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Others can hopefully chime in with more, but when I first was learning about it, my reaction to the word "hologram" was the same as your (1). My understanding is that when they say "hologram", they're simply meaning an n dimensional object that's encoded in n-1 dimensional space.

If you're not familiar with the basics of the Holographic Principle, start here: https://en.wikipedia.org/wiki/Holographic_principle

It's been a while since I've watched these, but IIRC these are very good videos to start with:

- http://www.youtube.com/watch?v=2DIl3Hfh9tY

- http://www.youtube.com/watch?v=GHgi6E1ECgo

EDIT:

Key clippings from the wikipedia article-

"But Jacob Bekenstein noted that this leads to a violation of the second law of thermodynamics. If one throws a hot gas with entropy into a black hole, once it crosses the event horizon, the entropy would disappear. The random properties of the gas would no longer be seen once the black hole had absorbed the gas and settled down. The second law can only be salvaged if black holes are in fact random objects, with an enormous entropy whose increase is greater than the entropy carried by the gas.

Bekenstein argued that black holes are maximum entropy objects—that they have more entropy than anything else in the same volume. In a sphere of radius R, the entropy in a relativistic gas increases as the energy increases. The only limit is gravitational; when there is too much energy the gas collapses into a black hole. Bekenstein used this to put an upper bound on the entropy in a region of space, and the bound was proportional to the area of the region. He concluded that the black hole entropy is directly proportional to the __area__ of the event horizon."

(__'s mine)

⬐ rthomas6

>Bekenstein argued that black holes are maximum entropy objects

So would it follow that the equilibrium state of the universe is one gigantic black hole?

⬐ Ygg2

We are essentially sitting inside a giant black hole.

As our cosmos expands faster than speed of light, we can't ever escape this cosmos. Our light cone is similar to one that sits in a giant black hole.

⬐ 001sky

Is there any issue here about fundamental stability? I'm struggling with how the universe can be at once expanding and some form of dimensionalized representation. Unless the other half of the relation is also in some sort of dynamic transition. Which might be true but suggest (perhaps as you do) there are things outside our perception that we can never perceive, not to mention measure or experience (ie travel too) because they are outside the space of our cognitive faculties. Or like you say, we are in a black hole and can't see out.

⬐ mmastrac

> we can't ever escape this cosmos

Unless we figure out how to emit ourselves as Hawking Radiation in the outer universe?

⬐ X4

wow, this thread gets more and more interesting. I think the discovery of the holographic universe just broke all norms and worldviews of physics for the most of us.

⬐ Ygg2

Unless we figure how to tunnel to the other side of the universe. Because quantum tunneling would allow us to move faster than light which is necessary to escape.

⬐ 10098

So the key takeaway from that, for me, is that this research does NOT prove that we live in a "simulation".

⬐ None

None

⬐ andrewflnr

It's impossible in principle to prove that we are or are not living in a simulation.

⬐ ericbb

The simulation is always buggy. Don't you watch movies? ;)

⬐ kamaal

>>My understanding is that when they say "hologram", they're simply meaning an n dimensional object that's encoded in n-1 dimensional space.

If you apply that definition recursively. i.e, n in n - 1 , n - 1 in n - 2 and so on. You can ideally represent every thing in the very first dimension itself.

⬐ dTal

Ah, but you already knew that - anything computable can be represented on a Turing machine's 1-dimensional tape.

Makes me wonder what it actually means to say a system is n-dimensional, if you can equally well "implement" it for any n.

Such phrasing is not all that uncommon. But I agree the following few paragraphs could do a better job explaining what the word means.

http://www.youtube.com/watch?v=GHgi6E1ECgo

⬐ jessriedel

Frankly, I'm more inclined to fault Bousso for using misleading language. That's a lecture for a general audience. The word "hologram" isn't used in physics articles except for poetic fluff. For instance, in Bousso's much-cited review article, the word is used exactly once in the main text:

"Holographic screens with this information density can be constructed for arbitrary spacetimes—in this sense, the world is a hologram."

This is mostly marketing.