On Wed, Feb 5, 2020 at 12:13 AM Bruno Marchal <[email protected]> wrote:
> On 3 Feb 2020, at 22:46, Bruce Kellett <[email protected]> wrote: > > On Tue, Feb 4, 2020 at 2:48 AM Bruno Marchal <[email protected]> wrote: > >> On 2 Feb 2020, at 12:32, Alan Grayson <[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. > 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 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. 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. 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. That is OK for you, but it says nothing about the actual question at issue, which is what QM predicts about these situations. 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]. To view this discussion on the web visit https://groups.google.com/d/msgid/everything-list/CAFxXSLRmu6PsQPDV0hGDLJ47ChgGLABXCpoDs%2B0DUeDLA6wmGQ%40mail.gmail.com.
