
Holographic universe experiment begins - saticmotion
http://www.symmetrymagazine.org/article/august-2013/holographic-universe-experiment-begins
======
colanderman
I've never understood why proof that the universe is "holographic" (= 2+1
dimensions of information projected as 3+1) does not fall out of the
Schrödinger’s/Maxwell’s field equations.

After all, the equations, _by their very nature as equations_ , constrain the
dimensionality of possible universes (field configurations) by one, from 4
down to 3. The fourth is always derivable from the other three (e.g., X-Y-Z
intial conditions at T=0 define X-Y-Z-T fields for all T).

To believe that the universe contains four dimensions of information (i.e., is
not a hologram), would imply that the field equations do not universally hold.
So what this experiment is actually testing is the truth of QED, which implies
holography.

Does anyone know why this is not so? (I tried asking a while ago on Physics
StackExchange and only got flippant responses.)

(As an analogy for CS types: consider the game of Life. It is 3-dimensional (2
space + 1 time), but constrained by the Life equation. So it cannot contain
three dimensions full of arbitrary information; only a two-dimensional slice
can be arbitrarily instantiated. The analogy is not perfect, as Life is
neither reversible nor fully observable from any 2D slice, but it is close.)

~~~
cgs1019
I may be off base here, but I think the distinction is between number of
degrees of freedom (what you describe) and density of bits of information.
Bekenstein's result showed that the information in a black hole is
proportional to its surface area, not its volume. This seems unintuitive in
the sense that if you, e.g., stuff more ram chips into a box, its information
content seems to increase as a function of volume; the disparity lies in the
fact that bits in ram are not as densely packed as in a black hole.

EDIT: misspelled Bekenstein

~~~
colanderman
I think there is no distinction to be made. Consider encoding information in a
4-cube (hypercube) constrained by Maxwell's equations. (Let's make the space
discrete so our heads don't explode.) You will find that you can only encode
an amount of information proportional to the cube of the 4-cube's edge length,
not the 4th power, because you are constrained by Maxwell's equations. If you
further insist on keeping the information unchanged with respect to time,
you'll be restricted to an amount proportional to the square of the 4-cube's
edge length.

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VLM
The FAQ is very good. I wish the experimental section went into a discussion
of error sources. There may be unexpected error sources which are just as
interesting as the signal they're searching for (gravitational waves, who
knows)

As one example of an error source, I can predict this thing would make a beast
of a seismometer. Which in itself is interesting.

[http://holometer.fnal.gov/faq.html#experiment](http://holometer.fnal.gov/faq.html#experiment)

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lynndylanhurley
There's also a theory that our universe is a 3-D hologram that was spawned
from a black hole in a 4-D universe [1]. Would there be any way to test this
theory as well?

[1] [http://gizmodo.com/our-universe-might-just-be-fourth-
dimensi...](http://gizmodo.com/our-universe-might-just-be-fourth-dimensional-
black-hol-1410271260)

~~~
tfb
That actually makes a lot of sense. For quite a while, I've been trying to
imagine some rules for how some parent system might guide the laws of physics
behind our universe, and your comment seems to have lit a bulb in my head. I
haven't yet read the source link and I wish I could offer more input on it
right now, but I'll have to check it out later.

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iammyIP
here is a related lecture: "Leonard Susskind on The World As Hologram":
[https://www.youtube.com/watch?v=2DIl3Hfh9tY](https://www.youtube.com/watch?v=2DIl3Hfh9tY)

~~~
3rd3
Great lecture. When information moves outside of the shell of our observable
universe due to expansion, shouldn't we be able to receive Hawking radiation
from this process?

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chton
I'm very excited about this experiment. Even if it completely fails, we're
bound to learn something interesting. Spacetime fluctuations haven't been
examined at this level before, so anything they find out is new.

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czbond
Someone educate me. Isn't this farcical at the core? If we are living in a
hologram, then why is our world visible inside of structures, even when devoid
of light (eg: buildings, dark tunnels, etc).

~~~
jarin
They're not saying the universe is a light hologram like the one on your
credit card, they're saying it might be holographic in the sense that our 3d
space could be a projection of a 2d boundary.

The idea came about as a way to resolve the black hole information paradox in
a way compatible with string theory (the idea is that information can never be
destroyed, but black holes appear to destroy information). One interesting
consequence would be that our universe could be the result of a black hole in
some other universe.

