Re: Many-minds interpretation?

[Bruce Kellett]

From: *Bruno Marchal* mailto:marc...@ulb.ac.be>>
On 13 Aug 2018, at 00:55, Bruce Kellett > wrote:


Baylock made valiant attempts to introduce some measurements that 
were not made in order to show that Bell assumed counterfactual 
definiteness, but his attempts to reconstruct Bell's arguments in 
this way were so contrived as to be laughable -- Bell's result does 
not depend on the assumption of counterfactual definiteness.


You have not et convince me.


Why does Baylock introduce unnecessary references to experiments that 
were not performed?


To have, or not, a notion of counterfactual definiteness.


If you can think of any reason other than a silly attempt to deflect 
Bell's theorem, then tell me.



Would you have a link to Baylock? Maybe you gave one in your paper?


I gave comprehensive references in the notes I posted to the list.


In this discussion we should perhaps  distinguish:

1) FTL-with-tranfer-of-information (we all agree, I think, that this 
does not exist, even with QM+collapse)


Yes, the no-signalling theorems rule this out.

2) FTL-without-tranfer-of-information. (This has to exist with 
QM+collapse+the wave-is-physically-real)


I have no reason to suppose that the wave function is physically real.

3) No FTL-at-all (this is realised, I think, by any sensible 
interpretation of QM-without collapse).


Interaction with the entangled state instantaneously destroys the 
symmetry. No need for physical FTL.


Do you have the book by Susskind & Friedman “Quantum Mechanics, the 
theoretical minimum”. A lovely book.
Last year I gave as exercise for some of my students to criticise its 
sections 7.9/10/11 “Entanglement and Locality, ...”. Susskind and 
Friedamn shows correctly that if you want to simulate Bell’s 
inequality violation with two computers (one for Alice and one for 
Bob), That requires necessarily an “instantaneous cable” between the 
two computers.


I do not have this book. But this argument was also given in the paper 
by Brunner et al. (also referenced in my paper).


The proof is correct, only by assuming (as they do implicitly in the 
whole book) a unique universe. What they show (implicitly) is that if 
wa want simulate QM with a computer, the only way to get the violation 
of Bell’s inequality requires to simulate the observers too, and apply 
QM to them too. But they do not even mention tat possibility,


For this to work you would have to simulate a non-local connection as well.

and indeed Everett is not mentioned in the index, and the MW is to 
even suggested nowhere in the book (which is still a very good 
 introduction to QM, a good companion to Albert’s book, for the 
beginners).


I have other reasons for not liking Susskind's approach to things. But I 
have heard that this book is a good introduction to QM.


Bruce

--
You received this message because you are subscribed to the Google Groups 
"Everything List" group.
To unsubscribe from this group and stop receiving emails from it, send an email 
to everything-list+unsubscr...@googlegroups.com.
To post to this group, send email to everything-list@googlegroups.com.
Visit this group at https://groups.google.com/group/everything-list.
For more options, visit https://groups.google.com/d/optout.

Re: Many-minds interpretation?

[Brent Meeker]

On 8/13/2018 6:31 PM, Jason Resch wrote:



On Mon, Aug 13, 2018 at 4:32 PM Brent Meeker > wrote:




On 8/13/2018 7:27 AM, Jason Resch wrote:
> I bring this question up because you repeatedly refer to only "one
> Alice" before the measurement, and also say that Alice and Bob
are "in
> one and the same branch" prior to measurement.  But normal QM
without
> collapse would say Alice and Bob are branching all the time, even
> before they measure their entangled pair.  So isn't it necessary to
> take this into consideration (that this is implicitly the original
> scenario):

There are many branchings of the wf describing Alice, almost all
of them
are irrelevant to who Alice is.  They are below the quasi-classical
level at which "Alice" exists; below the level at which her brain
decides at what angle to measure the particle.  All those Alices
are one
person.  So they are treated as one classical being.  That they split
into two (up or down) classically distinct beings, is unrelated to
the
fact there are many microscopically different Alices.


I agree.

I believe this is exactly why Bruno raised the issue of whether Bruce 
was operating under the "Mind-brain identity" theory of mind, vs. the 
"computational/mechanist" theory of mind.


The former would attribute 1 mind per each physical incarnation, while 
the latter would say there is a 1-to-many relationship between a mind 
and its physical instantiations.


Bruce thinks it is irrelevant, but I think your point above shows one 
needs to make explicit the theory of mind one is operating within.



It is not clear to me how Bruno thinks of these many quasi-classical,
Alices.  He seems to just dismiss their differences as below
replacement
level the Doctor promises.  That seems like assuming that they are
really classical entities, just similar computational threads in
the UD.


Computation is a classical notion.  I believe Bruno would say there is 
a 1-to-many relationship between a mind and its implementations, so 
long as those implementations differ functionally only below the level 
of detail necessary to describe the computation associated with that 
mind (i.e. they differ only below that "substitution level").


This actually seems incoherent though.  The very idea of a substitution 
level is part of our theory of physics and how computations are 
implemented.  If computations are in Platonia and physics is just an 
inference from computational consciousness there isn't really any lower 
level.  Physics and the world and personal identity are all illusions 
instantiated in all possible computations.


As I understand Bruno's UD theory, there are many threads being 
implemented that correspond, over some number of computational states, 
to the same thoughts and hence represent only one person during that 
interval.


Brent



Jason
--
You received this message because you are subscribed to the Google 
Groups "Everything List" group.
To unsubscribe from this group and stop receiving emails from it, send 
an email to everything-list+unsubscr...@googlegroups.com 
.
To post to this group, send email to everything-list@googlegroups.com 
.

Visit this group at https://groups.google.com/group/everything-list.
For more options, visit https://groups.google.com/d/optout.


--
You received this message because you are subscribed to the Google Groups 
"Everything List" group.
To unsubscribe from this group and stop receiving emails from it, send an email 
to everything-list+unsubscr...@googlegroups.com.
To post to this group, send email to everything-list@googlegroups.com.
Visit this group at https://groups.google.com/group/everything-list.
For more options, visit https://groups.google.com/d/optout.

Re: Many-minds interpretation?

[Bruce Kellett]

From: *Bruno Marchal* mailto:marc...@ulb.ac.be>>
On 13 Aug 2018, at 00:48, Bruce Kellett > wrote:


but the FTL are needed only if we associate the mind on Bob and 
Alice to the same branche, which has no meaning for me once they are 
space separated.


You might not accept that they can be in the same branch, but that 
does not mean that it is not a proven fact.


If they are space separated, I am not sure I can make sense of being 
in the same branch.


You appear to be referring to the presence of quantum fluctuations 
continually splitting the classical Alice and Bob into multiple copies 
-- the point that Jason has made. I think I have answered this in my 
reply to Jason. Different disjoint classical worlds arise only if the 
quantum events are amplified to classical significance by decoherence 
forming thermodynamically irreversible records of the event in the 
environment. This does not happen for the majority of quantum 
fluctuations that underlie our classical states. Alice and Bob both have 
(quasi-)classical identities that are unaffected by such fluctuations. 
Just as the temperature of the air is not affected by random molecular 
motions. As in statistical mechanics, these fluctuations are averaged 
over and essentially all cancel out. They can be safely ignored (FAPP if 
you must, but we are talking practicalities here, not undetectable 
quantum events.)




Determinism has nothing to do with it. Aspect and Bell rule out 
deterministic local theories, so non-locality is the only 
possibility. Many-worlds does not change that.


Determinism is the issue. In a collapse theory, you need indeterminism 
to assure the non signalling FTL of information. But you have still 
some physical FTL/simultaneous  action.


No, you just need randomness. That is necessary in MWI as well. Physical 
FTL is not necessary.


With the MW, the situation is entirely deterministic and there is no 
need of any FTL.


MWI may be deterministic. But then, the loss of symmetry when Alice 
measures the singlet state is also entirely deterministic -- it is part 
of what unitary evolution according to the Schrödinger equation gives 
you. It is not different with many-worlds.



Both Bell's theorem and Aspect's results are true in many-worlds as 
in any other interpretation of QM.


