On Tue, Jan 07, 2025 at 09:20:52AM +1100, Bruce Kellett wrote:
> On Tue, Jan 7, 2025 at 9:11 AM Russell Standish <li...@hpcoders.com.au> wrote:
>
> On Tue, Jan 07, 2025 at 08:42:15AM +1100, Russell Standish wrote:
> > On Mon, Jan 06, 2025 at 09:50:47PM +1100, Bruce Kellett wrote:
> > >
> > > My point about S-G magnets to measure spin values was that they can
> easily be
> > > rotated away from the 50/50 position. The exact values do not matter
> in
> this
> > > context. You still get either an UP or a DOWN result along the axis of
> the
> > > magnet in its final position. The only thing that changes are the
> probabilities
> > > for each outcome.
> > >
> >
> > Yes - and my point is that branch counting will probably explain the
> > variation in probability in this experiment too. But my main point is
> > that your argument fails, and that is most clearly seen when creating
> > outcomes that are simple logical functions of the 50/50 case.
> >
>
> For example:
>
> Sebens & Carroll (2014) arXiv:1405.7577v1 has quite a good discussion
> of this. Bruce's argument could be classified as an inappropriate
> application of the "indifference principle" (the assignment of uniform
> probability when no further information is available).
>
>
> I do not apply any "indifference principle" in that I do not assign any prior
> probability distribution to anything.
Let me quote you:
"I am just pointing out that if every outcome occurs for any
measurement, then you get results that contradict the Born rule probabilities."
"The point is that, according to Everett, if there are two possible outcomes for
each trial, then each is realized on any measurement. This leads to the same 2^
N sequences for any magnet orientation, contradicting the expectation from the
Born rule which is that the proportion of, say, UP results, should follow a cos
^2(theta/2) distribution, where theta is the angle between the x-direction and
the magnet orientation."
"The probability of an UP result depends on the magnet
orientation, which is not what is found if every outcome is realized in every
trial."
In each of these sentences, you have assigned a uniform probability to each
outcome.
You haven't explicitly said why you do this, but it certainly appears you are
applying the indifference principle in so doing.
>
>
> This is not to say that branch counting and frequentism don't have
> problems - just that they're more nuanced than Bruce would have you
> believe.
>
>
> How many times do I have to say that branch counting and frequentism have
> nothing at all to do with the argument that I am making.
Saying something over and over again does not make it more believable.
> I am well aware that
> branch counting fails as an account of probability in Everettian quantum
> mechanics. For that reason I have nothing to do with any such approach. I do
> not apply any particular theory of probability, I merely point out the
> consequences of assuming that every outcome is realized in every experiment.
>
--
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Dr Russell Standish Phone 0425 253119 (mobile)
Principal, High Performance Coders hpco...@hpcoders.com.au
http://www.hpcoders.com.au
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