It is just as incomprehensible to me that the Flatlanders cannot fathom the depth of a third dimension, as does it strike them as unphysical that there should be one. And then I find myself being a 3 dimensional Flatlander, for it seems so self-evident to me that my mind cannot comprehend 4 spatial dimensions, and I seek no further explanation as to why that is so.
And so it strikes me, that in this world we are all Flatlanders of different dimensionality, but with this one thing in common: If we don’t look up, we will never fathom the depth of reality.
Oh, did you know that the universe is about flat? According to the most recent Planc-data the curvature is k= -0.0013 ish. (arXiv: 1303.5076[astro-ph.CO])