On Thu, Jan 2, 2014 at 12:21 PM, John Clark <[email protected]> wrote:
> On Tue, Dec 31, 2013 at 5:07 PM, Jason Resch <[email protected]> wrote: > > > I would add a (*) on "observer role". In MWI the observer plays no >> special function in the evolution of the wave function. This is not the >> case for many interpretations where the observer plays some special >> privileged role, such as having the ability to collapse wave functions. >> > > Yes, and that is why I believe the MWI is superior to other > interpretations, but that's only my opinion and the universe may have a > different one. > > > [your chart] says for MWI the observer plays no part in many world but >>> it also says "no" to counterfactual definiteness meaning you can't speak >>> meaningfully of the definiteness of the results of measurements that have >>> not been observed. >> >> >> > That is true for MWI because measurements don't have (single) definite >> results. >> > > Yes they do, the photon I just measured has a polarization of exactly > 42.7%, true other John Clarks measured other photons and found other > values, but this john Clark got exactly 42.7% for this photon. > > Okay, we are only disagreeing on the meaning of "single definite result", here you are using it in the third-person sense. > >> Both those things can't be right. >>> >> >> > Can you explain why not? >> > > Not having counterfactual definiteness means something is NOT in a > definite state if you don't observe it, observer independent says they ARE > in a definite state even if you don't know what it is. > > >> And in many world there is no unique future but it says there is no >>> unique past, and that's not what the theory says. >>> >> >> > There is no unique past as shown in the quantum erasure experiment. >> > > OK you got me, I should have said with the MWI there is ALMOST a unique > past. According to Everett when 2 different things could happen then both > do, one happens in one universe and one happens in the other; for example a > photon goes through a half silvered mirror in one universe and is reflected > in the other. Usually after that the differences between the universes > increase and they remain separated for eternity, however if the initial > difference is very small and if you set up the experiment very very > carefully then the 2 universes might not further diverge but instead evolve > into identical states again. Because the 2 universes are identical again > they come back together and we in the single merged universe see evidence > that the photon was reflected off the half silvered mirror and equally > strong evidence that the photon went straight through the half silvered > mirror. The information to decide between these 2 possibilities no longer > exists in our universe because both past states could have evolved into the > present state. But none of the possible alternate pasts we see from > looking back from our particular thread of the multiverse are very > different from each other, but our alternate futures can be radically > different. > > > The wave function says everything there is to be said about how >> something is right now. >> > > The wave function says nothing about where the electron is right now, the > square of the wave function (I'm not being pedantic the distinction is > important) does tell you something but not enough, it can only give you > probable locations of the electron but it could be anywhere. > Up above, you were saying MWI implies a single definite result (which it does in the third person perspective), but here you are using the uncertainty in the first person perspective. You should stick to one or the other, or at least be explicit when you switch between them. > You can find out more and find out exactly where is is but to do that > you're going to need to get your hands dirty and perform a experiment, then > the squared wave function collapses from everywhere to one specific dot on > a photographic plate. This is the measurement problem and the problem that > the MWI elegantly solves that most other quantum interpretations do not; > it's the only reason I think MWI is better than the competition. > There are other reasons to prefer it besides it's answer to the measurement problem without magical observers, including: - Fewer assumptions - Explains more (appearance of collapse, and arguably also the Born rule (with Gleason's theorem)) - Explains how quantum computers work - Fully mathematical theory (no fuzziness, or loose definitions) - No faster-than-light influences - Explains universe at times before there was conscious life to observe it - Preserves CPT symmetry, time reversibility, linearity - Is realist on things other than our observations (here is "something else" out there, besides what is in our minds) I would say the evidence for MWI isn't just strong, but overwhelming, given the evidence for QM is overwhelming and MWI is the only theory of QM consistent with other (overwhelmingly established theories such as special relativity). > But that doesn't prove its correct of course, everybody could be wrong, > maybe MWI is just the best of a bad lot. > It's strange, but I wouldn't say the MWI is bad. I see no problems with it, and is just part of a continuing "deprovincialization" of our world view, to use a word Sagan was fond of. You wouldn't say cosmic inflation is bad just because it implies the existence of an infinite number of unseen galaxies, would you? Jason > The only thing I'm certain of is that whatever turns out to be true will > be crazy. > > 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 [email protected]. > To post to this group, send email to [email protected]. > 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 [email protected]. 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