Re: R: Re: R: Re: Non-locality and MWI (literature)

[Bruce Kellett]

On 11/05/2016 2:31 am, Bruno Marchal wrote:


The question is: are the probabilities, or the indeterminacies, and 
the non locality,   phenomenological (1p)  or factual (ontological, 
real, 3p)?


QM+collapse admit factual indeterminacies  (God plays dice, and there 
are action at a distance, even if they cannot be used to transmit 
signal quicker than light).


QM-without-collapse is purely deterministic at the 3p level, and 
admits indeterminacies at the phenomenological level.


I think everyone agree on this.


I think that your confidence here is a bit premature. The Schrödinger 
equation was devised for the quantum behaviour of a single 
non-relativistic particle. It is local and deterministic in the many 
worlds interpretation for that case. However, the Schrödinger equation 
does not relate easily to relativity or spin degrees of freedom (spin is 
an intrinsically relativistic notion). These can be tacked on, but not 
always with great felicity.


The main problem, however, is that once you move beyond a single 
particle system, you have to move from physical space into configuration 
space, where there are three independent 'spatial' coordinates for each 
particle. This caused consternation for the early practitioners of QM, 
and still causes problems today for the overly naïve. So while the 
Schrödinger equation for a multi-particle system might be local and 
deterministic in configuration space, there is no guarantee that this 
will remain true when one moves back into physical space to confront 
experiment.


This is precisely the problem that one encounters with the current 
example of entangled pairs of spinning particles. Single particle 
non-relativistic intuitions can mislead, and do so here. Your confidence 
in determinism and locality for this system is seriously misplaced.


The debate is on the following question: does QM-without-collapse 
admit factual non-locality (real physical action at a distance, like 
QM-with-collapse), or do the non-locality becomes, like the 
indeterminacy, phenomenological?
(I think yes, as Jesse, Saibal and others, but it seems Bruce and John 
C. differ on this).


Given that one cannot simply assume locality or determinism for the 
multi-particle system, one is led back to the Bell and CHSH 
inequalities. These apply to the two particle case, and the experimental 
confirmation of the violation of these inequalities for entangled 
particles leads to the conclusion that quantum mechanics is 
intrinsically non-local. Since Everettian QM is claimed to reproduce all 
the standard quantum results, it must also violate these inequalities. 
So either Everettian QM is as non-local as standard QM, or the Bell and 
CHSH theorems do not apply to the no-collapse theory.


This latter has been claimed, and people have sought for assumptions 
that these theorems make that are not true in MWI. For example, Price 
claims: "Bell and Eberhard had implicity assumed that every possible 
measurement - even if not performed - would have yielded a /single/ 
definite result. This assumption is called contra-factual definiteness 
or CFD [S]. What Bell and Eberhard really proved was that every quantum 
theory must either violate locality /or/ CFD." The trouble here is that 
CFD is either trivially violated in ordinary quantum mechanics, or it is 
without content. CFD, if it is to mean anything at all, would be the 
claim that an unperformed experiment would produce a definite result 
*that could be predicted in advance*. That is, of course false in any 
version of quantum mechanics. An unperformed experiment would 
necessarily produce a result, not necessarily predictable, in a collapse 
model;  and all possible results in a many worlds model. But in neither 
case is there any lack of a result.


So the notion of CFD remains murky, and its relevance to the Bell and 
CHSH derivations is even less clear -- in exactly which line of the 
proofs is that assumption made? and what happens if that assumption is 
not made? I think the claim of counterfactual indefiniteness, if it 
means anything, reduces to the claim that Bell assumes a collapse model.


This is the other argument that is raised against the Bell and CHSH 
proofs -- they assume that experiments have single outcomes. In other 
words, they assume a collapse model. But this is not true either, or, if 
it is true, it is not fatal to the applicability of these theorems to 
MWI. I will post a full derivation of the CHSH inequality shortly, and I 
claim that this does not make any assumption about single results. In 
fact, the whole proof is cast in terms of expectation values over 
results, so this works for both single and multiple outcomes for any 
particular experiment. The proof is not invalidated by moving to a many 
worlds scenario because, for any particular set of outcomes from the 
measurements on each of the entangled particles, there is only a finite 
number of possible joint worlds that can be produced. Each of these 

Re: Non-locality and MWI

[smitra]

