an actual entity can completely contain indefinitely many other actual entities.

Whitehead's theory of extension concerns the spatio-temporal features of his occasions of experience. Fundamental to both Newtonian and to quantum theoretical mechanics is the concept of velocity. The measurement of a velocity requires a finite spatiotemporal extent. Because it has no finite spatiotemporal extent, a single event of Minkowski space cannot be an occasion of experience, but is an abstraction from