paper

From a large-deviations principle to the Wasserstein gradient flow: a new micro-macro passage

arXiv:1004.4076 · doi:10.1007/s00220-011-1328-4

Abstract

We study the connection between a system of many independent Brownian particles on one hand and the deterministic diffusion equation on the other. For a fixed time step , a large-deviations rate functional characterizes the behaviour of the particle system at in terms of the initial distribution at . For the diffusion equation, a single step in the time-discretized entropy-Wasserstein gradient flow is characterized by the minimization of a functional . We establish a new connection between these systems by proving that and are equal up to second order in as . This result gives a microscopic explanation of the origin of the entropy-Wasserstein gradient flow formulation of the diffusion equation. Simultaneously, the limit passage presented here gives a physically natural description of the underlying particle system by describing it as an entropic gradient flow.

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