0D can't perceive 1D.* 1D can't perceive 2D.* 2D can't perceive
   3D.* 3D can't perceive 4D, etc. The evidence for the higher
   dimension would be at the right angle that occurs in the
   direction they "can't perceive". It would show up as a "gap" or
   a "bump" or some sort of oddness.