Re: aiming to complete Everett's derivation of the Born Rule

[Brent Meeker]

On 4/21/2022 5:49 PM, Alan Grayson wrote:



On Wednesday, April 20, 2022 at 7:53:33 PM UTC-6 meeke...@gmail.com wrote:



On 4/20/2022 6:42 PM, Alan Grayson wrote:



On Wednesday, April 20, 2022 at 6:14:31 PM UTC-6 Alan Grayson wrote:

On Wednesday, April 20, 2022 at 5:21:47 PM UTC-6 Alan Grayson
wrote:



On Friday, April 15, 2022 at 12:41:03 PM UTC-6
meeke...@gmail.com wrote:



On 4/14/2022 2:00 PM, George Kahrimanis wrote:

On Wednesday, April 13, 2022 at 8:55:48 PM UTC+3
meeke...@gmail.com (Brent) wrote:

Decoherence has gone part way in solving the
when/where/what basis questions, but only part way.


As I wrote at the end of my first reply to your
message, I share your concern about decoherence but
I see the glass as half-full; that is, with a little
more subtlety I hope that the matter can be
formulated in clear terms.

Surely collapse is easier to handle as a general
concept (except, on the other hand, that it requires
new dynamics). I forgot to mention that *my argument
for deriving the Born Rule works with collapse, too*
-- so it is an alternative to Gleason's theorem.

Here I define colapse as an irreversible process,
violating unitarity of course, and I keep it
separate from randomisation. The latter means that
each outcome is somehow randomised -- an assumption
we can do without.

*Collapse can also be described in a many-world
formulation!* It differs from the no-collapse MWI
only in being irreversible.


If you can throw away low probability branches,
what's to stop you from throwing away all but one? 
You've already broken unitary evolution.  If you read
Hardy's axiomatization of QM you see that the
difference between QM and classical mechanics turns
on a single word in Axiom 5 Continuity: There exists
a *continuous *reversible transformation on a system
between any two pure states of that system.


My argument in outline is
1. assessment that MWI-with-collapse is workable;
2. therefore, outcomes of small enough measure can
be neglected in practice;


Yes, I've wondered if a smallest non-zero probability
could be defined consistent with the data.


3. now Everett's argument can proceed, concluding
that the Born Rule is a practically safe assumption
(to put it briefly).

So I have replaced two assumptions of Gleason's
theorem, randomisation and non-contextuality, by the
assessment of workability only.

If you don't feel comfortable yet with formulating
collapse in a many-world setting, let us also assume
randomisation (God plays dice), for the sake of the
argument, in a single-world formulation. That is, we
ASSUME the existence of probability; then the
previous argument just guarantees that this
probability follows the Born Rule.


Assume?  Randomness is well motivated by evidence. 
And it's more random than just not knowing some
inherent variable, because in the EPR experiment a
randomized hidden variable can on explain the QM
result if it's non-local.





Of course I favour the first version of the
argument, using the many-world formulation of
collapse, to avoid the "God plays dice" nightmare.


Why this fear of true randomness?  We have all kinds
of classical randomness we just attributed to
"historical accident". Would it really make any
difference it were due to inherent quantum
randomness? Albrect and Phillips have made an
argument that there is quantum randomness even
nominally classical dynamics.
https://arxiv.org/abs/1212.0953v3


The authors regard quantum fluctuations as fundamental.
How are they defined? AG

I think I get it. Whereas before QM we could attribute
single, unpredictABLE outcomes to ignorance of initial
conditions, and but with QM our understanding is augmented;
now we can attribute it to ... nothing? AG

Is that because, if we could attribute a single, unpredictable
outccome to ignorance, that would be, 

Re: aiming to complete Everett's derivation of the Born Rule

[Alan Grayson]

On Wednesday, April 20, 2022 at 7:53:33 PM UTC-6 meeke...@gmail.com wrote:

>
>
> On 4/20/2022 6:42 PM, Alan Grayson wrote:
>
>
>
> On Wednesday, April 20, 2022 at 6:14:31 PM UTC-6 Alan Grayson wrote:
>
>> On Wednesday, April 20, 2022 at 5:21:47 PM UTC-6 Alan Grayson wrote:
>>
>>>
>>>
>>> On Friday, April 15, 2022 at 12:41:03 PM UTC-6 meeke...@gmail.com wrote:
>>>


 On 4/14/2022 2:00 PM, George Kahrimanis wrote:

 On Wednesday, April 13, 2022 at 8:55:48 PM UTC+3 meeke...@gmail.com 
 (Brent) wrote:

 Decoherence has gone part way in solving the when/where/what basis 
> questions, but only part way.
>

 As I wrote at the end of my first reply to your message, I share your 
 concern about decoherence but I see the glass as half-full; that is, with 
 a 
 little more subtlety I hope that the matter can be formulated in clear 
 terms.

 Surely collapse is easier to handle as a general concept (except, on 
 the other hand, that it requires new dynamics). I forgot to mention that 
 *my 
 argument for deriving the Born Rule works with collapse, too* -- so it 
 is an alternative to Gleason's theorem.

 Here I define colapse as an irreversible process, violating unitarity 
 of course, and I keep it separate from randomisation. The latter means 
 that 
 each outcome is somehow randomised -- an assumption we can do without.

 *Collapse can also be described in a many-world formulation!* It 
 differs from the no-collapse MWI only in being irreversible. 


 If you can throw away low probability branches, what's to stop you from 
 throwing away all but one?  You've already broken unitary evolution.  If 
 you read Hardy's axiomatization of QM you see that the difference between 
 QM and classical mechanics turns on a single word in Axiom 5 Continuity: 
 There exists a *continuous *reversible transformation on a system 
 between any two pure states of that system.

 My argument in outline is
 1. assessment that MWI-with-collapse is workable;
 2. therefore, outcomes of small enough measure can be neglected in 
 practice;


 Yes, I've wondered if a smallest non-zero probability could be defined 
 consistent with the data.

 3. now Everett's argument can proceed, concluding that the Born Rule is 
 a practically safe assumption (to put it briefly).

 So I have replaced two assumptions of Gleason's theorem, randomisation 
 and non-contextuality, by the assessment of workability only.

 If you don't feel comfortable yet with formulating collapse in a 
 many-world setting, let us also assume randomisation (God plays dice), for 
 the sake of the argument, in a single-world formulation. That is, we 
 ASSUME 
 the existence of probability; then the previous argument just guarantees 
 that this probability follows the Born Rule.


 Assume?  Randomness is well motivated by evidence.  And it's more 
 random than just not knowing some inherent variable, because in the EPR 
 experiment a randomized hidden variable can on explain the QM result if 
 it's non-local.

