Comment on "Experimental motivation and empirical consistency in minimal no-collapse quantum mechanics"

Fred H. Thaheld

REVIEW

Comment on "Experimental motivation and empirical consistency in minimal no-collapse quantum mechanics"

Fred H. Thaheld

Quantum Physics · Submitted 22 Feb 2006 · 2 references

Pith's verdict: The comment fails because it equates decoherence with collapse, so the empirical facts it cites are compatible with the no-collapse account it attacks.

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CitationFred H. Thaheld. "Comment on "Experimental motivation and empirical consistency in minimal no-collapse quantum mechanics"." arXiv:quant-ph/0602190 (2006). https://pith.science/paper/QGBFKRDU

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Editor's note

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Both the reader's report and the stress-test are on target. This comment fails for a simple reason: it treats fast environmental interaction and neural amplification as if they were collapse, when they are exactly the decoherence mechanisms Schlosshauer's no-collapse theory relies on.

The empirical material is not the problem. The 200 fs cis-trans isomerization is real, the sodium-ion amplification is real, and the retina is indeed a hostile place for any fragile superposition. Thaheld is right that the visual system does not wait until the occipital cortex to do something drastic with a photon signal. That is worth saying, and he has said it before.

But the conclusion doesn't follow. After quoting Schlosshauer's own statement that rhodopsin molecules are subject to strong decoherence that preselects robust states, Thaheld writes that the photon interaction 'is not of a superposed state, as there would have already been a collapse.' That is the load-bearing step, and it is an assertion, not an argument. Strong decoherence and state preselection are what a no-collapse theory uses to explain definite outcomes; they do not constitute evidence for collapse. The rest of the comment—sodium ions, action potentials, LGN burst modes—all assumes that the superposition must survive intact to the cortex. But Schlosshauer's theory does not require that. The faster and more thoroughly the environment kills the superposition, the better for his story. So the cited neurophysiology, even if accurate, only relocates the effective branch separation to the retina. That is a possible point of dispute, but it is not a refutation.

Novelty is thin. The core objections are repetitions of refs 2 and 5, and the 200 fs datum is from 1991. The comment adds little beyond applying old arguments to Schlosshauer's 2006 article. Self-citation is heavy but not disqualifying by itself.

Who is this for? People interested in the measurement problem and the retina as a possible locus of collapse. But the paper does not deserve peer review: the central inference is a conceptual error that is visible from the target paper's own quoted text. A referee would have to point out the decoherence/collapse equivocation and send it back, and there is no prospect of a viable revision that keeps the claim. The author might have a narrower defensible point about where the effective decoherence event occurs, but that is not what is argued here. I would not send this to review.

Referee report

Significance

If the argument were valid, it would be a serious empirical challenge to no-collapse resolutions of the measurement problem. The cited retinal measurements are plausible and relevant, and the paper usefully draws attention to the retina as a locus of rapid environment-system interaction. However, the central inference fails because it equates decoherence with collapse. The processes described (photoisomerization, ionic currents, action potentials, LGN bursts) are exactly the sort of environmental interactions that a no-collapse theory treats as decoherence, and the paper itself quotes Schlosshauer's statement that strong decoherence at the rhodopsin stage already selects robust states. No new experimental data are presented, and the conclusion that Schlosshauer's theory is untenable does not follow.

Major objections (2)

[p.3, paragraph beginning 'This is incorrect'] The load-bearing claim that 'there would have already been a collapse of the wave function of the superposed photon state prior to this point in time' is asserted rather than argued. The 200 fs cis-to-trans isomerization is a molecular conformational change driven by the photon interaction; in a no-collapse theory it is an instance of environment-induced decoherence, not a non-unitary collapse. The author's own citation of Schlosshauer's statement that rhodopsin molecules undergo strong decoherence and that robust states are preselected at that stage directly addresses the objection. The timing of the isomerization therefore supplies no evidence against the no-collapse account.
[p.3-4, 'First', 'Second', and 'Third' arguments] All three objections presuppose that a no-collapse account must preserve a fully coherent superposition through the entire retinal pathway to the occipital cortex. But Schlosshauer's proposal explicitly relies on decoherence at the rhodopsin stage and at later stages; the single-photon-induced flux of about 10^7 sodium ions, the retraction of retinal synaptic processing, and LGN burst-mode transformations are additional decoherence sources, not collapse events. The author's arguments therefore attack an unstated and stronger version of the target theory. At most, the facts suggest that the relevant state selection may occur earlier than the cortex, which is compatible with Schlosshauer's framework rather than a refutation of it.

