I've never understood why proof that the universe is "holographic" (= 2+1 dimensions of information projected as 3+1) does not fall out of the Schrödinger’s/Maxwell’s field equations.<p>After all, the equations, <i>by their very nature as equations</i>, constrain the dimensionality of possible universes (field configurations) by one, from 4 down to 3. The fourth is always derivable from the other three (e.g., X-Y-Z intial conditions at T=0 define X-Y-Z-T fields for all T).<p>To believe that the universe contains four dimensions of information (i.e., is not a hologram), would imply that the field equations do not universally hold. So what this experiment is actually testing is the truth of QED, which implies holography.<p>Does anyone know why this is not so? (I tried asking a while ago on Physics StackExchange and only got flippant responses.)<p>(As an analogy for CS types: consider the game of Life. It is 3-dimensional (2 space + 1 time), but constrained by the Life equation. So it cannot contain three dimensions full of arbitrary information; only a two-dimensional slice can be arbitrarily instantiated. The analogy is not perfect, as Life is neither reversible nor fully observable from any 2D slice, but it is close.)