Re: What is the quantum state of a macro object?

[agrayson2000]

On Wednesday, November 15, 2017 at 11:33:46 PM UTC-7, Brent wrote:
>
>
>
> On 11/15/2017 9:25 PM, agrays...@gmail.com  wrote:
>
>
>
> On Wednesday, November 15, 2017 at 9:08:29 PM UTC-7, Brent wrote: 
>>
>>
>>
>> On 11/15/2017 7:36 PM, agrays...@gmail.com wrote:
>>
>>
>>
>> On Wednesday, November 15, 2017 at 7:54:27 PM UTC-7, Brent wrote: 
>>>
>>> Interesting questions.  Whenever we talk about a system being in a 
>>> quantum state, we're thinking of the "system" as some degrees of freedom 
>>> that are isolated, so they are not interacting with and becoming entangled 
>>> with other things.  An SG experiment typically uses silver atoms and refers 
>>> to their state as UP or DOWN or LEFT or RIGHT.  But that's not a complete 
>>> description of the silver atom.  It has other degrees of freedom, which we 
>>> ignore as irrelevant to the SG measurement.  So a "system" which we 
>>> describe as having a state, isn't necessarily the same as an object, like a 
>>> baseball or even an atom.  A classical object like a baseball has lots of 
>>> degrees of freedom and they are interacting with the environment, so they 
>>> are entangled with states of the environment.  Only certain collective 
>>> variables, e.g. the conserved ones like momentum, are stable in the stat 
>>> mech sense.  These ones that are stable against interaction with the 
>>> environment are the einselected values we can measure classically.   So we 
>>> could write a wave-function for the baseball as if it were an isolated 
>>> particle, like the silver atom, and ignore all the internal dof which are 
>>> not in any definite state because they're entangled with atmospheric 
>>> molecules and IR photons, etc. 
>>>
>>> Whether something is in a superposition of states isn't an interesting 
>>> question because the answer is always "Yes...relative to some basis."  The 
>>> interesting point is that since constituents in the baseball have 
>>> interacted with and are now entangled with air molecules, those 
>>> constituents of the baseball are not in any definite state.  Only the 
>>> constituent PLUS the molecules it is entangled with has a definite state.  
>>> In any basis we can imagine measuring, they will be in a superposition 
>>> relative to that basis.  But in theory there would some basis in which the 
>>> isolated baseball plus molecules would be an eigenstate; it's just so 
>>> complicated we could never measure in that basis.   But if were to consider 
>>> a very simple system, like a few electrons then we might be able to measure 
>>> in the eigenbasis.
>>>
>>> Brent
>>>
>>
>> TY.  That was very informative. Let's go on. How does a micro constituent 
>> of a macro object get entangled with, say, an air molecule? When I think of 
>> entanglement, I think of some special process to it.create it. How does it 
>> happen spontaneously? Is it stable or does it decay rapidly, and if so into 
>> what? TIA.
>>
>>
>> Don't think of the constituents as objects, think of them as degrees of 
>> or modes of excitations.  So an N2 molecule collides with the baseball and 
>> it excites a certain vibration mode of the ball.  Now that mode and the 
>> motion of the N2 molecule are entangled.  If you're just interested in the 
>> ball you can just average over, trace out, the N2 molecule modes and then 
>> you're left with a mixed density matrix for the modes of the baseball.  Of 
>> course all this changes very quickly, spreading the entanglement to more 
>> modes of the baseball, radiating some away as IR photons, more collisions 
>> of N2 and O2 molecules.  That's decoherence that washes out all the 
>> coherent interference that we can observe with carefully isolated systems.  
>> It isn't decaying, it's diffusing the information about the microscopic dof 
>> into the environment.
>>
>> Brent
>>
>
> Generally speaking, some particles of the macro object are entangled with 
> the environment, and some not. 
>
>
> Didn't I just tell you not to think that!?  
>

I didn't forget. I just wanted to say something about the constituent 
particles and their entanglement with the environment, not about excited 
modes. Thanks for your time. 
 

