[biggerfisch]

There is such a limit to areal density. The math involved dives into entropy and the planck length, but the short answer is that any information at a quantum level must be quantized in some form and the smallest possible quantization is the planck length squared, called the "planck area".

reference: https://physics.stackexchange.com/a/2283

[bsamuels]

this is probably a silly question, but why isnt the smallest possible quantization just planck length, or planck length cubed?

[spiralx]

The holographic principle says that all of the information required to represent a 3-D volume is encoded on the 2-D surface of its boundary i.e. in one sense there is no difference between e.g. a black hole and its surface.

https://en.wikipedia.org/wiki/Holographic_principle

[smilliken]

The idea is that our universe has three spatial dimensions, but only two are needed to represent a given volume of space. All the information is on the boundary surface.

In other words, we live in a hologram.

[eximius]

I think they're talking about _area_ specifically.

[spiralx]

It's actually 2x2 Planck lengths per bit, so 4 Planck areas.

https://en.wikipedia.org/wiki/Bekenstein_bound