One State, Many Perspectives: Everett's Interpretation Without Worlds, and Without a Special Problem of Probability

Everett's interpretation is best known under the name "many worlds", a name Everett never used in his published writings and which has concentrated the criticism directed at it: how many worlds are there? when do they split? what can probability mean if everything happens? We argue that these questions target the popularization of the theory rather than the theory itself, and that the last of them can now be retired on a precise ground. The probability problem divides into a quantitative question (why the Born weights?) and a question of meaning (what is there to be uncertain about?). The quantitative question is closed by a theorem, T*: the Born rule is the unique weighting of alternatives that is independent of the chosen grain of description, convergent among observers sharing the same records, and stable under branching. T* is established in a companion article by reduction to two published theorems, Gleason (1957) and Short (2023); non-contextuality, the traditionally contested premise of Gleason-type arguments, is derived there from grain coherence rather than postulated; convergence turns out to be a corollary; and the central theorem is verified end to end in Lean 4 with Mathlib, in full generality, with Gleason's theorem as the single declared axiom. The question of meaning is answered by internality: an observer who is part of the state is, by theorem, ignorant of their own location in it, and self-locates on accessible records. What then remains is one posited principle, the bridge between an objective measure and rational expectation, and we show step by step that it is the same principle a deterministic coin already exacts from classical physics. Everett's interpretation, properly formulated, therefore has no special problem of probability: it carries the normative residue that all probabilistic physics carries, and one postulate fewer, since the Born measure is derived and nothing collapses.