Common Misconceptions Index

Foundational mistakes often arise when a valid statement is extended beyond its assumptions. This index gives short corrections and routes to the full discussion. Start with Common Misconceptions for an introduction through concrete examples.

Measurement and observers

“A measurement requires a conscious observer.” Standard measurement theory models interactions, records, and conditioning without a consciousness postulate. Interpretations disagree about outcomes, but that disagreement does not establish a special mental dynamics. See Observer in Quantum Mechanics and Consciousness Claims.

“Decoherence selects exactly one result.” Decoherence suppresses local interference and helps explain stable records. A reduced mixture alone does not specify a unique global outcome. See Decoherence’s Scope.

“A quantum eraser changes the past.” The experiment sorts joint records into conditional subensembles. It does not alter an earlier unconditioned record or enable backward signaling. See Quantum Eraser.

“A wavefunction update must be a physical wave collapsing everywhere.” Conditional update and dynamical collapse are distinct claims. See Collapse as Postulate.

Locality and no-go theorems

“Bell proves faster-than-light communication.” Bell excludes a specified local model class; quantum marginals still obey no-signaling. See What Bell Proves.

“Bell assumes deterministic hidden variables.” Stochastic local response functions are included. Deterministic strategies can be used as extremal descriptions without adding determinism as a new empirical premise. See Bell Assumptions.

“All hidden-variable theories are ruled out.” No-go theorems constrain particular combinations of locality, noncontextuality, independence, or other premises. Bohmian mechanics illustrates an explicitly nonlocal theory. See the theorem matrix.

“Contextuality means that every apparatus imperfection is quantum.” Contextuality concerns the failure of a defined noncontextual representation under specified equivalences or compatibility relations. Ordinary disturbance can invalidate a proposed test. See Contextuality.

States and interpretations

“The PBR theorem proves the wavefunction is a material field.” Its conclusion concerns overlap of ontological distributions under preparation independence. It does not select one ontology for the wavefunction. See PBR.

“Every interpretation makes the same predictions.” Pure reinterpretations may do so, but modified collapse dynamics and some extensions can differ quantitatively. Compare fully specified models, not labels. See Comparing Interpretations.

“Many worlds means counting branches equally.” Branch structure is approximate, and equal counting is not the Born measure. The probability problem needs its own argument. See Probability in Many Worlds.

“A reconstruction derives quantum theory without assumptions.” A representation theorem uses a framework and an axiom package. Its explanatory value depends on those premises. See Reconstructions.

How to repair an overstatement

Replace an unrestricted claim with four items: the model class, the precise result, the supporting experiment or theorem, and the limit of the inference. This usually makes the correct statement more informative rather than less interesting.

References

• Bell, John S., Speakable and Unspeakable in Quantum Mechanics, second edition, Cambridge University Press, 2004. Publisher.
• Pusey, Matthew F., Jonathan Barrett, and Terry Rudolph, “On the reality of the quantum state,” Nature Physics 8, 475–478 (2012). Paper.
• Schlosshauer, Maximilian, “Decoherence, the measurement problem, and interpretations of quantum mechanics,” Reviews of Modern Physics 76, 1267–1305 (2005). Review.