> The particles of an object are all interacting with one another (which is 
> how they make an 'object') so they are all entangled with one another and 
> with the environment.  But if you think about some mode that might be 
> excited, then you could represent that mode as a "thing" which was 
> entangled with a single N2 that had collided with the ball and created that 
> excitation.
>
> In some basis, the entangled states are definite states (maybe not the 
> same basis for each). 
>
>
> In theory, any isolated system, not entangled with anything outside the 
> system,  has a definite state.  The problem with entanglement is that it 
> quickly diffuses out of the isolation unless extraordinary circumstances 
> obtain.
>
> Can we say the same about unentangled particles (understood as modes of 
> excitations)? Do 

Re: Consistency of Postulates of QM

[agrayson2000]

On Wednesday, November 15, 2017 at 3:00:22 PM UTC-7, John Clark wrote:
>
> On Tue, Nov 14, 2017 at 6:17 PM,  
> wrote:
>
> ​> ​
>> Any macro object is in a definite state
>>
>
> ​That is incorrect. An electron an be in a single quantum state with just 
> one associated wave function, 2 electrons can do the sane thing in 
> superconductors they're called "Cooper pairs", and the same can also be 
> true for several million atoms in a Bose–Einstein condensate but you have 
> to cool them  to less than a millionth of a degree above absolute zero; but 
> all the 10^25 atoms in a baseball have their own different wave function 
> because unlike the atoms in a Bose–Einstein condensate all the atoms in a 
> baseball are NOT entangled with each other, if they were a baseball would 
> exhibit the same weird behavior as an electron.  That would certainly make 
> for a more interesting game and might even be enough to turn me into a 
> baseball fan.
>
> Two atoms are quantum entangled entangled if they have the same wave 
> function but it's a delicate condition and must be carefully isolated from 
> the environment, the more atoms the more delicate it is, 10^25 atoms is so 
> delicate we never see it.
>

I didn't mean to imply that all atoms in a baseball have the same entangled 
state. Some may be entangled with the environment, some with each other, or 
not entangled but in stationary states. I just meant that whatever state 
it's in, it's not in contradiction with REALISM. Even superpositions are 
not in contradiction with REALISM,  

>
> ​>​
>> Multiverse arose in the context of string theory, after Everett's MWI. 
>> The difference between Multiverse and MWI is striking and obvious.
>>
>
> ​Explain to me how ​
> Everett's MWI
> ​ can work without the Multiverse.​ The fact that string theory also needs 
> a Multiverse just give more support to Everett, or at least it would if 
> there were any experimental evidence to indecate string theory was true,  
>

The Many Worlds of Everett and String Theory have no direct or indirect 
relationship, other than invoking other possible universes. You keep 
ignoring the fact that these other worlds, if they exist, arise in totally 
different contexts and theories and to continue to conflate them obfuscates 
any understanding we might arrive at.

>
> ​>
 ​>>​
 ​
 For example, we know that irrational numbers exist

>>>
>>> ​>> ​
>>> Do we? 
>>>
>>
>> ​> ​
>> O
>> ​​
>> f course. It has been proven that pi and e are not rational.
>>
>
> ​Yes, in the language of mathematics there are stories about rational and 
> irrational numbers and there are also stories about pi and e and you can 
> prove that the stories abut irrationality are consistent with pi and e. And 
> in the language of English there are stories about Harry Potter and it can 
> be proven that Harry's aunt is named Petunia, but there is no proof that 
> harry or Petunia exist in the physical world and there is no proof 
> pi or e (not to be confused with the approximations of pi and e) have any 
> effect on the laws of physics.  ​
>  
>  
>
>> It's also been proven that the irrationals are dense in the reals; that 
>> is, many "more" irrationals than rationals;
>>
>
> ​And the stories also say there are many more  non-computable Real 
> numbers ​
> ​than computable Real numbers, the set of computable numbers is not dense 
> on the reals, its countably infinite with a cardinality of 
> Aleph-naught
> ​. If a number is not computable, ​that is to say  unlike pi or e then is 
> no procedure for even approximating it then I don't see how it cold be of 
> any importance to physics. And I say again Many Worlds is a theory about 
> physics not mathematics.  
>
> What about the rational numbers, does physics need all of them? 
>  The answer in not certain but we already have good reason to suspect that 
> neither time nor space is continuous, although although we won't know for 
> sure until we understand quantum gravity.  
>

Says a lot that you take such a dim view of mathematics, except when it 
comes to reifying the wf. Not just "stories" but real knowledge; maybe the 
only real knowledge. As for the continuity of time and space, to the extent 
we can test for it, continuity is so far affirmed. Others can cite the 
experiments. And if affirmed it means the possible outcomes in a slit 
experiment is uncountable -- and this, my friend, IS physics. 
 

