A Holographic principle (I'm looking for a paper that I read)

[Heidi]

I read a paper a long time ago. And i forgot who wrote it. The author said that information was not encoded on space time but on the boundaries of regions of space time.
there was 3 parts on this boundaries.
a space like part (for the initial conditions) . another one for the "out" state. between them a time like region.
i think that they had the same dimension (2 or 3)
have you an idea? maybe Rovelli?

 

[atyy]

https://www.scientificamerican.com/article/the-illusion-of-gravity-2007-04/
The Illusion of Gravity
Juan Maldacena

 

[Heidi]

It was neither him nor Verlinde. I read in the wiki spin foam article that spin networks are boundaries of spin foams. (i was still thinking of Rovelli).

 

[Klystron]

I read a paper a long time ago. And i forgot who wrote it. The author said that information was not encoded on space time but on the boundaries of regions of space time.
there was 3 parts on this boundaries.
a space like part (for the initial conditions) . another one for the "out" state. between them a time like region.
i think that they had the same dimension (2 or 3)
have you an idea? maybe Rovelli?

Reminds me of Leonard Susskind.

The holographic principle is a tenet of string theories and a supposed property of quantum gravity that states that the description of a volume of space can be thought of as encoded on a lower-dimensional boundary to the region—such as a light-like boundary like a gravitational horizon. First proposed by Gerard 't Hooft, it was given a precise string-theory interpretation by Leonard Susskind,[1] who combined his ideas with previous ones of 't Hooft and Charles Thorn.

 

[Heidi]

You are right but in the paper i read there was not one screen at infinity for the universe but many screens. one for each compact region.

 

[atyy]

You are right but in the paper i read there was not one screen at infinity for the universe but many screens. one for each compact region.

https://www.frontiersin.org/articles/10.3389/fphy.2020.00111/full
Holographic Space-Time and Quantum Information
Tom Banks

 

[Heidi]

I think it was an old (2008) article written by Oeckl. General boundary QFT.
I will download it .

 

[Heidi]

Does somebody read this article? I see how it is an extension of the standard quantum theory. But i do not see how to interpret the functions on a time like part of a boundary (the vertical region of the cylinder in the figure)

 

[Heidi]

I see now. if take a 4 dimensional cylinder its boundary is 3 dimensional. it may be timelike:1 dimension for time and 2 for space (the screens)
they can wrap finite regions. It is the case with Verlinde screens.