Dmitry67 said:
2 Do you agree that the CI definition is badly recursive, because it defines the properties of the particles based on "what we know". 'What we know' is quite a high level thing because it requires to be consciouss and intelligent.
You are making the mistake (or are you? maybe I'm misreading) of assuming the opposite of what you pretend to assume when considering CI. Quantum actuality keeps on zippin' along regardless of consciousness or intelligence. But the first assumption of QM is that you cannot separate what we know from the act of knowing. That's why the principle objects in QM are Observables and not State variables.
Measurement does not require consciousness, just an amplifying mechanism to correlate those quantum variables with a large scale observable such as where a meter needle points or where a meteor lands etc but when we speak of wave functions we must acknowledge
their existence is only in conscious minds and not "out there" and thus identify them as such.
Further there is no problem invoking "what we know" about physical systems provided you are being operational... "what we know" must come from a physical observation and physical constraints placed on a system. This is how entropy gets defined. It is a measure of ignorance about a physical system said ignorance assumed by the physical definition and constraints of said system.
If it is not enough, let me ask you a question, had wavefunction ever collapsed in the first 1000 years after Big Bang? :)
Now here you are really missing the point. CI doesn't posit wave-functions exit! They are not "out there" they are in our heads. Again they have the exact same status as a probability... a prediction about what may happen. They are more precise in what they predict but they are none-the-less of the same family as classical probability distributions.
And they collapse upon actualization of the coin-flip or spin-spin measurement for exactly the same reason.
As we have only invented wave-functions in the past half century I can only say for certain that some have collapsed in that period. Who knows what other beings in the past have developed the equivalent in their descriptions of nature. And update their wave-function equivalents when they learn what a quantum actually does rather than what they know it might do.
If yes, what should be used for 'WE' and 'KNOW' in your claim?
If no, then it appears that the universe had developed fine without any collapse, so we get MWI where there is no collapse :)
Again you keep trying to give wave functions reality even in pretending to adopt my point of view. Of course the universe developed fine without any collapse. Again collapse is a conceptual act and not a physical one (according to the interp. I am positing.) Again MWI only if you either mean Many conceptual worlds existing in our imagination given my interp. or many real worlds given your reification of the wave-function. The psi's we write on paper are not describing physical wave-functions they
are the wave functions.
The collapse recipe is an instruction in sequential calculation not a physical process.
Adopt this position in earnest just for a moment... make sure you understand it clearly just for the sake of argument. Then revisit your counterpoints and see if they make any sense.
The inconsistencies you think you see are inconsistencies with your implicit
a priori assumptions which you still hold even as you consider what CI says. You need to recognize these explicitly and de-invoke them for a moment to see what I'm saying.
It is just like asking "But which twin is
really older when considering the twin's paradox in SR. One must first understand all the precepts of SR, and especially the loss of absolute simultaneity and time which we are assuming when we ask "who's older" without qualifying "as seen from what perspective?"
It would be awfully silly to invoke parallel worlds to explain the twin's paradox...
"You see in one universe twin A is older but in the other universe twin B is older"
...just so one could hold onto the absoluteness being denied by the very term
relativity in SR. But further absurd is to then claim that SR predicts such parallel worlds because you can't fit your mind around what SR really does say.
As a matter of fact it is the same sort of relativization occurring in the transition from CM to QM. David Finkelstein (under whom I've had the honor to study) wrote a book "Quantum Relativity" which makes this very point. In QM we relativize the classical concept of absolute state.
3 in MWI wavefunction IS reality (from the birds view), not knowledge
As the fundamental christian also claims the bible IS reality. Again how is your belief in many worlds anything but a religious faith?
1 As a sidenote, I was always curious about that interpretation from the popular books. This claim is true... but it is only a part of the truth!
It comes from 2 extremes of HUP: we know position precisely we don't know the momentum, and vice versa.
So if we apply one of these 2 extremes to the wavefunction, we get this interpretation with the square root. But we can apply another side of HUP as well, getting another 'meaning' of a wavefunction.
I'm not sure I follow your meaning here. But let me say that HUP generalizes to any non-commuting observables. Momentum and position are not two endpoints they are two of a continuum of possible incompatible position-momentum measurements. Any one set of commuting observables defines a classical logic of "what is" just as any set of space-time coordinates defines a frame of simultaneity in SR. Once you step outside this choice of frame you can no longer speak of simultaneity in the case of SR or state of reality in the case of QM. (Actually you have a problem with "the state of reality" in SR as well given there is an implicit "now" of time in the phrase "state of reality" however it is less of a problem in a classically deterministic SR).
As I see it, the MWI is a conceptual black hole into which one can be sucked so that one need never truly understand the operational meaning of QM. If it were only a matter of sleeping better at night then that would be fine. I don't deny any person the comfort of their faith. But the noise of it confuses the new students of QM. Especially as was the case here I will strongly object to statements claiming "QM says" when it is not QM saying it but instead an article of someone's faith.
So let me ask you one question...
Do you deny that
if you don't consider the wave-function a physical object then wave-function collapse is a non-issue?