>
> ​>> ​
>>> there might be a infinite number of Turing Machines in the Multiverse 
>>> but they couldn't communicate with each other and none of them would have a 
>>> infinite amount of tape. So any real Turing Machine in the Multiverse is 
>>> certain to eventually stop, not for any software reason but because of 
>>> hardware failure. Eventual any real Turing machine will get a command like 
>>> "move the read/wright head one box to the left write a 1 in the box and 
>>> then change to state 6.02*10^23" but it will be unable 

Re: What is the quantum state of a macro object?

[Brent Meeker]

On 11/15/2017 9:25 PM, agrayson2...@gmail.com wrote:



On Wednesday, November 15, 2017 at 9:08:29 PM UTC-7, Brent wrote:



On 11/15/2017 7:36 PM, agrays...@gmail.com  wrote:



On Wednesday, November 15, 2017 at 7:54:27 PM UTC-7, Brent wrote:

Interesting questions.  Whenever we talk about a system being
in a quantum state, we're thinking of the "system" as some
degrees of freedom that are isolated, so they are not
interacting with and becoming entangled with other things. 
An SG experiment typically uses silver atoms and refers to
their state as UP or DOWN or LEFT or RIGHT.  But that's not a
complete description of the silver atom.  It has other
degrees of freedom, which we ignore as irrelevant to the SG
measurement.  So a "system" which we describe as having a
state, isn't necessarily the same as an object, like a
baseball or even an atom.  A classical object like a baseball
has lots of degrees of freedom and they are interacting with
the environment, so they are entangled with states of the
environment.  Only certain collective variables, e.g. the
conserved ones like momentum, are stable in the stat mech
sense.  These ones that are stable against interaction with
the environment are the einselected values we can measure
classically.   So we could write a wave-function for the
baseball as if it were an isolated particle, like the silver
atom, and ignore all the internal dof which are not in any
definite state because they're entangled with atmospheric
molecules and IR photons, etc.

Whether something is in a superposition of states isn't an
interesting question because the answer is always
"Yes...relative to some basis."  The interesting point is
that since constituents in the baseball have interacted with
and are now entangled with air molecules, those constituents
of the baseball are not in any definite state.  Only the
constituent PLUS the molecules it is entangled with has a
definite state.  In any basis we can imagine measuring, they
will be in a superposition relative to that basis.  But in
theory there would some basis in which the isolated baseball
plus molecules would be an eigenstate; it's just so
complicated we could never measure in that basis.   But if
were to consider a very simple system, like a few electrons
then we might be able to measure in the eigenbasis.

Brent


TY.  That was very informative. Let's go on. How does a micro
constituent of a macro object get entangled with, say, an air
molecule? When I think of entanglement, I think of some special
process to it.create it. How does it happen spontaneously? Is it
stable or does it decay rapidly, and if so into what? TIA.


Don't think of the constituents as objects, think of them as
degrees of or modes of excitations.  So an N2 molecule collides
with the baseball and it excites a certain vibration mode of the
ball.  Now that mode and the motion of the N2 molecule are
entangled.  If you're just interested in the ball you can just
average over, trace out, the N2 molecule modes and then you're
left with a mixed density matrix for the modes of the baseball. 
Of course all this changes very quickly, spreading the
entanglement to more modes of the baseball, radiating some away as
IR photons, more collisions of N2 and O2 molecules.  That's
decoherence that washes out all the coherent interference that we
can observe with carefully isolated systems.  It isn't decaying,
it's diffusing the information about the microscopic dof into the
environment.

