Artful Dodger: That other dimension we can't access, at the moment, is something I'm sure isn't factored into String theory. I don't really care if it is or not... I don't store my personal beliefs on the same shelf with the toys I play with.

I don't know if anyone else is going to weigh in on this, so instead of waiting for something that may not happen, I'll just go ahead and tell you what my answer is.

A three dimensional object has length, width, and depth. A two dimensional object would only have length and width, which means it has zero depth. Without that third dimensional depth, a two dimensional object could only exist as a plane bordered by a line made up of imaginary points. With no depth at all, the two dimensional 'object' cannot exist as an object, because the line made up of imaginary points doesn't actually exist. It is imaginary.

Here's the bit you might like, because it's something I didn't know until you told me about it a few years back. You told me about irreducible complexity. The principle of irreducible complexity shows that physical reality is dependant on all three dimensions existing at the same time, otherwise no physical reality can exist. There may only be three, but it can't be reduced from that.