Oriented spheres in complex Euclidean three-space can be represented as lines in complex projective three-space ("Lie correspondence"), and the spheres may be thought of as the t = 0 representation of the light cones of events in Minkowski space. In effect, the Lie correspondence represents the points of (complexified compactified) Minkowski space by lines in complex projective three-space, where meeting lines describe null-separated Minkowski points. This is the twistor correspondence.

Minkowski space | twistor