On Saturday, November 3, 2018 at 9:33:54 PM UTC, Philip Thrift wrote:
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>
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> On Saturday, November 3, 2018 at 3:50:30 PM UTC-5, agrays...@gmail.com 
> wrote:
>>
>>
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>> On Thursday, November 1, 2018 at 11:22:46 PM UTC, Pierz wrote:
>>>
>>>
>>>
>>> On Monday, October 15, 2018 at 9:40:39 PM UTC+11, agrays...@gmail.com 
>>> wrote:
>>>>
>>>>
>>>>
>>>> On Sunday, October 14, 2018 at 5:08:42 PM UTC, smitra wrote:
>>>>>
>>>>> On 14-10-2018 15:24, agrays...@gmail.com wrote: 
>>>>> > In a two state system, such as a qubit, what forces the 
>>>>> interpretation 
>>>>> > that the system is in both states simultaneously before measurement, 
>>>>> > versus the interpretation that we just don't what state it's in 
>>>>> before 
>>>>> > measurement? Is the latter interpretation equivalent to Einstein 
>>>>> > Realism? And if so, is this the interpretation allegedly falsified 
>>>>> by 
>>>>> > Bell experiments? AG 
>>>>>
>>>>> It is indeed inconsistent with QM itself as Bell has shown. 
>>>>> Experiments 
>>>>> have later demonstrated that the Bell inequalities are violated in 
>>>>> precisely the way predicted by QM.  This then rules out local hidden 
>>>>> variables, therefore the information about the outcome of a 
>>>>> measurement 
>>>>> is not already present locally in the environment. 
>>>>>
>>>>> Saibal 
>>>>>
>>>>
>>>> What puzzles me is this; why would the Founders assume that a system in 
>>>> a superposition is in all component states simultaneously -- contradicting 
>>>> the intuitive appeal of Einstein realism -- when that assumption is not 
>>>> used in calculating probabilities (since the component states are 
>>>> orthogonal)? AG 
>>>>
>>>
>>> I think because of interference. Consider the paradigmatic double slit, 
>>> with the single electron going through it. It sure looks like the electron 
>>> was in two place at once, doesn't it?
>>>
>>
>> *Yes, that's my assessment how the erroneous interpretation took hold, 
>> but only if you restrict yourself to the particle interpretation. If the 
>> electron travels as a wave, it can go through both slits simultaneously and 
>> interfere with itself. This is my preferred interpretation; the only one 
>> that makes sense. AG*
>>
>> I'm not sure what you mean by "that assumption is not used in calculating 
>>> probabilities". 
>>>
>>
>> *If the operator whose eigenvalues are being measured has a well defined 
>> mathematical form -- e.g., not like |alive> -- it has specific eigenvectors 
>> and eigenvalues, and the state function can be written as superposition of 
>> these eigenvectors. It can be shown that eigenvectors with distinct 
>> eigenvalues are orthogonal, meaning the Kronecker delta applies to their 
>> mutual inner products. Therefore, to calculate the probability of observing 
>> a particular eigenvalue, one must take the inner product of the wf with the 
>> eigenvector which has that eigenvalue. Due to the orthogonality, all terms 
>> drop out except for the term in the superposition which contains the 
>> eigenvector whose eigenvalue you want to measure. As you should see, there 
>> is nothing in this process of calculating probabilities that in any way 
>> implies, assumes, or uses, the concept that the system is simultaneously in 
>> ALL component states of the superposition (written as a sum of 
>> eigenvectors). AG*
>>  
>>
>>> If you take a sum-over-histories approach it's explicitly assumed the 
>>> electron went via all possible paths.
>>>
>>
>> *I don't know that method, but offhand POSSIBLE PATHS might have nothing 
>> to do with, and possibly independent of SUPERPOSITIONS OF STATE. AG*
>>
>> I don't see what the orthogonality of the basis vectors (and hence 
>>> component states) has to do with the question of interpretation of 
>>> superposition. 
>>>
>>
>> *Explained in detail above. AG*
>>
>> Clearly the system will be measured in only one state, and this is what 
>>> the orthogonal vectors represent. However the quantum state itself 
>>> typically spans more than one dimension of the vector space - that's what a 
>>> superposition is. However I think when physicists say that the 
>>> superposition is in all states simultaneously, it's only in a manner of 
>>> speaking - a way of conveying the mathematical situation in natural 
>>> language that is inherently classical. 
>>>
>>
>>
>> *It's a totally misleading way to discuss the quantum superpositions.  
>> Even classically, say for the vector space of "little pointy things" in a 
>> plane, each vector can be expressed in uncountably many bases, both 
>> orthogonal and non-orthogonal. So to claim that one basis is somehow 
>> preferred, and the vector being expressed as a sum or superposition in that 
>> basis, is simultaneously in all components of that particular basis, make 
>> no sense whatsoever. AG*
>>
>> Reading Born's exchange of letters with Einstein (I'm proud to say Born 
>>> was my great grandfather), it's clear that Born had a conception of QM that 
>>> was still very realistic in the Einstein sense. Though they disagreed 
>>> significantly and somewhat heatedly, Born still seems to have regarded QM 
>>> probabilities as classical probabilities in disguise.
>>>
>>
>> *Einstein realism seems to have been falsified due to Bell experiments. 
>> If that's the case, it would mean that BEFORE measurement of a quantum 
>> system, it is not only NOT in all states of a superposition simultaneously 
>> for the reasons I have argued (nothing to do with Bell), but ALSO has no 
>> local preexisting value. AG*
>>
>> I don't think he would ever have endorsed the notion that a particle is 
>>> truly in all of the states of the superposition simultaneously. 
>>>
>>
>> *Thanks for your input. AG *
>>
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> The (complex-number-weighted) "path"s of the path integral 
> (sum-over-histories) formulation are all that are needed to define 
> superpositions. 
>

*Can you flesh that out? How can complex numbers be weighted and result in 
superpositions? AG*

"Einstein realism" is restored if *retrocausality* (the path futures can 
> *stochastically* influence the path pasts) is allowed.
>

*I don't believe it. I think it has hugely absurd implications. AG *

>
> - pt
>
>
>

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