>>>


 Of course I favour the first version of the argument, using the 
 many-world formulation of collapse, to avoid the "God plays dice" 
 nightmare.


 Why this fear of true randomness?  We have all kinds of classical 
 randomness we just attributed to "historical accident".  Would it really 
 make any difference it were due to inherent quantum randomness?  Albrect 
 and Phillips have made an argument that there is quantum randomness even 
 nominally classical dynamics. https://arxiv.org/abs/1212.0953v3

>>>
>>> The authors regard quantum fluctuations as fundamental. How are they 
>>> defined? AG
>>>
>> I think I get it. Whereas before QM we could attribute single, 
>> unpredictABLE outcomes to ignorance of initial conditions, and but with QM 
>> our understanding is augmented; now we can attribute it to ... nothing? AG
>>
> Is that because, if we could attribute a single, unpredictable outccome to 
> ignorance, that would be, defacto, a hidden variable theory? AG 
>
>
> Roughtly, yes.  That's what a hidden variable is, a value that if you knew 
> it you could predict the outcome.
>
> Brent
>
 
Why the quaified "yes"? Does Bell's theorem exclude ignorance as a hidden 
variable? AG

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Re: The Nature of Contingency: Quantum Physics as Modal Realism

[Bruce Kellett]

On Thu, Apr 21, 2022 at 11:58 PM smitra  wrote:

> On 21-04-2022 14:13, Bruce Kellett wrote:
> >
> > As has been pointed out by others, superpositions are ubiquitous. It
> > is only superpositions of the basis vectors of pointer states that are
> > relevant. Pointer states are those that are robust under environmental
> > decoherence. Once you trace over the unobserved environmental degrees
> > of freedom, the superposition is gone, and the worlds no longer
> > interfere -- there is no macro-superposition.
> >
> While that's how we do computations in practice, superpositions of
> observers having made different observations will continue to exist.
> That one can trace out the unobserved environmental degrees of freedom
> does not cause the superposition to vanish.
>

So what? That is what FAPP is for: there is no practical purpose in
continuing to insist that the superposition exists.

> So what does she branch due to? Of course Alice is subject to
> > decoherence as much as anyone else.
>
> The information content describing what she is aware of can be factored
> out of the superposition.
>

In which case it is entirely useless. Physics does not exist to satisfy
your metaphysical urges.

The many minds interpretation of MWI has been abandoned for very good
reasons. It actually makes no sense, and cannot be derived from the
Schrodinger equation or any other dynamical theory. It was introduced by
Albert and Loewer in an attempt to make sense of probabilities in MWI. It
failed in that attempt, and we now know that MWI is inconsistent with any
sensible interpretation of probability; strict MWI is inconsistent with the
Born rule.

Bruce

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Re: aiming to complete Everett's derivation of the Born Rule

[Brent Meeker]

On 4/21/2022 3:03 PM, George Kahrimanis wrote:
In my current way of thinking, the disagreement between Alan Grayson 
and John K. Clark is about two subtly different concepts under the 
same name, "probability". For example, when I read "80% chance of rain 
today", I may think that in some possible futures it will not rain (so 
probability is meaningless), yet I feel an instinctive urge for 
protection from bad weather, so I take my umbrella. We are programmed 
to act in this way, due to Darwinian selection -- but it is a 
different matter to claim that QM (without collapse) issues a 
probability for each possible outcome so that then we are rationally 
obliged to apply Maximisation of Expected Utility. I grant the former 
but not the latter.


Part of the trouble is that serious philosophical issues about 
probability are still debated, so that there are traps for anyone who 
deals with these things. Here is an example.


> [...] until Alan Grayson sees the end of the race, or somebody tells Alan Grayson about it, Alan 
Grayson can't be certain what world Alan Grayson is in. Alan Grayson 
could be in a world where horse X won or Alan Grayson could be in a 
world where horse Y won, until Alan Grayson receives more information 
Alan Grayson would have to say the odds are 50-50.


If you mean that on sheer ignorance the odds are 50-50, we need some 
clarifications. Strictly speaking, zero information implies "undefined 
probability", or "imprecise probability between 0 and 1". The reason 
it is commonly mistaken as 50-50 is an implied strategy, flipping a 
coin in case of ignorance, but then the odds are of the coin instead 
of the object of the bet. (This strategy works only if the agent is 
free to choose which side of the bet she underwrites.)


If the odds 50/50 can apply to the coin...because you don't know which 
way it will come down...then the same concept applies to the horse race.




For the instrumentalists among us (glad to have you, BTW): the 
question of interest to me is not about which way is best to derive 
probability from QM -- that would be a pointless discussion, I agree! 
The question is whether all of them beg the question, so that we have 
to think of a rational decision theory without probability.


Rational decision theory only exists because of uncertainty.  If there 
were no uncertainty one wouldn't need theory to inform your choice, you 
would directly by value.


Brent



Although Everett's argument (whose improvement I have proposed) grants 
that in the long run (that is, large samples) the Born Rule is 
practically certain to apply, this is not technically the same as 
probability for each single outcome -- though I admit that it works 
the same, to trigger an instinctive impulse. But for a RATIONAL 
decision theory this probability is not granted, IMO.


I can give examples of a decision theory w/o probability, but they 
would dilute the focus of this message.


George K. --
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Re: aiming to complete Everett's derivation of the Born Rule

[George Kahrimanis]

In my current way of thinking, the disagreement between Alan Grayson and 
John K. Clark is about two subtly different concepts under the same name, 
"probability". For example, when I read "80% chance of rain today", I may 
think that in some possible futures it will not rain (so probability is 
meaningless), yet I feel an instinctive urge for protection from bad 
weather, so I take my umbrella. We are programmed to act in this way, due 
to Darwinian selection -- but it is a different matter to claim that QM 
(without collapse) issues a probability for each possible outcome so that 
then we are rationally obliged to apply Maximisation of Expected Utility. I 
grant the former but not the latter.

Part of the trouble is that serious philosophical issues about probability 
are still debated, so that there are traps for anyone who deals with these 
things. Here is an example.

> [...] until Alan Grayson sees the end of the race, or somebody tells Alan 
Grayson about it, Alan Grayson can't be certain what world Alan Grayson is 
in. Alan Grayson could be in a world where horse X won or Alan Grayson 
could be in a world where horse Y won, until Alan Grayson receives more 
information Alan Grayson would have to say the odds are 50-50.

If you mean that on sheer ignorance the odds are 50-50, we need some 
clarifications. Strictly speaking, zero information implies "undefined 
probability", or "imprecise probability between 0 and 1". The reason it is 
commonly mistaken as 50-50 is an implied strategy, flipping a coin in case 
of ignorance, but then the odds are of the coin instead of the object of 
the bet. (This strategy works only if the agent is free to choose which 
side of the bet she underwrites.)

