### „Almost all of fluid dynamics follows from a differential equation called the Navier-Stokes equation. But this general equation has not, in practice, led to solutions of real problems of any complexity. In this sense, the curve of a baseball is not understood; the Navier-Stokes equation applied to a base ball has not been solved.“

— Robert Adair (physicist)

The Physics Of Baseball (Second Edition - Revised), Chapter 2, The Flight Of The baseball, p. 22