arxiv: 2604.12094 · v1 · submitted 2026-04-13 · 🪐 quant-ph · physics.hist-ph

Recognition: unknown

Why does the wavefunction 'collapse' in relational approaches to quantum mechanics?

Emily Adlam

Authors on Pith no claims yet

Pith reviewed 2026-05-10 15:18 UTC · model grok-4.3

classification 🪐 quant-ph physics.hist-ph

keywords relational quantum mechanicswavefunction collapsequantum eventsreference systemsdiscontinuityincompleteness of quantum mechanics

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The pith

Relational quantum mechanics explains wavefunction collapses as discontinuities arising when a system interacts with its reference, which cannot describe itself.

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

The paper proposes a direct explanation for why wavefunction collapse happens in relational quantum mechanics. When describing a system relative to a reference, any interaction between them creates a break in the description because the reference system cannot be described relative to itself. This approach clarifies how quantum events occur without extra assumptions beyond the relational framework. It also highlights that this understanding demands accepting quantum mechanics as an incomplete theory of all physical facts. The author contends that such incompleteness is probably unavoidable for any precise account of these events.

Core claim

In relational approaches to quantum mechanics, wavefunction collapses or quantum events occur due to a necessary discontinuity in our description whenever a system interacts with the reference system relative to which it is being described. This discontinuity stems from the fact that the reference system cannot be described relative to itself. This provides a straightforward way to understand these events and resolves recent concerns about them in relational quantum mechanics. However, this solution requires accepting that quantum mechanics does not provide a complete description of all physical facts, and such incompleteness is likely inevitable for a precise description of quantum events.

What carries the argument

Relational reference: the use of one system as a frame for describing another, which excludes any description of the reference system's own interactions with the observed system.

If this is right

Quantum events arise naturally as breaks in relational descriptions during interactions.
Concerns about the status of quantum events in relational quantum mechanics are resolved without new postulates.
Quantum mechanics must be viewed as incomplete to allow precise tracking of these events.
Incompleteness becomes a required feature for any framework that aims to describe quantum events exactly.

Where Pith is reading between the lines

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

This view could extend to other quantum interpretations by highlighting self-reference limits in any measurement process.
It suggests developing explicit models that track how reference choices affect the completeness of descriptions.
Experiments with systems where reference frames change dynamically might show the expected descriptive breaks.

Load-bearing premise

Accepting that quantum mechanics is an incomplete description of all physical facts is both necessary and acceptable for giving a precise account of quantum events.

What would settle it

A consistent relational description of a quantum interaction that includes the reference system describing its own role without introducing any discontinuity.

read the original abstract

I argue that there is a straightforward way to understand the occurrence of wavefunction collapses or 'quantum events' in relational approaches to quantum mechanics: we necessarily encounter a discontinuity in our description when a system interacts with the reference relative to which we are describing it, since the reference system cannot be described relative to itself. This makes it clear how recent concerns around quantum events in relational quantum mechanics should be resolved. However, the solution requires accepting that quantum mechanics is not a complete description of all physical facts, and moreover I argue that this is most likely inevitable if we want to be able to give a precise description of quantum events.

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

Adlam frames collapse in relational QM as a self-reference discontinuity but the account lacks a dynamical derivation to match standard quantum rules.

read the letter

The key takeaway from Adlam's paper is that in relational quantum mechanics, the wavefunction collapse or quantum event arises as a necessary discontinuity in description when the observed system interacts with the reference system, because no system can describe itself. This is presented as a way to handle recent concerns about how events occur in relational frameworks. The paper does a good job of making this point cleanly. It starts from the core relational idea that all physical descriptions are relative to some reference and shows why that forces a break at the point of interaction with the reference. The logic is straightforward and avoids unnecessary complications. It also ties the resolution to accepting that quantum mechanics cannot be a complete description of everything, which the author argues is likely required anyway for precision about events. The main soft spot is that the argument stays at the level of conceptual assertion rather than providing a derivation. As the stress-test points out, there is no calculation demonstrating that the discontinuity corresponds to the standard collapse update in the relative-state formalism or that the probabilities follow the Born rule from the interaction. The paper does not walk through an example with a specific Hamiltonian or relative vector to show the post-interaction state. This leaves the claim that this resolves the issue somewhat open to the objection that it is just re-describing the problem without solving the dynamics. The incompleteness requirement is also taken as given without much exploration of whether other approaches could avoid it. This paper is aimed at people already working in quantum foundations, particularly those interested in relational interpretations like Rovelli's. A reader familiar with the literature on quantum events and relational QM will get value from the clear framing, even if they find the lack of technical detail limiting. It is not for someone looking for new predictions or formal results. I would recommend sending this to peer review. The central idea is coherent enough on its own terms that referees can assess whether the self-reference discontinuity really does the explanatory work, and the author can address the derivation gap if needed. It shows clear thinking about the interpretive issues.

