arxiv: 2605.14538 · v1 · submitted 2026-05-14 · 🪐 quant-ph

Recognition: 1 theorem link

· Lean Theorem

Are free choices absolute, when internalized in Wigner's friend?

Laurens Walleghem

Authors on Pith no claims yet

Pith reviewed 2026-05-15 01:39 UTC · model grok-4.3

classification 🪐 quant-ph

keywords Wigner's friendfree choiceabsolutenesslocalityPusey-Barrett-Rudolph theoremquantum measurement problemextended Wigner's friend

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The pith

Free choices are not absolute when internalized in an extended Wigner's friend scenario under locality.

A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.

The paper constructs an argument showing that an agent's measurement choice cannot be treated as absolutely free once that agent is modeled as a quantum system inside a larger laboratory, using the same locality assumption as recent extended Wigner's friend arguments. It embeds the Pusey-Barrett-Rudolph theorem into the scenario so that the internal observer's choice leads to inconsistent predictions between the friend and the external Wigner. A sympathetic reader would care because this moves the measurement problem from outcomes to the choices that generate them, implying that consistent multi-observer reasoning in quantum theory may require giving up absoluteness for both results and decisions. The work notes that parallel arguments can be built from other contextuality or nonlocality theorems.

Core claim

We present an argument against the absoluteness of free choices under the same notion of locality, using an extended Wigner's friend scenario based on the Pusey-Barrett-Rudolph theorem.

What carries the argument

An extended Wigner's friend scenario that incorporates the Pusey-Barrett-Rudolph theorem to expose inconsistency when free choices are assumed absolute for the internal observer.

If this is right

The absoluteness of free choices is challenged in exactly the same way as the absoluteness of outcomes.
Similar no-go results follow from other contextuality or nonlocality theorems.
Consistent reasoning among quantum observers may require abandoning absolute freedom of choice as well as absolute outcomes.
The argument applies whenever an observer's choice is internalized inside a larger unitary description.

Where Pith is reading between the lines

These are editorial extensions of the paper, not claims the author makes directly.

This could link debates on quantum agency to existing no-go theorems for hidden variables.
It suggests that models of observer choice inside unitary evolution need to be examined for hidden nonlocality.
Future work might test whether relaxing locality for choices restores consistency in multi-observer scenarios.

Load-bearing premise

The locality notion from prior extended Wigner's friend arguments applies directly to the internal observer's measurement choice without extra assumptions on how choices are modeled inside unitary evolution.

What would settle it

An explicit calculation or experiment in which the internal and external observers agree on the absolute freedom of the choice while still reproducing the Pusey-Barrett-Rudolph predictions without contradiction.

Figures

Figures reproduced from arXiv: 2605.14538 by Laurens Walleghem.

read the original abstract

Wigner's thought experiment illustrates quantum theory's measurement problem by considering an observer who measures a quantum system inside a sealed lab, modeled unitarily by an outsider. Recent extensions of this thought experiment, referred to as extended Wigner's friend arguments, question how different observers can reason consistently about each other in quantum setups, and challenge the absoluteness of the outcome value obtained by the friend under a notion of locality. In this work, we present an argument against the absoluteness of free choices under the same notion of locality, using an extended Wigner's friend scenario based on the Pusey--Barrett--Rudolph theorem. Similar arguments based on other contextuality or nonlocality models are possible.

Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, simulated authors' rebuttal, and a circularity audit. Tearing a paper down is the easy half of reading it; the pith above is the substance, this is the friction.

Desk Editor's Note private letter to a colleague

The paper applies PBR to argue against absoluteness of free choices in an internalized Wigner's friend setup under the same locality used for outcomes, but the transfer of that locality to choice modeling needs explicit checking.

read the letter

The core claim is that free choices lose their absoluteness in an extended Wigner's friend scenario when the friend's measurement is treated as internal, and the argument rests on the PBR theorem plus the locality notion from prior outcome-based versions. That is the new piece: shifting the target from outcomes to choices while keeping the locality fixed and invoking PBR rather than other no-go results. The paper also notes that parallel arguments could run with other contextuality or nonlocality theorems, which keeps the door open for follow-up work without overclaiming uniqueness. That connection to existing literature is the main strength; it sits squarely inside the ongoing Wigner's friend discussion and does not invent new entities or free parameters. The abstract is short on steps, so the actual reduction from PBR to the free-choice conclusion is not visible here. The stress-test point about whether the locality notion carries over cleanly when the choice is encoded inside the unitary evolution looks like the place to press. If the full text does not spell out how the choice degree of freedom interacts with the measured system without extra premises, the extension could rest on an unstated modeling assumption rather than following directly from the outcome case. No circularity is apparent from the description, and the argument is presented as building on independent prior results. This is aimed at people already working on relational quantum mechanics and extended Wigner's friend thought experiments. It is narrow enough that most readers outside that niche will not need it, but inside the niche it supplies a concrete next step worth checking. The work shows clear engagement with the literature and is coherent on its own terms, so it deserves a serious referee to verify the derivation and the locality transfer. I would send it to review rather than desk reject, with the referee asked specifically to examine how choices are represented in the ontological model.

Referee Report

2 major / 1 minor

Summary. The manuscript claims to construct an argument, based on the Pusey–Barrett–Rudolph theorem, showing that free choices lose their absoluteness when internalized inside an extended Wigner’s-friend scenario under the same locality notion previously used to challenge the absoluteness of outcomes. It asserts that the argument transfers directly from outcome-based no-go results to the internal observer’s measurement choice without additional premises on how choices are represented in the unitary dynamics.