Of course.

Don't you understand that that is why most commentators from the 
many-worlds perspective try to show that Bell's theorem does not 
apply to many worlds?


They are wrong. Bell’s violation is necessary in all branches. But 
what happens is that if one branch is selected, by collapse or by 
hidden variables, then *that* transform the non-locality (Bell’s 
violation) into FTL.


That is not true. What happens in a typical branch of a superposition is 
true for all branches. And what is true for all branches is necessarily 
true for the whole. The "one branch" is not selected by collapse or 
hidden variables, it is selected as typical for the purposes of 
calculation -- 'in the mind' as it were.


Without collapse, we don’t need hidden variables, nor any FTL, to 
explain the non-locality and why it never disappears.


Many-worlds is non local because it is non-local in every branch. Can't 
you see the logic of this?


Bruce

--
You received this message because you are subscribed to the Google Groups 
"Everything List" group.
To unsubscribe from this group and stop receiving emails from it, send an email 
to everything-list+unsubscr...@googlegroups.com.
To post to this group, send email to everything-list@googlegroups.com.
Visit this group at https://groups.google.com/group/everything-list.
For more options, visit https://groups.google.com/d/optout.

Re: Many-minds interpretation?

[Bruce Kellett]

From: *Bruno Marchal* mailto:marc...@ulb.ac.be>>
On 12 Aug 2018, at 14:59, Bruce Kellett > wrote:
No, Price is wrong. He collapses the wave function in a non-local 
manner, even though he doesn't seem to realize it. Let me try again. 
The state is


    |psi>= (|u>|d> - |d>|u>).

Let Alice interact with particle 1 at one end:

    |Alice>|psi> = |Alice>|u>|d> - |Alice>|d>|u>

Alice interacts only with particle 1 (locally), so |Alice>|u>|d> --> 
|Alice sees u>|u>|d>, and similarly for the other component.
Now Bob interacts with a different state. He does not see |psi> as 
above, but rather


    |Alice sees u>|u>|d>|Bob>  - |Alice sees d>|d>}u>|Bob>

The, if Bob measures along the same axis, he gets down for Alice's 
up, or up for Alice's down. If he measures at some different angle, 
he gets the appropriate rotated results. But Bob NEVER sees the 
original unaltered rotationally symmetric singlet state:


I have never disagreed with this. But Bob’s view is only a part of the 
picture. Any particular Bob cannot see the symmetry; because it is 
part of the symmetry.


But it is Bob's view here that is relevant to the formation of the 
correlations. Bob measures that state he sees, not some phantom 
symmetric state. Alice's measurement destroys the symmetry of the 
singlet state -- it is not preserved magically in any many-worlds 
picture. There is no 'outside view' in MWI as there is in your classical 
M/W duplication thought experiments. There is no view where the symmetry 
is preserved. Not even Tegmark's imaginary bird view preserves the 
symmetry. You are mistaken here.


Alice's measurement (assuming Alice measures first in some frame) 
collapses the state non-locally to affect the state that Bob sees.


That makes no sense to me.


Then you don't understand quantum mechanics.

Since the original state is non-separable, the fact that Alice has 
interacted with it changes the whole state.


No measurement makes any change in any state, except local memories. 
Even Bohr acknowledge this in his reply to EPR (but then get irrational).


Bohr did not really understand what Einstein was on about. He thought it 
was determinism, whereas Einstein was always concerned about locality: 
"No spooky action at a distance". But never mind Bohr or Einstein, the 
measurement changes the state by destroying the original symmetry. The 
singlet state is different from the conventional collapse picture used 
to explain the formation of spots on the screen in the double slit 
experiment. Everett removed the collapse in the double slit case, but he 
did not remove it for the entangled state. Tell me, where in your 
many-worlds picture is the measured singlet state still symmetrical?




This is the calculation as Price and Tipler give it, and this 
calculation is clearly non-local.


It is non local, but does not involve any physical FTL or 
instantaneous action at a distance. There would be some FTL in case 
the collapse are real.



You are still obsessing about FTL. The collapse is instantaneous, but 
there is no physical FTL. Maudlin finally got to understand this in his 
2011 book. He adopts the relativistically covariant "flash GRW" idea for 
the non-local collapse.


Going to the GHZ state will not change anything. What you have to do 
is show how to re-interpret this calculation so that Bob sees the 
original singlet AFTER Alice has measured her particle. I insist that 
the original non-separability of the state makes any such 
demonstration impossible.


I agree with this.

And even if it were possible, it would not reproduce the known 
quantum correlations; the non-separability and the above non-local 
reduction of the state is an essential part of quantum mechanics.


Nor with this.


Maybe you mean to say that you do *not* agree with the above?

Bruce

--
You received this message because you are subscribed to the Google Groups 
"Everything List" group.
To unsubscribe from this group and stop receiving emails from it, send an email 
to everything-list+unsubscr...@googlegroups.com.
To post to this group, send email to everything-list@googlegroups.com.
Visit this group at https://groups.google.com/group/everything-list.
For more options, visit https://groups.google.com/d/optout.

Re: Many-minds interpretation?

[Stathis Papaioannou]

On Tue, 14 Aug 2018 at 06:58,  wrote:

>
>
> On Monday, August 13, 2018 at 2:27:55 PM UTC, Jason wrote:
>>
>>
>>
>> On Mon, Aug 13, 2018 at 12:05 AM Bruce Kellett 
>> wrote:
>>
>>> From: Jason Resch 
>>>
>>>
>>> On Sun, Aug 12, 2018 at 5:06 AM Bruno Marchal  wrote:
>>>

 On 11 Aug 2018, at 02:29, Bruce Kellett 
 wrote:

 They do not "belong to different branches" because they do not exist,
 and have never existed. This notion seems to be important to your idea, and
 I can assure you that you are wrong about this.


 How could that be possible? You suppress the infinities of Alice and
 Bob only because you know in advance what is the direction in which Alice
 will make her measurement. What if she changes her mind?


>>> Right.
>>>
>>> I would like Bruce to consider the case Alice measures alternately x and
>>> z spin axes of an electron 1000 times and interprets those measurement
>>> results as binary digits following a decimal point to define the real
>>> number to which she will set her measurement angle to (before she measures
>>> her entangled particle).
>>>
>>> Certainly in the no-collapse case there would be at least 2^1000 Alices
>>> who perform the measurement at each of the possible measurement angles that
>>> can be defined by 1000 binary digits.  What I wonder is how many Alices
>>> Bruce would believe to exist in this scenario before she measures her
>>> entangled particle.
>>>
>>>
>>> How do 2^1000 copies of Alice make any difference? Each measures the
>>> entangled particles only once. Besides, This is not what is done. I see
>>> little point in making up alternative scenarios -- why not explain the
>>> straightforward original scenario? Imaginary copies are beside the point.
>>>
>>> If you cannot focus your attention on the original scenario, I see
>>> little point in your trying to do physics.
>>>
>>
>> I bring this question up because you repeatedly refer to only "one Alice"
>> before the measurement, and also say that Alice and Bob are "in one and the
>> same branch" prior to measurement.  But normal QM without collapse would
>> say Alice and Bob are branching all the time, even before they measure
>> their entangled pair.
>>
>
>
> *They're branching all the time prior to measurement, that is without
> collapse? Pretty fantastic. Where, how, is this affirmed by QM? AG*
>

Collapse is not part of the formalism of QM, so "branching all the time" is
what it affirms. That is the whole point of no-collapse interpretations.


-- 
Stathis Papaioannou

-- 
You received this message because you are subscribed to the Google Groups 
"Everything List" group.
To unsubscribe from this group and stop receiving emails from it, send an email 
to everything-list+unsubscr...@googlegroups.com.
To post to this group, send email to everything-list@googlegroups.com.
Visit this group at https://groups.google.com/group/everything-list.
For more options, visit https://groups.google.com/d/optout.

Re: Many-minds interpretation?

