1. Do I understand correctly that closed curves on a 3-dimensional torus are represented as closed ribbons lying freely (with the possibility of inverting) on a classical torus?
2. Do I understand correctly that if all the isotropic straight lines of a Minkowski space are mapped on the corresponding circles, then the isotropic cone is mapped on the product S2 x S1, and if all the isotropic straight lines of a 4-dimensional space with a neutral metric are mapped on the corresponding circles, then the isotropic cone turns into a 3-dimensional torus? Finally, is it true that with this compactification of an 8-dimensional space with a neutral metric, we get a product S3 x S3 x S1 instead of a cone?