~~~
snowwrestler
Where does the idea come from that information cannot be destroyed? Is that
supported by strong evidence, or is it just an assumption, axiom, or
hypothesis?

My intuitive sense is that information can be created and destroyed. For
example if I arrange wooden block letters to form a sentence, I have expended
energy to encode information. If I scatter the blocks randomly, I have
expended more energy to destroy information.

~~~
jarin
It's supported in both classical mechanics (Liouville's theorem, which is a
vital component of the proof of Newton's second law) and in quantum mechanics
(quantum unitarity).

[http://van.physics.illinois.edu/qa/listing.php?id=24045](http://van.physics.illinois.edu/qa/listing.php?id=24045)

~~~
snowwrestler
Ah, looks like I am confused between quantum information and classical
information (bits). We can create and destroy the latter.

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trhway
and there is kind of option in between - we can be a fractal foam with 2.781
(or 3.083 or whatever) Hausdorff dimension.

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smanuel
I really enjoyed reading "The holographic universe"
([http://www.amazon.com/gp/aw/d/0062014102](http://www.amazon.com/gp/aw/d/0062014102))
some time ago but how can an experiment which is entirely based on science,
physical laws, empirical evidences and so on, prove something which would make
all these means... meaningless. This looks like a paradox to me.

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seoguru
reminded me of this Michael Talbot interview, author of "The Holographic
Universe":
[https://www.youtube.com/watch?v=6rgYz_BU2Ew](https://www.youtube.com/watch?v=6rgYz_BU2Ew)

Sadly, Mr. Talbot died in 1992, six months after this interview.

~~~
3rd3
LOL, entanglement, twins feeling the same pain and telepathy... I should have
noticed immediately that this is some spiritual rubbish.

~~~
seoguru
I found his explanation of the 2 views of the fishtank to explain quantum
entanglement quite interesting.

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buovjaga
The article is from 2013, this is the latest:
[http://www.symmetrymagazine.org/article/april-2014/searching...](http://www.symmetrymagazine.org/article/april-2014/searching-
for-the-holographic-universe)

Holometer site: [http://holometer.fnal.gov/](http://holometer.fnal.gov/)

~~~
chton
The Fermilab press release the article is based on is dated at today (august
26, 2014):
[http://www.fnal.gov/pub/presspass/press_releases/2014/2-D-Ho...](http://www.fnal.gov/pub/presspass/press_releases/2014/2-D-Hologram-20140826.html)

I've also asked Fermilab directly and they confirm the article is from today,
the holometer came online very recently:
[https://twitter.com/FermilabToday/status/504286464637939712](https://twitter.com/FermilabToday/status/504286464637939712)

~~~
gshubert17
The August 2014 issue of Scientific American had an article by Afshordi, Mann,
and Pourhasan entitled "The Black Hole That Birthed the Big Bang" on a
holographic theory of the universe.

The article [0] is paywalled, but the preview contains a note from a reader
suggesting "the holographic principle shares the same problems of all Idealist
notions: rather than relying on evidence, it puts the elegance of the model
first as an argument in its favor."

I hope the Fermilab experiments provide some useful data.

[0] [http://www.scientificamerican.com/article/the-black-hole-
tha...](http://www.scientificamerican.com/article/the-black-hole-that-birthed-
the-big-bang/)

~~~
xico
Yeah, formalizing thoughts into models, and then testing them to validate or
invalidate them is sooo idealist. I wish scientists would only rely on common
sense and holy books, trusting their guts to do the right thing.

~~~
marcosdumay
The alternative is first collecting empirical results that current theories do
not explain, and only then work on a model for explaining them.

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SeeThroughCloth
No one has experienced security so, its not like anyone actually cares if its
any dimension at all.

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dchichkov
Seems to be a bit dangerous experiment. I remember reading something in some
kind of a manual that it is definitely dangerous to put to much information in
one place. It gets hungry for more information and then things get complicated
pretty quickly.

~~~
dlsym
Sounds like some pretty good description of the library in Pratchett's
discworld universe to me.

~~~
dchichkov
I was referring to a physics textbook, Bekenstein Bound [
[http://en.wikipedia.org/wiki/Bekenstein_bound](http://en.wikipedia.org/wiki/Bekenstein_bound)
] and a gravitational collapse. Doesn't look like downvoters had gotten the
point through though ;)

