Earlier quoted context omitted.
> Various specific kinds of measuring devices the details of which are an established part of QM. They're not though. There's no generally accepted definition of what is and isn't a measuring device. And, as per the quantum eraser experiment, the exact same equipment might be considered as a measuring device or not a measuring device, depending on what happens in the future. > So, which is the interaction that causes…
> But, broadly, interacting with an object in superposition in a way that depends on that superposition will cause entanglement. This doesn't explain the cause of entanglement. It just explains the circumstances under which entanglement occurs. > I appreciate that this must sound exactly as vague as the definition of a measurement That's because it is beyond the mathematics. > But for those familiar with QM it really…
"Entanglement" is just a term for a particular kind of behaviour that (some) solutions to the Schrodinger equation exhibit. I can't tell you why physical reality conforms to the Schrodinger equation, but I believe we're all agreed that it does.
> That's because it is beyond the mathematics.
No it isn't. It's right there in the mathematics.
> This is not true. I'm familiar with QM and it is vague to me.
With all due respect, if entanglement is vague to you then you're not familiar with QM. Entanglement is a basic quantum phenomenon and the results of quite simple experiments cannot be understood without it. You will find respected authorities on QM who disagree on interpretations, or disagree on how we should think about measurements. But you will not find any who disagree on what the phenomenon of entanglement is or when it occurs, regardless of what interpretation of QM they subscribe to.
> I wouldn't know, because it's not what can be experienced. Some folks argue this is exactly what makes many worlds unscientific.
Just the opposite: blithely asserting that you're not in a superposition, based on zero scientific evidence, is what's unscientific. Unless and until we can come up with some experiment that would distinguish being in a superposition from not being in a superposition, we should be agnostic about whether we're in a superposition, and have no particular reason to favour a theory that claims we're in a superposition over one that claims we're not (or vice versa).
> What kind of microscope are you using to look at wave functions? Or do you mean at the mathematical expression of the wavefunction?
If you're claiming that the wavefunction is a physically real thing then the Copenhagenists will kick you out :P.
> Another empty word.
Not at all; while it's a word that's frequently abused, it does mean something specific and well-defined.
> Yes. And if you think about it, this is the same mystery which makes Copenhagen so unsatisfactory, just put into a different framework.
I don't think it is so mysterious: if that mathematical description of reality is accurate, what else could we possibly expect to experience? To claim that subjective experience is messy and complicated is a much smaller assertion than to claim that this messy complication exists in objective physical reality, as the Copenhagenists do.