For the instrumentalists among us (glad to have you, BTW): the question of 
interest to me is not about which way is best to derive probability from QM 
-- that would be a pointless discussion, I agree! The question is whether 
all of them beg the question, so that we have to think of a rational 
decision theory without probability.

Although Everett's argument (whose improvement I have proposed) grants that 
in the long run (that is, large samples) the Born Rule is practically 
certain to apply, this is not technically the same as probability for each 
single outcome -- though I admit that it works the same, to trigger an 
instinctive impulse. But for a RATIONAL decision theory this probability is 
not granted, IMO.

I can give examples of a decision theory w/o probability, but they would 
dilute the focus of this message.

George K.

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Re: The Nature of Contingency: Quantum Physics as Modal Realism

[Brent Meeker]

On 4/21/2022 1:27 PM, smitra wrote:

On 21-04-2022 20:18, Brent Meeker wrote:

On 4/21/2022 1:32 AM, smitra wrote:

On 21-04-2022 02:53, Bruce Kellett wrote:

On Thu, Apr 21, 2022 at 10:05 AM George Kahrimanis
 wrote:


On Tue, Apr 19, 2022 at 11:09 AM Brent Meeker 
wrote:

The only purpose of the box in Schroedinger's thought experiment was
to put off the observers perception.  Really the thought experiment
is over when the radioactive decay occurs.  That atom has
transitioned to a different nuclear state which is entangled with
and recorded in the environment.


On Tuesday, April 19, 2022 at 4:20:49 AM UTC+3 Bruce wrote:


Yes. Schrodinger had the cat in a box to emphasize the idea that the
cat was in a macro-superposition of alive/dead. This misled Wigner
to the extent that he thought the state collapsed only when the box
was opened. All of this was made redundant when it was realized that
decoherence  rendered the state definite almost instantaneously.
Saibal makes the same mistake when he claims that Alice, after her
measurement, is still in a superposition until Bob sees her result.
The idea that the superposition still exists since decoherence is
only FAPP is something of a red herring -- in MWI, Alice has
branched according to her result into up and down branches that no
longer interfere. There is no macro-superposition.




This is wrong, because inability to demonstrate interference does 
not mean that there is no superposition.


Alice does not branch due to decoherence. It is true that there are 
two branches where the results of Bob are different due to rapid 
decoherence. But before Alice knows the result of Bob, the state of 
the algorithm that represent Alice's mind will be identical in both 
branches. What matters is whether or not information about Bob's 
result can change Alice's subjective state. Only then can the two 
branches from Alice's point of view, diverge. If this were possible, 
then that means that Alice could obtain information about Bob's 
result without even looking at his result. So, Alice would have 
psychic abilities.


Of course she can obtain information about Bob's result without
looking at it.  That's what decoherence does, spread information into
the environment so that there is a fact-of-the-matter as to the
result.

You've apparently bought into the Many Minds interpretation of MWI, so
the cat isn't dead, the vial isn't broken, and the atom isn't decayed
until Wigner's friend looks in.



Yes, the Many Minds version of the MWI makes the most sense. The mind 
as defined by the algorithm the brain is running is the same in the 
different sectors.










-1- Decoherence (by a chaotic environment) turns an entangled
superposition into a non-coherent density matrix, only if we
subsequently omit the environment from the description of the system.
(Not if we keep the environment in the description.)

FAPP is for a reason -- we automatically trace out unneeded
environmental variables.


-2- The "box" (in which Scroedinger's cat is enclosed, with the
lethal apparatus) contains also its "environment", so a quantum
descrition of this box describes the environment also. Therefore I
do not agree that decoherence INSIDE THE BOX will ruin the
superposition ASSESSED FROM OUTSIDE THE BOX. So, Wigner was right. I
suppose that Saibal also is right, though I have not checked that
message (sorry).


Unfortunately for this idea, decoherence does not stop at the box. In
the time that Wigner thinks about this before he opens the box,
decoherence has enveloped essentially the whole world, so Wigner
himself has decohered into either a world with a dead cat or a world
with a live cat. He can't dissociate himself from the split that
occurs, so from his point of view outside the box, the superposition
is long gone, and he has to deal with a simple classical state of
either a dead cat or a live cat -- no superposition remains.



The superposition does remain, it's just that it cannot be probed in 
interference experiments. Before Wigner knows the result, his 
subjective state of his mind is the same in both branches. It 
doesn't matter that everything in his environment  including the 
atoms in his brain is entangled with the state after the experiment. 
What matters is that Wigner cannot know the result without observing 
it. The bitstring that contains all the information he is aware of, 
is the same in both branches.


What if he forgets what he saw?


If he forgets, then he'll merge with the versions in the other sectors 
that also forgot what he saw. What matters is the bit string that 
represents everything she is aware of at a certain moment. When he 
remembers again then he'll spit again. 


This splitting an merging dozens of times per second.  But merging with 
what or whom.  Is Bob merging with other Bob's who have different 
memories but aren't recalling them at the moment?


You do realize don't you that if you take this view you've made QM 
personal and epistemic so we 

Re: The Nature of Contingency: Quantum Physics as Modal Realism

[smitra]

On 21-04-2022 20:18, Brent Meeker wrote:

On 4/21/2022 1:32 AM, smitra wrote:

On 21-04-2022 02:53, Bruce Kellett wrote:

On Thu, Apr 21, 2022 at 10:05 AM George Kahrimanis
 wrote:


On Tue, Apr 19, 2022 at 11:09 AM Brent Meeker 
wrote:

The only purpose of the box in Schroedinger's thought experiment was
to put off the observers perception.  Really the thought experiment
is over when the radioactive decay occurs.  That atom has
transitioned to a different nuclear state which is entangled with
and recorded in the environment.


On Tuesday, April 19, 2022 at 4:20:49 AM UTC+3 Bruce wrote:


Yes. Schrodinger had the cat in a box to emphasize the idea that the
cat was in a macro-superposition of alive/dead. This misled Wigner
to the extent that he thought the state collapsed only when the box
was opened. All of this was made redundant when it was realized that
decoherence  rendered the state definite almost instantaneously.
Saibal makes the same mistake when he claims that Alice, after her
measurement, is still in a superposition until Bob sees her result.
The idea that the superposition still exists since decoherence is
only FAPP is something of a red herring -- in MWI, Alice has
branched according to her result into up and down branches that no
longer interfere. There is no macro-superposition.




This is wrong, because inability to demonstrate interference does not 
mean that there is no superposition.


