Diffusion of a population of retrograde test wires of individual mass μ_t = μ_⋆ as a function of time. The evolution of each star is driven by the Langevin Eq. (64). The initial PDF of the population is represented by the red histogram, while the coloured histograms describe the statistics of the population after a time ΔT = 200 and 2ΔT. Solving the dynamics of this population via the Langevin Eq. (64)allows for the integration forward in time of the Fokker-Planck Eq. (62), which describes the diffusion of the test wires’ PDF as a whole, without resorting to direct N-body simulations.