Decomposition-Indexed Classicality and the Resolution of Nested-Observer Paradoxes

This paper proposes a new way to understand when a quantum event becomes a classical “fact.” Instead of assuming that classical outcomes are universal, the framework shows that they depend on how an observer divides the world into system, detector, observer, and environment. Each such decomposition follows its own trajectory, and classicality appears only when enough information is accessible, redundantly recorded, and irreversibly amplified.

Using this structure, the article shows that famous multi-observer paradoxes—especially Frauchiger–Renner—do not reveal a flaw in quantum theory but arise from mixing statements that belong to incompatible viewpoints. When each statement is used only within its proper context, the contradictions disappear.

The result is a simple idea with broad implications: classical facts are not global features of the universe but local features of how observers interface with it. This framework provides a clear, intuitive way to understand why quantum theory remains consistent even in complex nested-observer scenarios.