On Wed, Mar 4, 2020 at 11:01 PM Stathis Papaioannou <stath...@gmail.com> wrote:
> On Fri, 28 Feb 2020 at 08:40, Bruce Kellett <bhkellet...@gmail.com> wrote: > >> On Fri, Feb 28, 2020 at 4:21 AM 'Brent Meeker' via Everything List < >> everything-list@googlegroups.com> wrote: >> >>> On 2/27/2020 3:45 AM, Bruce Kellett wrote: >>> >>> >>> That is probably what all this argument is actually about -- the maths >>> show that there are no probabilities. Because there are no unique >>> probabilities in the classical duplication case, the concept of probability >>> has been shown to be inadmissible in the deterministic (Everettian) quantum >>> case. The appeal by people like Deutsch and Wallace to betting quotients, >>> or quantum credibility measures, are just ways of forcing a probabilistic >>> interpretation on to quantum mechanics by hand -- they are not derivations >>> of probability from within the deterministic theory. There are no >>> probabilities in the deterministic theory, even from the 1p perspective, >>> because the data are consistent with any prior assignment of a probability >>> measure. >>> >>> >>> The probability enters from the self-location uncertainty; which is >>> other terms is saying: Assume each branch has the same probability (or some >>> weighting) for you being in that branch. Then that is the probability that >>> you have observed the sequence of events that define that branch. >>> >> >> I think that is Sean Carroll's approach. I am uncertain as to whether >> this really works or not. The concept of a 'weight' or 'thickness' for each >> branch is difficult to reconcile with the first-person experience of >> probability: which is obtained within the branch, so is independent of any >> overall 'weight'. But that aside, self-locating uncertainty is just another >> idea imposed on quantum mechanics and, like decision-theoretic ideas, it is >> without theoretical foundation -- it is just imposed by fiat on a >> deterministic theory. It makes probability a subjective notion imposed on >> a theory that is supposedly objective: there is an objective probability >> that a radioactive nucleus will decay in a certain time period -- >> independent of our subjective impressions, or self-location. (I can develop >> this thought further, if required, but I think it shows Sean's approach to >> fail.) >> > > Probability derived from self-locating uncertainty is an idea independent > of any particular physics. It is also independent of any theory of > consciousness, since we can imagine a non-conscious observer reasoning in > the same way. To some people it seems trivially obvious, to others it seems > very strange. I don’t know if which group one falls into correlates with > any other beliefs or attitudes. > As I said, self-locating uncertainty is just another idea imposed on the quantum formalism without any real theoretical foundation -- "it is just imposed by fiat on a deterministic theory." If nothing else, this shows that Carroll's claim that Everett is just "plain-vanilla" quantum mechanics, without any additional assumptions, is a load of self-deluded hogwash. 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 everything-list+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/everything-list/CAFxXSLRKUmzW3Db2kze0RHOKbTYkna_5gWnmxi3onB_KhFmUcw%40mail.gmail.com.
