If the many worlds interpretation of quantum mechanics is true isn’t anthropic reasoning involved in making predictions about the future of quantum systems.
Basic QM seems to say that probability is ontologically basic. In a collapse point of view, it’s what we usually think of as probability that shows up in decision theory. In MWI, both events happen. But you could talk about usual probability either way. (“classical probability is a degenerate form of quantum probability” with or without collapse)
Anthropics is about the interaction of probability with the number of observers.
Replacing usual probability with QM doesn’t seem to me to make a difference. Quantum suicide is a kind of anthropics, but it’s not clear to me in what sense it’s really quantum. It’s mainly about rejecting the claim that the Born probabities are ontologically basic, that they measure how real an outcome is.
But in MWI isn’t the observed probability of some quantum state just the fraction of worlds in which an observer would detect that quantum state? As such, doesn’t keeping the probabilities of quantum events as QM predicts require that “one should reason as if one were a random sample from the set of all observers in one’s reference class” (from a Nick Bostrom piece). The reason we think our theory of QM is right is that we think our branch in the multi-verse didn’t get cursed with an unrepresentative set of observed phenomena.
Wouldn’t a branch in the multi-verse that observed quantum events in which values were systematically distorted (by random chance) come up with slightly different equations to describe quantum mechanics? If so, what reason do we have to think that our equations are correct if we don’t consider our observations to be similar to the observations made in other possible worlds?
It’s not just world counting… (Although Robin Hanson’s Mangled World’s idea does suggest a way that it may turn out to amount to world counting after all)
essentially one has to integrate the squared modulus of quantum amplitude over a world. This is proportional to the subjective probability of experiencing that world.
Yes… that it isn’t simple world counting does seem to be a problem. This is something that we, or at least I, am confused about.
As I said, that’s something I’m confused about, and apparently others are as well.
We’ve got the linear rules for how quantum amplitude flows over configuration space, then we’ve got this “oh, by the way, the subjective probability of experiencing any chunk of reality is proportional to the square of the absolute value” rule.
Basic QM seems to say that probability is ontologically basic. In a collapse point of view, it’s what we usually think of as probability that shows up in decision theory. In MWI, both events happen. But you could talk about usual probability either way. (“classical probability is a degenerate form of quantum probability” with or without collapse)
Anthropics is about the interaction of probability with the number of observers.
Replacing usual probability with QM doesn’t seem to me to make a difference. Quantum suicide is a kind of anthropics, but it’s not clear to me in what sense it’s really quantum. It’s mainly about rejecting the claim that the Born probabities are ontologically basic, that they measure how real an outcome is.
But in MWI isn’t the observed probability of some quantum state just the fraction of worlds in which an observer would detect that quantum state? As such, doesn’t keeping the probabilities of quantum events as QM predicts require that “one should reason as if one were a random sample from the set of all observers in one’s reference class” (from a Nick Bostrom piece). The reason we think our theory of QM is right is that we think our branch in the multi-verse didn’t get cursed with an unrepresentative set of observed phenomena.
Wouldn’t a branch in the multi-verse that observed quantum events in which values were systematically distorted (by random chance) come up with slightly different equations to describe quantum mechanics? If so, what reason do we have to think that our equations are correct if we don’t consider our observations to be similar to the observations made in other possible worlds?
It’s not just world counting… (Although Robin Hanson’s Mangled World’s idea does suggest a way that it may turn out to amount to world counting after all)
essentially one has to integrate the squared modulus of quantum amplitude over a world. This is proportional to the subjective probability of experiencing that world.
Yes… that it isn’t simple world counting does seem to be a problem. This is something that we, or at least I, am confused about.
Thanks. Good to know. I don’t suppose you can explain why it works that way?
As I said, that’s something I’m confused about, and apparently others are as well.
We’ve got the linear rules for how quantum amplitude flows over configuration space, then we’ve got this “oh, by the way, the subjective probability of experiencing any chunk of reality is proportional to the square of the absolute value” rule.
There’re a few ideas out there, but...