Alice does not branch due to decoherence. It is true that there are 
two branches where the results of Bob are different due to rapid 
decoherence. But before Alice knows the result of Bob, the state of 
the algorithm that represent Alice's mind will be identical in both 
branches. What matters is whether or not information about Bob's 
result can change Alice's subjective state. Only then can the two 
branches from Alice's point of view, diverge. If this were possible, 
then that means that Alice could obtain information about Bob's 
result  without even looking at his result. So, Alice would have 
psychic abilities.


Of course she can obtain information about Bob's result without
looking at it.  That's what decoherence does, spread information into
the environment so that there is a fact-of-the-matter as to the
result.

You've apparently bought into the Many Minds interpretation of MWI, so
the cat isn't dead, the vial isn't broken, and the atom isn't decayed
until Wigner's friend looks in.



Yes, the Many Minds version of the MWI makes the most sense. The mind as 
defined by the algorithm the brain is running is the same in the 
different sectors.










-1- Decoherence (by a chaotic environment) turns an entangled
superposition into a non-coherent density matrix, only if we
subsequently omit the environment from the description of the system.
(Not if we keep the environment in the description.)

FAPP is for a reason -- we automatically trace out unneeded
environmental variables.


-2- The "box" (in which Scroedinger's cat is enclosed, with the
lethal apparatus) contains also its "environment", so a quantum
descrition of this box describes the environment also. Therefore I
do not agree that decoherence INSIDE THE BOX will ruin the
superposition ASSESSED FROM OUTSIDE THE BOX. So, Wigner was right. I
suppose that Saibal also is right, though I have not checked that
message (sorry).


Unfortunately for this idea, decoherence does not stop at the box. In
the time that Wigner thinks about this before he opens the box,
decoherence has enveloped essentially the whole world, so Wigner
himself has decohered into either a world with a dead cat or a world
with a live cat. He can't dissociate himself from the split that
occurs, so from his point of view outside the box, the superposition
is long gone, and he has to deal with a simple classical state of
either a dead cat or a live cat -- no superposition remains.



The superposition does remain, it's just that it cannot be probed in 
interference experiments. Before Wigner knows the result, his 
subjective state of his mind is the same in both branches. It doesn't 
matter that everything in his environment  including the atoms in his 
brain is entangled with the state after the experiment. What matters 
is that Wigner cannot know the result without observing it. The 
bitstring that contains all the information he is aware of, is the 
same in both branches.


What if he forgets what he saw?


If he forgets, then he'll merge with the versions in the other sectors 
that also forgot what he saw. What matters is the bit string that 
represents everything she is aware of at a certain moment. When he 
remembers again then he'll spit again. Remembering is the result of 
consulting the memory and the memory was in a superposition entangled 
with the environment. If information in the memory is processed by the 
algorithm that represents the mind of the person, then the person's mind 
will split again.


Saibal




Brent

If not and the bitstring would have diverged 

Re: The Nature of Contingency: Quantum Physics as Modal Realism

[George Kahrimanis]

On Thursday, April 21, 2022 at 3:54:04 AM UTC+3 Bruce wrote:

> On Thu, Apr 21, 2022 at 10:05 AM George Kahrimanis  
> wrote:
>
>> -2- The "box" (in which Scroedinger's cat is enclosed, with the lethal 
>> apparatus) contains also its "environment", so a quantum descrition of this 
>> box describes the environment also. Therefore I do not agree that 
>> decoherence INSIDE THE BOX will ruin the superposition ASSESSED FROM 
>> OUTSIDE THE BOX. So, Wigner was right. I suppose that Saibal also is right, 
>> though I have not checked that message (sorry).
>>
>
> Unfortunately for this idea, decoherence does not stop at the box. In the 
> time that Wigner thinks about this before he opens the box, decoherence has 
> enveloped essentially the whole world, so Wigner himself has decohered into 
> either a world with a dead cat or a world with a live cat. He can't 
> dissociate himself from the split that occurs, so from his point of view 
> outside the box, the superposition is long gone, and he has to deal with a 
> simple classical state of either a dead cat or a live cat -- no 
> superposition remains.
>

I see we have converged on other technical issues, so maybe this works out, 
too. Perhaps I did not make it clear enough that the environment inside 
this "box" is isolated from the environment outside the box. Only then the 
cat is in a superposition as commonly understood. Otherwise we need the 
environment to define the superposition, which Saibal does in the recent 
messages, but I think it is pointless. So, I meant that Wigner is right but 
under this assumption only: of the two environments.

I had always made a distinction between faster-than-light influences, which 
> are intrinsically local since they involve the local transfer of 
> information via some medium (albeit FTL), and non-local influences, which 
> do not involve any FTL transfers. They are instantaneous and non-local.  So 
> that does not violate relativity. [...]
>

I cannot tell, from this brief comment, whether HV theories become more 
plausible in this way, but I will congratulate you if this is so. I am not 
ready though to enter this discussion now.

George K.

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Re: The Nature of Contingency: Quantum Physics as Modal Realism

[Brent Meeker]

On 4/21/2022 1:32 AM, smitra wrote:

On 21-04-2022 02:53, Bruce Kellett wrote:

On Thu, Apr 21, 2022 at 10:05 AM George Kahrimanis
 wrote:


On Tue, Apr 19, 2022 at 11:09 AM Brent Meeker 
wrote:

The only purpose of the box in Schroedinger's thought experiment was
to put off the observers perception.  Really the thought experiment
is over when the radioactive decay occurs.  That atom has
transitioned to a different nuclear state which is entangled with
and recorded in the environment.


On Tuesday, April 19, 2022 at 4:20:49 AM UTC+3 Bruce wrote:


Yes. Schrodinger had the cat in a box to emphasize the idea that the
cat was in a macro-superposition of alive/dead. This misled Wigner
to the extent that he thought the state collapsed only when the box
was opened. All of this was made redundant when it was realized that
decoherence  rendered the state definite almost instantaneously.
Saibal makes the same mistake when he claims that Alice, after her
measurement, is still in a superposition until Bob sees her result.
The idea that the superposition still exists since decoherence is
only FAPP is something of a red herring -- in MWI, Alice has
branched according to her result into up and down branches that no
longer interfere. There is no macro-superposition.




This is wrong, because inability to demonstrate interference does not 
mean that there is no superposition.


Alice does not branch due to decoherence. It is true that there are 
two branches where the results of Bob are different due to rapid 
decoherence. But before Alice knows the result of Bob, the state of 
the algorithm that represent Alice's mind will be identical in both 
branches. What matters is whether or not information about Bob's 
result can change Alice's subjective state. Only then can the two 
branches from Alice's point of view, diverge. If this were possible, 
then that means that Alice could obtain information about Bob's 
result  without even looking at his result. So, Alice would have 
psychic abilities.


