Holographic principle aside, I believe that there is no theoretical basis for a 3rd spatial dimension, only experiential, since we can see and measure depth, as well as height and length. From what I've read, however, all forms of depth perception require movement, or otherwise don't allow measurements to be made(perspective). That lead me to the conclusion that the 3rd dimension of space may be just the illusion created by several 2-dimensional "frames" super-imposing over an infinitesimal amount of time in our memory. In other words, there'd be 2 space dimensions, one time dimension and one "memory" dimension, or imaginary time. If "the present moment" is a volume in this 2+1 spacetime with an infinitesimal depth(=time), therefore mathematically real, "memory", or "past+future" are the rest of the volume and mathematically defined as real+imaginary(or, we always relate the past/future to the present). Technically, I suppose this would be a 2+2 dimensional universe, what with time being complex. So, am I making an error in judgement, or can I commence bedazzling my drinking buddies with this little revelation of mine? And if I'm really on to something, who else thought of this before me? I just recently found out that complex time has already been proposed by Hawking.