On 11-05-2016 00:39, Bruce Kellett wrote:

On 11/05/2016 1:54 am, smitra wrote:

On 10-05-2016 06:04, Bruce Kellett wrote:


Non-locality was not the issue with this example of the cat in the
box. All I was seeking to establish was that the observer maybe on
definite branches of the wave function (i.e., have been "split")
without knowing about it. The wave function here is taken to be an
objective description of the system, and the observer is part of the
wave function. So the observer might well be on both the cat-dead and
cat-alive branches, but be unaware of which. The cat is definitely
dead on the cat-dead branch and alive on the cat-alive branch. So 
this

is an objective fact of the evolved wave function, even thought the
observer has no yet self-located. Opening the box then conveys
information to the observer, but does not kill the cat, or cause the
split in the wave function, or the observer. The duplicated persons
may objectively be, one in Washington and one in Moscow, without 
being
aware of which city (branch of the wave function) they are in. 
Opening

the door and finding out conveys information, but does not transport
the person to that city.


Yes, but even in the case of the observer getting localized without he 
or she consciously being aware of that, this localization effect will 
still be due to local interaction with the branches in the region 
he/she is in. So whether or not localization in a branch requires 
conscious awareness of the differences between the two branches isn't 
relevant.


This means that when Alice is on her way to meet with Bob, she won't 
be localized inside Bob's branches corresponding to Bob having 
obtained definite results with definite polarizer settings, at least 
until that time she gets located inside the light cone emanating from 
the points at Bob's location at the times when the relevant 
information about these facts were created.


So what? The information is already present in the wave function--
nothing new is created when the light cones overlap.



The localization of Alice inside Bob's branches and vice versa can only 
start at that point. Decoherence happens fast but this entanglement 
involving more and more of he environmental degrees of freedom can only 
spread at the speed of light.


This means that the MWI does not have the same issue w.r.t. non-locality 
as collapse interpretations have where only one branch is real.


Saibal

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Re: Non-locality and MWI

[Bruce Kellett]

On 11/05/2016 1:54 am, smitra wrote:

On 10-05-2016 06:04, Bruce Kellett wrote:


Non-locality was not the issue with this example of the cat in the
box. All I was seeking to establish was that the observer maybe on
definite branches of the wave function (i.e., have been "split")
without knowing about it. The wave function here is taken to be an
objective description of the system, and the observer is part of the
wave function. So the observer might well be on both the cat-dead and
cat-alive branches, but be unaware of which. The cat is definitely
dead on the cat-dead branch and alive on the cat-alive branch. So this
is an objective fact of the evolved wave function, even thought the
observer has no yet self-located. Opening the box then conveys
information to the observer, but does not kill the cat, or cause the
split in the wave function, or the observer. The duplicated persons
may objectively be, one in Washington and one in Moscow, without being
aware of which city (branch of the wave function) they are in. Opening
the door and finding out conveys information, but does not transport
the person to that city.


Yes, but even in the case of the observer getting localized without he 
or she consciously being aware of that, this localization effect will 
still be due to local interaction with the branches in the region 
he/she is in. So whether or not localization in a branch requires 
conscious awareness of the differences between the two branches isn't 
relevant.


This means that when Alice is on her way to meet with Bob, she won't 
be localized inside Bob's branches corresponding to Bob having 
obtained definite results with definite polarizer settings, at least 
until that time she gets located inside the light cone emanating from 
the points at Bob's location at the times when the relevant 
information about these facts were created.


So what? The information is already present in the wave function-- 
nothing new is created when the light cones overlap.


Bruce

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R: Re: R: Re: R: Re: R: Re: Non-locality and MWI (literature)

['scerir' via Everything List]

.
I think we all agree that QM-with-collapse entails a violation of Locality. The 
debate was for the case of the non-single value QM, that is 
QM-without-collapse, where all branches of the wave are kept "alive".
Bruno

As somebody wrote "Algebraic nonseparability entails geometric nonlocality; 
emphasis on its time aspect can be worded atemporality." (Olivier Costa de 
Beauregard).
And yes, in QM without collapse (without reduction of probability packet), all 
branches are kept alive (with some probability or weight attached to each 
world; with a conservation of energy not well defined in each world or, better, 
during each split; and with a strange concept of locality - because there are 
"many" decohering "worlds").
s.