Of course she can obtain information about Bob's result without looking 
at it.  That's what decoherence does, spread information into the 
environment so that there is a fact-of-the-matter as to the result.


You've apparently bought into the Many Minds interpretation of MWI, so 
the cat isn't dead, the vial isn't broken, and the atom isn't decayed 
until Wigner's friend looks in.


Brent






-1- Decoherence (by a chaotic environment) turns an entangled
superposition into a non-coherent density matrix, only if we
subsequently omit the environment from the description of the system.
(Not if we keep the environment in the description.)

FAPP is for a reason -- we automatically trace out unneeded
environmental variables.


-2- The "box" (in which Scroedinger's cat is enclosed, with the
lethal apparatus) contains also its "environment", so a quantum
descrition of this box describes the environment also. Therefore I
do not agree that decoherence INSIDE THE BOX will ruin the
superposition ASSESSED FROM OUTSIDE THE BOX. So, Wigner was right. I
suppose that Saibal also is right, though I have not checked that
message (sorry).


Unfortunately for this idea, decoherence does not stop at the box. In
the time that Wigner thinks about this before he opens the box,
decoherence has enveloped essentially the whole world, so Wigner
himself has decohered into either a world with a dead cat or a world
with a live cat. He can't dissociate himself from the split that
occurs, so from his point of view outside the box, the superposition
is long gone, and he has to deal with a simple classical state of
either a dead cat or a live cat -- no superposition remains.



The superposition does remain, it's just that it cannot be probed in 
interference experiments. Before Wigner knows the result, his 
subjective state of his mind is the same in both branches. It doesn't 
matter that everything in his environment  including the atoms in his 
brain is entangled with the state after the experiment. What matters 
is that Wigner cannot know the result without observing it. The 
bitstring that contains all the information he is aware of, is the 
same in both branches. 


What if he forgets what he saw?

Brent

If not and the bitstring would have diverged across the two branches 
and Wigner could then simply feel the result without having to do any 
observation.



Saibal




I rephrase my conclusion. I agree with you, on the splits being
technically non-local, but this is only an artifact of describing
the dynamical evolution of the wavefunction in space-like slices
forming a time-like stack. Thus a split affects the whole slice in
which it occurs. But seen from a moving train, it would be a
different slice! Only on and inside the light cone, the split is
physically meaningful.


The split is associated with the light cone, so it is Lorentz
invariant.


Thanks to your insistence, now I see the difference between
non-local HV theories, which violate 

Re: NYTimes.com: Don’t Just Freeze Russia’s Money. Seize It.

[spudboy100 via Everything List]

Last, first, JC. There were things about him that I liked immediately. He was 
asked by a reporter from NBC when he announced his campaign in 2015, about 
money buying politicians. He replied, "You give them money they'll do whatever 
you want." That blunt honesty was amazing for me, because it explained 
everything that happened in DC for decades. He was so refreshing compared to 
racist, self righteous, Obama, that clicked for me. It also give word, flesh, 
as related to the Princeton study of 2014.
https://www.bbc.com/news/blogs-echochambers-27074746
I never expected him to do as well as he did with unemployment, The Border, the 
middle east, after everyone told him no way. He did shoot his mouth off with 
tweets but was good at hitting back against the dems who simply are good with a 
dictatorship as long as it doesn't affect them personally via inflation, 
employment, crime, freedom of speech. 
On your points, yes Trumpo loved to squeeze back on what he considered America 
getting screwed.He thought we should have taken over and sold Iraqi oil under 
Bush43 for compensation for getting rid of Saddam.He bitched at and called out 
Merkel who for 16 years made pals with Putin by buying his gas and funding his 
military. 
The Ukrainians are no saints and neither are the Bidens, taking bribes from the 
Ukraine, Russia, and China, with Hunter and Joe's brother being the bag men. 
Hunter does have a preference for expensive prostitutes but this is a remark on 
my part, not a condemnation. On Trump and Putin, Trump always tried to butter 
Vlad's ass in order (my assessment) to keep the door open and not as Khrushchev 
said during the Cuban Missile Crisis "to tie the knot tighter." 
The Afghanistan thing was always with the Taliban, a nuanced deal. He could go, 
but not without an observed, cessation of violence. Example, is that Trump ok'd 
the bombing of Putin's mercenaries in Syria when they were attacking. 
https://www.nytimes.com/2018/05/24/world/middleeast/american-commandos-russian-mercenaries-syria.html
https://www.newsweek.com/total-f-russian-mercenaries-syria-lament-us-strike-killed-dozens-818073
So, JC, your characterization of Orangey as a Putin puppet is disproven by 
Trumpo's actions. Biden, well, I suspect that he took orders on foreign policy 
directly from Obama regarding the debacle in Afghanistan 2021, and the failed 
Ayatollah nuke deal, which will likely cause nuclear war, tween the holy 
ayatollahs and Israel. Some scientists say that even a small nuke war would 
cause nuclear winter, so we may find this out? 
https://www.axios.com/leaked-document-reveals-bidens-afghan-failures-c27d790c-3a50-4734-8543-7db710898bb2.html

https://www.cnn.com/2021/04/14/politics/biden-overrules-advisers-afghanistan-withdrawal/index.html

Don's digs were sometimes really funny, but the main reason is that I felt if 
Comrade Xi or Putin attacked, Donny would retaliate. For your peeps, not so 
much. Witness-
https://www.reuters.com/article/us-nuclear-usa-announcement/obama-limits-u-s-use-of-nuclear-arms-idUSTRE6352YK20100406

https://www.nytimes.com/2010/04/06/world/06arms.html

Then, later on 
overseas..https://www.washingtonpost.com/opinions/global-opinions/allies-unite-to-block-an-obama-legacy/2016/08/14/cdb8d8e4-60b9-11e6-8e45-477372e89d78_story.html

Thus, is a world filled with people who want to get to heaven over our dead 
bodies, or see nothing beyond the limits of their party ideology, the dems 
ain't making it! On your team, even though you'll wince at this, I could see me 
supporting Manchin on energy over zero availability of mass solar that the dems 
keep promising without doing, or Tulsi Gabbard who would strike back against 
Xi, Putin, or some other nazi?
For El Donaldo, he keeps yakking about stolen elections, and I keep asking 
where's the evidence? If the courts won't hear it the public still could! This 
depends only if Ballot Harvesting was corrupt and was just a way of Ballot Box 
Box Tammany Hall 19th century Fraud??
Donaldo is not my 1st choice for 24, by the way...
-Original Message-
From: John Clark 
To: spudboy...@aol.com
Cc: everything-list@googlegroups.com 
Sent: Thu, Apr 21, 2022 6:11 am
Subject: Re: NYTimes.com: Don’t Just Freeze Russia’s Money. Seize It.

