I think mass is attracted to the center of a 4th dimensional hypersphere (time neglected). Where there is a 4th spacial dimension. If by some craziness there was both an attraction betweent objects and the center of this 4D sphere, and objects to other objects(in the 4D) then you in theory could have really dense objects connect in the (x < radius4dHS) section, thus creating a tunnel between distant points in spacetime. Unfortunately we don't really have a way of telling if there are attractions in 4D between objects. This is how I think the universe is.