The main reason for not favouring the Everett interpretation is that it doesn’t predict classical observations , unless you make further assumptions about basis, the “preferred basis problem”. There is therefore room for an even simpler interpretation.
There is an approach to MWI based on coherent superpositions, and a version based on decoherence. These are (for all practical purposes) incompatible opposites, but are treated as interchangeable in Yudkowsky’s writings.
The original, Everettian, or coherence based approach , is minimal, but fails to predict classical observations. (At all. It fails to predict the appearance of a broadly classical universe). The later, decoherence based approach, is more emprically adequate, but seems to require additional structure, placing its simplicity in doubt
Coherent superpositions probably exist, but their components aren’t worlds in any intuitive sense. Decoherent branches would be worlds in the intuitive sense, and while there is evidence of decoherence, there is no evidence of decoherent branching.There could be a theoretical justification for decoherent branching , but that is what much of the ongoing research is about—it isn’t a done deal, and therefore not a “slam dunk”. And, inasmuch as there is no agreed mechanism for decoherent branching, there is no definite fact about the simplicity of decoherent MWI.
Everett’s thesis doesn’t give an answer to how an observer makes sharp-valued classiscal observations, and doesn’t flag the issue either, although much of the subsequent literature does.
The main reason for not favouring the Everett interpretation is that it doesn’t predict classical observations , unless you make further assumptions about basis, the “preferred basis problem”. There is therefore room for an even simpler interpretation.
There is an approach to MWI based on coherent superpositions, and a version based on decoherence. These are (for all practical purposes) incompatible opposites, but are treated as interchangeable in Yudkowsky’s writings.
The original, Everettian, or coherence based approach , is minimal, but fails to predict classical observations. (At all. It fails to predict the appearance of a broadly classical universe). The later, decoherence based approach, is more emprically adequate, but seems to require additional structure, placing its simplicity in doubt
Coherent superpositions probably exist, but their components aren’t worlds in any intuitive sense. Decoherent branches would be worlds in the intuitive sense, and while there is evidence of decoherence, there is no evidence of decoherent branching.There could be a theoretical justification for decoherent branching , but that is what much of the ongoing research is about—it isn’t a done deal, and therefore not a “slam dunk”. And, inasmuch as there is no agreed mechanism for decoherent branching, there is no definite fact about the simplicity of decoherent MWI.
I’m confused about what distinction you are talking about, possibly because I haven’t read Everett’s original proposal.
Everett’s thesis doesn’t give an answer to how an observer makes sharp-valued classiscal observations, and doesn’t flag the issue either, although much of the subsequent literature does.
Eg. https://iep.utm.edu/everett/ for an overview (also why it’s more than one theory, and a work-in-progress).
What’s the evidence for these “sharp-valued classical observations” being real things?
Err...physicists can make them in the laboratory. Or were you asking whether they are fundamental constituents of reality?
I’m asking how physicists in the laboratory know that their observation are sharp-valued and classical?
Same way you know anything. “Sharp valued” and “classical” have meanings, which cash out in expected experience.