Brent


Generally speaking, some particles of the macro object are entangled 
with the environment, and some not.


Didn't I just tell you not to think that!?  The particles of an object 
are all interacting with one another (which is how they make an 
'object') so they are all entangled with one another and with the 
environment.  But if you think about some mode that might be excited, 
then you could represent that mode as a "thing" which was entangled with 
a single N2 that had collided with the ball and created that excitation.


In some basis, the entangled states are definite states (maybe not the 
same basis for each).


In theory, any isolated system, not entangled with anything outside the 
system,  has a definite state.  The problem with entanglement is that it 
quickly diffuses out of the isolation unless extraordinary circumstances 
obtain.


Can we say the same about unentangled particles (understood as modes 
of excitations)? Do they have definite states? Is there any sense in 
which the entire macro object is "in a definite state" (albeit 
fluctuating)? TIA.


An entire macro object could be in a 

Re: Consistency of Postulates of QM

[Brent Meeker]

On 11/15/2017 10:23 PM, smitra wrote:

No time to find the right branch in this thread.

Briefly the point I'm making is not really conditional on the details 
of quantum mechanics or the MWI, except that I'm assuming multiple 
worlds. The point is that in any parallel universes situation where I 
exist an I have a lot of hair on my head which I have bothered to 
count, I should consider myself to be  present in the set of all 
universes where the knowledge I have about myself and my surroundings 
are the same. So, this then includes copies that are not exact copies, 
some will have a different number of hair on their head.


Only when I count the number of hair on my head will I split away from 
the copies that find different results.  So, this is not per se a 
quantum mechanical issue, but you could say that the effectively 
classical world where I exist in well defined states where I can do 
such things as count the number of hair on my head arises due to 
decoherence.


If you forget the number of hairs will your worlds merge again? What if 
you're just not thinking about the number of hairs?


Brent

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Re: Consistency of Postulates of QM

[smitra]

No time to find the right branch in this thread.

Briefly the point I'm making is not really conditional on the details of 
quantum mechanics or the MWI, except that I'm assuming multiple worlds. 
The point is that in any parallel universes situation where I exist an I 
have a lot of hair on my head which I have bothered to count, I should 
consider myself to be  present in the set of all universes where the 
knowledge I have about myself and my surroundings are the same. So, this 
then includes copies that are not exact copies, some will have a 
different number of hair on their head.


Only when I count the number of hair on my head will I split away from 
the copies that find different results.  So, this is not per se a 
quantum mechanical issue, but you could say that the effectively 
classical world where I exist in well defined states where I can do such 
things as count the number of hair on my head arises due to decoherence.


Saibal

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Re: Consistency of Postulates of QM

[Brent Meeker]

On 11/15/2017 9:09 PM, Bruce Kellett wrote:

On 16/11/2017 11:30 am, Russell Standish wrote:

On Thu, Nov 16, 2017 at 10:20:45AM +1100, Bruce Kellett wrote:

On 16/11/2017 9:14 am, Russell Standish wrote:

That is because we're considering an SG experiment, with an SG
experimenter. That breaks the symmetry.

The environment breaks the symmetry. The environment may contain an
experimenter, but need not. A camera would do the job.

The camera merely decoheres the system, which remains in a superposition
of the two possible outcomes of the SG experiment. To break that
symmetry requires an observer looking at the photo plate, or
downloading the image from the camera's CCD and observing it on a 
screen.


The observer looking at the plate merely becomes entangled with the 
result on that plate -- splits along with the original split caused by 
the measurement. This does not break any symmetry that might be 
present. I am still not sure exactly what symmetry you are seeking to 
break. At some point, separation into separate non-interacting worlds 
requires the the superposed pure state be broken into a mixed state, 
but I would not see that particularly as a symmetry breaking. Exactly 
how the transition from pure to mixed comes about is somewhat unclear 
at present.  One could simply say that the 'worlds' are relative 
states, relative to the original experimental result. Or one could 
call on coarse graining, or take a partial trace. Zurek has what I 
consider a better scheme, whereby the fact that the experimental 
result is immediately repeatable -- the experiment leave the system in 
an eigenstate -- is sufficient to cause the separate worlds to be 
exactly orthogonal, so that the density matrix is exactly diagonal.


