Quantum magic: A skeptical perspective (2011)
A few thoughts:<p>The Monty Hall comparison is about shifting human knowledge about an underlying system with a definite state. What, then, is the source of the uncertainty in QM in this author&#x27;s view? It is not our <i>knowledge</i> about the &quot;true state&quot; of things, because of course there <i>is</i> no single true state.<p>The same could be said about any appeal to &quot;perturbations&quot; from the measurements we make-- in order for a &quot;push&quot; from our measurement instruments be the source of uncertainty, we must explain it in terms of an unknown disturbance making a precise value imprecise (otherwise, the use of &quot;our instruments&quot; as an explanation for &quot;uncertainty&quot; can&#x27;t be the final tortoise upon which the world stands). Because of the impossibility of a &quot;precise physical value&quot; this explanation doesn&#x27;t seem satisfactory to me.<p>It seems the article (like many interpretations) does no better than to say &quot;don&#x27;t ask&quot; about what lies underneath those probabilities. At best it says &quot;our knowledge is uncertain&quot; but then stops before it says precisely what we are uncertain about.<p>His points about analogues with classical probability are well taken, but I don&#x27;t think they suffice to explain or dismiss quantum &quot;weirdness&quot;, though it&#x27;s quite possible I missed the point he was trying to make.<p>In particular, the article sweeps many-worlds away too quickly, IMO. Many worlds is what we get if we assume that observers are ensembles of particles which can exist in a state of superposition, just like any other ensemble of particles in the universe. &quot;Wavefunction collapse&quot; is what such an observer would expect to see upon becoming entangled with another system, without any additional a priori assumptions. Fundamentally it means that, after measurement, we cannot treat the system and the environment (and the observer therein) as separate-- another way of stating the phenomenon of decoherence.<p>In other words, I think it is not unparsimonious to assume that &quot;multiple universes&quot; exist, because we already know that ensembles of particles exist in a multitude of states. We simply note that the universe, too, is an ensemble of particles and draw a straightforward conclusion from well-established facts. To me, it seems almost more ontologically bold to <i>reject</i> this.<p>It is <i>also</i> not unparsimonious to assume that &quot;multiple universes&quot; exist, even after measurement, because delayed-choice eraser demonstrates that wavefunctions can be &quot;un-collapsed&quot;; that is to say re-combined with the other superpositions that Copenhagen supposes &quot;disappear&quot; after measurement. It fact it seems to me a fairly clear refutation of (common presentations of) Copenhagen-- But perhaps the author is on my side about that one.<p>Either way, this article seems to be a quite thoughtful overview, and I quite agree there&#x27;s a lot of confusion and woo both within and outside the field.