[kawa]

Observation means: Interaction with a 'classical system'. Now because of entanglement this also works if we look at chains of interactions: Interaction with another single atom for example is no observation, but if this other atom interacts with a 'classical system' at some point earlier or later we have again an 'observation'.

Now 'classical systems' are systems made of so many elements that we can only make statistical statements about it because we can't ever determine the state of each of it's constituents.

I suspect for some time now that this is also the source for the "quantum randomness". In principle, everything is deterministic, but to observe something we always have interactions with a "big classical system" (in the end it's always our brain). And because we don't know the exact state of those systems but only statistical averages, quantum mechanics looks random for us, even if it's perfectly deterministic in itself. But that's my personal view of the matter.

[JabavuAdams]

The first couple of paragraphs are a great summary. Prof. Binney has some interesting observations on the non-physicality of quantum measurement (the formalism).

One of the postulates of QM is that after a measurement the system is in a well-defined state (the one we measured). But this is aphysical.

It's an artifact of the deliberate choice to formally model measurement in a way that simultaneously recognizes that all measurements disturb the measured system, while also wanting to abstract away the particular hardware used.

So, I'm starting to see wavefunction collapse and the whole Copenhagen interpretation as artifacts of the the formalism, not any kind of physical truth.