I like Zurek's point, but in most measurements the system measured is 
destroyed.  The measurement that acts as a preparation, leaving the 
system in an eigenstate is rare.


Brent

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Re: What is the quantum state of a macro object?

[agrayson2000]

On Wednesday, November 15, 2017 at 9:08:29 PM UTC-7, Brent wrote:
>
>
>
> On 11/15/2017 7:36 PM, agrays...@gmail.com  wrote:
>
>
>
> On Wednesday, November 15, 2017 at 7:54:27 PM UTC-7, Brent wrote: 
>>
>> Interesting questions.  Whenever we talk about a system being in a 
>> quantum state, we're thinking of the "system" as some degrees of freedom 
>> that are isolated, so they are not interacting with and becoming entangled 
>> with other things.  An SG experiment typically uses silver atoms and refers 
>> to their state as UP or DOWN or LEFT or RIGHT.  But that's not a complete 
>> description of the silver atom.  It has other degrees of freedom, which we 
>> ignore as irrelevant to the SG measurement.  So a "system" which we 
>> describe as having a state, isn't necessarily the same as an object, like a 
>> baseball or even an atom.  A classical object like a baseball has lots of 
>> degrees of freedom and they are interacting with the environment, so they 
>> are entangled with states of the environment.  Only certain collective 
>> variables, e.g. the conserved ones like momentum, are stable in the stat 
>> mech sense.  These ones that are stable against interaction with the 
>> environment are the einselected values we can measure classically.   So we 
>> could write a wave-function for the baseball as if it were an isolated 
>> particle, like the silver atom, and ignore all the internal dof which are 
>> not in any definite state because they're entangled with atmospheric 
>> molecules and IR photons, etc. 
>>
>> Whether something is in a superposition of states isn't an interesting 
>> question because the answer is always "Yes...relative to some basis."  The 
>> interesting point is that since constituents in the baseball have 
>> interacted with and are now entangled with air molecules, those 
>> constituents of the baseball are not in any definite state.  Only the 
>> constituent PLUS the molecules it is entangled with has a definite state.  
>> In any basis we can imagine measuring, they will be in a superposition 
>> relative to that basis.  But in theory there would some basis in which the 
>> isolated baseball plus molecules would be an eigenstate; it's just so 
>> complicated we could never measure in that basis.   But if were to consider 
>> a very simple system, like a few electrons then we might be able to measure 
>> in the eigenbasis.
>>
>> Brent
>>
>
> TY.  That was very informative. Let's go on. How does a micro constituent 
> of a macro object get entangled with, say, an air molecule? When I think of 
> entanglement, I think of some special process to it.create it. How does it 
> happen spontaneously? Is it stable or does it decay rapidly, and if so into 
> what? TIA.
>
>
> Don't think of the constituents as objects, think of them as degrees of or 
> modes of excitations.  So an N2 molecule collides with the baseball and it 
> excites a certain vibration mode of the ball.  Now that mode and the motion 
> of the N2 molecule are entangled.  If you're just interested in the ball 
> you can just average over, trace out, the N2 molecule modes and then you're 
> left with a mixed density matrix for the modes of the baseball.  Of course 
> all this changes very quickly, spreading the entanglement to more modes of 
> the baseball, radiating some away as IR photons, more collisions of N2 and 
> O2 molecules.  That's decoherence that washes out all the coherent 
> interference that we can observe with carefully isolated systems.  It isn't 
> decaying, it's diffusing the information about the microscopic dof into the 
> environment.
>
> Brent
>

Generally speaking, some particles of the macro object are entangled with 
the environment, and some not. In some basis, the entangled states are 
definite states (maybe not the same basis for each). Can we say the same 
about unentangled particles (understood as modes of excitations)? Do they 
have definite states? Is there any sense in which the entire macro object 
is "in a definite state" (albeit fluctuating)? TIA. 
 

