The argument rests on three axioms: superposition is real, the world evolves unitarily with no collapse added, and the Born measure weights the branches. Everett’s reading is presented as the conservative one, the refusal to add, with the alternatives costed. Every step can be followed with a diagram and a willingness to sit with where it leads.

Part III is where the book earns its subtitle. The measure runs over all the branches and weights them by amplitude, never by worth. What that does to choice, to death (the sensitive chapter, written carefully), to love and grief, and to the self is the territory of the closing chapters. The structure does not love the people whose branches run alongside yours. It does not love anything. The caring is the only warmth the structure contains, and it comes from us, or it comes from nowhere.

Multitudes is the second volume of The Indifference Suite. Its companion is Worldlines: The Indifference of Geometry (Vol I), which runs the same move on relativity. The suite’s fiction is Measure, a novel whose antagonist commits exactly the error this book refutes.

Related: Epilogue: measure and meaning, the closing post of the quantum-from-scratch series, is a short-form companion to this book.

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