The reason I commented was mostly to clarify that Schrödinger’s cat is not like the meme implies. It’s meant to illustrate how weird it is that the cat would be neither alive nor dead until you open the box, not “the cat is in fact both at the same time.”
But that is exactly the point Schrödinger was criticizing, not supporting.
I was under the impression this was more a question than a criticism. He’s asking where the line is between this indeterminacy and determinacy. At what scale to things move from quantum to “real” and why?
Also Bell experiments have proven this indeterminacy you say is absurd. No theory of local hidden variables can describe quantum mechanics. The state is not a local property of the particle/system until it is “measured.” I’ll admit it’s an uncomfortable truth that sounds absurd, but it’s a truth nonetheless.
Anyway, thank you for the more in depth explanations of both the thought experiment and quantum computing.
bunchberry@lemmy.world 1 week ago
You say Bell’s theorem disproves realism, but then you immediately follow it up with saying it disproved local realism…
It never even crossed Bell’s mind to deny reality. He believed that the conclusion to his own theorem is just that it is not local.
Also, again, this is not about indeterminacy and indeterminacy, but about indefiniteness and definiteness. These are not the same things. To say something is indeterminate is merely to imply it is random. To say something is indefinite is to say it doesn’t even have a value at all.
You could in principle make this non-realism make sense if you imposed some sort of well-defined physical conditions as to when particles take on real values, but it turns out that you cannot do this without contradicting the mathematics of quantum mechanics.
These are called physical collapse models, like GRW theory, but these transitions are non-reversible even though all evolution operators in quantum mechanics are reversible, and so in principle if you rigorously define what conditions would cause this transition, you could conduct an experiment where you set up those conditions, and then try to reverse it. Orthodox quantum theory and the physical collapse model would make different predictions at that point.
These models never end up being local, anyways.
The reason I say value indefiniteness is absurd as a way to interpret quantum mechanics is because it is not necessitated by the mathematics at all, and if you believe it:
So, either it devolves into solipsism, or it is a different theory to begin with.
Bell was fine with #2 as long as people were honest about that being what they were doing. He wrote an article “Against ‘Measurement’” where he criticized the vagueness of people who claim there is a transition “at measurement” but then do not even rigorously define what qualifies as a “measurement.” He wrote positively of GRW theory in his paper “Are there Quantum Jumps?” precisely because they do give a rigorous mathematical definition of how this process takes place.
But Bell also didn’t particularly believe there was any reason to believe in value indefiniteness to begin with. You can just interpret quantum mechanics as a kind of stochastic mechanics, just one with non-local features, where it is random but particles still have definite values at all times. The same year he published his famous theorem in 1964 in the paper “On the Einstein Podolsky Rosen Paradox” he also published the paper “On the Problem of Hidden Variables” debunking von Neumann’s proof that supposedly you cannot interpret quantum mechanics in value definite terms. He also wrote a paper “Beables in Quantum Field Theory” where he shows QFT can be represented as a stochastic theory. He also wrote a paper “On the Impossible Pilot Wave” where he promoted pilot wave theory, not necessarily because he believed it, but because he saw it as a counterexample to all the supposed “proofs” that quantum mechanics cannot be interpreted as a value definite theory.
My point isn’t about randomness/indeterminacy. It is about “indefiniteness,” the claim that things have no values until you look. This either devolves into solipsism, or into a theory which is not quantum mechanics.
AnarchoEngineer@lemmy.dbzer0.com 1 week ago
First, I would like to note that I’m not here to assert any “quantum woo” about measurement and the soul or anything. I don’t think conscious observation has anything to do with the collapse; more likely it’s our method of measurement that affects the outcome. In fact I’d assume these phenomena would exist even in a universe without sentient beings. I’m not advocating for solipsism.
My intuition would be that certain kinds of common interactions “cause the collapse” and then: more particles -> more interaction -> more collapse, which would explain the fact we don’t see macro scale indeterminacy but do notice it at a quantum level.
Second, I’ll admit this really isn’t my field. You sound like you know what you’re talking about and have pointed me towards interesting theories and people to look into, so thanks for that, and I’ll defer to your judgement until I have a better grasp on this topic