What is the holographic principle?
The holographic principle says the most information a region of space can hold is fixed by the area of the surface around it, and the volume inside does not enter. Everything the outside world can learn about a region arrives through that surface, so two interiors showing the same readings all over the boundary are one state to everybody outside. The boundary is tiled with identical patches, each holding the same finite amount, which makes a region's memory a count of the patches on its edge. Double the shelving in a sealed room and its capacity stays put, because the walls have not moved. Black holes fixed the exchange rate at one natural unit of memory per four Planck squares, each a square 1.6×10⁻³⁵ meters on a side. A square ten centimeters across holds about 10⁶⁷ units.
Also in Chapter 13: What Is One Piece of Reality Actually Made Of?.
This answer comes from OPH, Observer Patch Holography. OPH is a rigorous, consistent and complete description of the unified, self-creating computational Universe we inhabit. Its consistency is machine-checked: the fixed point at its core is constructed explicitly, and a theory with a model contains no contradiction.
To understand OPH and check every step yourself, start with the free book Reverse Engineering Reality. It builds the theory from the ground up, and the OPH Notebook answers your questions while you read.
read the free bookask the notebookor ask sage:read chapter 24: Why Does a Region's Memory Scale With Its Surface?watch a universe make its own particles