> On 4 Feb 2020, at 23:13, Bruce Kellett <[email protected]> wrote: > > On Wed, Feb 5, 2020 at 12:13 AM Bruno Marchal <[email protected] > <mailto:[email protected]>> wrote: > On 3 Feb 2020, at 22:46, Bruce Kellett <[email protected] > <mailto:[email protected]>> wrote: >> On Tue, Feb 4, 2020 at 2:48 AM Bruno Marchal <[email protected] >> <mailto:[email protected]>> wrote: >> On 2 Feb 2020, at 12:32, Alan Grayson <[email protected] >> <mailto:[email protected]>> wrote: >>> On Saturday, February 1, 2020 at 11:42:12 PM UTC-7, Brent wrote: >>> First, it's false. You can make it true by interpreting "can happen" to >>> mean "can happen according the prediction of quantum mechanics for this >>> situation", but then it becomes trivial. Second, it's not "at the heart of >>> MWI"; the trivial version is all that MWI implies. Read the first few >>> paragraphs of this paper: >>> >>> arXiv:quant-ph/0702121v1 13 Feb 2007 >>> >>> Brent >>> >>> In posing the question, I want to give its advocates such as Clark the >>> opportunity to justify the postulate. It goes way beyond the MWI and QM. >>> E.g., it means that if someone puts on his/her right shoe first this >>> morning, there must be a universe in which a copy of the person puts on >>> his/her left shoe first. It seems way, way over the top, but oddly many >>> embrace it with gusto. AG >> >> >> That is already completely different, as it seems to say that everything >> happen with the same probability, but that is non sense, >> >> No, it is exactly what Everett predicts. > > If that was the case, I don’t think we would still be here discussing > Everett. > >> Everything that happens happens with probability one. > > Everett insists, perhaps wrongly (but then that is what should be debated) > that he recovers the usual quantum statistics, where the probability is given > by the square of the amplitude of the wave. > > It turns out, in fact, that Everett did not prove this result. As in > conventional QM, he just asserted it.
He provides argument, which actually were already found by Paulette Février-destouche in France 20 years before Everett, and correspond more or less to the argument made by Graham in the selected paper by DeWitt and Graham on the MWI, and by Preskill in his textbook in Quantum Mechanics. Is that argument totally convincing? Perhaps not, but let us say that I think it is improvable, and it is going in the direction that we can expect when postulating Mechanism (as do Everett, and many others, consciously or unconsciously). >> All possible outcomes occur with unit probability in any >> interaction/experiment. David Albert makes the very good point that in your >> W/M duplication scenario, for example, no first person probabilities for >> potential outcomes can be defined. > > Where? In his book “quantum mechanics and experience”? Albert has clearly not > understand Everett Imo. > > Can you do this point here? > > I have read a lot of Albert's more recent work, and I can't remember exactly > where he makes this point. I expect it was in a Podcast discussion with Sean > Carroll: > > https://www.youtube.com/watch?v=AglOFx6eySE > <https://www.youtube.com/watch?v=AglOFx6eySE> > > The problem is that this is nearly two hours long, and I haven't time to > listen to the whole thing again. He talks in detail about probability in > Everett about half way through this discussion. Of course we agree that if a theory predicts that all outcome comes with probability one, mechanism, but also nature refutes this fact, but neither QM-copenhague nor QM-everett claims this, unless they are talking about the 3p picture, in which there are no probabilities. What Everett call “subjective probabilities” is equivalent, in the mechanist setting, with the first person indeterminacy. I suspect that taken out of context, Everett might have looked like saying that all outcome have probability one, but in his texts he made clear when he talk about a result being accessible to an observer, and the universal wave as seen from “outside” (that is the mathematical 3p solution of the wave equation). > > The basic argument is that people use symmetry arguments and the like to > claim that the probabilities for H-man to end up in M or W are each equal to > one-half. Albert points out that the same symmetries are respected by the > claim that H-man has no idea where he will end up -- he cannot assign > probabilities to the separate outcomes since each occurs with probability one. Which is refuted by all persons after the experience, as both the M and W men, who remember rightly to have been the H-guy, can only write the name of the once city they see after having push the button. So indeed the idea that all outcome have probability one is the 3p description of the protocole of the experience. I recall that the question is not about where the guy will be from a 3p view, but where the guy will feel himself, given that he survives (vy mechanism) and know that he can survive only with a first person experience of effacing to be in only once city (as that is true for both copies). We can come back on this with more details if something still seems mysterious to you. Iy works as well with robots in place of the humans: the whole thing can be described in a pure 3p way. > > >> both with Mechanism (the many-worlds interpretation of arithmetic) and with >> Everett (the many-worlds formulation of QM). Thinking is presumably >> classical so when you take decision, you take the same decision in all >> worlds, with rare exceptions. >> >> Only if it is the same person in all those worlds. > > But there are the same by definition, given that that they are supposed to be > the same above the substitution level by construction. Keep in mind that I am > reasoning in the frame of the Mechanist hypothesis, like Darwin, Descartes, > but revised by the digital Church-Turing thesis. > > The trouble with all these arguments that you make is that you move away from > quantum mechanics and argue in terms of you mechanism. Everett requires Mechanism, and what Everett missed is that once you assume mechanism, not only you need to recover the collapse of the wave in the first person discourse, but you have to recover the wave itself, and thus quantum mechanics. > That is OK for you, but it says nothing about the actual question at issue, > which is what QM predicts about these situations. QM needs a precise theory of mind. Everett use Mechanism, but fail to see all the consequences of that move. Now, with Copenhagen you can invoke a non mechanist theory of mind, but that is a bit like invoking God when we lack understanding. Today, there are simply no non-mechanist theory of mind, other than untestable fairy tales imposed by tyran and manipulators since long. Bruno > > Bruce > > >> Different people make different (classical) decisions. > > No problem. In the case above, those are not different people. They are > numerically identical at the right level substitution per definition, which > makes sense with the digital mechanist hypothesis. > > Bruno > > -- > 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] > <mailto:[email protected]>. > To view this discussion on the web visit > https://groups.google.com/d/msgid/everything-list/CAFxXSLRmu6PsQPDV0hGDLJ47ChgGLABXCpoDs%2B0DUeDLA6wmGQ%40mail.gmail.com > > <https://groups.google.com/d/msgid/everything-list/CAFxXSLRmu6PsQPDV0hGDLJ47ChgGLABXCpoDs%2B0DUeDLA6wmGQ%40mail.gmail.com?utm_medium=email&utm_source=footer>. -- 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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