> For instance, what does this even mean? I'm not a physicist. Here is my lay understanding of the holographic principle. Let's think of a physical theory (t

> For instance, what does this even mean? I'm not a physicist. Here is my lay understanding of the holographic principle. Let's think of a physical theory (that attempts to describe the universe) as space of states together with a "time evolution operator" that says how states move around in the state space as time goes forward. Now, one such theory might be, say, the location and velocity of matter in 3-dimensional space as the state space, together with the laws of Newtonian mechanics. Another theory is given by particles on a 2-dimensional film together with the laws of fluid mechanics. Now, how are we to decided when two theories A and B are the same? Basically, we need to identify the states of A with the states of B, such that the identification respects the time evolution operator. (Mathematically, this is an isomorphism of theories.) The holographic principle says basically there are isomorphic 2- and 3-dimensional physical theories.