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Diffusion via evaluation map: approximation of the uniform measure

Establish that for any epsilon > 0 and any point p in a closed symplectic manifold (M, ω), there exists a centered, time-symmetric law-defining datum D (as defined in the paper) such that the push-forward of the probability measure μ^D on Ham(M, ω) under the evaluation map ev_p: Ham(M, ω) → M is within epsilon of the uniform probability measure on M in a specified metric (for example, total variation or Wasserstein distance).

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Background

In the simulations section, the author observes a diffusion-like phenomenon: points concentrated in a small region of the torus spread out rapidly under time-evolution by random Hamiltonian flows sampled from the constructed measures. Motivated by these observations, the author formulates a conjectural description of this diffusion effect in terms of the evaluation map from the Hamiltonian diffeomorphism group to the manifold.

The conjecture seeks a rigorous probabilistic statement asserting that, for an appropriate choice of law-defining datum D, the push-forward of the measure μD under ev_p approximates the uniform distribution on M arbitrarily well, thereby formalizing the numerically suggested diffusion behavior.

References

We thus formulate the following conjecture: Let p \in M be arbitrary and let ev_p: \Ham(M,\omega) \to M be the evaluation map at p. Then for any > 0, there exists a law-defining datum \mathcal{D} such that the push-forward measure (ev_p)_* {\mathcal{D} and the uniform measure on M are $$-close in a suitable metric, e.g. the total variation or Wasserstein distance.

Random Hamiltonians I: Probability measures and random walks on the Hamiltonian diffeomorphism group (2510.03190 - Dawid, 3 Oct 2025) in Simulations, Diffusion subsection