Quantum mechanics and our part in creating reality
I&#x27;ve never found epistemic interpretations compelling (like QBism, which is what the article is about). I&#x27;ll try to explain why.<p>First, the stuff we do with quantum mechanics just seems sort of... really obviously objective? It&#x27;s not like Bell tests work for me but not for you, or quantum computers factor numbers for me but not for you. If I sell you a machine to produce a specific superposition, and it produces the wrong one, you can tell. Yes you need to run it multiple times and do statistics, but <i>ultimately anyone can check that the machine is doing the wrong thing</i>.<p>Second, two agents can&#x27;t actually disagree on what the superposition of a state is, to any appreciable degree, without one of them being provably irrational (modulo some weak-sauce assumptions we take for absolute granted in classical mechanics). [1]<p>Third, note that (w.l.o.g) diagonally polarized photons are superpositions of horizontally and vertically polarized photons. This suggests that, in an interpretation where superpositions are less real than classical states, slightly rotating a polarizing filter radically changes the conceptual machinery used to understand a photon passing through the filter. That seems... silly? There is a rotational symmetry in the system that should be natural in the model (e.g. see how special relativity reifies Lorentz boosts).<p>Fourth, although this is ironically subjective, I&#x27;ve never read an epistemic explanation of some quantum phenomenon and thought &quot;Ah, that makes it clearer!&quot;. But that <i>has</i> happened with collapse interpretations, with path integral interpretations, and with many-worlds.<p>[1]: <a href="https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;PBR_theorem" rel="nofollow">https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;PBR_theorem</a>