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Re: R: Re: R: Re: R: Re: Non-locality and MWI (literature)

[Bruno Marchal]

On 10 May 2016, at 19:06, 'scerir' via Everything List wrote:




Messaggio originale
Da: Bruno Marchal 
Data: 10/05/2016 18.31
A: 
Ogg: Re: R: Re: R: Re: Non-locality and MWI (literature)


On 10 May 2016, at 15:37, 'scerir' via Everything List wrote:



Thanks Scerir, but yet again, this paper get the same conclusion as  
mine (and most people here). With the MWI, non-locality does not  
imply action-at-a distance. (d'Espagnat would call it non- 
separability).


What I look for would be a paper which would show that in the MWI  
there are action-at-a-distance, like Bruce and John C claim.


I might comment later, as I am late in my scheduling, but will just  
notice that Gisin's paper (mentionned by Brent) use the non- 
compatibilist theory of free-will, which makes no-sense to a  
mechanist. I think Brent concluded similarly.


Bruno




If A and B are two wings of a typical Bell apparatus, i the  
observable to be measured in A
and x its possible value, j is the observable to be measured in B  
and y its possible value,

and if Lambda are hidden variables, we could write


Locality Condition
p_A,Lambda (x|i,j) = p_A,Lambda (x|i)
p_B,Lambda (y|i,j) = p_B,Lambda (y|j)

Separability Condition
p_A,Lambda (x|i,j,y) = p_A,Lambda (x|i,j)
p_B,Lambda (y|i,j,x) = P_B,Lambda (y|i,j)

There is (was) some agreement that a (phantomatic) deterministic  
theory (i.e. one in which
the range of any probability distribution of outcomes is the set: 0  
or 1)



?

The question is: are the probabilities, or the indeterminacies, and  
the non locality,   phenomenological (1p)  or factual (ontological,  
real, 3p)?


QM+collapse admit factual indeterminacies  (God plays dice, and  
there are action at a distance, even if they cannot be used to  
transmit signal quicker than light).


QM-without-collapse is purely deterministic at the 3p level, and  
admits indeterminacies at the phenomenological level.


I think everyone agree on this.

The debate is on the following question: does QM-without-collapse  
admit factual non-locality (real physical action at a distance, like  
QM-with-collapse), or do the non-locality becomes, like the  
indeterminacy, phenomenological?
(I think yes, as Jesse, Saibal and others, but it seems Bruce and  
John C. differ on this).


 Frankly it is not easy for me to say anything about that, at  
least something consistent. Mainly because "Many-worlds with its  
multiplicity of results in different worlds violates CFD, of course,  
and thus can be local. Thus many-worlds is the only local quantum  
theory in accord with the standard predictions of QM and, so far,  
with experiment.".





reproducing all the predictions of QM, can not violate the
Separability Condition, (the specification of Lambda, i, j, in  
principle determines

completely the outcomes x, y, then any additional conditioning on
x or y is superfluous, having x and y just one value allowed, so they
cannot affect the probability, which - in a deterministic theory -  
can

just take the values 0 or 1) and must violate the Locality
Condition.

Following the above reasoning MWI (if it is a truly deterministic  
theory)

should violate the locality condition.


I doubt this, but if you find a proof, in the literature (or not), I  
am interested. As I explained, and also give references, it seems to  
me that the MWI restores both 3p determinacy and 3p locality, making  
both the indeterminacy and non-locality only first person plural  
phenomenological happening. That is also Everett's position, and I  
would say the position of most Everettian (I still don't find any  
Everettian claiming that the MWI remains non-local, except the  
beginners who often think at first that the entire universe split  
instantaneously, but this does not deserve to be commented as nobody  
believes in this anymore).


Bruno

 Jarrett, but also Shimony, and also Ghirardi, gave the proof  
that a *deterministic* QM (I should say a *deterministic and single- 
valued* QM)


Yes, that is important to add. It was notoriously implicit in EPR and  
Bell 1964, even after.




must violate the Locality Condition.


EPR and Bell shows this, and the usual papers (Clauser and Horne,  
Clauser Horne Shimony, Holt, Aspect, ...).




I do not have references at hand, right now. I'll write down  
something as soon as possible.