On Wed, Apr 20, 2022 at 6:26 PM  wrote:


> Biden gave 1000's of Javs to the Ukrainians

Yes, and unlike Trump Biden did it without demanding that the Ukrainian 
president "do me a favor"  before he got any Javelins so Ukraine could defend 
itself from Russia. Trump insisted that Zelenskyy dig up dirt on his political 
opponent, or rather PUBLICLY announce that he was going to dig up dirt on his 
political opponent; Trump made it clear there was no need for Ukraine to actual 
do any investigation, just an announcement would be sufficient provided it was 
done publicly.



> but there was no Ukraine invasion under Trumpy.

Bullshit! The Russo-Ukrainian War started in 2014 when Russia invaded Crimea 
and the Donetsk 

RE: Unspoken Reasons for Russio-Ukraine War: An Unawakened Consciousness Problem

[Philip Benjamin]

[Philip Benjamin]
   I cannot read Putin's mind!! I simply presented some news clips. I also 
restated what I have done so many times that the West in  general has lost her 
"Awakened" moorings to Marxist pagan-Socialist-Fascist globalists. Philip 
Benjamin

From: spudboy...@aol.com https://www.newsweek.com/russias-putin-says-he-always-liked-communist-socialist-ideas-419289

So, Vlad plays both ends against the middle as Genghis Khan always did. In 
2022, Putin plays Xi's China versus Modi's India, with hopes of obtaining 
economic and political advantage. Same with communist atheists, and foreign 
nationalists as well. Wait! Isn't this what the Devil is supposed to do too??!!


-Original Message-
From: Philip Benjamin mailto:medinucl...@hotmail.com>>
To: Everything List 
mailto:everything-list@googlegroups.com>>
Cc: general_the...@googlegroups.com 
mailto:general_the...@googlegroups.com>>
Sent: Mon, Apr 18, 2022 4:32 pm
Subject: Unspoken Reasons for Russio-Ukraine War: An Unawakened Consciousness 
Problem
[Philip Benjamin]  References given at the bottom.
  NYTimes.com: "Don't Just Freeze Russia's Money. Seize It. " The WAMP defined 
below knows that the unspoken reason for the Russo-Ukraine war is moral not 
political- an unenergized bio dark-matter twin body problem.
" Western nations commit genocide upon other countries that refuse to hold gay 
pride parades." Says the Orthodox Patriarch of Russia. "Ukraine's LGBTQ is 
forced to confront this as a threat to its own community" reports NY Times. 
Russia was frightened by the decrepit Western cultural onslaught on their 
traditional institutions especially the school systems. So they amend their 
Constitution to ban LGBTQ agenda. "Super Power" America & the West has long 
forgotten their 
Patriarchal-Prophetic-Aostolic-Augustinian-Athanesian-Reformation- 
Puritan-"Great Awakening" roots which have now become largely  a terra 
incognita (verisimilar to Judges 2:10). Instead they conformed to 
Marxist-Socialist-pagan globalism which Russia has rejected. The cowardice of 
unawakened consciousness created a leadership vacuum which Russia now 
presumably decided to fill.
Philip Benjamin
(Nonconformist to Marxist pagan globalism)

NY Times. 
https://www.nytimes.com/2022/03/17/world/russia-ukraine-queer-activists.html 

 "But the war that started when Russia invaded on Feb. 24 has forced Ukraine's 
L.G.B.T.Q. movement to confront a threat not only to national sovereignty, but 
also to its own community. A pro-Russian puppet government, they say, would be 
less supportive of the L.G.B.T.Q. agenda."
https://god.dailydot.com/russian-bishop-gay-pride/ 

 Russian Orthodox bishop Kirill, the official Orthodox Patriarch of Moscow, 
came out with a rather wild claim about "the West" during a sermon, saying that 
Western nations commit genocide upon other countries that refuse to hold gay 
pride parades. No, really.
https://god.dailydot.com/russian-bishop-gay-pride/ 

 
https://god.dailydot.com/russian-bishop-gay-pride/
"In a sermon held on Sunday, Russian Church leader, Kirill justified Ukraine's 
invasion & blamed gay pride parades for Russia's invasion of the war-hit 
Ukraine". Written By Ajay Sharma
  CNN. 
https://edition.cnn.com/europe/live-news/ukraine-russia-putin-news-03-08-22/ 

Re: The Nature of Contingency: Quantum Physics as Modal Realism

[smitra]

On 21-04-2022 14:13, Bruce Kellett wrote:

On Thu, Apr 21, 2022 at 6:32 PM smitra  wrote:


On 21-04-2022 02:53, Bruce Kellett wrote:

On Thu, Apr 21, 2022 at 10:05 AM George Kahrimanis
 wrote:


On Tue, Apr 19, 2022 at 11:09 AM Brent Meeker



wrote:

The only purpose of the box in Schroedinger's thought experiment

was

to put off the observers perception.  Really the thought

experiment

is over when the radioactive decay occurs.  That atom has
transitioned to a different nuclear state which is entangled with
and recorded in the environment.


On Tuesday, April 19, 2022 at 4:20:49 AM UTC+3 Bruce wrote:


Yes. Schrodinger had the cat in a box to emphasize the idea that

the

cat was in a macro-superposition of alive/dead. This misled

Wigner

to the extent that he thought the state collapsed only when the

box

was opened. All of this was made redundant when it was realized

that

decoherence  rendered the state definite almost instantaneously.
Saibal makes the same mistake when he claims that Alice, after

her

measurement, is still in a superposition until Bob sees her

result.

The idea that the superposition still exists since decoherence is
only FAPP is something of a red herring -- in MWI, Alice has
branched according to her result into up and down branches that

no

longer interfere. There is no macro-superposition.




This is wrong, because inability to demonstrate interference does
not
mean that there is no superposition.


As has been pointed out by others, superpositions are ubiquitous. It
is only superpositions of the basis vectors of pointer states that are
relevant. Pointer states are those that are robust under environmental
decoherence. Once you trace over the unobserved environmental degrees
of freedom, the superposition is gone, and the worlds no longer
interfere -- there is no macro-superposition.

While that's how we do computations in practice, superpositions of 
observers having made different observations will continue to exist. 
That one can trace out the unobserved environmental degrees of freedom 
does not cause the superposition to vanish.




Alice does not branch due to decoherence.


