Philosophy

This is easiest to see through relational quantum mechanics, which holds that physical reality consists only of relations between systems. Instead of particles existing independently between events, reality is an unfolding sequence of discrete, probabilistic interactions. Interactions always involve more than one system, so the properties always exist relationally in terms of what they are interacting with, and never autonomously on their own.

This was close to Heisenberg’s original matrix mechanics. Schrödinger hated matrix mechanics, saying that he "cannot believe that an electron hops about like a flea," and introduced wave mechanics instead. Both formalisms made identical predictions, showing that the wavefunction is not fundamental but optional.

Francois-Igor Pris has argued this should be taken further in a Machian direction. Mach rejected any absolute, godlike viewpoint and argued that reality consists only of relative perspectives. Even acceleration, he argued, can be explained relationally. When you accelerate in a car, what you actually observe is the rest of the universe "accelerating" in a particular way that violates conservation of momentum relative to you.

Newton accepted relativity for velocity but not for acceleration, treating the latter as merely apparent and requiring a hidden third-person frame. Mach rejected this move. Pris adopts a similar stance and applies it to quantum mechanics. Like relational quantum mechanics, his view is perspectival, but he drops the idea that interactions are fundamental.

An interaction requires two systems and can only be described from a third-person viewpoint. If no such absolute perspective exists, then interactions cannot be basic. If someone from a third-person perspective observes you looking at a tree, they can explain it by saying the light reflected from the tree interacts with your eyes. From a first-person perspective, you do not observe light interacting with your eyes, you simply observe the tree. The tree is realized or actualized for you on its own, without your eyeball being in the picture.

Pris' thus argues that instead of invoking an imagined godlike third-party observer, you describe what everything else is doing within the given perspective. He calls the "context." It's sort of like, if you look at your computer screen, the "context" is not just the computer screen, but everything else in your perspective, everything around you, as well as the history of those things. The computer screen is realized or actualized in front of you, not in complete isolation, but in a particular real-world context.

Rather than describing physical reality in terms of an unfolding sequence of "interactions," Pris thus argues you can describe reality in terms of an unfolding sequence of realizations or actualizations or happenings which are predictable based on context. The object you are observing is itself part of the context of your perspective, and these realizations are random, so the context changes randomly. This requires you to have to re-orient yourself when the context changes, kind of like taring a scale or re-centering a coordinate system.

That's how the collapse of the wavefunction is understood by Pris. The Born rule gives you the probabilities for possible realizations or actualizations of the system within a particular perspective, usually the observer's perspective, but the observer is not fundamental; Pris rejects the notion of "observer-dependence" for context-dependence). Thus, it tells you the possible contexts you might find yourself in, based on your current context, and then the collapse of the wavefunction is just kind of like a re-centering of your coordinate system after the context spontaneously changes.

The correlated quantum events are not autonomous, but they are determined in the context of their observation. Independently from the means of their identification, there are no events. The reduction of a wave function in the «process of measurement» is not a real physical process, requiring an explanation, but a move to a context of measurement of a concrete value of a physical quantity. Respectively, the measurement is not a physical interaction leading to a change in the state of a system, but the identification of a contextual physical reality. That is, in a sense, in measuring (always in a context), one identifies just the fragment of reality where the (quantum) correlation takes place. As the elements of reality, the correlated events do not arise; they are. Only their identifications do arise.

https://arxiv.org/abs/2107.10666