I think we all agree that QM-with-collapse entails a violation of  
Locality. The debate was for the case of the non-single value QM, that  
is QM-without-collapse, where all branches of the wave are kept "alive".


Bruno










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Re: R: Re: R: Re: Non-locality and MWI (literature)

[Bruno Marchal]

On 10 May 2016, at 18:36, 'scerir' via Everything List wrote:



scerir wrote:

If A and B are two wings of a typical Bell apparatus, i the  
observable to be measured in A
and x its possible value, j is the observable to be measured in B  
and y its possible value,

and if Lambda are hidden variables, we could write

Locality Condition
p_A,Lambda (x|i,j) = p_A,Lambda (x|i)
p_B,Lambda (y|i,j) = p_B,Lambda (y|j)

Separability Condition
p_A,Lambda (x|i,j,y) = p_A,Lambda (x|i,j)
p_B,Lambda (y|i,j,x) = p_B,Lambda (y|i,j)

There is (or was) some agreement that a (phantomatic) deterministic  
theory (i.e. one in which
the range of any probability distribution of outcomes is the set: 0  
or 1)

reproducing all the predictions of QM, can not violate the
Separability Condition, (the specification of Lambda, i, j, in  
principle determines

completely the outcomes x, y, then any additional conditioning on
x or y is superfluous, having x and y just one value allowed, so they
cannot affect the probability, which - in a deterministic theory - can
just take the values 0 or 1) and must violate the Locality
Condition.

Following the above reasoning, MWI (if it is a truly deterministic  
theory)

should violate the Locality Condition.

 ---

### Since the Everett faq gives the following .

"To recap. Many-worlds is local and deterministic. Local  
measurements split local systems (including observers) in a  
subjectively random fashion; distant systems are only split when the  
causally transmitted effects of the local interactions reach them.  
We have not assumed any non-local FTL effects, yet we have  
reproduced the standard predictions of QM. So where did Bell and  
Eberhard go wrong? They thought that all theories that reproduced  
the standard predictions must be non-local. It has been pointed out  
by both Albert [A] and Cramer [C] (who both support different  
interpretations of QM) that Bell and Eberhard had implicity assumed  
that every possible measurement - even if not performed - would have  
yielded a single definite result. This assumption is called contra- 
factual definiteness or CFD [S]. What Bell and Eberhard really  
proved was that every quantum theory must either violate locality or  
CFD. Many-worlds with its multiplicity of results in different  
worlds violates CFD, of course, and thus can be local."


So, I should say that . MWI (if it is a truly deterministic  
theory, reproducing all the
predictions of QM) should violate the Locality Condition but, in  
fact, it violates CFD only :-).


Exactly.  I think we are on the same length wave (as we say in french  
for assessment). And that is why QM-without collapse needs only the  
computationalist First Person Indeterminacy (FPI), making QM facts  
confirming mechanism instead of threatening it (which is what would  
happen if we allow collapse, or worst, direct action of consciousness  
on the physical).


Like with Gödels theorem, QM seems to threat mechanism, but eventually  
appears to be an ally, and perhaps a confirmation, (which of course is  
not a proof, but we can't prove anything on reality, nor even that it  
exists. We can only bet on it.).


Bruno














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R: Re: R: Re: R: Re: Non-locality and MWI (literature)

['scerir' via Everything List]

Messaggio originale

Da: Bruno Marchal 

Data: 10/05/2016 18.31

A: 

Ogg: Re: R: Re: R: Re: Non-locality and MWI (literature)




On 10 May 2016, at 15:37, 'scerir' via Everything List wrote:
Thanks Scerir, but yet again, this paper get the same conclusion as mine (and 
most people here). With the MWI, non-locality does not imply action-at-a 
distance. (d'Espagnat would call it non-separability).
What I look for would be a paper which would show that in the MWI there are 
action-at-a-distance, like Bruce and John C claim.
I might comment later, as I am late in my scheduling, but will just notice that 
Gisin's paper (mentionned by Brent) use the non-compatibilist theory of 
free-will, which makes no-sense to a mechanist. I think Brent concluded 
similarly.
Bruno



If A and B are two wings of a typical Bell apparatus, i the observable to be 
measured in A
and x its possible value, j is the observable to be measured in B and y its 
possible value,
and if Lambda are hidden variables, we could write