So what does she branch due to? Of course Alice is subject to
decoherence as much as anyone else.



The information content describing what she is aware of can be factored 
out of the superposition.



It is true that there are two
branches where the results of Bob are different due to rapid
decoherence. But before Alice knows the result of Bob, the state of
the
algorithm that represent Alice's mind will be identical in both
branches


The state of Alice's mind is of minor relevance. You are coming close
to Wigner's failed idea that consciousness collapses the wave
function.



There is no collapse of the wavefunction. What matters is that Alice 
considered as an algorithm run by her brain can be factored out of the 
global superposition as long as that algorithm does not process the 
information from Bob's result.



What matters is whether or not information about Bob's result
can change Alice's subjective state. Only then can the two branches
from
Alice's point of view, diverge. If this were possible, then that
means
that Alice could obtain information about Bob's result  without even

looking at his result. So, Alice would have psychic abilities.


If Alice's mind/brain is entangled with the results of Bob's
measurement, then if she can access that brain state directly, that
will enable her to ascertain Bob's result. There are multiple copies
of the result entangled with the environment. But people can seldom
directly access the state of their own brain. (It is all irrelevant,
anyway. Physics is not determined by subjective states.)

As long as she doesn't succeed in doing that and doesn't know the 
result, she is identical in the different sectors.



-1- Decoherence (by a chaotic environment) turns an entangled
superposition into a non-coherent density matrix, only if we
subsequently omit the environment from the description of the

system.

(Not if we keep the environment in the description.)

FAPP is for a reason -- we automatically trace out unneeded
environmental variables.


-2- The "box" (in which Scroedinger's cat is enclosed, with the
lethal apparatus) contains also its "environment", so a quantum
descrition of this box describes the environment also. Therefore

I

do not agree that decoherence INSIDE THE BOX will ruin the
superposition ASSESSED FROM OUTSIDE THE BOX. So, Wigner was

right. I

suppose that Saibal also is right, though I have not checked that
message (sorry).


Unfortunately for this idea, decoherence does not stop at the box.

In

the time that Wigner thinks about this before he opens the box,
decoherence has enveloped essentially the whole world, so Wigner
himself has decohered into either a world with a dead cat or a

world

with a live cat. He can't dissociate himself from the split that
occurs, so from his point of view outside the box, the

superposition

Re: The Nature of Contingency: Quantum Physics as Modal Realism

[Bruce Kellett]

On Thu, Apr 21, 2022 at 6:32 PM smitra  wrote:

> On 21-04-2022 02:53, Bruce Kellett wrote:
> > On Thu, Apr 21, 2022 at 10:05 AM George Kahrimanis
> >  wrote:
> >
> >> On Tue, Apr 19, 2022 at 11:09 AM Brent Meeker 
> >> wrote:
> >>
> >> The only purpose of the box in Schroedinger's thought experiment was
> >> to put off the observers perception.  Really the thought experiment
> >> is over when the radioactive decay occurs.  That atom has
> >> transitioned to a different nuclear state which is entangled with
> >> and recorded in the environment.
> >
> > On Tuesday, April 19, 2022 at 4:20:49 AM UTC+3 Bruce wrote:
> >
> >> Yes. Schrodinger had the cat in a box to emphasize the idea that the
> >> cat was in a macro-superposition of alive/dead. This misled Wigner
> >> to the extent that he thought the state collapsed only when the box
> >> was opened. All of this was made redundant when it was realized that
> >> decoherence  rendered the state definite almost instantaneously.
> >> Saibal makes the same mistake when he claims that Alice, after her
> >> measurement, is still in a superposition until Bob sees her result.
> >> The idea that the superposition still exists since decoherence is
> >> only FAPP is something of a red herring -- in MWI, Alice has
> >> branched according to her result into up and down branches that no
> >> longer interfere. There is no macro-superposition.
> >
>
> This is wrong, because inability to demonstrate interference does not
> mean that there is no superposition.
>

As has been pointed out by others, superpositions are ubiquitous. It is
only superpositions of the basis vectors of pointer states that are
relevant. Pointer states are those that are robust under environmental
decoherence. Once you trace over the unobserved environmental degrees of
freedom, the superposition is gone, and the worlds no longer interfere --
there is no macro-superposition.


Alice does not branch due to decoherence.


So what does she branch due to? Of course Alice is subject to decoherence
as much as anyone else.

> It is true that there are two
> branches where the results of Bob are different due to rapid
> decoherence. But before Alice knows the result of Bob, the state of the
> algorithm that represent Alice's mind will be identical in both
> branches


The state of Alice's mind is of minor relevance. You are coming close to
Wigner's failed idea that consciousness collapses the wave function.

What matters is whether or not information about Bob's result
> can change Alice's subjective state. Only then can the two branches from
> Alice's point of view, diverge. If this were possible, then that means
> that Alice could obtain information about Bob's result  without even
> looking at his result. So, Alice would have psychic abilities.
>

If Alice's mind/brain is entangled with the results of Bob's measurement,
then if she can access that brain state directly, that will enable her to
ascertain Bob's result. There are multiple copies of the result entangled
with the environment. But people can seldom directly access the state of
their own brain. (It is all irrelevant, anyway. Physics is not
determined by subjective states.)


> -1- Decoherence (by a chaotic environment) turns an entangled
> > superposition into a non-coherent density matrix, only if we
> > subsequently omit the environment from the description of the system.
> > (Not if we keep the environment in the description.)
> >
> > FAPP is for a reason -- we automatically trace out unneeded
> > environmental variables.
> >
> >> -2- The "box" (in which Scroedinger's cat is enclosed, with the
> >> lethal apparatus) contains also its "environment", so a quantum
> >> descrition of this box describes the environment also. Therefore I
> >> do not agree that decoherence INSIDE THE BOX will ruin the
> >> superposition ASSESSED FROM OUTSIDE THE BOX. So, Wigner was right. I
> >> suppose that Saibal also is right, though I have not checked that
> >> message (sorry).
> >
> > Unfortunately for this idea, decoherence does not stop at the box. In
> > the time that Wigner thinks about this before he opens the box,
> > decoherence has enveloped essentially the whole world, so Wigner
> > himself has decohered into either a world with a dead cat or a world
> > with a live cat. He can't dissociate himself from the split that
> > occurs, so from his point of view outside the box, the superposition
> > is long gone, and he has to deal with a simple classical state of
> > either a dead cat or a live cat -- no superposition remains.
> >
>
> The superposition does remain, it's just that it cannot be probed in
> interference experiments.


