When string theorists say that higher dimensions are "too small" or "curled up," what do they mean? Suppose, for instance, that the x dimension was curled up in three dimensions. Could someone draw a picture that? If the x dimension was too tiny to be measured, what would this mean? Would we ever be able to get off the y-z plane? Coudl someone draw or point me to a picture of 1) a curled dimension, or a 2) dimension too tiny to be ssen? Thanks!