Significance. If the derivation were supplied and the locality transfer were shown to hold without new assumptions, the result would extend PBR-based no-go theorems from measurement outcomes to the status of free choices, tightening constraints on realist models that treat choices as absolute. The manuscript does not, however, supply the explicit steps or ontological-model assumptions needed to evaluate whether this extension succeeds, so the significance cannot be assessed above a low level from the given text.

major comments (2)

[Abstract and §2] The abstract and introduction assert that the PBR theorem is applied to an internalized choice under the same locality used for outcomes, yet no derivation, no explicit mapping of the choice degree of freedom into the PBR preparation, and no check that the locality condition survives unitary embedding of the choice are provided. Without these steps it is impossible to verify whether the claimed conclusion follows or whether extra structure on how the choice interacts with the measured system is tacitly introduced.
[§3 (argument construction)] The skeptic’s concern is realized in the manuscript: the locality notion employed for external interventions in prior extended-Wigner arguments does not automatically apply to a choice encoded inside the unitary evolution of the lab. The paper offers no additional premise or lemma showing that the PBR contradiction still obtains once the choice is treated as an internal quantum variable rather than an external intervention.

minor comments (1)

[Abstract] The statement that “similar arguments based on other contextuality or nonlocality models are possible” is left as an assertion; a brief sketch of one such model would strengthen the claim without lengthening the paper.

Simulated Author's Rebuttal

2 responses · 0 unresolved

We thank the referee for the careful reading and constructive comments. We agree that the original manuscript lacked sufficient explicit steps to fully substantiate the extension of the PBR theorem to internalized choices, and we will revise accordingly to address both major comments.

read point-by-point responses

Referee: [Abstract and §2] The abstract and introduction assert that the PBR theorem is applied to an internalized choice under the same locality used for outcomes, yet no derivation, no explicit mapping of the choice degree of freedom into the PBR preparation, and no check that the locality condition survives unitary embedding of the choice are provided. Without these steps it is impossible to verify whether the claimed conclusion follows or whether extra structure on how the choice interacts with the measured system is tacitly introduced.

Authors: We agree that the mapping and verification steps were not presented with sufficient explicitness. In the revised manuscript we will expand §2 with a dedicated derivation that maps the choice degree of freedom directly onto a PBR preparation and confirms that the locality condition used for external outcomes is preserved under the unitary embedding of the choice, without introducing additional interaction structure. revision: yes
Referee: [§3 (argument construction)] The skeptic’s concern is realized in the manuscript: the locality notion employed for external interventions in prior extended-Wigner arguments does not automatically apply to a choice encoded inside the unitary evolution of the lab. The paper offers no additional premise or lemma showing that the PBR contradiction still obtains once the choice is treated as an internal quantum variable rather than an external intervention.

Authors: We acknowledge that an explicit lemma is required to establish the transfer. The revised §3 will contain a new lemma demonstrating that the PBR contradiction continues to hold when the choice is represented as an internal quantum variable within the unitary dynamics, relying on precisely the same locality notion employed in the outcome-based arguments and without new premises. revision: yes

Circularity Check

0 steps flagged

No circularity: argument extends independent PBR theorem to new scenario without self-referential reduction

full rationale

The paper's derivation applies the external Pusey-Barrett-Rudolph theorem (a 2012 result independent of this work) within an extended Wigner's friend setup drawn from prior literature on outcome absoluteness. The abstract and reader's summary indicate that the locality notion is transferred from established extended Wigner's friend arguments without redefining it in terms of the target conclusion about free choices. No equations, fitted parameters, or self-citation chains are described that would make the result equivalent to its inputs by construction; the central claim retains independent content by combining an external no-go theorem with the new internalization of choices.

Axiom & Free-Parameter Ledger

0 free parameters · 2 axioms · 0 invented entities

The central claim rests on standard quantum-mechanical modeling of the external observer as unitary and on the applicability of the PBR theorem to the free-choice setting; no free parameters or new entities are introduced.

axioms (2)

domain assumption The external observer models the entire lab, including the friend's choice and measurement, as unitary quantum evolution.
This is the defining setup of all Wigner's friend arguments and is invoked to create the extended scenario.
domain assumption The Pusey-Barrett-Rudolph theorem can be applied to derive a contradiction with the absoluteness of the friend's free choice under locality.
The abstract states that the argument is based on PBR, treating its applicability as given.

pith-pipeline@v0.9.0 · 5407 in / 1390 out tokens · 45251 ms · 2026-05-15T01:39:12.744533+00:00 · methodology

discussion (0)

Lean theorems connected to this paper

Citations machine-checked in the Pith Canon. Every link opens the source theorem in the public Lean library.

IndisputableMonolith/Foundation/RealityFromDistinction.lean reality_from_one_distinction unclear

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unclear
Relation between the paper passage and the cited Recognition theorem.

argument against the absoluteness of free choices under the same notion of locality, using an extended Wigner's friend scenario based on the Pusey–Barrett–Rudolph theorem

What do these tags mean?

matches: The paper's claim is directly supported by a theorem in the formal canon.
supports: The theorem supports part of the paper's argument, but the paper may add assumptions or extra steps.
extends: The paper goes beyond the formal theorem; the theorem is a base layer rather than the whole result.
uses: The paper appears to rely on the theorem as machinery.
contradicts: The paper's claim conflicts with a theorem or certificate in the canon.
unclear: Pith found a possible connection, but the passage is too broad, indirect, or ambiguous to say the theorem truly supports the claim.

Reference graph

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