[Jason Resch]

On Mon, Aug 13, 2018 at 4:32 PM Brent Meeker  wrote:

>
>
> On 8/13/2018 7:27 AM, Jason Resch wrote:
> > I bring this question up because you repeatedly refer to only "one
> > Alice" before the measurement, and also say that Alice and Bob are "in
> > one and the same branch" prior to measurement.  But normal QM without
> > collapse would say Alice and Bob are branching all the time, even
> > before they measure their entangled pair.  So isn't it necessary to
> > take this into consideration (that this is implicitly the original
> > scenario):
>
> There are many branchings of the wf describing Alice, almost all of them
> are irrelevant to who Alice is.  They are below the quasi-classical
> level at which "Alice" exists; below the level at which her brain
> decides at what angle to measure the particle.  All those Alices are one
> person.  So they are treated as one classical being.  That they split
> into two (up or down) classically distinct beings, is unrelated to the
> fact there are many microscopically different Alices.
>

I agree.

I believe this is exactly why Bruno raised the issue of whether Bruce was
operating under the "Mind-brain identity" theory of mind, vs. the
"computational/mechanist" theory of mind.

The former would attribute 1 mind per each physical incarnation, while the
latter would say there is a 1-to-many relationship between a mind and its
physical instantiations.

Bruce thinks it is irrelevant, but I think your point above shows one needs
to make explicit the theory of mind one is operating within.


>
> It is not clear to me how Bruno thinks of these many quasi-classical,
> Alices.  He seems to just dismiss their differences as below replacement
> level the Doctor promises.  That seems like assuming that they are
> really classical entities, just similar computational threads in the UD.
>
>
Computation is a classical notion.  I believe Bruno would say there is a
1-to-many relationship between a mind and its implementations, so long as
those implementations differ functionally only below the level of detail
necessary to describe the computation associated with that mind (i.e. they
differ only below that "substitution level").

Jason

-- 
You received this message because you are subscribed to the Google Groups 
"Everything List" group.
To unsubscribe from this group and stop receiving emails from it, send an email 
to everything-list+unsubscr...@googlegroups.com.
To post to this group, send email to everything-list@googlegroups.com.
Visit this group at https://groups.google.com/group/everything-list.
For more options, visit https://groups.google.com/d/optout.

Re: Many-minds interpretation?

[Bruce Kellett]

From: *Jason Resch* mailto:jasonre...@gmail.com>>
On Mon, Aug 13, 2018 at 12:05 AM Bruce Kellett 
mailto:bhkell...@optusnet.com.au>> wrote:


From: *Jason Resch* mailto:jasonre...@gmail.com>>


On Sun, Aug 12, 2018 at 5:06 AM Bruno Marchal mailto:marc...@ulb.ac.be>> wrote:



On 11 Aug 2018, at 02:29, Bruce Kellett
mailto:bhkell...@optusnet.com.au>> wrote:

They do not "belong to different branches" because they do
not exist, and have never existed. This notion seems to be
important to your idea, and I can assure you that you are
wrong about this.


How could that be possible? You suppress the infinities of
Alice and Bob only because you know in advance what is the
direction in which Alice will make her measurement. What if
she changes her mind?


Right.

I would like Bruce to consider the case Alice measures
alternately x and z spin axes of an electron 1000 times and
interprets those measurement results as binary digits following a
decimal point to define the real number to which she will set her
measurement angle to (before she measures her entangled particle).

Certainly in the no-collapse case there would be at least 2^1000
Alices who perform the measurement at each of the possible
measurement angles that can be defined by 1000 binary digits. 
What I wonder is how many Alices Bruce would believe to exist in
this scenario before she measures her entangled particle.


How do 2^1000 copies of Alice make any difference? Each measures
the entangled particles only once. Besides, This is not what is
done. I see little point in making up alternative scenarios -- why
not explain the straightforward original scenario? Imaginary
copies are beside the point.

If you cannot focus your attention on the original scenario, I see
little point in your trying to do physics.


I bring this question up because you repeatedly refer to only "one 
Alice" before the measurement, and also say that Alice and Bob are "in 
one and the same branch" prior to measurement.  But normal QM without 
collapse would say Alice and Bob are branching all the time, even 
before they measure their entangled pair.  So isn't it necessary to 
take this into consideration (that this is implicitly the original 
scenario):


You seem to be trying to re-introduce the 'jellification' or 'mushiness' 
that so worried Schrödinger. Fortunately, that worry has long since been 
laid to rest by the advent of modern decoherence theory. In that theory, 
splitting of the world into distinct (quasi-)classical branches occurs 
only when the microscopic quantum phenomenon has been amplified to 
macroscopic level, and a thermodynamically irreversible record (or many 
records, as suggested by Zurek) has been laid down in the environment.  
So micro-level quantum events generally do not lead to splittings into 
disjoint worlds, and we don't need to worry about the fact that a 
genuine classical world emerges from the quantum substrate.


So there are no 'many Alices and Bobs' before or during the experiment 
-- there is only one classical Alice and one classical Bob who get 
involved in the experiment. Besides, even if, by chance, some quantum 
event in Alice's makeup does get amplified, so that copies of Alice 
exist in superposition, that makes no essential difference. In the 
normal way with quantum superpositions, we simply select out one typical 
Alice-Bob pair and work with these. So my implicit assumption of just 
one Alice-Bob pair is completely harmless. If you want to claim that 
quantum jellification makes a difference, then it is up to you do make 
the case -- which no one has seriously attempted to do, for very good 
reason.


There are many Alices, and many Bobs, and depending on the 
experimental setup, many measurement angle choices?


No, there are not, and even if there were it would make no difference. 
Alice and Bob have to measure the same entangled pair and persist as 
identifiable individuals for long enough to record their results and 
later compare them -- or else they would not observe any correlations at 
all! The entangled singlet does not change its identity in its passage 
between Alice and Bob -- it has to maintain its coherence, or else it is 
not en entangled pair. So the Bob that measures the partner of Alice's 
particle is really and truly the same Bob that she met for breakfast 
before the experiment began.


Your (and Bruno's) idea that somehow their identities are not fixed 
because of quantum fluctuations is truly fatuous.


Bruce

--
You received this message because you are subscribed to the Google Groups 
"Everything List" group.
To unsubscribe from this group and stop receiving emails from it, send an email 
to everything-list+unsubscr...@googlegroups.com.
To post to this group, send email to everything-list@googlegroups.com.
Visit this group at https://groups.google.

Re: Many-minds interpretation?

[Brent Meeker]

On 8/13/2018 3:20 PM, agrayson2...@gmail.com wrote:



If you start with impossible initial conditions you get
impossible results.  Doesn't mean the theory is wrong.

Brent


What are the impossible initial conditions? AG


You apparently contemplated a perfectly plane wave, so that it
extends to infinity and yet meets an infinite screen in finite time.


*I'm not sure. Wouldn't any spherical wave impacting the screen extend 
as far as the length of the screen, hence infinitely distant? AG *


You illustrate my point by immediately abandoning one idealized initial 
condition by posing another idealization. Engineers and scientists 
realize they are always calculating with idealizations. Only 
mathematicians and metaphysicians think the idealizations of their 
symbol manipulation is reality.


Brent
As far as the laws of mathematics refer to reality, they are not
certain, and as far as they are certain, they do not refer to
reality.
    -- Albert Einstein

--
You received this message because you are subscribed to the Google Groups 
"Everything List" group.
To unsubscribe from this group and stop receiving emails from it, send an email 
to everything-list+unsubscr...@googlegroups.com.
To post to this group, send email to everything-list@googlegroups.com.
Visit this group at https://groups.google.com/group/everything-list.
For more options, visit https://groups.google.com/d/optout.

Re: Many-minds interpretation?

