  We briefly discuss the concepts of immersion and embedding of space-times in
higher-dimensional spaces. We revisit the classical work by Kasner in which he
constructs a model of immersion of the Schwarzschild exterior solution into a
six-dimensional pseudo-Euclidean manifold. We show that, from a physical point
of view, this model is not entirely satisfactory since the causal structure of
the immersed space-time is not preserved by the immersion.
