  We discuss a new notion of distance on the space of finite and nonnegative
measures which can be seen as a generalization of the well-known
Kantorovich-Wasserstein distance. The new distance is based on a dynamical
formulation given by an Onsager operator that is the sum of a Wasserstein
diffusion part and an additional reaction part describing the generation and
absorption of mass.
  We present a full characterization of the distance and its properties. In
fact the distance can be equivalently described by an optimal transport problem
on the cone space over the underlying metric space. We give a construction of
geodesic curves and discuss their properties.
