Interesting that TI might show this. Q-interpretations can have their 
utility.

LC

On Sunday, October 30, 2022 at 8:27:56 PM UTC-5 meeke...@gmail.com wrote:

> Thanks.  I found this critique by Kastner (who of course says that the 
> transactional interpretation solves the problem).
>
> https://arxiv.org/ftp/arxiv/papers/1308/1308.4272.pdf
>
> Brent
>
>
>
> On 10/30/2022 4:41 PM, Lawrence Crowell wrote:
>
> I remember some issue surrounding this. I do not remember the way it was 
> resolved, but I do recall that Hobson was considered wrong. 
>
> LC
>
> On Saturday, October 29, 2022 at 8:04:35 PM UTC-5 meeke...@gmail.com 
> wrote:
>
>>
>>
>> On 10/29/2022 6:29 AM, Lawrence Crowell wrote:
>>
>> On Friday, October 28, 2022 at 10:55:50 PM UTC-5 Bruce wrote:
>>
>>> On Sat, Oct 29, 2022 at 1:42 PM Brent Meeker <meeke...@gmail.com> wrote:
>>>
>>>>
>>>> On 10/28/2022 6:43 PM, Bruce Kellett wrote:
>>>>
>>>> Look, "ad hoc" is frequently bandied about as a fatal flaw in any 
>>>> theory. Just as Putin waves about the nuclear threat: this is just to 
>>>> intimidate the opposition, it doesn't mean anything more. Any theory has 
>>>> ad 
>>>> hoc elements, or else it would not be of any value in explaining our 
>>>> experience. There is always a theoretical part, and then a collection of 
>>>> elements that serve to relate the theory to observation. Everything is 
>>>> ultimately ad hoc, because it is for the particular purpose of explaining 
>>>> observation.
>>>>
>>>>
>>>> I think you've stretched it's meaning beyond recognition.  If every 
>>>> theory that is devised to match experiment is ad hoc then indeed all 
>>>> science is ad hoc...and the better for it.  But there is real ad hockery 
>>>> that is deserving of criticism.
>>>>
>>>> The real question on the table is what would you take to be not ad hoc; 
>>>> what would be better than "... measurement is then not treated in terms of 
>>>> the fundamental  dynamics of the theory."  Do you see MWI doing this?
>>>>
>>>
>>> No. MWI takes unitary dynamics of the Schrodinger equation to be 
>>> fundamental. But unitary dynamics and the SE are deterministic, and 
>>> incompatible with a probabilistic interpretation. So MWI is not going to be 
>>> able to give a completely satisfactory account of measurement since the 
>>> outcomes of measurement are inherently probabilistic. So whatever you do in 
>>> MWI, measurement is not treated in terms of the fundamental dynamics of the 
>>> theory; there is always some ad hoc element required to make contact with 
>>> experiment. In that context MWI, is simply engaging in a double standard 
>>> when it criticizes collapse theories as ad hoc.
>>>
>>> Bruce
>>>
>>
>> Quantum mechanics deals with the evolution of probability amplitudes a_i 
>> and probabilities are p_i = |a_i|^2. The probabilities are the trace of the 
>> density matrix and the density matrix by the Schrodinger equation is  dρ/dt 
>> = [H, ρ], and this describes the evolution of probabilities. With an actual 
>> outcome the probabilities are no longer applicable due to there being only 
>> one outcome. 
>>
>> LC
>>
>>
>> Art Hobson has a series of papers on the "measurement problem" in which 
>> he argues that past analyses, by von Neumann and others, incorrectly ignore 
>> non-local entanglement in going from the density matrix of the 
>> system+instrument to the diagonalized system+instrument representing a 
>> mixture.  And when this is correctly accounted for he says the non-local 
>> entanglement causes the measured value (which is random per Born) to be a 
>> unique realization of the eigenvector...no multiple worlds.  
>>
>> SUMMARY AND CONCLUSION
>> Using only the standard principles of quantum physics, but minus the
>> collapse postulate, we have shown that quantum state collapse occurs as a
>> consequence of the entanglement that occurs upon measurement as described 
>> in
>> 1932 by von Neumann (Equation (4)). The entangled "measurement state" of a
>> quantum system and its detector is the collapsed state: It incorporates 
>> the required
>> perfect correlations between the system and its detector, it predicts 
>> precisely one
>> definite outcome, and it incorporates the nonlocal properties--the 
>> instantaneous
>> collapse across all branches of the superposition--that Einstein showed 
>> to be
>> required in quantum measurements
>>
>> See attached.
>>
>> Brent
>>
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