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Re: Consistency of Postulates of QM

[Bruce Kellett]

On 16/11/2017 11:30 am, Russell Standish wrote:

On Thu, Nov 16, 2017 at 10:20:45AM +1100, Bruce Kellett wrote:

In the first place, it is unlikely that all possible outcomes of an
experiment are equally likely. But I think you are confusing symmetry
breaking with the observer self-locating in one of the possible outcome
worlds.

Where is the confusion? Prior to self-location, the observer is in all
possible worlds, afterwards in just one.


No, the observer is in all branches equally at all times. His view of 
the experimental result is just the result that obtained in the word to 
which he has self-located. But all other results are also in worlds with 
equivalent observers who have self-located differently. No symmetry has 
been broken by this. Observers have just become entangled with the results.


Bruce

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Re: Consistency of Postulates of QM

[Bruce Kellett]

On 16/11/2017 11:30 am, Russell Standish wrote:

On Thu, Nov 16, 2017 at 10:20:45AM +1100, Bruce Kellett wrote:

On 16/11/2017 9:14 am, Russell Standish wrote:

That is because we're considering an SG experiment, with an SG
experimenter. That breaks the symmetry.

The environment breaks the symmetry. The environment may contain an
experimenter, but need not. A camera would do the job.

The camera merely decoheres the system, which remains in a superposition
of the two possible outcomes of the SG experiment. To break that
symmetry requires an observer looking at the photo plate, or
downloading the image from the camera's CCD and observing it on a screen.


The observer looking at the plate merely becomes entangled with the 
result on that plate -- splits along with the original split caused by 
the measurement. This does not break any symmetry that might be present. 
I am still not sure exactly what symmetry you are seeking to break. At 
some point, separation into separate non-interacting worlds requires the 
the superposed pure state be broken into a mixed state, but I would not 
see that particularly as a symmetry breaking. Exactly how the transition 
from pure to mixed comes about is somewhat unclear at present.  One 
could simply say that the 'worlds' are relative states, relative to the 
original experimental result. Or one could call on coarse graining, or 
take a partial trace. Zurek has what I consider a better scheme, whereby 
the fact that the experimental result is immediately repeatable -- the 
experiment leave the system in an eigenstate -- is sufficient to cause 
the separate worlds to be exactly orthogonal, so that the density matrix 
is exactly diagonal.


Bruce

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Re: Consistency of Postulates of QM

[Bruce Kellett]

On 16/11/2017 11:30 am, Russell Standish wrote:

On Thu, Nov 16, 2017 at 10:20:45AM +1100, Bruce Kellett wrote:

On 16/11/2017 9:14 am, Russell Standish wrote:

The choice between circularly polarised filter and linear polarised
filters is binary. Obviously, there follows the choice of orientation,
which is continuous...

Whatever the choice of orientation, the outcome is binary, pass or not pass.


Yes - but I was referring to what is the preferred basis, not the
experimental outcome.


Choosing the orientation is choosing what to measure, it is not the 
measurement itself. It is just like choosing to measure either the 
position or the momentum of a particle - any particular choice rules out 
other choices. But once the choice is made, one can do the measurement. 
The orientation angle does not set the preferred basis, which is decided 
by environmental decoherence. In the polarization case it is the 
observation of reaction with a screen or photomultiplier tube - the 
photon passed or failed to pass.  The polarization state is an inference 
from this measurement.


Bruce

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Re: What is the quantum state of a macro object?

[Brent Meeker]

On 11/15/2017 7:36 PM, agrayson2...@gmail.com wrote:



On Wednesday, November 15, 2017 at 7:54:27 PM UTC-7, Brent wrote:

Interesting questions. Whenever we talk about a system being in a
quantum state, we're thinking of the "system" as some degrees of
freedom that are isolated, so they are not interacting with and
becoming entangled with other things.  An SG experiment typically
uses silver atoms and refers to their state as UP or DOWN or LEFT
or RIGHT.  But that's not a complete description of the silver
atom.  It has other degrees of freedom, which we ignore as
irrelevant to the SG measurement.  So a "system" which we describe
as having a state, isn't necessarily the same as an object, like a
baseball or even an atom.  A classical object like a baseball has
lots of degrees of freedom and they are interacting with the
environment, so they are entangled with states of the
environment.  Only certain collective variables, e.g. the
conserved ones like momentum, are stable in the stat mech sense. 
These ones that are stable against interaction with the
environment are the einselected values we can measure classically.
  So we could write a wave-function for the baseball as if it were
an isolated particle, like the silver atom, and ignore all the
internal dof which are not in any definite state because they're
entangled with atmospheric molecules and IR photons, etc.