Minor objections (5)

[p.1, footnote discussion] The complaint about Schlosshauer's footnote is an editorial grievance rather than a scientific point; it should be removed or, if kept, reframed as a matter of citation practice rather than as evidence bearing on the theory's validity.
[p.3, sentence 'The photon interaction that he proposes is not of a superposed state'] This sentence is ambiguous: it should specify whether it refers to the photon state before interaction, the entangled photon-rhodopsin state, or the molecular state after isomerization, because the argument's premise depends on that distinction.
[p.2, comparison with Ghirardi] The statement that Schlosshauer's approach is 'practically the equivalent' of Ghirardi's is not substantiated and is misleading because Ghirardi's spontaneous localization model adds a collapse mechanism, whereas Schlosshauer's no-collapse account does not.
[Reference (7)] There is a typo in the reference: 'Responses to single quanta' should not be split as 'Re sponses'.
[Abstract and conclusion] The abstract says Schlosshauer's theory is 'shown' to be untenable; given the above problems, a more cautious phrasing such as 'argued' would be more accurate, and the conclusion should acknowledge that the empirical facts are compatible with a decoherence-based account.

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The paper

The paper claims

The paper argues that the superposed photon state collapses at the rhodopsin molecule within 200 femtoseconds, so no-collapse decoherence theories of visual perception are untenable.

The reading

This comment takes aim at a recent decoherence-based account of visual perception in which superposed quantum states survive past the retina and are resolved only when neurons in the occipital cortex decohere. The paper argues this is untenable because the first step in vision itself is a collapse: the rhodopsin molecule completes its cis-to-trans shape change in about 200 femtoseconds, and that shape change is the classical signal of the absorption event. The comment then lists three further barriers—the rod's amplified single-photon response, the retinal ganglion cell spike trains, and the tonic-versus-burst conversion in the lateral geniculate nucleus—any of which would destroy a superposition before the occipital cortex. If right, the paper would push the collapse point out of the brain and into the retina, restoring a traditional collapse mechanism.

What carries the argument

The load-bearing object is the 200 fs cis-to-trans isomerization of the rhodopsin molecule, the light-sensitive pigment in rod photoreceptors, taken as the definitive classical sign that a photon has been absorbed and therefore as the collapse event. This is carried through a chain of amplifications—one rhodopsin molecule, roughly $10^7$ blocked sodium ions, 2–3 retinal ganglion cell action potentials, and tonic or burst mode relay through the lateral geniculate nucleus—which the comment treats as a sequence of irreversible classicalizing stages that a superposed state could not survive.

Extended reading notes

Core claim

The central claim is that minimal no-collapse quantum mechanics cannot explain the visual perception of a single outcome, because the superposed photon state does not reach the cortex. The photon-rhodopsin interaction produces a complete cis-to-trans isomerization within about 200 fs, and this is characterized as the classical signal of the photoabsorption quantum event; the paper takes this to mean the wave function has already collapsed before any retinal neuron is involved. Even on a generous reading, the single-photon response (roughly $10^7$ sodium ions failing to enter the cell, leading to 2–3 action potentials in the retinal ganglion cell) and the later conversion of retinal ganglion cell spikes into tonic or burst mode firing in the lateral geniculate nucleus would decohere or destroy any surviving superposition. The conclusion is that collapse occurs at the retinal molecule itself, as conjectured by an earlier reference, and that extrapolating from SQUIDs, molecular interferometry, or Bose-Einstein condensates to the brain is unwarranted.

Load-bearing premise

The argument depends on treating the 200 femtosecond shape change of the light-sensitive molecule and the resulting electrical amplification as the collapse itself rather than as an ordinary loss of quantum coherence.

Editorial extensions

If this is right

If the central claim is right, no-collapse decoherence theories must move the resolution of the measurement problem out of the brain and back to the sensory periphery.
A superposition of cis and trans rhodopsin conformations would be forbidden in nature, effectively a superselection rule at the retinal molecule.
The single-photon retinal response, with its huge ionic amplification, would count as a macroscopic collapse event rather than a mere environmental disturbance.
Proposed brain-based experiments for quantum effects in perception would need to target the retinal stage, not cortical neurons.

Reading between the lines

Editorial extensions of the paper, not claims the author makes directly.

The argument only refutes no-collapse decoherence if the 200 fs isomerization is genuinely collapse rather than decoherence; if it is decoherence, the cited neurophysiology is compatible with the target theory.
The same retinal facts could be modeled as a very fast decoherence rate rather than collapse, so the empirical data alone may not distinguish the two families of theories without an independent criterion for collapse.
A testable extension would be to place a single rhodopsin molecule in a quantum interference setup and check whether the conformational state after 200 fs displays coherence; this would adjudicate the collapse-versus-decoherence reading.