[agrayson2000]

On Monday, August 13, 2018 at 10:20:09 PM UTC, agrays...@gmail.com wrote:
>
>
>
> On Monday, August 13, 2018 at 5:51:17 AM UTC, Brent wrote:
>>
>>
>>
>> On 8/12/2018 10:13 PM, agrays...@gmail.com wrote:
>>
>>
>>
>> On Monday, August 13, 2018 at 2:10:33 AM UTC, Brent wrote: 
>>>
>>>
>>>
>>> On 8/12/2018 9:26 AM, agrays...@gmail.com wrote:
>>>
>>> *I meant to write; Just DO the math! Since QM allows the probability 
>>> calculation for the double slit from minus to plus infinitely for any 
>>> moment in time, it means we have and know the data simultaneously for all 
>>> positions on the screen. This has nothing to do with branches or collapse. 
>>> AG*
>>>
>>>
>>> If you start with impossible initial conditions you get impossible 
>>> results.  Doesn't mean the theory is wrong.
>>>
>>> Brent
>>>
>>
>> What are the impossible initial conditions? AG
>>
>>
>> You apparently contemplated a perfectly plane wave, so that it extends to 
>> infinity and yet meets an infinite screen in finite time.
>>
>
> *I'm not sure. Wouldn't any spherical wave impacting the screen extend as 
> far as the length of the screen, hence infinitely distant? AG *
>

*I think it would (extend to infinity), but not instantaneously. AG* 

>
>
>> And even for a wave that extends to infinity, it's amplitude may go to 
>> zero such that the observation of even one photon is improbable within the 
>> age of the universe.
>>
>
> *I don't like, and avoid FAPP arguments when arguing about first 
> principles. Suppose I have a wf in one spatial dimension and calculate the 
> probability density at some value of x. Isn't any x acceptable, say for a 
> free particle, implying the wf extends to infinity? TIA, AG*
>
> Brent
>
>>

-- 
You received this message because you are subscribed to the Google Groups 
"Everything List" group.
To unsubscribe from this group and stop receiving emails from it, send an email 
to everything-list+unsubscr...@googlegroups.com.
To post to this group, send email to everything-list@googlegroups.com.
Visit this group at https://groups.google.com/group/everything-list.
For more options, visit https://groups.google.com/d/optout.

Re: Many-minds interpretation?

[agrayson2000]

On Monday, August 13, 2018 at 5:51:17 AM UTC, Brent wrote:
>
>
>
> On 8/12/2018 10:13 PM, agrays...@gmail.com  wrote:
>
>
>
> On Monday, August 13, 2018 at 2:10:33 AM UTC, Brent wrote: 
>>
>>
>>
>> On 8/12/2018 9:26 AM, agrays...@gmail.com wrote:
>>
>> *I meant to write; Just DO the math! Since QM allows the probability 
>> calculation for the double slit from minus to plus infinitely for any 
>> moment in time, it means we have and know the data simultaneously for all 
>> positions on the screen. This has nothing to do with branches or collapse. 
>> AG*
>>
>>
>> If you start with impossible initial conditions you get impossible 
>> results.  Doesn't mean the theory is wrong.
>>
>> Brent
>>
>
> What are the impossible initial conditions? AG
>
>
> You apparently contemplated a perfectly plane wave, so that it extends to 
> infinity and yet meets an infinite screen in finite time.
>

*I'm not sure. Wouldn't any spherical wave impacting the screen extend as 
far as the length of the screen, hence infinitely distant? AG *

>
> And even for a wave that extends to infinity, it's amplitude may go to 
> zero such that the observation of even one photon is improbable within the 
> age of the universe.
>

*I don't like, and avoid FAPP arguments when arguing about first 
principles. Suppose I have a wf in one spatial dimension and calculate the 
probability density at some value of x. Isn't any x acceptable, say for a 
free particle, implying the wf extends to infinity? TIA, AG*

Brent

>

-- 
You received this message because you are subscribed to the Google Groups 
"Everything List" group.
To unsubscribe from this group and stop receiving emails from it, send an email 
to everything-list+unsubscr...@googlegroups.com.
To post to this group, send email to everything-list@googlegroups.com.
Visit this group at https://groups.google.com/group/everything-list.
For more options, visit https://groups.google.com/d/optout.

A Brief History of Metaphysics

[Brent Meeker]

A Brief History of Metaphysics


Brent
P.S. But has Wittgenstein heard about computationalism?



--
You received this message because you are subscribed to the Google Groups 
"Everything List" group.
To unsubscribe from this group and stop receiving emails from it, send an email 
to everything-list+unsubscr...@googlegroups.com.
To post to this group, send email to everything-list@googlegroups.com.
Visit this group at https://groups.google.com/group/everything-list.
For more options, visit https://groups.google.com/d/optout.

Re: Many-minds interpretation?

[Brent Meeker]

On 8/13/2018 7:27 AM, Jason Resch wrote:
I bring this question up because you repeatedly refer to only "one 
Alice" before the measurement, and also say that Alice and Bob are "in 
one and the same branch" prior to measurement.  But normal QM without 
collapse would say Alice and Bob are branching all the time, even 
before they measure their entangled pair.  So isn't it necessary to 
take this into consideration (that this is implicitly the original 
scenario):


There are many branchings of the wf describing Alice, almost all of them 
are irrelevant to who Alice is.  They are below the quasi-classical 
level at which "Alice" exists; below the level at which her brain 
decides at what angle to measure the particle.  All those Alices are one 
person.  So they are treated as one classical being.  That they split 
into two (up or down) classically distinct beings, is unrelated to the 
fact there are many microscopically different Alices.


It is not clear to me how Bruno thinks of these many quasi-classical, 
Alices.  He seems to just dismiss their differences as below replacement 
level the Doctor promises.  That seems like assuming that they are 
really classical entities, just similar computational threads in the UD.


Brent



There are many Alices, and many Bobs, and depending on the 
experimental setup, many measurement angle choices?


--
You received this message because you are subscribed to the Google Groups 
"Everything List" group.
To unsubscribe from this group and stop receiving emails from it, send an email 
to everything-list+unsubscr...@googlegroups.com.
To post to this group, send email to everything-list@googlegroups.com.
Visit this group at https://groups.google.com/group/everything-list.
For more options, visit https://groups.google.com/d/optout.

Re: Many-minds interpretation?

[Brent Meeker]

On 8/13/2018 6:41 AM, Bruno Marchal wrote:
The wave function is not a "physical" object -- it can easily change 
instantaneously, just as probabilities change on the advent of new 
information.


Then we are no more in Everett non-collapse QM, and I am not sure how 
you can explain the double slit or spin polarisation without a 
physical wave.


But you are the one who notes that "physical" is not very sharply 
defined.  If you take Dr. Johnson's view, you can't kick it and have it 
kick back.  It acts very strangely compared to water and sound waves.  
If you provide a photosensitive screen or a detector in front of it, it 
will only act at one point, like a particle.


Brent

--
You received this message because you are subscribed to the Google Groups 
"Everything List" group.
To unsubscribe from this group and stop receiving emails from it, send an email 
to everything-list+unsubscr...@googlegroups.com.
To post to this group, send email to everything-list@googlegroups.com.
Visit this group at https://groups.google.com/group/everything-list.
For more options, visit https://groups.google.com/d/optout.

Re: Many-minds interpretation?

[agrayson2000]

On Monday, August 13, 2018 at 2:27:55 PM UTC, Jason wrote:
>
>
>
> On Mon, Aug 13, 2018 at 12:05 AM Bruce Kellett  > wrote:
>
>> From: Jason Resch >
>>
>>
>> On Sun, Aug 12, 2018 at 5:06 AM Bruno Marchal > > wrote:
>>
>>>
>>> On 11 Aug 2018, at 02:29, Bruce Kellett >> > wrote:
>>>
>>> They do not "belong to different branches" because they do not exist, 
>>> and have never existed. This notion seems to be important to your idea, and 
>>> I can assure you that you are wrong about this.
>>>
>>>
>>> How could that be possible? You suppress the infinities of Alice and Bob 
>>> only because you know in advance what is the direction in which Alice will 
>>> make her measurement. What if she changes her mind? 
>>>
>>>
>> Right.
>>
>> I would like Bruce to consider the case Alice measures alternately x and 
>> z spin axes of an electron 1000 times and interprets those measurement 
>> results as binary digits following a decimal point to define the real 
>> number to which she will set her measurement angle to (before she measures 
>> her entangled particle).
>>
>> Certainly in the no-collapse case there would be at least 2^1000 Alices 
>> who perform the measurement at each of the possible measurement angles that 
>> can be defined by 1000 binary digits.  What I wonder is how many Alices 
>> Bruce would believe to exist in this scenario before she measures her 
>> entangled particle.
>>
>>
>> How do 2^1000 copies of Alice make any difference? Each measures the 
>> entangled particles only once. Besides, This is not what is done. I see 
>> little point in making up alternative scenarios -- why not explain the 
>> straightforward original scenario? Imaginary copies are beside the point.
>>
>> If you cannot focus your attention on the original scenario, I see little 
>> point in your trying to do physics.
>>
>
> I bring this question up because you repeatedly refer to only "one Alice" 
> before the measurement, and also say that Alice and Bob are "in one and the 
> same branch" prior to measurement.  But normal QM without collapse would 
> say Alice and Bob are branching all the time, even before they measure 
> their entangled pair. 
>


