The Consistent-Histories Approach Viewed Through Systemic Functional Linguistics

Penrose (2004: 810-1):

If the ‘extravagant’ ontology for the consistent-histories approach (d) is adopted, in which reality is represented as a totality of maximally refined consistent-history sets, then a criticism can be raised which is somewhat similar to that of the many-worlds case (b). As with (b), a detailed and precise theory of conscious perceivers seems to be needed in order that (d) can conjure up a picture that is consistent with the physical world that we know. … Alternatively, one might prefer something like the more economical ontology in which a single maximally refined consistent history set might be considered as a plausible candidate for a ‘real-world’ ontology. …

In my own view, a major drawback with (d) is that … it does not seem to get us any closer to an understanding of what a physical measurement actually is than do the more conventional ontologies of (a) or (b). … 

Why, according to (d), do we not actually witness things like Schrödinger cats, in superposed limbo between life and death? The theory does not seem to give any improvement on the standard Copenhagen position (a) in explaining which systems (such as pieces of physical apparatus or cats) should behave classically, whereas neutrons or photons do not. 

… the criteria that have so far been put forward do not do enough to narrow down the model’s behaviour so that an unambiguous picture of something resembling the world we know can arise. This seems to be true both at the macroscopic ‘classical-like’ level … and also at the ‘quantum level’ at which one would hope to see undisturbed unitary evolution. Since the measurement paradox is concerned with the seeming conflict between physical behaviour at these two different levels, it is hard to see how the consistent-history viewpoint (d) is yet in a position to shed much light on this paradox.

Blogger Comments:

From the perspective of Systemic Functional Linguistic Theory, the consistent histories approach mistakes potential (a consistent set of histories) for actual instances of that potential. Conscious perceivers are needed because it is a conscious act of perception that instantiates one of the potential construals of experience as meaning (pieces of physical apparatus and a dead cat or a live cat).