He endorses “many worlds” in the sense that he thinks the wave-function formalism corresponds to something real and mind-independent, and that this wave function evolves over time to yield many different macroscopic states like our “classical” world. I’ve heard this family of views called “(QM) multiverse” views to distinguish this weak claim from the much stronger claim that, e.g., decoherence on its own resolves the whole question of where the Born rule comes from.
One serious mystery of decoherence is where the Born probabilities come from, or even what they are probabilities of.
[… W]hat does the integral over squared moduli have to do with anything? On a straight reading of the data, you would always find yourself in both blobs, every time. How can you find yourself in one blob with greater probability? What are the Born probabilities, probabilities of? Here’s the map—where’s the territory?
I don’t know. It’s an open problem. [...]
This problem is even worse than it looks, because the squared-modulus business is the only non-linear rule in all of quantum mechanics. Everything else—everything else—obeys the linear rule that the evolution of amplitude distribution A, plus the evolution of the amplitude distribution B, equals the evolution of the amplitude distribution A + B.
Ah, it has been a while since I engaged with this stuff. That makes sense. I think we are talking past each other a bit though. I’ve adopted a moderately modest approach to QM since I’ve not touched it in a bit and I expect the debate has moved on a bit.
We started from a criticism of a particular position (the copenhagen interpretation) which I think is a fair thing to do for the modest and immodest. The modest person might misunderstand a position and be able to update themselves better if they criticize it and get a better explanation.
The question is what happens when you criticize it and don’t get a better explanation. What should you do? Strongly adopt a partial solution to the problem, continue to look for other solutions or trust the specialists to figure it out?
I’m curious what you think about partial non-reality of wavefunctions (as described by the AncientGeek here and seeming to correspond to the QIT interpretation on the wiki page of interpretations, which fits with probabilities being in the mind ).
I don’t think we should describe all instances of deference to any authority, all uses of the outside view, etc. as “modesty”. (I don’t know whether you’re doing that here; I just want to be clear that this at least isn’t what the “modesty” debate has traditionally been about.)
The question is what happens when you criticize it and don’t get a better explanation. What should you do? Strongly adopt a partial solution to the problem, continue to look for other solutions or trust the specialists to figure it out?
I don’t think there’s any general answer to this. The right answer depends on the strength of the object-level arguments; on how much reason you have to think you’ve understood and gleaned the right take-aways from those arguments; on your model of the physics community and other relevant communities; on the expected information value of looking into the issue more; on how costly it is to seek different kinds of further evidence; etc.
I’m curious what you think about partial non-reality of wavefunctions (as described by the AncientGeek here and seeming to correspond to the QIT interpretation on the wiki page of interpretations, which fits with probabilities being in the mind ).
In the context of the measurement problem: If the idea is that we may be able to explain the Born rule by revising our understanding of what the QM formalism corresponds to in reality (e.g., by saying that some hidden-variables theory is true and therefore the wave function may not be the whole story, may not be the kind of thing we’d naively think it is, etc.), then I’d be interested to hear more details. If the idea is that there are ways to talk about the experimental data without committing ourselves to a claim about why the Born rule holds, then I agree with that, though it obviously doesn’t answer the question of why the Born rule holds. If the idea is that there are no facts of the matter outside of observers’ data, then I feel comfortable dismissing that view even if a non-negligible number of physicists turn out to endorse it.
I also feel comfortable having lower probability in the existence of God than the average physicist does; and “physicists are the wrong kind of authority to defer to about God” isn’t the reasoning I go through to reach that conclusion.
I also feel comfortable having lower probability in the existence of God than the average physicist does; and “physicists are the wrong kind of authority to defer to about God” isn’t the reasoning I go through to reach that conclusion.
Out of curiosity, what is the reasoning you would go through to reach that conclusion?
In the context of the measurement problem: If the idea is that we may be able to explain the Born rule by revising our understanding of what the QM formalism corresponds to in reality (e.g., by saying that some hidden-variables theory is true and therefore the wave function may not be the whole story, may not be the kind of thing we’d naively think it is, etc.), then I’d be interested to hear more details.
Heh, I’m in danger of getting nerd sniped into physics land, which would be a multiyear journey. I’m found myself trying to figure out whether the stories in this paper count as real macroscopic worlds or not (or hidden variables). And then I tried to figure out whether it matters or not.
I’m going to bow out here. I mainly wanted to point out that there are more possibilities than just believe in Copenhagen and believe in Everett.
He endorses “many worlds” in the sense that he thinks the wave-function formalism corresponds to something real and mind-independent, and that this wave function evolves over time to yield many different macroscopic states like our “classical” world. I’ve heard this family of views called “(QM) multiverse” views to distinguish this weak claim from the much stronger claim that, e.g., decoherence on its own resolves the whole question of where the Born rule comes from.
From a 2008 post in the MWI sequence:
Ah, it has been a while since I engaged with this stuff. That makes sense. I think we are talking past each other a bit though. I’ve adopted a moderately modest approach to QM since I’ve not touched it in a bit and I expect the debate has moved on a bit.
We started from a criticism of a particular position (the copenhagen interpretation) which I think is a fair thing to do for the modest and immodest. The modest person might misunderstand a position and be able to update themselves better if they criticize it and get a better explanation.
The question is what happens when you criticize it and don’t get a better explanation. What should you do? Strongly adopt a partial solution to the problem, continue to look for other solutions or trust the specialists to figure it out?
I’m curious what you think about partial non-reality of wavefunctions (as described by the AncientGeek here and seeming to correspond to the QIT interpretation on the wiki page of interpretations, which fits with probabilities being in the mind ).
I don’t think we should describe all instances of deference to any authority, all uses of the outside view, etc. as “modesty”. (I don’t know whether you’re doing that here; I just want to be clear that this at least isn’t what the “modesty” debate has traditionally been about.)
I don’t think there’s any general answer to this. The right answer depends on the strength of the object-level arguments; on how much reason you have to think you’ve understood and gleaned the right take-aways from those arguments; on your model of the physics community and other relevant communities; on the expected information value of looking into the issue more; on how costly it is to seek different kinds of further evidence; etc.
In the context of the measurement problem: If the idea is that we may be able to explain the Born rule by revising our understanding of what the QM formalism corresponds to in reality (e.g., by saying that some hidden-variables theory is true and therefore the wave function may not be the whole story, may not be the kind of thing we’d naively think it is, etc.), then I’d be interested to hear more details. If the idea is that there are ways to talk about the experimental data without committing ourselves to a claim about why the Born rule holds, then I agree with that, though it obviously doesn’t answer the question of why the Born rule holds. If the idea is that there are no facts of the matter outside of observers’ data, then I feel comfortable dismissing that view even if a non-negligible number of physicists turn out to endorse it.
I also feel comfortable having lower probability in the existence of God than the average physicist does; and “physicists are the wrong kind of authority to defer to about God” isn’t the reasoning I go through to reach that conclusion.
Out of curiosity, what is the reasoning you would go through to reach that conclusion?
Heh, I’m in danger of getting nerd sniped into physics land, which would be a multiyear journey. I’m found myself trying to figure out whether the stories in this paper count as real macroscopic worlds or not (or hidden variables). And then I tried to figure out whether it matters or not.
I’m going to bow out here. I mainly wanted to point out that there are more possibilities than just believe in Copenhagen and believe in Everett.