Most of this is me thinking out loud. Feel free to ignore it.

With regard to consciousness, I meant only that we are only conscious of the classical universe. This is not an assumption but a statement of fact. It is why QM seems weird to us, because we are only aware of quantum effects via inference from statistical distributions, not a conscious awareness of the wavefunction in the way we are we are conscious of rocks.

I'm not concerned with nor do I need to make any claim about the mechanisms of consciousness, but only rely on the factual and uncontroversial observation that "We are consciously aware of only the classical world". There is a case to be made that this defines the classical world.

> Quantum mechanics predicts that entanglement will cause that physical system to separate into a superposition of non-interacting states.

This is actually a vastly more coherent way (as it were) of putting the argument than it is usually stated. I don't find it immediately convincing for a variety of reasons, but it is at least a testable claim. I'm particularly concerned about the role of weak measurements in breaking the "non-interacting" aspect, and the potential for delayed-choice measurements. But even without those there is trouble.

There are also the usual conservation concerns: how is it that both states end up with all the mass, energy, charge and other quantum numbers we normally consider to be conserved? That is, what is the ontology of these non-interacting states?

Consider an ion and a photon that interact such that they are entangled. The ion has a net charge as well as a mass and angular momentum. For fun, let's say that the photon starts out unpolarized, as does the ion, which is in a magnetic field. The ion has spin 1/2 and the interaction is such that the photon goes from right to left circularly polarized and the atom goes from Jz = -1/2 -> 1/2, or vice versa. So we end up with states that look like |L 1/2> and |R -1/2>.

The claim is that no future evolution of the system will allow these states to ever interact with each other. But we know this is not the case. We could easily pass the photon through a beam-splitter and 1/4-wave plates to interfere with each other. We can do anything we like to the ion--pass it through a dipole, accelerate it, whatever, and it will not change this. So long as we don't "measure" it (whatever that is) it will be possible to get the components of the photon wavefunction to detectably interact. But it won't do to talk about "measurement" in such a context, because that's what we're trying to avoid.

The question is: what is the condition such that the components of the individual particle wavefunctions may never be brought back together to show an interference pattern again? "Thermalization" (entanglement with a heat bath) is the usual claim, but I'm unconvinced that this is not simply hiding the quantum mystery behind a thermodynamic one (and the thermodynamic mystery would require a proof of something like Boltzmann's H-theorem to actually work.)

Nor does this answer the real question, which is: why is it that we are aware of all this only via inference from interference patterns? The quantum state formalism captures that fact, but does not explain it (Note to self: I need to formulate more clearly what I would consider an "explanation" in this regard.)