On 11/19/2023 10:09 AM, John Clark wrote:
On Sat, Nov 18, 2023 at 8:25 PM Brent Meeker <meekerbr...@gmail.com> wrote:

    /> A good letter to Brandes, but I think you use Schroedinger's
    cat to much.  If one imagines a clock attached to the poison vial,
    then it's clear that on opening the box you will see an alive or
    dead cat and a running clock or one that marks the exact time in
    the past that the cat was killed. /

The entire purpose of a thought experiment is to help you understand something, if you replace the radioactive decay of an atom, which according to quantum mechanics is supposed to be random, an event without a cause, with a mechanical clock then I don't see how your modification of Schrodinger's cat helps anybody understand anything.
I didn't replace the atom.  I connected a clock to the vial so there's a record or when it is broken.

    /> So decoherence theory has answered the problem of why we don't
    see superpositions of alive and dead cats. /

Decoherence theoryis fine but it can't resolve  Schrodinger's cat paradox, at least not to my satisfaction.

    /> I notice that you never entertain QBism and seem to dismiss it
    as "just not an intuitively satisfying theory;/

QBismcertainly works, but I dismiss it because it's just "shut up and calculate" with a different name.

When calculate the impact of two boxcars do you refuse to use the concept of inertia becasue there's no storybook about where it comes from?  Familiarity breeds the illusion of understanding.


John K Clark    See what's on my new list at Extropolis <https://groups.google.com/g/extropolis>


        On Sat, Nov 18, 2023, 6:58 AM John Clark
        <johnkcl...@gmail.com> wrote:

            /I read an article called The multiverse is unscientific
<https://iai.tv/articles/the-multiverse-is-unscientific-nonsense-auid-2668> by
            Jacob Barandes, a lecturer in physics at Harvard
            University, and I wrote a letter to professor //Barandes
            commenting on it. He responded with a very polite letter
            saying he read it and appreciated what I said but didn't
            have time to comment further. This is the letter I sent: /

            *Hello Professor Barandes
            *I read your article The multiverse is unscientific
            nonsense with interest and I have a few comments:*
            *Nobody is claiming that the existence of the multiverse
            is a provenfact, but I think the idea needs to be taken
            seriously because:*

            *1) Unlike Bohr's Copenhagen interpretation, the Many
            Worlds theory is clear about what it's saying. *
            *2) It is self consistent and conforms with all known
            experimental results. *
            *3) It has no need to speculate about new physics as
            objective wave collapse theories like GRW do.*
            *4) It doesn't have to explain what consciousness or a
            measurement is because they have nothing to do with it,
            all it needs is Schrodinger's equation.
            *I don't see how you can explain counterfactual quantum
            reasoning and such things as the Elitzur–Vaidman bomb
            tester without making use of many worlds. Hugh Everett
            would say that by having a bomb in a universe we are not
            in explode we can tell if a bomb that is in the branch of
            the multiverse that we are in is a dud or is a live fully
            functional bomb.  You say that many worlds needs to
            account for probability and that's true, but then you say
            many worlds demands that some worlds have “higher
            probabilities than others" but that is incorrect.
            According to many worlds there is one and only one
            universe for every quantum state that is not forbidden by
            the laws of physics. So when you flip a coin the universe
            splits many more times than twice because there are a
            vast number, perhaps an infinite number, of places where
            a coin could land, but you are not interested in exactly
            where the coin lands, you're only interested if it lands
            heads or tails. And we've known for centuries how to
            obtain a useful probability between any two points on the
            continuous bell curve even though the continuous curve is
            made up of an unaccountably infinite number of points,
            all we need to do is perform a simple integration to
            figure out which part of the bell curve we're most likely on.
            *Yes, that's a lot of worlds, but you shouldn't object
            that the multiverse really couldn't be that big unless
            you are a stout defender of the idea that the universe
            must be finite, because even if many worlds turns out to
            be untrue the universe could still be infinite and an
            infinity plus an infinity is still the an infinity with
            the same Aleph number. Even if there is only one universe
            if it's infinite then a finite distance away there must
            be a doppelgänger of you because, although there are a
            huge number of quantum states your body could be in, that
            number is not infinite, but the universe is. *
            *And Occam's razor is about an economy of assumptions not
            an economy of results.  As for the "Tower of assumptions"
            many worlds is supposed to be based on, the only
            assumption that many worlds makes is that Schrodinger's
            equation means what it says, and it says nothing about
            the wave function collapsing. I would maintain that many
            worlds is bare-bones no-nonsense quantum mechanics with
            none of the silly bells and whistles that other theories
            stick on that do nothing but get rid of those  pesky
            other worlds that keep cropping up that they personally
            dislike for some reason. And since Everett's time other
            worlds do seem to keep popping up and in completely
            unrelated fields, such as string theory and inflationary
            *You also ask what a “rational observer” is and how they
            ought to behave, and place bets on future events, given
            their self-locating uncertainty. I agree with David Hume
            who said that "ought" cannot be derived from "is", but
            "ought" can be derived from "want". So if an observer is
            a gambler that WANTS to make money but is irrational then
            he is absolutely guaranteed to lose all his money if he
            plays long enough, while a rational observer who knows
            how to make use of continuous probabilities is guaranteed
            to make money, or at least break even. Physicists WANT
            their ideas to be clear, have predictive power, and to
            conform with reality as described by experiment;
            therefore I think they OUGHT to embrace the many world's
            *And yes there is a version of you and me that flips a
            coin 1 million times and see heads every single time even
            though the coin is 100% fair, however it is extremely
            unlikely that we will find ourselves that far out on the
            bell curve, so I would be willing to bet a large sum of
            money that I will not see 1 million heads in a row.  You
            also say that "the Dirac-von Neumann axioms don’t support
            oft-heard statements that an atom can be in two places at
            once, or that a cat can be alive and dead at the same
            time", but there are only two possibilities, either there
            is an alive cat and a dead cat in two different places or
            there is a live/dead cat that instantly snaps into being
            either alive or dead by the act of "measurement" even
            though the standard textbook Copenhagen interpretation
            can't say exactly what a measurement is, or even
            approximately what it is for that matter. In many worlds
            a measurement is simply any change in a quantum system,
            it makes no difference if that quantum system is a human
            being or an unconscious brick wall. So in that sense many
            worlds is totalitarian because everything that is not
            forbidden by the laws of Quantum Physics and General
            Relativity must exist.
            *You correctly point out that nobody has ever "seen an
            atom in two places at once, let alone a cat being both
            alive and dead", but nobody has ever seen infinite
            dimensional operators in Hilbert space that the Dirac-von
            Neumann axioms use either, all they've seen is ink on
            paper in mathematical books. And you can't get milk from
            the word "cow". *
            *I'll close by just saying although I believe there is
            considerable evidence in favor of the many worlds view I
            admit it falls far short of a proof, maybe tomorrow
            somebody will come up with a better idea but right now
            many worlds is the least bad quantum interpretation
            around. And speculation is not a dirty word, without it
            science would be moribund, Richard Feynman said science
            is imagination in a tight straight jacket and I agree
            with him.

            Best wishes

            John K Clark*


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