Locality Condition 
p_A,Lambda (x|i,j) = p_A,Lambda (x|i)
p_B,Lambda (y|i,j) = p_B,Lambda (y|j)
Separability Condition 
p_A,Lambda (x|i,j,y) = p_A,Lambda (x|i,j)
p_B,Lambda (y|i,j,x) = P_B,Lambda (y|i,j)
There is (was) some agreement that a (phantomatic) deterministic theory (i.e. 
one in which the range of any probability distribution of outcomes is the set: 
0 or 1)


?
The question is: are the probabilities, or the indeterminacies, and the non 
locality,   phenomenological (1p)  or factual (ontological, real, 3p)?
QM+collapse admit factual indeterminacies  (God plays dice, and there are 
action at a distance, even if they cannot be used to transmit signal quicker 
than light).
QM-without-collapse is purely deterministic at the 3p level, and admits 
indeterminacies at the phenomenological level. 
I think everyone agree on this.
The debate is on the following question: does QM-without-collapse admit factual 
non-locality (real physical action at a distance, like QM-with-collapse), or do 
the non-locality becomes, like the indeterminacy, phenomenological? (I think 
yes, as Jesse, Saibal and others, but it seems Bruce and John C. differ on 
this).
 Frankly it is not easy for me to say anything about that, at least 
something consistent. Mainly because "Many-worlds with its multiplicity of 
results in different worlds violates CFD, of course, and thus can be local. 
Thus many-worlds is the only local quantum theory in accord with the standard 
predictions of QM and, so far, with experiment.". 


reproducing all the predictions of QM, can not violate the
Separability Condition, (the specification of Lambda, i, j, in principle 
determines
completely the outcomes x, y, then any additional conditioning on
x or y is superfluous, having x and y just one value allowed, so they
cannot affect the probability, which - in a deterministic theory - can
just take the values 0 or 1) and must violate the Locality
Condition.
Following the above reasoning MWI (if it is a truly deterministic theory) 
should violate the locality condition.
I doubt this, but if you find a proof, in the literature (or not), I am 
interested. As I explained, and also give references, it seems to me that the 
MWI restores both 3p determinacy and 3p locality, making both the indeterminacy 
and non-locality only first person plural phenomenological happening. That is 
also Everett's position, and I would say the position of most Everettian (I 
still don't find any Everettian claiming that the MWI remains non-local, except 
the beginners who often think at first that the entire universe split 
instantaneously, but this does not deserve to be commented as nobody believes 
in this anymore).
Bruno
 Jarrett, but also Shimony, and also Ghirardi, gave the proof that a 
*deterministic* QM (I should say a *deterministic and single-valued* QM) must 
violate the Locality Condition. I do not have references at hand, right now. 
I'll write down something as soon as possible.



 
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R: Re: R: Re: Non-locality and MWI (literature)

['scerir' via Everything List]

scerir wrote:

If A and B are two wings of a typical Bell apparatus, i the observable to be 
measured in A
and x its possible value, j is the observable to be measured in B and y its 
possible value,
and if Lambda are hidden variables, we could write
Locality Condition 
p_A,Lambda (x|i,j) = p_A,Lambda (x|i)
p_B,Lambda (y|i,j) = p_B,Lambda (y|j)
Separability Condition 
p_A,Lambda (x|i,j,y) = p_A,Lambda (x|i,j)
p_B,Lambda (y|i,j,x) = p_B,Lambda (y|i,j)
There is (or was) some agreement that a (phantomatic) deterministic theory 
(i.e. one in which the range of any probability distribution of outcomes is the 
set: 0 or 1)
reproducing all the predictions of QM, can not violate the
Separability Condition, (the specification of Lambda, i, j, in principle 
determines
completely the outcomes x, y, then any additional conditioning on
x or y is superfluous, having x and y just one value allowed, so they
cannot affect the probability, which - in a deterministic theory - can
just take the values 0 or 1) and must violate the Locality
Condition.
Following the above reasoning, MWI (if it is a truly deterministic theory) 
should violate the Locality Condition.
 ---
### Since the Everett faq gives the following .
"To recap.  Many-worlds is local and deterministic.  Local measurements split 
local systems (including observers) in a subjectively random fashion; distant 
systems are only split when the causally transmitted effects of the local 
interactions reach them.  We have not assumed any non-local FTL effects, yet we 
have reproduced the standard predictions of QM. So where did Bell and Eberhard 
go wrong?  They thought that all theories that reproduced the standard 
predictions must be non-local.  It has been pointed out by both Albert [A] and 
Cramer [C] (who both support different interpretations of QM) that Bell and 
Eberhard had implicity assumed that every possible measurement - even if not 
performed - would have yielded a single definite result.  This assumption is 
called contra-factual definiteness or CFD [S].  What Bell and Eberhard really 
proved was that every quantum theory must either violate locality or CFD.  
Many-worlds with its multiplicity of results in different worlds violates CFD, 
of course, and thus can be local."
So, I should say that . MWI (if it is a truly deterministic theory, 
reproducing all thepredictions of QM) should violate the Locality Condition 
but, in fact, it violates CFD only :-).