No one is doing interference experiments on Schrodinger's cat

Before Wigner knows the result, his subjective
> state of his mind is the same in both branches. It doesn't matter that
> everything in his environment  including the atoms in his brain is
> entangled with the state after the experiment. What matters is that
> Wigner 

Re: NYTimes.com: Don’t Just Freeze Russia’s Money. Seize It.

[John Clark]

On Wed, Apr 20, 2022 at 6:26 PM  wrote:

*> Biden gave 1000's of Javs to the Ukrainians*
>

Yes, and unlike Trump Biden did it without demanding that the Ukrainian
president "do me a favor"  before he got any Javelins so Ukraine could
defend itself from Russia. Trump insisted that Zelenskyy dig up dirt on his
political opponent, or rather PUBLICLY announce that he was going to dig up
dirt on his political opponent; Trump made it clear there was no need for
Ukraine to actual do any investigation, just an announcement would be
sufficient provided it was done publicly.


*> but there was no Ukraine invasion under Trumpy.*
>

Bullshit! The Russo-Ukrainian War started in 2014 when Russia invaded
Crimea and the Donetsk region, both are parts of Ukraine. Ukraine resisted
with force, since then it had been a low intensity war, about one Ukrainian
was killed by a Russian soldier every three days, and Russia has been
relentless in its cyber attacks on Ukraine. The war went into high gear
when Russia invaded all of Ukraine on February 24, 2022,  and the death
toll jumped to the tens of thousands of Ukrainian dead, and not just
soldiers, civilians too. And yet TO THIS DAY Trump has refused to criticize
his buddy Vladimir Putin, in fact even AFTER  February 24 he called Putin a
"genius" and "savy" for having invaded Ukraine. Maybe when Trump focuses
his very dim mind on Putin he does seem like a genius by comparison, but
when anybody of even average intelligence looks at Putin and his February
24 decision all he sees is a dumbass.


> * > Vlad looked at Biden's withdrawal in Afghanistan, and was able to
> conjure up a weakling policy that offered a real opportunity.*
>

Trump had long publicly advocated that the US get out of Afghanistan, but
even after being president for 4 years he never had the guts to actually do
it because he knew there is just no getting around the fact that when you
officially lose a war it looks very bad, so he decided to let his successor
clean up the mess.

Spud, I just don't understand why you and other members of Trump's cult of
personality feel it is their sacred duty to twist themselves into logical
and ethical contortions to defend everything that their guru does and says.
Is Trump's "comic timing" really *THAT* good?

John K ClarkSee what's on my new list at  Extropolis

tct

r
>

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Re: The Nature of Contingency: Quantum Physics as Modal Realism

[smitra]

On 21-04-2022 02:53, Bruce Kellett wrote:

On Thu, Apr 21, 2022 at 10:05 AM George Kahrimanis
 wrote:


On Tue, Apr 19, 2022 at 11:09 AM Brent Meeker 
wrote:

The only purpose of the box in Schroedinger's thought experiment was
to put off the observers perception.  Really the thought experiment
is over when the radioactive decay occurs.  That atom has
transitioned to a different nuclear state which is entangled with
and recorded in the environment.


On Tuesday, April 19, 2022 at 4:20:49 AM UTC+3 Bruce wrote:


Yes. Schrodinger had the cat in a box to emphasize the idea that the
cat was in a macro-superposition of alive/dead. This misled Wigner
to the extent that he thought the state collapsed only when the box
was opened. All of this was made redundant when it was realized that
decoherence  rendered the state definite almost instantaneously.
Saibal makes the same mistake when he claims that Alice, after her
measurement, is still in a superposition until Bob sees her result.
The idea that the superposition still exists since decoherence is
only FAPP is something of a red herring -- in MWI, Alice has
branched according to her result into up and down branches that no
longer interfere. There is no macro-superposition.




This is wrong, because inability to demonstrate interference does not 
mean that there is no superposition.


Alice does not branch due to decoherence. It is true that there are two 
branches where the results of Bob are different due to rapid 
decoherence. But before Alice knows the result of Bob, the state of the 
algorithm that represent Alice's mind will be identical in both 
branches. What matters is whether or not information about Bob's result 
can change Alice's subjective state. Only then can the two branches from 
Alice's point of view, diverge. If this were possible, then that means 
that Alice could obtain information about Bob's result  without even 
looking at his result. So, Alice would have psychic abilities.





-1- Decoherence (by a chaotic environment) turns an entangled
superposition into a non-coherent density matrix, only if we
subsequently omit the environment from the description of the system.
(Not if we keep the environment in the description.)

FAPP is for a reason -- we automatically trace out unneeded
environmental variables.


-2- The "box" (in which Scroedinger's cat is enclosed, with the
lethal apparatus) contains also its "environment", so a quantum
descrition of this box describes the environment also. Therefore I
do not agree that decoherence INSIDE THE BOX will ruin the
superposition ASSESSED FROM OUTSIDE THE BOX. So, Wigner was right. I
suppose that Saibal also is right, though I have not checked that
message (sorry).


Unfortunately for this idea, decoherence does not stop at the box. In
the time that Wigner thinks about this before he opens the box,
decoherence has enveloped essentially the whole world, so Wigner
himself has decohered into either a world with a dead cat or a world
with a live cat. He can't dissociate himself from the split that
occurs, so from his point of view outside the box, the superposition
is long gone, and he has to deal with a simple classical state of
either a dead cat or a live cat -- no superposition remains.



The superposition does remain, it's just that it cannot be probed in 
interference experiments. Before Wigner knows the result, his subjective 
state of his mind is the same in both branches. It doesn't matter that 
everything in his environment  including the atoms in his brain is 
entangled with the state after the experiment. What matters is that 
Wigner cannot know the result without observing it. The bitstring that 
contains all the information he is aware of, is the same in both 
branches. If not and the bitstring would have diverged across the two 
branches and Wigner could then simply feel the result without having to 
do any observation.



Saibal




I rephrase my conclusion. I agree with you, on the splits being
technically non-local, but this is only an artifact of describing
the dynamical evolution of the wavefunction in space-like slices
forming a time-like stack. Thus a split affects the whole slice in
which it occurs. But seen from a moving train, it would be a
different slice! Only on and inside the light cone, the split is
physically meaningful.


The split is associated with the light cone, so it is Lorentz
invariant.


Thanks to your insistence, now I see the difference between
non-local HV theories, which violate relativity, and MWI, which does
not.


I had always made a distinction between faster-than-light influences,
which are intrinsically local since they involve the local transfer of
information via some medium (albeit FTL), and non-local influences,
which do not involve any FTL transfers. They are instantaneous and
non-local.  So that does not violate relativity. In fact, FTL
transmission does not strictly violate relativity either -- tachyons
are perfectly consistent with relativity.