# Thread: Sides of a holographic screen?

1. When it is said that the holographic principle states that the description of a volume of space can be thought of as encoded on a boundary to the region, I am made to wonder what the screen encodes when viewed from the other side. Or, to make a more precise situation, consider a volume enclosed by a sphere. Now divide this into to two hemispheres with an additional portion of screen. Presumably now each resulting hemispherical screen encodes the description of its contents. If the contents differ, does the encoding on the two sides of the partition then differ? If screens are infinitely thin mathematical objects, how is this possible? Has anyone suggested that they are something more material?

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3. I've seen (in video) of a holographic color photography... in which a thin film is used to store a hologram of an object behind it. First.. a film is put infront of an object in a brightly lit box, and then when the object is removed : you'll see the same object behind the glass again (in 3d and in color. Viewable in multiple angle). -I guess this is possible because the film are able to re-create all the multiple light rays/path and color that represent and object by just using a mere 2D pattern & light interference on the film.

I guess the closest analogy to it is data compression in computers.

Not sure what theoretician suggest of a "hologram universe", but physical hologram exist and you can use it to see/imagine how powerful a hologram is.
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Here's a youtube vid of a conventional laser hologram: Holograms at MIT Museum - YouTube .As you can see... its really really mind boogling how it can store all those information in a mere thin film. It even store the optical effect of the object being captured, and can be viewed in 3D in almost all angle (the hologram is not in full color because they use laser *single color* to light up the film).

4. Originally Posted by msafwan
I've seen (in video) of a holographic color photography... in which a thin film is used to store a hologram of an object behind it. First.. a film is put infront of an object in a brightly lit box, and then when the object is removed : you'll see the same object behind the glass again (in 3d and in color. Viewable in multiple angle). -I guess this is possible because the film are able to re-create all the multiple light rays/path and color that represent and object by just using a mere 2D pattern & light interference on the film.
I don't believe the cosmological holographic principle and photographic holography actually have much to do with one another outside of the name. The name was suggested by the fact that the holographic principle, like holography, involves description of an n-dimensional volume on an n-1 dimensional surface, but the surfaces and the physics involved are not comparable.

5. Okay, thanks.

This remind me of one documentary I watch. It says that the horizon of a black hole (or something like that?) is a surface that represent what is happening inside black hole(?). -It says something like: when something fall into black hole the information doesn't necessarily disappear, it actually get stored in the surface?

Not sure, maybe someone know what it actually mean? is it related to this holographic universe? -maybe someone can help add some detail?

6. Originally Posted by msafwan
It says something like: when something fall into black hole the information doesn't necessarily disappear, it actually get stored in the surface? Not sure, maybe someone know what it actually mean? is it related to this holographic universe? -maybe someone can help add some detail?
Yes, that's the origin of it, but recently it's used in more general cases such as Verlinde's speculation on entropic gravity, etc.