The three body problem

Newton's law of gravitation reduces to Kepler's deterministic equations... for two bodies at a safe mutual distance (e.g. past Mercury). If you add a third body, like, oh, a cycler; calculations get more difficult, especially as these bodies near one another. For these Newton never figured out a deterministic equation. Lagrange figured out regions of stability and metastability, given some assumptions of relative mass; but he left the rest to posterity. The Three Body Problem contributed to Chaos Theory: simple nonlinear differential equations in a Phase Space ending up in a massive unpredictable mess.

Hebrew University is sorting out some of the chaos. The approach is statistical, based on phase-space volume. From it, there's a phase volume flux, which they say they can constrain. Sounds to me like the borders to Libration Point 3.

For that they use a fudge, "emissivity". The idea is that if this emissivity can be averaged out, the rest of the system can be predicted... statistically.

Or so I surmise. I remain unsure on the details.

It does seem to me that, if Lorenzian fluid dynamics (alias butterfly-effect) are an analogy to the three body problem; that more progress on the latter might help toward Navier-Stokes and turbulence. And: what is emissivity, but surgery on a manifold.