Brent, Section 3b of ( http://arxiv.org/pdf/quant-ph/9709032v1.pdf ) seems to also answer some of the questions you posed recently regarding superposition in MWI:
B. “It doesn’t explain why we don’t perceive weird superpositions” That’s right! The Everett postulate doesn’t! Since the state corresponding to a superposition of a pencil lying in two macroscopically different positions on a table-top is a perfectly permissible quantum state in the MWI, why do we never perceive such states? The inability to answer this question was originally a serious weakness of the MWI, which can equivalently be phrased as follows: why is the position representation so special? Why do we perceive macroscopic objects in approximate eigenstates of the position operator r and the momentum operator p but never in approximate eigenstates of other Hermitian operators such as r + p? The answer to this important question was provided by the realization that environment-induced decoherence rapidly destroys macrosuperpositions as far as the inside view is concerned, but this was explicitly pointed out only in the 70’s  and 80’s , more than a decade after Everett’s original work. This elegant mechanism is now well-understood and rather uncontroversial , and the interested reader is referred to  and a recent book on decoherence  for details. Essentially, the position basis gets singled out by the dynamics because the field equations of physics are local in this basis, not in any other basis. If you do not find this answer satisfying, I would be interested to know why. Thanks. Jason On Sat, Oct 26, 2013 at 12:09 PM, Jason Resch <jasonre...@gmail.com> wrote: > John, > > I came across this today, which you might find of interest: > http://arxiv.org/pdf/quant-ph/9709032v1.pdf > > In particular section 3 goes to great pains to describe the importance of > the first person / third person distinction. From the paper: > > A. “It doesn’t explain why we perceive randomness” > > Everett’s brilliant insight was that the MWI does > explain why we perceive randomness even though the > Schrodinger equation itself is completely causal. To avoid > linguistic confusion, it is crucial that we distinguish between > > • the outside view of the world (the way a mathematical > thinks of it, i.e., as an evolving wavefunction), > and > > • the inside view, the way it is perceived from the > subjective frog perspective of an observer in it. > > Therefore, the 1st / 3rd person views are not just some obscure aspect of > Bruno's theory that is unknown or unused in any other part of science, it > is critical in other theories of science too. You dismiss it as "pee pee" > and that is what prevents you from arriving at the correct conclusion, I > think. If you take into account the first person "inside view" or "frog > perspective", you get a different result than when you use only the third > person "outside view" or "bird perspective". > > Your confusion regarding the third step has nothing to do with pronouns or > personal identity, it is purely due to a focus on only the objective > perspective when the experiment calls for use of the subjective perspective. > > Jason > > > On Fri, Oct 25, 2013 at 1:59 PM, John Clark <johnkcl...@gmail.com> wrote: > >> On Fri, Oct 25, 2013 at 12:27 PM, Quentin Anciaux <allco...@gmail.com>wrote: >> >> >> In the MWI John Clark doesn't have to worry about who "you" is because >>>> however many copies of "you" there may or may not be they will never meet >>>> >>> >>> > What does it have to do with prediction and probability ? >>> >> >> In the MWI if John Clark is asked for a prediction or a probability or >> anything for that matter about "you" further clarification is not needed, >> in a thought experiment involving people duplicating machines it is. >> >> > you refuse to let work your brain while you doesn't do *as you should* >>> >> >> You doesn't well speak. >> >> John K Clark >> >> -- >> 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 post to this group, send email to firstname.lastname@example.org. >> Visit this group at http://groups.google.com/group/everything-list. >> For more options, visit https://groups.google.com/groups/opt_out. >> > > -- 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 post to this group, send email to email@example.com. Visit this group at http://groups.google.com/group/everything-list. For more options, visit https://groups.google.com/groups/opt_out.