Okon, Sudarsky & Wiedemann argue the 'preparer' reference-frame justification for individual-outcome conservation generates an infinite regress

physicsquantum-mechanicsquantum-measurementconservation-lawsreference-framesquant-phphysics.hist-ph

Okon, Sudarsky & Wiedemann (2026, arXiv:2610.29804) critique a specific justificatory move made by Collins & Popescu (Quantum 9, 1815, 2025) in support of restoring non-statistical conservation to individual quantum measurement outcomes. Collins & Popescu argue that a quantum system can never simply be "given" in an isolated superposition of a conserved quantity, because a quantity like angular position is only meaningful relative to a physical reference frame — and identify that frame with a physical "preparer" system that stays correlated with the measured system after preparation.

Okon, Sudarsky & Wiedemann argue the inference does not follow: that a quantity is meaningful only relative to a frame does not by itself establish that the frame must be an additional material system. Worse, if the inference is granted anyway, the same reasoning applies to the enlarged system-plus-frame composite, which itself then needs a further frame — generating an unbounded regress of reference systems. They make the point concrete with a classical analogy: applied to ordinary Newtonian mechanics, the same argument would imply no finite collection of particles can be consistently described, since each additional particle supplying a reference frame would itself need one.

This is one of two independent grounds on which the paper rejects the Collins & Popescu mechanism, alongside the separate claim that the mechanism — even granted — only restores statistical conservation (claim-okon-sudarsky-wiedemann-preparer-never-definite-only-statistical-conservation-restored).