*They're branching all the time prior to measurement, that is without 
collapse? Pretty fantastic. Where, how, is this affirmed by QM? AG*
  

> So isn't it necessary to take this into consideration (that this is 
> implicitly the original scenario):
>
> There are many Alices, and many Bobs, and depending on the experimental 
> setup, many measurement angle choices?
>
> Jason
>
>
>

-- 
You received this message because you are subscribed to the Google Groups 
"Everything List" group.
To unsubscribe from this group and stop receiving emails from it, send an email 
to everything-list+unsubscr...@googlegroups.com.
To post to this group, send email to everything-list@googlegroups.com.
Visit this group at https://groups.google.com/group/everything-list.
For more options, visit https://groups.google.com/d/optout.

Re: Many-minds interpretation?

[Brent Meeker]

On 8/13/2018 6:25 AM, Bruno Marchal wrote:
...the measure on the set of branches are always 2^(aleph_0), and the 
measure is given by the square of the the amplitude of probability. 


?? 2^(aleph_0) is never the square of the amplitude of probability.

Brent

--
You received this message because you are subscribed to the Google Groups 
"Everything List" group.
To unsubscribe from this group and stop receiving emails from it, send an email 
to everything-list+unsubscr...@googlegroups.com.
To post to this group, send email to everything-list@googlegroups.com.
Visit this group at https://groups.google.com/group/everything-list.
For more options, visit https://groups.google.com/d/optout.

Re: Many-minds interpretation?

[Bruno Marchal]

> On 13 Aug 2018, at 03:32, agrayson2...@gmail.com wrote:
> 
> 
> 
> On Sunday, August 12, 2018 at 6:51:23 PM UTC, agrays...@gmail.com wrote:
> 
> 
> On Sunday, August 12, 2018 at 4:44:18 PM UTC, agrays...@gmail.com <> wrote:
> 
> 
> On Sunday, August 12, 2018 at 4:26:39 PM UTC, agrays...@gmail.com <> wrote:
> 
> 
> On Sunday, August 12, 2018 at 12:01:56 PM UTC, agrays...@gmail.com <> wrote:
> 
> 
> On Sunday, August 12, 2018 at 9:55:39 AM UTC, Bruno Marchal wrote:
> 
>> On 10 Aug 2018, at 22:05, agrays...@gmail.com <> wrote:
>> 
>> 
>> 
>> On Friday, August 10, 2018 at 4:01:37 PM UTC, Bruno Marchal wrote:
>> 
>>> On 9 Aug 2018, at 18:50, agrays...@gmail.com <> wrote:
>>> 
>>> 
>>> 
>>> On Thursday, August 9, 2018 at 7:32:07 AM UTC, Bruno Marchal wrote:
>>> 
 On 9 Aug 2018, at 02:02, agrays...@gmail.com <> wrote:
 
 
 
 On Wednesday, August 8, 2018 at 5:46:22 PM UTC, Bruno Marchal wrote:
 
> On 8 Aug 2018, at 13:50, Bruce Kellett > wrote:
> 
> From: Bruno Marchal >
>>> On 8 Aug 2018, at 01:39, Bruce Kellett > 
>>> wrote:
>>> 
>>> From: Bruno Marchal >
 
 If there is a FTL physical influence, even if there is no information 
 transfer possible, it leads to big problems with any reality 
 interpretation of special relativity, notably well described by 
 Maudlin. Maudlin agrees that many-mind restore locality, and its 
 “many-mind” theory is close to what I think Everett had in mind, and 
 is close to what I defended already from the mechanist hypothesis. To 
 be sure, Albert and Lower Many-Minds assumes an infinity of mind for 
 one body, where in mechanism we got an infinity of relative body for 
 one mind, but the key issue is that all measurement outcomes belongs 
 to some mind. The measurement splits locally the observers, and 
 propagate at subliminal speed.
>>> 
>>> I don't think that the many-minds interpretation is really what you 
>>> would want to support. In many-minds, the physical body is always in 
>>> the superposition of all possible results, but the 'mind' can never be 
>>> in such a superposition,
>> 
>> That sides with Mechanism. In arithmetic there is an infinity of 
>> identical (at the relevant representation level) brains. Now Albert and 
>> Loewer seems to associate an infinity of mind with one body.
> 
> The 'infinity of minds for each body' was postulated by Albert and Lowe 
> to avoid the 'mindless hulk' problem. In other words, it was just an ad 
> hoc fix for a problem in the theory. This alone should have been 
> sufficient to render the theory unacceptable.
 
 I agree. That is why I remain closer to Everett. This problem is 
 automatically solved with Mechanism. There is no empty hulk, given that 
 there is no hulk. 
 
 
 
> 
>> I do not understand this, and with the Mechanist “many-dreams” it is the 
>> contrary: each mind as an infinity of (virtual) bodies, and the 
>> consciousness will differentiate along their computational different 
>> continuations. Take the WM-duplication. After the reconstitution, but 
>> before the copies open the door, one mind is associated to two bodies, 
>> and then differentiates in W or in M from each location perspective. To 
>> say that the mind is not in a superposition is equivalent with Everett’s 
>> justification that the observer cannot feel the split, and it is where 
>> Everett use (more or less explicitly) the mechanist hypothesis.
> 
> The splitting in Everett's theory at least makes some sort of sense, and 
> is not postulated ad hoc.
 
 I agree.
 
 
 
> The real problem I see with many-minds theory is that it does not 
> actually explain the observed correlations. The correlations are presumed 
> not to exist in reality -- all possible combinations of experimental 
> outcomes happen, but when Alice and Bob meet, their bodies are still in 
> indefinite states -- no actual results are recorded by entanglement with 
> their bodies -- but their minds will be in definite states that agree 
> with the quantum correlations. This step seems to introduce yet more 
> unreasonable magic into the 'explanation'. Why are the minds like this 
> when they communicate?
 
 Because all Alice and Bob are coupled in that way, by the singlet state. 
 That works if we keep in mind that the singlet state (when not already 
 observed by neither Alice nor Bob) describes an infinity of Alice and Bob, 
 with the spin in all directions, but always correlated. When Alice and Bob 
 make their measurement, if they are space separated, it makes no sense to 
 ask if they are or not in the same world or branches. The result they 
 obtained only entangle each of them with the environment, locally, and

Re: Many-minds interpretation?

