I have been reading about http://en.wikipedia.org/wiki/3-sphere" [Broken] and found it was impossible for me to visualize it. I tried visualizing a 4d structure with 3 space-like and one time-like dimensions by imagining a sphere (with 3 dimensions) growing with time, with successive layers (formed every second) coloured differently (a bit like tree rings). Any point inside the solid sphere would represent 4 values: 3 spatial dimensions and the fourth being the time taken for the sphere to reach the point. Please correct me if I'm wrong here. Coming back to 3-Spheres, with all four space-like dimensions, can anyone guide me in layman terms to visualize this structure? Thanks.