Referee Report

1 major / 0 minor

Summary. The paper argues that wavefunction collapses or 'quantum events' in relational quantum mechanics arise straightforwardly from a necessary discontinuity in the description of a system upon interaction with its reference frame, since the reference system cannot be described relative to itself. This is presented as resolving recent concerns about the status of quantum events in relational approaches, but the solution requires accepting that quantum mechanics provides an incomplete description of all physical facts—an incompleteness the author claims is inevitable for any precise account of such events.

Significance. If the central conceptual argument holds, the paper offers a clear interpretive resolution to the measurement problem within relational QM by grounding apparent collapses in the relational character of descriptions rather than additional dynamical postulates. It explicitly credits the relational premise that no system can serve as its own reference and highlights the trade-off between descriptive completeness and the ability to track events, which could clarify ongoing debates in the field.

major comments (1)

[main argument (following abstract)] The central claim that interaction with the reference induces a discontinuity matching the standard collapse (including Born-rule probabilities) is asserted from the relational premise but lacks an explicit derivation. No calculation is supplied showing how the post-interaction relative state in the Everett/Rovelli formalism undergoes a discontinuous jump rather than remaining continuous unitary evolution of the composite system.

Simulated Author's Rebuttal

1 responses · 0 unresolved

We thank the referee for their careful reading and for identifying a point where the central argument would benefit from greater explicitness. We address the major comment below and will revise the manuscript accordingly.

read point-by-point responses

Referee: The central claim that interaction with the reference induces a discontinuity matching the standard collapse (including Born-rule probabilities) is asserted from the relational premise but lacks an explicit derivation. No calculation is supplied showing how the post-interaction relative state in the Everett/Rovelli formalism undergoes a discontinuous jump rather than remaining continuous unitary evolution of the composite system.

Authors: The referee is correct that the manuscript presents the discontinuity as a direct consequence of the relational premise without supplying an explicit calculation. Our argument is that any description is always relative to a chosen reference system, and the reference system cannot be described relative to itself; therefore, an interaction between the system and its reference necessarily requires a change of reference frame, producing a discontinuity in the descriptive account even though the global state evolves unitarily. This discontinuity reproduces the standard collapse and Born-rule probabilities as they appear in the relative-state formalism. We acknowledge, however, that an illustrative calculation would make the distinction between global unitary evolution and the jump in the relative description clearer. In the revised manuscript we will add a short section containing a concrete example (a spin measurement) worked out in the relational/Everett formalism, showing explicitly how the post-interaction relative state from the reference system's perspective exhibits the apparent collapse while the composite state remains continuous. revision: yes

Circularity Check

0 steps flagged

No circularity: discontinuity follows directly from standard relational premise without reduction to inputs or self-citation

full rationale

The paper's core claim—that interaction with a reference system induces a descriptive discontinuity because the reference cannot describe itself—is presented as a direct logical consequence of the relational QM premise that descriptions are always relative to some system. This is a conceptual clarification rather than a mathematical derivation involving equations, fitted parameters, or ansatzes. No self-citations, uniqueness theorems, or renamings of known results are invoked in the abstract to support the central step, and the argument does not equate any output to its inputs by construction. The requirement to accept QM as incomplete is stated explicitly as an additional philosophical commitment, not smuggled in via definition.

Axiom & Free-Parameter Ledger

0 free parameters · 1 axioms · 0 invented entities

The claim rests on the domain assumption of relational quantum mechanics that all physical descriptions are relative to a chosen reference system and that no system can describe its own state relative to itself. No free parameters or invented entities are introduced in the abstract.

axioms (1)

domain assumption All descriptions in quantum mechanics are relative to a reference system, and a reference system cannot be described relative to itself.
This is the foundational premise of relational QM invoked to derive the discontinuity at interaction.

pith-pipeline@v0.9.0 · 5390 in / 1251 out tokens · 47572 ms · 2026-05-10T15:18:22.931406+00:00 · methodology

discussion (0)

Reference graph

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