Answers to a few questions regarding the BMV experiment
Pith reviewed 2026-05-24 18:34 UTC · model grok-4.3
The pith
Alleged counter-examples do not refute the claim that gravity must be non-classical to mediate entanglement.
A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.
Core claim
Alleged counter-examples stating that gravity can create entanglement while complying with locality do not invalidate the result; the original claim that such gravity must be non-classical still stands because the proposed scenarios do not meet the locality condition and classicality definition used in the 2017 argument.
What carries the argument
The locality condition and the definition of a classical mediator from the 2017 argument, which together prohibit entanglement creation by any local classical interaction.
If this is right
- The BMV experimental proposal remains a valid test for whether gravity is classical.
- No local classical field or interaction can generate the predicted entanglement in this setup.
- Any mediator of the gravitational interaction that produces entanglement must fail to be classical under the stated definitions.
- The result applies to any interaction mediator, not only gravity.
Where Pith is reading between the lines
- Similar locality-plus-classicality arguments might be used to test the quantum character of other long-range forces.
- Numerical simulations of the two-mass system could make explicit whether a given classical model violates the locality condition when it attempts to entangle the particles.
- The defense implies that future proposals for classical gravity theories must explicitly demonstrate how they avoid creating entanglement under the same locality rules.
Load-bearing premise
The locality condition and definition of classicality from the 2017 argument are the correct standards to use when checking whether a proposed scenario counts as a counter-example.
What would settle it
A concrete model or experiment in which a mediator satisfies the original locality condition and classical definition yet still produces entanglement between the two masses would falsify the claim.
read the original abstract
We provide brief answers to a number of recurring questions about the BMV effect and the related experimental proposal (Bose et al., 2017; Marletto and Vedral, 2017). Some of these questions include alleged counter-examples to our result, stating that if gravity (or anything mediating the interaction) can create entanglement while complying with locality, then it must then be non-classical. Here we explain why these objections are not counter-examples and why our result still stands; we also explore a few other important subtleties often disregarded on a first read of our paper (Marletto and Vedral, 2017).
Editorial analysis
A structured set of objections, weighed in public.
Referee Report
Summary. The manuscript provides brief answers to recurring questions about the BMV experiment (Bose et al. 2017; Marletto and Vedral 2017). It focuses on alleged counter-examples claiming that gravity (or another mediator) can generate entanglement while remaining local, arguing that these examples fail to satisfy the original locality condition and definition of a classical mediator; the central claim that a non-classical mediator is required therefore stands. The paper also addresses other subtleties in the 2017 argument that are often overlooked.
Significance. If the defense of the locality and classicality conditions is correct, the clarifications strengthen the theoretical foundation of the BMV proposal for testing the quantum nature of gravity. The work supplies explicit rebuttals to common objections, which may reduce misinterpretation in future theoretical and experimental discussions of mediator-mediated entanglement.
minor comments (1)
- The abstract refers to 'our result' and 'our paper (Marletto and Vedral, 2017)' without a dedicated section summarizing the precise locality condition being defended; adding a short recap of the 2017 definition (e.g., in §2) would improve self-contained readability.
Simulated Author's Rebuttal
We thank the referee for their positive assessment of the manuscript and for recommending acceptance. The report correctly identifies that the paper supplies explicit rebuttals to common objections regarding the locality and classicality conditions in the BMV proposal.
Circularity Check
No significant circularity
full rationale
The paper is a clarification responding to objections against the authors' own 2017 BMV argument. It does not introduce any new derivation, prediction, or first-principles result whose validity reduces by construction to inputs, fitted parameters, or self-citations within this manuscript. The central claim—that alleged counter-examples fail the original locality and 'classical' definitions—is defended by reference to the 2017 paper, but this is a normal citation to prior work being clarified rather than a load-bearing self-referential reduction (no equations, ansatzes, or uniqueness theorems are shown to collapse into the citation itself). No patterns from the enumerated list are exhibited with direct quotes demonstrating equivalence by construction. The paper is self-contained as a response document against external benchmarks (the objections themselves).
discussion (0)
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