Geometric hydrodynamics via Madelung transform.

Khesin, Boris; Misiolek, Gerard; Modin, Klas · Proc Natl Acad Sci U S A · 2018

basic_science · Level V

Where this comes from

Abstract

We introduce a geometric framework to study Newton's equations on infinite-dimensional configuration spaces of diffeomorphisms and smooth probability densities. It turns out that several important partial differential equations of hydrodynamical origin can be described in this framework in a natural way. In particular, the Madelung transform between the Schrödinger equation and Newton's equations is a symplectomorphism of the corresponding phase spaces. Furthermore, the Madelung transform turns out to be a Kähler map when the space of densities is equipped with the Fisher-Rao information metric. We describe several dynamical applications of these results.