On Mon, Feb 17, 2020 at 6:04 PM 'Brent Meeker' via Everything List <
[email protected]> wrote:

> On 2/16/2020 9:48 PM, Bruce Kellett wrote:
>
> On Mon, Feb 17, 2020 at 4:13 PM 'Brent Meeker' via Everything List <
> [email protected]> wrote:
>
>>
>> But exactly the same reasoning applies for any given true value of p.
>> There will be different estimates by different experimenters and they can't
>> all be right.  Each will infer that any proportion other than the one he
>> observed will have zero measure in the limit N->oo.
>>
>
> Exactly right. That is what my example of spin measurements on an ensemble
> of equally prepared spin states comes into play. If all 2^N bit strings are
> realized for one orientation of the S-G magnet, then exactly the same 2^N
> bit strings are realized for every other orientation.
>
>
> ?? Suppose the ensemble is equally prepared in spin-up.  What does it mean
> to say all 2^N bit strings are realized for the S-G oriented left/right?
> We may expect they will be for any number of trials >>N.  But certainly
> not for the S-G oriented up/down.
>

I think we are beginning to argue at cross-purposes, and I may not have
understood you correctly. Let me try to restate the position clearly, and
see if you can agree.

Take a spin-half state, and prepare a linear combination in the x-basis:

       |psi> = (alpha*|x-spin up> + beta*|x-spin down>),

where we assume that neither alpha nor beta is equal to zero. We can now
measure this state in the x-direction and assume Everett, so that every
result is obtained in a separate branch on every trial. Coding these
results as zero and one, a run of N experiments will give 2^N binary
strings of results, consisting of the set of all 2^N binary strings of
length N. Now rotate the S-G magnet from the x-direction by, say, 10
degrees. Your results are again the set of all binary strings of length N.
Similarly for any other angle (except those for which alpha or beta rotates
to zero). Since the set of results is the same in all cases, even though
rotation of the S-G magnet is equivalent to changing alpha and beta in the
superposition, the individual sets of results must be independent of alpha
and beta. However, the Born rule states that the probabilities depend on
|alpha|^2 and |beta|^. But we have seen that the many-worlds data are
actually independent of alpha and beta. The Born rule for probabilities is
thus disconfirmed in this Everettian case.

That is the crux of what I am trying to get across -- Everettian QM is
disconfirmed by experiment, since experiments show results that depend on
the coefficients alpha and beta, in accordance with the Born Rule. There
are other points that I have been making, but let's get this straight first.

Bruce

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