nucleation

THEORY-1230: In relational quantum mechanics, with facts fixed by interaction and the classical sum rule used only within one context or where facts are stable, facts relative to different systems never yield contradictory predictions in extended Wigner's-friend scenarios, and a superobserver's later facts agree with his friend's

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Properties4
StatusProposed
Tagsquantum-foundations, metaphysics
SourceLIT-1666 — Stable Facts, Relative Facts
ExtendsTHEORY-1081 — Di Biagio and Rovelli locate the Frauchiger–Renner contradiction and the violation of the Local Friendliness inequalities in one step, a superobserver using facts relative to a friend he holds in full quantum control as if they were his own, which is the classical sum rule applied where those facts are not stable for him; they base quantum ontology on facts relative to systems rather than on stable facts, arguing that stability is itself relational and only approximate and counting the Local Friendliness violation as evidence, with an absolute macroreality emerging only approximately and only relative to systems for which decoherence is strong

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Source

Di Biagio and Rovelli (2021), LIT-1666, read in full in NOTE-1226, §§2.2–2.3. The contradiction “follows from inappropriately mixing contexts” (p. 8), and “Wigner will always agree with his Friend about the value of L_S once he too interacts with them” (p. 10).

Where the evidence stands

What the paper argues is THEORY-1081, Active, which this entry extends. The decohered case is credited to others, agreement between observers is argued from one entangled state’s correlation (THEORY-1080), and an agent reasoning about an experiment on himself “has not been done within RQM yet”. THEORY-621, Proposed, carries the same gap for Rovelli’s single-friend rule from another source. The promote_when above is THEORY-1081’s condition before the twenty-fourth status review promoted it, carried here unchanged, because it asks what would make the thesis true and not what the source says.

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