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Re: R: Re: R: Re: Non-locality and MWI (literature)

[Bruno Marchal]

On 10 May 2016, at 15:37, 'scerir' via Everything List wrote:



Thanks Scerir, but yet again, this paper get the same conclusion as  
mine (and most people here). With the MWI, non-locality does not  
imply action-at-a distance. (d'Espagnat would call it non- 
separability).


What I look for would be a paper which would show that in the MWI  
there are action-at-a-distance, like Bruce and John C claim.


I might comment later, as I am late in my scheduling, but will just  
notice that Gisin's paper (mentionned by Brent) use the non- 
compatibilist theory of free-will, which makes no-sense to a  
mechanist. I think Brent concluded similarly.


Bruno




If A and B are two wings of a typical Bell apparatus, i the  
observable to be measured in A
and x its possible value, j is the observable to be measured in B  
and y its possible value,

and if Lambda are hidden variables, we could write


Locality Condition
p_A,Lambda (x|i,j) = p_A,Lambda (x|i)
p_B,Lambda (y|i,j) = p_B,Lambda (y|j)

Separability Condition
p_A,Lambda (x|i,j,y) = p_A,Lambda (x|i,j)
p_B,Lambda (y|i,j,x) = P_B,Lambda (y|i,j)

There is (was) some agreement that a (phantomatic) deterministic  
theory (i.e. one in which
the range of any probability distribution of outcomes is the set: 0  
or 1)



?

The question is: are the probabilities, or the indeterminacies, and  
the non locality,   phenomenological (1p)  or factual (ontological,  
real, 3p)?


QM+collapse admit factual indeterminacies  (God plays dice, and there  
are action at a distance, even if they cannot be used to transmit  
signal quicker than light).


QM-without-collapse is purely deterministic at the 3p level, and  
admits indeterminacies at the phenomenological level.


I think everyone agree on this.

The debate is on the following question: does QM-without-collapse  
admit factual non-locality (real physical action at a distance, like  
QM-with-collapse), or do the non-locality becomes, like the  
indeterminacy, phenomenological?
(I think yes, as Jesse, Saibal and others, but it seems Bruce and John  
C. differ on this).





reproducing all the predictions of QM, can not violate the
Separability Condition, (the specification of Lambda, i, j, in  
principle determines

completely the outcomes x, y, then any additional conditioning on
x or y is superfluous, having x and y just one value allowed, so they
cannot affect the probability, which - in a deterministic theory - can
just take the values 0 or 1) and must violate the Locality
Condition.

Following the above reasoning MWI (if it is a truly deterministic  
theory)

should violate the locality condition.


I doubt this, but if you find a proof, in the literature (or not), I  
am interested. As I explained, and also give references, it seems to  
me that the MWI restores both 3p determinacy and 3p locality, making  
both the indeterminacy and non-locality only first person plural  
phenomenological happening. That is also Everett's position, and I  
would say the position of most Everettian (I still don't find any  
Everettian claiming that the MWI remains non-local, except the  
beginners who often think at first that the entire universe split  
instantaneously, but this does not deserve to be commented as nobody  
believes in this anymore).


