On 3/4/2020 2:43 PM, Bruce Kellett wrote:
On Thu, Mar 5, 2020 at 9:15 AM 'Brent Meeker' via Everything List <everything-list@googlegroups.com <mailto:everything-list@googlegroups.com>> wrote:

    On 3/4/2020 1:54 PM, Bruce Kellett wrote:
    On Wed, Mar 4, 2020 at 11:01 PM Stathis Papaioannou
    <stath...@gmail.com <mailto:stath...@gmail.com>> wrote:


        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.

    Whether MWI is a satisfactory interpretation or not; do you have a
    preferred proposal for getting rid of the unobserved macroscopic
    states that are predicted by the formalism with a collapse
    postulate, e.g. gravitationally induced collapse, transactional
    interpretation, or what?


I do not think the problem is solved at the moment. Penrose's gravitational induced collapse still lacks a dynamical mechanism for the collapse when the gravitational superposition become unwieldy.

Have you looked at Laloe's paper which fills this in using some Bohmian ideas.  arXiv:1905.12047v3 [quant-ph] 6 Sep 2019

Cramer's (Kastner's) transactional interpretation introduces a whole new "possibility world", and relies on the failed absorber theory of radiation.

I think the function of the possibility space is to avoid the problems of the absorber theory.  The absorbtion is "transacted" in possibility space.  I'm note sure how it handles free radiation (e.g. the CMB) since nothing happens except by an exchange of energy/information between an emitter and absorber.


No-go there. Bohm is the preferred option of many philosophers of QM, but I think Flash-GRW is growing in plausibility. At least it does give an underlying stochastic dynamics, so doesn't suffer the problems of introducing probability that other approaches have.

It is still an open question, as far as I can see. The clear thing is that Everett plainly fails to make any sense of probability when all outcomes occur for any measurement.

I don't see that as particularly damning.  I just means you need another postulate of the form "And /this/ is a probability measure."  For example, if you take Zurek's quantum Darwinism to provide an objective pointer basis then you can say, in this basis, off-diagonal terms in the reduced density matrix that are so small they will never be observed can be set to zero and then the diagonal terms are just the probability of the (one) world that will be actual.

Brent


Bruce
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