The three-body problem, in physics, is a puzzle Newton posed and could not solve: given three masses and their initial velocities, predict where they will be in one hundred years. The answer is that you cannot — not analytically, not ever. The system is deterministic, but its behaviour is irreducible. You cannot compress it. You have to live through it.
This chapter proposes that intelligence, at universal scale, is a three-body problem of exactly this kind. Mind, world, and the coordination between them form a system that can be inhabited but not reduced. Alignment, agency, and what it might be like to meet a mind unlike our own — all three questions turn out to be the same question in different clothes.