Bruno







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Re: Non-locality and MWI

[smitra]

On 10-05-2016 06:04, Bruce Kellett wrote:


Non-locality was not the issue with this example of the cat in the
box. All I was seeking to establish was that the observer maybe on
definite branches of the wave function (i.e., have been "split")
without knowing about it. The wave function here is taken to be an
objective description of the system, and the observer is part of the
wave function. So the observer might well be on both the cat-dead and
cat-alive branches, but be unaware of which. The cat is definitely
dead on the cat-dead branch and alive on the cat-alive branch. So this
is an objective fact of the evolved wave function, even thought the
observer has no yet self-located. Opening the box then conveys
information to the observer, but does not kill the cat, or cause the
split in the wave function, or the observer. The duplicated persons
may objectively be, one in Washington and one in Moscow, without being
aware of which city (branch of the wave function) they are in. Opening
the door and finding out conveys information, but does not transport
the person to that city.


Yes, but even in the case of the observer getting localized without he 
or she consciously being aware of that, this localization effect will 
still be due to local interaction with the branches in the region he/she 
is in. So whether or not localization in a branch requires conscious 
awareness of the differences between the two branches isn't relevant.


This means that when Alice is on her way to meet with Bob, she won't be 
localized inside Bob's branches corresponding to Bob having obtained 
definite results with definite polarizer settings, at least until that 
time she gets located inside the light cone emanating from the points at 
Bob's location at the times when the relevant information about these 
facts were created.


Saibal

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R: Re: R: Re: Non-locality and MWI (literature)

['scerir' via Everything List]

Thanks Scerir, but yet again, this paper get the same conclusion as mine (and 
most people here). With the MWI, non-locality does not imply action-at-a 
distance. (d'Espagnat would call it non-separability).
What I look for would be a paper which would show that in the MWI there are 
action-at-a-distance, like Bruce and John C claim.
I might comment later, as I am late in my scheduling, but will just notice that 
Gisin's paper (mentionned by Brent) use the non-compatibilist theory of 
free-will, which makes no-sense to a mechanist. I think Brent concluded 
similarly.
Bruno



If A and B are two wings of a typical Bell apparatus, i the observable to be 
measured in A
and x its possible value, j is the observable to be measured in B and y its 
possible value,
and if Lambda are hidden variables, we could write

Locality Condition 
p_A,Lambda (x|i,j) = p_A,Lambda (x|i)
p_B,Lambda (y|i,j) = p_B,Lambda (y|j)
Separability Condition 
p_A,Lambda (x|i,j,y) = p_A,Lambda (x|i,j)
p_B,Lambda (y|i,j,x) = P_B,Lambda (y|i,j)
There is (was) some agreement that a (phantomatic) deterministic theory (i.e. 
one in which the range of any probability distribution of outcomes is the set: 
0 or 1)
reproducing all the predictions of QM, can not violate the
Separability Condition, (the specification of Lambda, i, j, in principle 
determines
completely the outcomes x, y, then any additional conditioning on
x or y is superfluous, having x and y just one value allowed, so they
cannot affect the probability, which - in a deterministic theory - can
just take the values 0 or 1) and must violate the Locality
Condition.
Following the above reasoning MWI (if it is a truly deterministic theory) 
should violate the locality condition.
 

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Re: R: Re: Non-locality and MWI (literature)

[Bruce Kellett]

On 10/05/2016 10:31 pm, Bruno Marchal wrote:

On 10 May 2016, at 09:00, 'scerir' via Everything List wrote:



Bruno (I suppose) wrote:

But in the MWI, some work needs to be done (at least) to
convince me. I don't even find a paper on the subject, only
paper which shows that MWI is local (some more rigorous than
other). Do you have a reference of a paper showing that Bell's
inequality violation entails non locality in the MWI? I would
like to take a look on it, if it exists.

### W. Myrvold wrote something here
http://philsci-archive.pitt.edu/11654/ (see ch. 0.8)




Thanks Scerir, but yet again, this paper get the same conclusion as 
mine (and most people here). With the MWI, non-locality does not imply 
action-at-a distance. (d'Espagnat would call it non-separability).


There seems to be a degree of terminological confusion surrounding this 
topic. Non-locality, for me, means that the measurement at A influences 
the measurement at B. But this influence is not manipulable, so it 
cannot be used for signalling. In other words, quantum mechanics obeys 
the standard no-signalling theorems (and is thus consistent with special 
relativity), while being non-local in the sense that the measurements at 
A and B are not independent. Call this non-separability if you will -- 
the terminology should not make any difference, provided we are clear as 
to what the terms mean.


