Could wavefunctions simultaneously represent knowledge and reality?

Abstract

In discussion of the interpretation of quantum mechanics the terms ‘ontic’ and ‘epistemic’ are often used in the sense of pertaining to what exists, and pertaining to cognition or knowledge respectively. The terms are also often associated with the formal definitions given by Harrigan and Spekkens for the wavefunction in quantum mechanics to be $$\psi $$ ψ -ontic or $$\psi $$ ψ -epistemic in the context of the ontological models framework. The formal definitions are contradictories, so that the wavefunction can be either $$\psi $$ ψ -epistemic or $$\psi $$ ψ -ontic but not both. However, we argue, nothing about the informal ideas of epistemic and ontic interpretations rules out wavefunctions representing both reality and knowledge. The implications of the Pusey–Barrett–Rudolph theorem and many other issues may be rethought in the light of our analysis.

Phenomenology, Perspectivalism and (Quantum) Physics

“…These are typically presented as dichotomous alternatives but this hinges on the assumption that the wave-function Ψ(x, y, z) in general either represents the state of the object in a (again typically, naïve) realist sense and so is 'ontic', or it represents the state of the observer and is correspondingly epistemic. However, there is nothing in principle that prevents it from representing both 'simultaneously' [43]. And of course, this is precisely how London and Bauer regard it, with their view of quantum mechanics as a theory of knowledge; that is, as much about us, as it has to be phenomenologically speaking, as it is about the world.…”

Quantum Reconstructions as Stepping Stones Toward ψ-Doxastic Interpretations?

“…Importantly, this is precisely why QBism avoids the PBR theorem. While the PBR theorem challenges ψ-epistemic interpretations, it is silent on the QBist claim that wave functions represent degrees of beliefs about one’s future experiences [ 44 , 48 , 80 ].…”

“… 26 A further option would be to combine these options. For instance, Hance, Rarity, and Ladyman [ 48 ] have recently pointed out that “there is no reason to suppose that a one–one map between the wavefunction and the ontic state rules out that the wavefunction represents knowledge” (see also [ 61 ]). This is to say that interpretations can be both ψ-ontic and ψ-epistemic (although not in the strict sense introduced in [ 50 ]).…”

What does it take to solve the measurement problem?

“…While attempts have been made at formalising this view [38,39] and using it to come to no-go theorems on the wavefunction being in some way epistemic [40][41][42], these formalisations have fundamental issues [43][44][45]. Therefore, these no-go theorems contribute little to telling us whether the wavefunction can or cannot be epistemic.…”