But really, here, I’m asking: “Does this theory have multiple worlds in it?” I care significantly less what it’s called
Right- in consistent histories there is 1 world. When you make a measurement, you get one answer. In ensemble quantum mechanics there is 1 world. Remember- the creators of consistent histories (Hartle, for instance) consider it a formalized and clarified copenhagen variant (though inspired by many worlds). Maybe think about it like Bohmian mechanics- the “world” that the Bohmian particle actually sits in is the ‘real’ one. Similarly, in consistent histories, the answer you get picks out a set of projection operators as “real.”
Side question- do you know a many worlds variant (in the sense of more than one world) that makes explicit what its “type 2” postulate is? The only variant I know of is many minds, which I find sort of abhorrent and disregard out of hand. The reason I insist that “many worlds” is incomplete is that the only formalized version I know is Everettian many worlds (which we both seem to agree IS incomplete).
The associations of the hermitian operators corresponding to observable quantities are very type-2.
But also type 1, because it defines the system (hermitian operators on a Hilbert space). What would you consider the type 2 postulates of Newtonian mechanics? What would you consider the type 2 postulates of GR?
In that case, Consistent Histories is both not WMI and I didn’t say it was, because it doesn’t consider the wavefunction fully real in its own right (there were two criteria, not just one, in that sentence)*. Just as Bohm isn’t, on the same grounds.
Type 1 vs type 2: Normally we don’t even talk about these types—if it were a matter of discussion, we wouldn’t be using these terms! With the observables, using them in the theory is type 1. Associating each one to a part of the world we experience is type 2.
As for the incompleteness of Everett, I hold that you can deduce that the Born Rule is one possible way of finding sapience within wavefunctions. I am not at all sure that you can prove that there aren’t others, so barring such a proof, a postulate is necessary to exclude them—“The way of getting to a perceivable world from this theory is… THIS one, not any others.”
ETA: and in this case Consistent Histories deserves every bit of scorn that Eliezer heaped on Copenhagen in the ‘what does it have to do, kill a puppy’ rant.
Right- in consistent histories there is 1 world. When you make a measurement, you get one answer. In ensemble quantum mechanics there is 1 world. Remember- the creators of consistent histories (Hartle, for instance) consider it a formalized and clarified copenhagen variant (though inspired by many worlds). Maybe think about it like Bohmian mechanics- the “world” that the Bohmian particle actually sits in is the ‘real’ one. Similarly, in consistent histories, the answer you get picks out a set of projection operators as “real.”
Side question- do you know a many worlds variant (in the sense of more than one world) that makes explicit what its “type 2” postulate is? The only variant I know of is many minds, which I find sort of abhorrent and disregard out of hand. The reason I insist that “many worlds” is incomplete is that the only formalized version I know is Everettian many worlds (which we both seem to agree IS incomplete).
But also type 1, because it defines the system (hermitian operators on a Hilbert space). What would you consider the type 2 postulates of Newtonian mechanics? What would you consider the type 2 postulates of GR?
In that case, Consistent Histories is both not WMI and I didn’t say it was, because it doesn’t consider the wavefunction fully real in its own right (there were two criteria, not just one, in that sentence)*. Just as Bohm isn’t, on the same grounds.
Type 1 vs type 2: Normally we don’t even talk about these types—if it were a matter of discussion, we wouldn’t be using these terms! With the observables, using them in the theory is type 1. Associating each one to a part of the world we experience is type 2.
As for the incompleteness of Everett, I hold that you can deduce that the Born Rule is one possible way of finding sapience within wavefunctions. I am not at all sure that you can prove that there aren’t others, so barring such a proof, a postulate is necessary to exclude them—“The way of getting to a perceivable world from this theory is… THIS one, not any others.”
ETA: and in this case Consistent Histories deserves every bit of scorn that Eliezer heaped on Copenhagen in the ‘what does it have to do, kill a puppy’ rant.