[Jason Resch]

On Mon, Aug 13, 2018 at 12:05 AM Bruce Kellett 
wrote:

> From: Jason Resch 
>
>
> On Sun, Aug 12, 2018 at 5:06 AM Bruno Marchal  wrote:
>
>>
>> On 11 Aug 2018, at 02:29, Bruce Kellett 
>> wrote:
>>
>> They do not "belong to different branches" because they do not exist, and
>> have never existed. This notion seems to be important to your idea, and I
>> can assure you that you are wrong about this.
>>
>>
>> How could that be possible? You suppress the infinities of Alice and Bob
>> only because you know in advance what is the direction in which Alice will
>> make her measurement. What if she changes her mind?
>>
>>
> Right.
>
> I would like Bruce to consider the case Alice measures alternately x and z
> spin axes of an electron 1000 times and interprets those measurement
> results as binary digits following a decimal point to define the real
> number to which she will set her measurement angle to (before she measures
> her entangled particle).
>
> Certainly in the no-collapse case there would be at least 2^1000 Alices
> who perform the measurement at each of the possible measurement angles that
> can be defined by 1000 binary digits.  What I wonder is how many Alices
> Bruce would believe to exist in this scenario before she measures her
> entangled particle.
>
>
> How do 2^1000 copies of Alice make any difference? Each measures the
> entangled particles only once. Besides, This is not what is done. I see
> little point in making up alternative scenarios -- why not explain the
> straightforward original scenario? Imaginary copies are beside the point.
>
> If you cannot focus your attention on the original scenario, I see little
> point in your trying to do physics.
>

I bring this question up because you repeatedly refer to only "one Alice"
before the measurement, and also say that Alice and Bob are "in one and the
same branch" prior to measurement.  But normal QM without collapse would
say Alice and Bob are branching all the time, even before they measure
their entangled pair.  So isn't it necessary to take this into
consideration (that this is implicitly the original scenario):

There are many Alices, and many Bobs, and depending on the experimental
setup, many measurement angle choices?

Jason

-- 
You received this message because you are subscribed to the Google Groups 
"Everything List" group.
To unsubscribe from this group and stop receiving emails from it, send an email 
to everything-list+unsubscr...@googlegroups.com.
To post to this group, send email to everything-list@googlegroups.com.
Visit this group at https://groups.google.com/group/everything-list.
For more options, visit https://groups.google.com/d/optout.

Re: Many-minds interpretation?

[Bruno Marchal]

> On 13 Aug 2018, at 00:55, Bruce Kellett  wrote:
> 
> From: Bruno Marchal mailto:marc...@ulb.ac.be>>
>>> On 11 Aug 2018, at 02:57, Bruce Kellett >> > wrote:
>>> 
>>> From: Bruno Marchal mailto:marc...@ulb.ac.be>>
>>> 
 You are the one telling that the Bell’s inequality violation entails FTL 
 influence. Personally, I do not dig on that issue, because I use only 
 Everett QM to evaluate what mechanism predicts. I might try to send a post 
 why I do not follow your critic of Tipler and Baylock, some day.
>>> 
>>> That would be useful. I was perhaps dismissive of Tipler and Baylock 
>>> because their analyses were so obviously incorrect -- for different 
>>> reasons, however.
>> 
>> Nothing is obvious here. The debate is far from finished. 
>> 
>>> Tipler simply collapsed the non-separable state without realizing that that 
>>> was a non-local operation.
>> 
>> I would suggest you elaborate on this in your paper. I see the non local 
>> consideration, but I do not see any FTL appearing from that. The EPR-Bell 
>> type of experience is non local, and bear on non separable entities, but 
>> only the collapse makes them into physical FTL/instantaneity.
> 
> If you see the non-locality in Tipler's account, why is there still an issue 
> about non-locality?

Non-locality, or inseparability, or Bell’s inequality violation is NOT the 
issue. As I said, my issue is only with those who claim that there is still 
need of some physical FTL influence in the MW theory.




> You are the only one obsessed about physical FTL.

Well, I was just replying (to Clark) that with the MW there is no more physical 
FTL influence.



> I have repeatedly stressed that there is no physical FTL or instantaneous 
> transfer of physical information.

But Clark was OK with this, and me too. But without the MW, there is still some 
action at a distance, even if they cannot be used to transfer information.

With the MW, there is no need for such action at a distance at all. 





> It is epistemological. As you say, EPR-Bell bear on non-separable states.

So it looks we agree again.



> That is all there is to it. When you interact with a non-separable state you 
> destroy the symmetry and make it separable. There need not be any collapse or 
> physical FTL.


OK. That is what I thought. We have never disagreed. My point is only that with 
the MW, or without collapse and without hidden variable, we have no need of a 
physical action at a distance. But for someone believing implicitly (or 
explicitly) in only one universe, in that case there are FTL influence, even if 
it remains true that there is no transfer of information at a distance.



> 
> 
>>> Baylock made valiant attempts to introduce some measurements that were not 
>>> made in order to show that Bell assumed counterfactual definiteness, but 
>>> his attempts to reconstruct Bell's arguments in this way were so contrived 
>>> as to be laughable -- Bell's result does not depend on the assumption of 
>>> counterfactual definiteness.
>> 
>> You have not et convince me.
> 
> Why does Baylock introduce unnecessary references to experiments that were 
> not performed?

To have, or not, a notion of counterfactual definiteness. 



> If you can think of any reason other than a silly attempt to deflect Bell's 
> theorem, then tell me.


Would you have a link to Baylock? Maybe you gave one in your paper?

In this discussion we should perhaps  distinguish:

1) FTL-with-tranfer-of-information (we all agree, I think, that this does not 
exist, even with QM+collapse)

2) FTL-without-tranfer-of-information. (This has to exist with QM+collapse+the 
wave-is-physically-real)

3) No FTL-at-all (this is realised, I think, by any sensible interpretation of 
QM-without collapse).

Do you have the book by Susskind & Friedman “Quantum Mechanics, the theoretical 
minimum”. A lovely book.
Last year I gave as exercise for some of my students to criticise its sections 
7.9/10/11 “Entanglement and Locality, ...”. Susskind and Friedamn shows 
correctly that if you want to simulate Bell’s inequality violation with two 
computers (one for Alice and one for Bob), That requires necessarily an 
“instantaneous cable” between the two computers. The proof is correct, only by 
assuming (as they do implicitly in the whole book) a unique universe. What they 
show (implicitly) is that if wa want simulate QM with a computer, the only way 
to get the violation of Bell’s inequality requires to simulate the observers 
too, and apply QM to them too. But they do not even mention tat possibility, 
and indeed Everett is not mentioned in the index, and the MW is to even 
suggested nowhere in the book (which is still a very good  introduction to QM, 
a good companion to Albert’s book, for the beginners).


Bruno



> 
> Bruce
> 
> -- 
> You received this message because you are subscribed to the Google Groups 
> "Everything List" group.
> To unsubscribe from this group and stop rec

Re: Many-minds interpretation?

[Bruno Marchal]

> On 13 Aug 2018, at 00:48, Bruce Kellett  wrote:
> 
> From: Bruno Marchal mailto:marc...@ulb.ac.be>>
>>> On 11 Aug 2018, at 02:49, Bruce Kellett >> > wrote:
>>> 
>>> From: Bruno Marchal mailto:marc...@ulb.ac.be>>
 On 9 Aug 2018, at 14:03, Bruce Kellett >>> > wrote:
> 
>> Without collapse and FTL potential, or FTL (non-local) hidden variable 
>> theory, how do you interpret the singlet state?
> 
> That is actually a rather strange question. How do you think I might 
> interpret the singlet state? I think that I have been talking about it 
> here for long enough for you to have worked it out. The singlet state is 
> a non-separable state that is symmetric under rotations about the axis 
> between the particles. However, that symmetry will generally be broken by 
> any interaction with one or other of the constituent particles.
 
 But it is here that I suspect you introduce some collapse.
>>> 
>>> The interaction with one particle reduces the symmetry of the non-separable 
>>> state so that it becomes separable.
>> 
>> Locally, and from the observer viewpoint, not in the big picture, as nothing 
>> is ever reduced. The superposition does not disappear.
> 
> There is still a superposition, even though it has decohered and the separate 
> results are in FAPP orthogonal branches. But the superposition is not the 
> issue -- that relevant fact is that the measurement has destroyed the 
> rotational symmetry of the state.
> 
> 
>>> You might call this a "collapse" if you wish, but this is an 
>>> epistemological collapse, not an ontological one. It is the nature of the 
>>> state representing one's knowledge that changes (the old state "collapses" 
>>> with the advent of new knowledge).
>> 
>> Then I agree. That makes things local, and personal somehow. You get close 
>> to “my” version of the many-mind account.
> 
> I doubt it. There is no "bigger picture" in which the symmetry is preserved.
> 
> 
>>> But that is purely epistemological, and does not involve any FTL 
>>> information transfer.
>> 
>> That’s my point.
> 
> But you apparently still do not accept that the symmetry of the state is 
> destroyed, even without physical FTL.

