# Holographic universe physiology

March 21, 2011 4:52 PM Subscribe

If the 2d universe is holographic, does the surface descriptor end at the "middle" of the universe?

If Leonard Susskind is correct, and the universe can be described on a 2-dimensional surface: if the 3d universe was the shape of the sphere, and the outer 2d surface of the sphere has the area of a sphere, does the descriptor of the surface end at the center of the universe, or half the diameter? Does it take two surfaces to describe the full width x planck-value of the universe? What about a non-spherical universe shape? Or is it redundantly described on both surfaces?

If Leonard Susskind is correct, and the universe can be described on a 2-dimensional surface: if the 3d universe was the shape of the sphere, and the outer 2d surface of the sphere has the area of a sphere, does the descriptor of the surface end at the center of the universe, or half the diameter? Does it take two surfaces to describe the full width x planck-value of the universe? What about a non-spherical universe shape? Or is it redundantly described on both surfaces?

mrs_roboto, read up on the Holographic Universe theory.

In the case of this theory, AFAIK, the descriptor just means the information that makes up what we perceive as our universe. It's an out-there thing.

I have no answer for torpark, though. This shit is just as confusing to me as it is to him.

posted by InsanePenguin at 6:03 PM on March 21, 2011

In the case of this theory, AFAIK, the descriptor just means the information that makes up what we perceive as our universe. It's an out-there thing.

I have no answer for torpark, though. This shit is just as confusing to me as it is to him.

posted by InsanePenguin at 6:03 PM on March 21, 2011

In general, holographic descriptions are

Also, a sphere has only one surface. The fact that a reference point in 3-space can be inside the sphere, part of the surface or outside the sphere doesn't change that.

posted by flabdablet at 2:39 AM on March 22, 2011

*not*one-to-one mappings between specific points on the holograph and specific points in the image; rather,*all*points in the holograph affect*each*point in the image and vice versa. In no sense is the holograph a projection of the image. I wouldn't expect the central point of a sphere whose contents are holographically encoded on its surface to be special in this regard.Also, a sphere has only one surface. The fact that a reference point in 3-space can be inside the sphere, part of the surface or outside the sphere doesn't change that.

posted by flabdablet at 2:39 AM on March 22, 2011

What flabdablet said-- a sphere has only one connected surface.

Most holographic physics involves one connected boundary (people wanting to consider a slighty odd case should look into AdS_2, but I really doubt that's what you're talking about here).

Can you restate your question a bit, given flabdablet's point re: a sphere has one connected surface? (that's true for any shape-of-constant radius in 2 or more dimensions... a disc shape has just a circle as its boundary, a solid sphere like an orange has just the surface (the peel of the orange) as its one boundary... and an object of constant radius embedded in 4 dimensions would have just one connected boundary too. Etc etc.)

posted by nat at 1:19 PM on March 22, 2011

Most holographic physics involves one connected boundary (people wanting to consider a slighty odd case should look into AdS_2, but I really doubt that's what you're talking about here).

Can you restate your question a bit, given flabdablet's point re: a sphere has one connected surface? (that's true for any shape-of-constant radius in 2 or more dimensions... a disc shape has just a circle as its boundary, a solid sphere like an orange has just the surface (the peel of the orange) as its one boundary... and an object of constant radius embedded in 4 dimensions would have just one connected boundary too. Etc etc.)

posted by nat at 1:19 PM on March 22, 2011

This thread is closed to new comments.

posted by mr_roboto at 5:42 PM on March 21, 2011