3dim on 4th sphere

Connections List
 * Space antinomy
 * Dimensions of universe

Our three dimensions are wrapped on a 4th dim sphere. So if you travel far enough in one direction you'll come full circle back to where you started.

Retains possibility of infinite expansion in the radial dimension.

Conflicts with euclidian geometry as it supposes parallel lines will meet after 90degrees.

What is the 4th like and can we travel in it?