The destruction is only in the mind of the observer, like the WM-duplication is 
symmetrical for an outsider, but non symmetrical for the experiencer. 



> The wave function is not a "physical" object -- it can easily change 
> instantaneously, just as probabilities change on the advent of new 
> information.

Then we are no more in Everett non-collapse QM, and I am not sure how you can 
explain the double slit or spin polarisation without a physical wave.




> 
>>> It is just as if the probability that your horse will win the race 
>>> "collapses" when you find out, after the race has been run, that it came 
>>> last!
>>> 
> In particular, the symmetry is broken by the imposition of a directional 
> magnetic field, as in a Stern-Gerlach magnet used to measure the spin 
> component of one of the particles in the direct defined by that external 
> magnetic field.
> 
> The singlet is strongly non-separable, so this external interaction with 
> one of the constituents is instantaneously felt by the other component 
> particle.
 
 How could this be verified?
>>> 
>>> It is verified by the Freedman-Clauser and Aspect experiments (and many 
>>> other more recent experiments). 
>> 
>> This tests only the non separability issue. Not the existence of a physical 
>> FTL in our branch. That follows from what you say above.
> 
> The non-separability is the non-locality. Do you not yet understand that?

Yes. I do understand that, and I prefer to use non-separability. “Non-locality” 
is ambiguous, because many are using that term for FTL influence (even if no 
transfer of information is involved). 



> 
> 
 Any verification possible will need further interaction, and we can see 
 only the branche of the universe our own result have spread on.
>>> 
>>> The verification comes from the results of remote experiments -- and those 
>>> results do not change during the time it takes for the experimenters to 
>>> come together to compare findings.
>> 
>> Those results makes just Alice and Bob knowing which branches they belong 
>> too. The non-locality is a global notion on the full wave/multiverse,
> 
> That has never been demonstrated. It is a pious hope of yours, but you always 
> shy away from proving it. 

If you believe in FTL, you are the one who should prove that remarkable fact. 
It follows indeed from all collapse theories, but not for the MW.

> 
> 
>> but the FTL are needed only if we associate the mind on Bob and Alice to the 
>> same branche, which has no meaning for me once they are space separated.
> 
> You might not accept that they can be in the same branch, but that does not 
> mean that it is not a proven fact.

If t

Re: Many-minds interpretation?

[Bruno Marchal]

> On 12 Aug 2018, at 14:59, Bruce Kellett  wrote:
> 
> From: Bruno Marchal mailto:marc...@ulb.ac.be>>
>>> On 11 Aug 2018, at 02:29, Bruce Kellett >> > wrote:
>>> 
>>> From: Bruno Marchal mailto:marc...@ulb.ac.be>>
> On 9 Aug 2018, at 14:03, Bruce Kellett  > wrote:
> 
> The original Alice and Bob are those in the same branch of the wave 
> function all the way along. There are no unmatched Alices or Bobs.
 
 In each branch, I agree. But to get the reasoning right, and treat the 
 case of the violation of Bell’s inequality, we need to take into account 
 the unmatched Alice and Bob who exist “transworldly” if I can say. They 
 belong to different branches, and can never meet again. That is important 
 to make the FTL eventually into an illusion, still keeping the violation 
 of the Bell’s inequality.
>>> 
>>> It is fairly clear that you are not talking about quantum mechanics here, 
>>> but rather about some weird theory of your own. There is no infinity of 
>>> Alices and Bobs who exist before any measurement is made.
>> 
>> Do you agree that there is an infinity of Alice in the case of aIu> + bId> 
>> when a^2 is irrational? I really don’t see how you interpret the singlet 
>> state in the non-collapse QM.
> 
> No, I don't agree that there are any infinities of anything in the case of 
> irrational coefficients (or of any other coefficients, for that matter). What 
> on earth are you talking about?

About QM-without collapse. Or about the MW theory, or Everett relative state 
theory.



> The Born rule gives a probability interpretation to the square of the 
> coefficients in the expansion the wave function. That is all that the 
> coefficients in the expansion are -- complex coefficients that when squared 
> give probabilities. You don't have to have the appropriate relative numbers 
> of branches to get the probabilities -- that is just naĩve branch counting, 
> which has long been known not to work. Besides, how do you ever get a complex 
> number of branches?

The “number of branches”, more exactly the measure on the set of branches are 
always 2^(aleph_0), and the measure is given by the square of the the amplitude 
of probability. 



> 
> If you are basing your notion of a pre-exisiting infinity of Alices on such 
> an idea, then you are simply wrong.

Actually I have extract the quantum formalism from elementary arithmetic. With 
mechanism: the existence of an infinity of “Alice” is a theorem. In my work I 
use only QM as a tool to verify if the prediction of Mechanism are realised. 




> No such interpretation of the wave function is even close to being correct.  
> Just think of probabilities as propensities rather than as relative numbers 
> of branches.

Like Popper did, but that makes no sense. The wave does behave like a physical 
wave, or we would not sen the interference pattern.

It seems you are again back to some implicit collapse. You have failed to tell 
me how you interpret the single state, or any quantum state actually.



> 
> 
>>> They do not "belong to different branches" because they do not exist, and 
>>> have never existed. This notion seems to be important to your idea, and I 
>>> can assure you that you are wrong about this.
>> 
>> How could that be possible? You suppress the infinities of Alice and Bob 
>> only because you know in advance what is the direction in which Alice will 
>> make her measurement. What if she changes her mind?
> 
> That is not the case either. I do not suppress any infinities because no such 
> infinities exist. They are only in your mind because you have strange notions 
> about the origin of probabilities in quantum mechanics. Alice makes a 
> measurement along a particular axis. She can change her mind an infinite 
> number of times before she makes that measurement, but in the end she 
> makes only one measurement in one direction. That is the only direction and 
> measurement that exists or matters.
> 
>>> If you think you can justify this, then I ask you to write out the full 
>>> quantum mechanical treatment, in Everett's relative state formulation, that 
>>> establishes that this infinity of pre-measurement people is a feature of 
>>> the actual theory, and not just a figment of your imagination.
>> 
>> Perhaps, after the combinators. If I do that I will use the GHZ state, to 
>> avoid the use of probability. But in my opinion, Price computations gives 
>> the right hint to proceed, and in the simple case we see what happens.
> 
> No, Price is wrong. He collapses the wave function in a non-local manner, 
> even though he doesn't seem to realize it. Let me try again. The state is
> 
> |psi>= (|u>|d> - |d>|u>).
> 
> Let Alice interact with particle 1 at one end:
> 
> |Alice>|psi> = |Alice>|u>|d> - |Alice>|d>|u>
> 
> Alice interacts only with particle 1 (locally), so |Alice>|u>|d> --> |Alice 
> sees u>|u>|d>, and sim

Re: The Ilusion of Branching and the MWI

[Bruno Marchal]

> On 6 Aug 2018, at 21:11, Brent Meeker  wrote:
> 
> 
> 
> On 8/6/2018 11:22 AM, Bruno Marchal wrote:
>> 
>>> On 6 Aug 2018, at 09:23, agrayson2...@gmail.com 
>>>  wrote:
>>> 
>>> 
>>> 
>>> On Sunday, August 5, 2018 at 5:50:56 PM UTC, agrays...@gmail.com 
>>>  wrote:
>>> 
>>> 
>>> On Sunday, August 5, 2018 at 4:43:21 PM UTC, Bruno Marchal wrote:
>>> 
 On 4 Aug 2018, at 23:32, agrays...@gmail.com <> wrote:
 
