dcl

>It makes sense to me to suspect that the three-dimensional world that we experience is actually the three-dimensional "surface" of a four-dimensional hypersphere.>

Makes sense to me also.
We would be four dimensional except for the spin of the universe which squashes us
and all matter (flat) into three dimensions because of the centripetal force.This also explains gravity and why all masses accelerate at the same rate in a G field.