Saibal wrote > [...] it's not appropriate to fix up the theory by introducing notions from the macroscopic domain that should in principle follow from the fundamental dynamics at the micro-level. [...]

Brent wrote > The notion of "result" and "measurement" are not introduced, they are fundamental to knowledge. They are exactly where MWI gets into trouble. [...] If there is a disagreement, we should take care to clarify what is it about. A putative reductionist view accepts a theory as fundamental, perhaps along with some constraints on initial conditions, and claims that "observer", "result", and "measurement" will emerge. Right? I think that this cannot work, because there is some unavoidable approximation in the translation from "a quantum state of a part of the world" to "this quasi-solid apparatus, observer, and environment (which may be part of the observer)". With conventional QM, we express this approximation as the very-very small probability of the apparatus quantum-tunneling through the floor, and so on. With a MWI, I do not see how we can formulate this approximation from the reductionist point of view. So there is a dualism: The supposedly fundamental theory applies to an imagined, objective world, and it also applies to the world of our experience. There is a connection of course, because if the latter were untrue then we could have no clue about the validity of the theory in the objective world. A key notion here is workability of the theory: that it tolerates the impossibility of infinite precision, so it works in both worlds. Brent continued > [...] By saying there is no result of an experiment it muddles the concept of probability. Although I have seen proposals for introducing probability in a MWI (Zurek, Vaidman, John K. Clark), they cannot refer to the notion of aleatory probability, involving randomisation, as when one shuffles a deck of cards or shakes and rolls dice. On the other hand, conventional QM does assume that dice are rolled, and so the requisite randomisation is supposedly introduced, and we can speak of probability proper. Where is the randomisation in a MWI? (A rhetorical question.) So, there is no probability (strictly speaking) in a MWI. We can only identify something-like-probability; I have posted about this subject in a recent thread. George K. -- You received this message because you are subscribed to the Google Groups "Everything List" group. To unsubscribe from this group and stop receiving emails from it, send an email to everything-list+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/everything-list/2d8ceac7-def7-4efd-a1a3-0fbe426ddd66n%40googlegroups.com.