On Fri, Sep 13, 2024 at 6:15 PM Quentin Anciaux <[email protected]> wrote:
> Le ven. 13 sept. 2024, 10:12, Stathis Papaioannou <[email protected]> a > écrit : > >> On Fri, 13 Sept 2024 at 17:30, Bruce Kellett <[email protected]> >> wrote: >> >>> On Fri, Sep 13, 2024 at 5:23 PM Stathis Papaioannou <[email protected]> >>> wrote: >>> >>>> On Fri, 13 Sept 2024 at 15:08, Bruce Kellett <[email protected]> >>>> wrote: >>>> >>>>> On Fri, Sep 13, 2024 at 1:07 PM Liz R <[email protected]> wrote: >>>>>>> >>>>>>> I don't think that works. The idea often put forward is something >>>>>>> along the lines of self-locating uncertainty -- out of all the branches, >>>>>>> which one am I on? But that is only apparent randomness, and to get >>>>>>> such an >>>>>>> idea to work, you need to be able to make a random choice between >>>>>>> branches. >>>>>>> Such randomness will be intrinsic in that It doesn't come from anywhere >>>>>>> else (it is not already part of the theory). So in order to generate >>>>>>> such >>>>>>> apparent randomness you actually need an independent source of intrinsic >>>>>>> randomness (to be able to make your self-locating choice.) >>>>>>> >>>>>> >>>>>> The intrinsic randomness arises from the fact that it is impossible >>>>>> to predict which branch you will end up in, even for an omniscient being. >>>>>> >>>>> >>>>> That is just a restatement of the traditional measurement problem. >>>>> Self-locating uncertainty is not intrinsic randomness. What is it that >>>>> selects which branch you are actually on? You need some means of random >>>>> selection which is not included in the underlying theory. You have to add, >>>>> by hand, some additional principle of randomness, such as the Born Rule. >>>>> >>>> >>>> Nothing selects which branch you will be on, since with certainty a >>>> version of you will end up in each branch. If the omniscient being predicts >>>> that you will end up in branch A, the prediction is wrong for the version >>>> of you in branch B, and if the omniscient being predicts that you will end >>>> up in branch B the prediction is wrong for the version of you in branch A. >>>> It is logically impossible to make an accurate prediction. >>>> >>> >>> It is unfortunate, therefore, that all real experiments result in just >>> one answer, which is the nub of the measurement problem. Which answer is >>> unpredictable, but that does not mean that there can be some omniscient >>> being that can predict your result. It is a matter of an intrinsic >>> probability -- *viz*. the Born Rule. >>> >> >> The branching makes the outcome fundamentally unpredictable, which is >> what randomness is. It results from the branching and nothing else. It is >> not specific to QM or MWI: it results from any process where the observer >> branches. >> > > The thing is to recover the born rules, some frequency must be in play, > some things are more likely than other, if you had to make a bet, it's > important and you wouldn't bet every outcome is equally likely. > That is a very important point. You need to be able to take account of probability, and in QM the Born Rule does this. Unfortunately, many-worlds or branching models have great problems giving any sensible account of probability. Attempts, such as those of Carroll and Zurek, make use of the assumption that equal amplitudes have equal probabilities. When you think about it, this is essentially the Born Rule, since it introduces both the concept of probability, and relates it to amplitudes. Thus all such attempts in the context of many-worlds or other branching models, are inherently circular. Bruce -- 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/CAFxXSLSA7AAWs0zQYUnOhruOLjqFoXc9_CxF2xGGBA1J-4TJjQ%40mail.gmail.com.
