  We discuss the question of whether the existence of singularities is an
intrinsic property of 4D spacetime. Our hypothesis is that singularities in 4D
are induced by the separation of spacetime from the other dimensions. We
examine this hypothesis in the context of the so-called canonical or warp
metrics in 5D. These metrics are popular because they provide a clean
separation between the extra dimension and spacetime. We show that the
spacetime section, in these metrics, inevitably becomes singular for some
finite (non-zero) value of the extra coordinate. This is true for all canonical
metrics that are solutions of the field equations in space-time-matter theory.
This is a geometrical singularity in 5D, but appears as a physical one in 4D.
At this singular hypersurface, the determinant of the spacetime metric becomes
zero and the curvature of the spacetime blows up to infinity. These results are
consistent with our hypothesis.