Original abstract

Schlosshauer has advanced a theory of minimal no-collapse quantum mechanics for a decoherence-based subjective resolution of the measurement problem. The basic premise being that superposition states are maintained beyond the retinal apparatus, becoming correlated with neuronal arrays located in the occipital lobe of the brain. Decoherence for these neurons in a superposition of firing and resting, leads to an irreversible dynamical decoupling of the two branches, resulting in the emergence of a single subjective perception. Based upon prior retinal research, it is shown that his theory is untenable for several reasons.

The compiled record

The paper's own sentences, arranged, kept beside the review and separate from it. Each label is drawn from a closed vocabulary; the number beside it is the probability the classifier gave that label. Numbers in the tables are the authors', checked by code. No sentence in this record was written by a model.

Compiled by classifier-1.13.0 via TypeSafe API, question bank abstract-p1-20260923, 2026-09-23: 1 request, 3,618 input tokens.

What the abstract itself states, as probabilities: claims first 0.04 · states limitation 0.15 · human participants 0.26 · controlled comparison 0.03 · randomized assignment 0.02 · states quantitative result 0.03 · compares with prior results 0.52 · mentions code or data availability 0.02.

The abstract, sentence by sentence

arXiv listing abstract v1. Results and the main claim are underlined; show every role.

Schlosshauer has advanced a theory of minimal no-collapse quantum mechanics for a decoherence-based subjective resolution of the measurement problem. The basic premise being that superposition states are maintained beyond the retinal apparatus, becoming correlated with neuronal arrays located in the occipital lobe of the brain. Decoherence for these neurons in a superposition of firing and resting, leads to an irreversible dynamical decoupling of the two branches, resulting in the emergence of a single subjective perception. Based upon prior retinal research, it is shown that his theory is untenable for several reasons.

background contribution method result interpretation main claim

What the classifier reports for each sentence. The number is the probability it gave the label.
#	sentence	role	the authors' own work	states the main conclusion	strength
s0	Schlosshauer has advanced a theory of minimal no-collapse quantum mechanics for a decoherence-based subjective resolution of the measurement problem.	background 0.99	0.04	0.05	asserted 1.00
s1	The basic premise being that superposition states are maintained beyond the retinal apparatus, becoming correlated with neuronal arrays located in the occipital lobe of the brain.	background 0.96	0.05	0.04	asserted 0.94
s2	Decoherence for these neurons in a superposition of firing and resting, leads to an irreversible dynamical decoupling of the two branches, resulting in the emergence of a single subjective perception.	background 0.87	0.08	0.06	asserted 1.00
s3	Based upon prior retinal research, it is shown that his theory is untenable for several reasons.	result 0.81	0.66	0.85	asserted 1.00

What kind of paper the classifier reports this is: position or commentary 1.00 · evidence from literature 0.63.

What was examined, and what was not

sources read

arXiv listing abstract v1

not examined

full text
figures and tables
references and citing sentences
relations to other papers

levels run

P abstract

not run

S sections
T body sentences
C citations
R cross-paper relations

Every quoted sentence on this record is the authors'. Every label is from Pith's closed vocabulary, with the probability shown beside it. Every number in the measurements table is the authors', checked by code. Record as JSON

References

Works cited (2)

[113]

Also: quant-ph/0509042 v2 (2005). (3) Shimony, A

View on Pith Pith review arXiv 2005
[2006]

Experimental motivation and empirical consistency in minimal no- collapse quantum mechanics. Ann. Phys. 321, 112-149. quant-ph/0506199 v3. 5 (2) Thaheld, F.H.2005. Does consciousness really collapse the wave function? A possible objective biophysical resolution of the measurement problem. BioSystems 81,

View on Pith Pith review arXiv 2005

How the literature uses it

Papers whose main result relates to this one's

How each label was checked · JSON

Found among the papers closest to this one by title and main claim. Pith's classifier compared each pair's main results and a second model family confirmed the relation; checked against two further families, shown conflicts agreed 118 times in 120 and shown same results 218 times in 239. The quoted sentence is the other paper's main claim.

States a conflicting result 1 paper

We conclude that it is not only viable, but moreover compelling to regard a minimal no-collapse quantum theory as a leading candidate for a physically motivated and empirically consistent interpretation of quantum mechanics.

Experimental motivation and empirical consistency in minimal no-collapse quantum mechanics · 0.98

Discussion

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[1] [113]

Also: quant-ph/0509042 v2 (2005). (3) Shimony, A

View on Pith Pith review arXiv 2005

[2] [2006]

Experimental motivation and empirical consistency in minimal no- collapse quantum mechanics. Ann. Phys. 321, 112-149. quant-ph/0506199 v3. 5 (2) Thaheld, F.H.2005. Does consciousness really collapse the wave function? A possible objective biophysical resolution of the measurement problem. BioSystems 81,

View on Pith Pith review arXiv 2005