporating
from it a holographic universe on its surface would also grow/shrink.

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phkahler
If the universe is a hologram (or sorts) then non-locality should be expected,
and spooky action at a distance is not paradoxical or terribly interesting.

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marvel_boy
Black holes dont exists. Good try, anyway.

~~~
artsyca
I'm pretty sure they only look like they exist from where we're looking and
they'll end up being cosmic mirages and this whole thing will reinforce the
hologram theory