Bruce


What I look for would be a paper which would show that in the MWI 
there are action-at-a-distance, like Bruce and John C claim.


I might comment later, as I am late in my scheduling, but will just 
notice that Gisin's paper (mentionned by Brent) use the 
non-compatibilist theory of free-will, which makes no-sense to a 
mechanist. I think Brent concluded similarly.


Bruno


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Re: R: Re: Non-locality and MWI (literature)

[Bruno Marchal]

On 10 May 2016, at 09:00, 'scerir' via Everything List wrote:



Bruno (I suppose) wrote:
But in the MWI, some work needs to be done (at least) to convince  
me. I don't even find a paper on the subject, only paper which  
shows that MWI is local (some more rigorous than other). Do you  
have a reference of a paper showing that Bell's inequality  
violation entails non locality in the MWI? I would like to take a  
look on it, if it exists.


### W. Myrvold wrote something here http://philsci-archive.pitt.edu/11654/ 
 (see ch. 0.8)






Thanks Scerir, but yet again, this paper get the same conclusion as  
mine (and most people here). With the MWI, non-locality does not imply  
action-at-a distance. (d'Espagnat would call it non-separability).


What I look for would be a paper which would show that in the MWI  
there are action-at-a-distance, like Bruce and John C claim.


I might comment later, as I am late in my scheduling, but will just  
notice that Gisin's paper (mentionned by Brent) use the non- 
compatibilist theory of free-will, which makes no-sense to a  
mechanist. I think Brent concluded similarly.


Bruno







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http://iridia.ulb.ac.be/~marchal/



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R: Re: R: Re: Non-locality and MWI (literature)

['scerir' via Everything List]

### W. Myrvold wrote something here 
http://philsci-archive.pitt.edu/11654/ (see
  ch. 0.8)
  

  





It seems that he is saying that 'action-at-a-distance' is something
that would violate the 'no-signalling theorem' of quantum mechanics.
So he sees experimental violation of the Bell inequalities as
evidence for non-locality, but not necessarily evidence for
action-at-a-distance in the above sense. I would agree with his
conclusion that both collapse and Everettian theories are like this
-- non-local, but also non-signalling at spacelike separations.



Bruce

  






### Yes, It seems so. There is - in general - some confusion between 
'nonlocality' and 'nonseparability'. Not to mention also 'action-at-a-distance' 
and 'locality of measurement' and "local causality" and so on. Myrvold et al. 
wrote something else here 
http://philsci-archive.pitt.edu/4222/1/everett_and_evidence_21aug08.pdf 
(general objections to Everettism).
"Now it is precisely in cleaning up intuitive ideas for mathematics that one is 
likely to throw out the baby with the bathwater."
J.S. Bell (quoted here https://arxiv.org/pdf/1007.3724.pdf )














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Re: R: Re: Non-locality and MWI (literature)

[Bruce Kellett]

On 10/05/2016 5:00 pm, 'scerir' via Everything List wrote:

Bruno (I suppose) wrote:


But in the MWI, some work needs to be done (at least) to convince
me. I don't even find a paper on the subject, only paper which
shows that MWI is local (some more rigorous than other). Do you
have a reference of a paper showing that Bell's inequality
violation entails non locality in the MWI? I would like to take a
look on it, if it exists.

### W. Myrvold wrote something here
http://philsci-archive.pitt.edu/11654/ (see ch. 0.8)





It seems that he is saying that 'action-at-a-distance' is something that 
would violate the 'no-signalling theorem' of quantum mechanics. So he 
sees experimental violation of the Bell inequalities as evidence for 
non-locality, but not necessarily evidence for action-at-a-distance in 
the above sense. I would agree with his conclusion that both collapse 
and Everettian theories are like this -- non-local, but also 
non-signalling at spacelike separations.


Bruce

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R: Re: Non-locality and MWI (literature)

['scerir' via Everything List]

Bruno (I suppose) wrote:

But in the MWI, some work needs to be done (at least) to
  convince me. I don't even find a paper on the subject, only
  paper which shows that MWI is local (some more rigorous than
  other). Do you have a reference of a paper showing that Bell's
  inequality violation entails non locality in the MWI? I would
  like to take a look on it, if it exists.
### W. Myrvold wrote something here http://philsci-archive.pitt.edu/11654/ (see 
ch. 0.8)
  





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