 AFAIK, no one has ever observed a probability wave, from which I conclude 
 the wave function has only epistemic content.
>>> 
>>> 
>>> Then you need to explain how that epistemic content interfere in nature. 
>>> Your idea might make sense, and indeed if we believe in a collapse (as you 
>>> have to do if you believe in QM and that the superposition does not apply 
>>> to us) the idea that consciousness collapse the wave is perhaps the less 
>>> ridiculous idea. That idea has indeed be defended by von Neumann, Wigner, 
>>> and some others. But has been shown to lead to many difficulties when taken 
>>> seriously by Abner Shimony, as well guessed by Wigner itself. Obviously 
>>> that idea would be inconsistent with Mechanism.
>>> 
>>> Easy to show that consciousness doesn't collapse the wf. Just do repeated 
>>> trials and don't look at the screen until the experiment is finished. I 
>>> forget; what is mechanism? AG 
>>> 
>>> There is no probability waves.
>>> 
>>> IIUC, the wf has the mathematical form of a wave, of which the amplitude is 
>>> part of. AG
>> 
>> The point is that it behave also like a wave. Even if I send only one 
>> particle, the position of the screen is determine by a wave which take into 
>> account all physical available path. 
>> 
>> You have proposed an instrumentalist interpretation, and that is OK if you 
>> goal is to build microscopic transistor or atomic bombs. Here we try to make 
>> sense of a theory. The choice is between a non-local guiding potential, the 
>> relative states or a (magical) collapse, also non local.
> 
> You want to make sense of a theory that is defined by complex valued fields 
> in a Hilbert space built on spacetime.  You begin by assuming mechanism,


Not in this thread. I am just discussing the MW theory. My point is only that 

QM + collapse entails physical FTL. If you prefer: QM+collapse is not covariant.

QM-without-collapse entails *apparent FTL* but no real FTL, and is a covariant 
theory.



> which implicitly replaces everything physical, including the spacetime, with 
> conscious thoughts which are realized as theorems in arithmetic (or 
> equivalent computation).  You have not shown how this entails conscious 
> thoughts about a quasi-classical world, i.e. one in which there appears a 
> shared reality. So wouldn't it be simpler to just adopt the interpretation of 
> QBism.  It seems compatible with the idea of a computational substrate, but 
> it doesn't need to assume one.  That fact tells me the computational 
> substrate is an independent assumption that does not follow from QM.

QM without collapse use Mechanism, and Mechanism implies that only numbers (or 
only combinators, …) exist. We have to explain the illusion of matter from only 
addition and multiplication of natural numbers (or from only K and S and the 
two axioms I have given).

Bruno



> 
> Brent
> 
> -- 
> You received this message because you are subscribed to the Google Groups 
> "Everything List" group.
> To unsubscribe from this group and stop receiving emails from it, send an 
> email to everything-list+unsubscr...@googlegroups.com 
> .
> To post to this group, send email to everything-list@googlegroups.com 
> .
> Visit this group at https://groups.google.com/group/everything-list 
> .
> For more options, visit https://groups.google.com/d/optout 
> .

-- 
You received this message because you are subscribed to the Google Groups 
"Everything List" group.
To unsubscribe from this group and stop receiving emails from it, send an email 
to everything-list+unsubscr...@googlegroups.com.
To post to this group, send email to everything-list@googlegroups.com.
Visit this group at https://groups.google.com/group/everything-list.
For more options, visit https://groups.google.com/d/optout.

Re: Combinators 1 (solutions to exercises)

[Bruno Marchal]

Hi Jason, Brent, others,


In this post, I sum up what we have seen so far, and provide the solutions to 
the (suggested) exercise. Skip the solutions if you still want to find by 
yourself.

The motivation is to better appreciate what is a computation, and why, when we 
assume Mechanism, the two axioms Kxy = x and Sxyz = xz(yz) are enough, and 
cannot be completed with other axioms, unless we describe observer (and not 
“reality”).



A combinator is a combination of S and K, i. e. S is a combinator, K is a 
combinator, and from two combinators x y you can build the combinator (x y).

>From this you can enumerate already easily all combinators. K, S, (K K), (K 
>S), (S K), (S S), ((K K) K), (K (K K)), …

Now, we use a convention to help the readability: we suppress the left most 
parentheses (and their right corresponding parenthesis).

So 

abc(def)ghu  

can be be read as the combinator abc(def)gh applied to u. But abc(def)gh can be 
seen itself as the combinator abc(def)g applied to h, and then abc(def)g can be 
seen as abc(def) applied to g. Then abc(def) is abc applied to (def).  abc is 
ab applied to c: ((a b) c), and def is de applied to c.

You can also read from the left: in abc(def)ghu, it means a is applied to b: (a 
b) and that is applied to c: ((ab)c) which is applied on (def), which is 
((de)f), and the result of that is applied to g, and the result is applied to 
h, and the result is applied to u.

With those conventions, the only two axioms, or laws, (besides some equality 
rules) are that, with x and y being any combinators.

Kxy = x

Sxyz = xz(yz)

It means that the combinators K, when he get two arguments x y, it becomes 
instable and reacts and gives x as a result.

S “reacts” only when he got his three arguments (in the “Curry” way: Sxyz is 
really (((Sx)y)z), and that gives xz(yz): S applies x on z, and that is applied 
on the result of applying y  on z. 

The expression Kxy and Sxyz are called redex, and a combinators is instable as 
long as it contains redexes. When it does no more contain a redex, we say that 
a combinator is in normal form (I use often “stable” also).

The computation are not deterministic. If a combinator contains two different 
regexes, you can reduce them in any order. It can be proved that if the 
combinator has a normal form, then all converging path will give the same 
result (but we will see this is untrue if some path are infinite).


Summary: combinators are combination of K and S, and their have a sort of 
dynamic provided by the two laws above.


The only difficulty is due to the explosion of parentheses, which is limited by 
our convention of not writing the left parentheses when there is no ambiguity. 
That can lead to a new difficulty, due to forgetting that those parenthesis are 
still there.  For example, let us compute:

KSxyz

x and y and z are just any combinators. Someone could wrongly claim that it 
contains the redex Sxyz, and that it might reduces to Kxz(yz), and then x. But 
that is incorrect. It would be correct if it was K(Sxyz). KSxyz gives (KSx)yz = 
Syz, not x.

If you substitute the combinator ab for c in cxyz, you can write abxyz. But if 
you substitute ab for x, that gives c(ab)yz. In that case the parentheses are 
obligatory, as a(bc) is different from abc = (ab)c.

OK. Please ask question if anything seems unclear. 


Let us see the combinators that we have already met.

Is there an identity combinator, i.e. a I such that Ix = x ?  Yes I = SKK. 
Indeed SKKx = Kx(Kx) = x. So SKK is the identity bird. Note that SKA is an 
identity bird for any combinator A. Exemple SK(KK)x = Kx(KKx) = x.

Is there a combinator M such that Mx = xx ? Yes. Mx = xx = Ix(Ix) = SIIx, so M 
= SII. Verification Mx = SIIx = Ix(Ix) = xx.

Is there a combinator f such that fxy = y ? Yes. f = KI. Verification fxy = 
KIxy = (KIx)y = Iy = y. So KI is the projection on the second coordinate. Why 
do I use the matter f for its name? Because later KI will play the role of the 
constant propositional false. We will come back on this. Similarly K will play 
the role of the truth constant t.

Is there a combinator B such that Bxyz = x(yz) ? Yes. Bxyz = x(yz) = (Kxz)(yz) 
= ((Kx)z)yz)  (I added left parenthesis to help seeing the matching with the 
second S redex) = S(Kx)yz = ((KS)x(Kx))yz = KSx(Kx)yz = S(KS)Kxyz, so B = 
S(KS)K. Verification: S(KS)Kxyz = KSx(Kx)yz = S(Kx)yz = Kxz(yz) = x(yz).

OK? 

I suggested some “exercises”. 

1) Is there a W such that Wxy = xyy ?
2) Is there a T such that Txy = yx ?
3) is there a L such that Lxy = x(yy) ?
4) is there a C such that Cxyz = xzy ?

The method consist is trying to introduce K and S, or other combinators already 
defined, to match the right hand part of the regexes, and go backward.

Solutions:(you can skip this if you want take more time to find them. 
Later, in "combinator 2”, I will give an algorithm to solve those problem.

1) Wxy = xyy = (xy)(Iy) = SxIy = Sx(KIx)y = SS(KI)xy, so W = SS(KI). 
Verifi