Whether something is in a superposition of states isn't an
interesting question because the answer is always "Yes...relative
to some basis."  The interesting point is that since constituents
in the baseball have interacted with and are now entangled with
air molecules, those constituents of the baseball are not in any
definite state.  Only the constituent PLUS the molecules it is
entangled with has a definite state.  In any basis we can imagine
measuring, they will be in a superposition relative to that
basis.  But in theory there would some basis in which the isolated
baseball plus molecules would be an eigenstate; it's just so
complicated we could never measure in that basis.   But if were to
consider a very simple system, like a few electrons then we might
be able to measure in the eigenbasis.

Brent


TY.  That was very informative. Let's go on. How does a micro 
constituent of a macro object get entangled with, say, an air 
molecule? When I think of entanglement, I think of some special 
process to it.create it. How does it happen spontaneously? Is it 
stable or does it decay rapidly, and if so into what? TIA.


Don't think of the constituents as objects, think of them as degrees of 
freedom or modes of excitations.  So an N2 molecule collides with the 
baseball and it excites a certain vibration mode of the ball. Now that 
mode and the motion of the N2 molecule are entangled.  If you're just 
interested in the ball you can just average over, trace out, the N2 
molecule modes and then you're left with a mixed density matrix for the 
modes of the baseball.  Of course all this changes very quickly, 
spreading the entanglement to more modes of the baseball, radiating some 
away as IR photons, more collisions of N2 and O2 molecules.  That's 
decoherence that washes out all the coherent interference that we can 
observe with carefully isolated systems.  It isn't decaying, it's 
diffusing the information about the microscopic dof into the environment.


Brent

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Re: What is the quantum state of a macro object?

[agrayson2000]

On Wednesday, November 15, 2017 at 7:54:27 PM UTC-7, Brent wrote:
>
> Interesting questions.  Whenever we talk about a system being in a quantum 
> state, we're thinking of the "system" as some degrees of freedom that are 
> isolated, so they are not interacting with and becoming entangled with 
> other things.  An SG experiment typically uses silver atoms and refers to 
> their state as UP or DOWN or LEFT or RIGHT.  But that's not a complete 
> description of the silver atom.  It has other degrees of freedom, which we 
> ignore as irrelevant to the SG measurement.  So a "system" which we 
> describe as having a state, isn't necessarily the same as an object, like a 
> baseball or even an atom.  A classical object like a baseball has lots of 
> degrees of freedom and they are interacting with the environment, so they 
> are entangled with states of the environment.  Only certain collective 
> variables, e.g. the conserved ones like momentum, are stable in the stat 
> mech sense.  These ones that are stable against interaction with the 
> environment are the einselected values we can measure classically.   So we 
> could write a wave-function for the baseball as if it were an isolated 
> particle, like the silver atom, and ignore all the internal dof which are 
> not in any definite state because they're entangled with atmospheric 
> molecules and IR photons, etc. 
>
> Whether something is in a superposition of states isn't an interesting 
> question because the answer is always "Yes...relative to some basis."  The 
> interesting point is that since constituents in the baseball have 
> interacted with and are now entangled with air molecules, those 
> constituents of the baseball are not in any definite state.  Only the 
> constituent PLUS the molecules it is entangled with has a definite state.  
> In any basis we can imagine measuring, they will be in a superposition 
> relative to that basis.  But in theory there would some basis in which the 
> isolated baseball plus molecules would be an eigenstate; it's just so 
> complicated we could never measure in that basis.   But if were to consider 
> a very simple system, like a few electrons then we might be able to measure 
> in the eigenbasis.
>
> Brent
>

TY.  That was very informative. Let's go on. How does a micro constituent 
of a macro object get entangled with, say, an air molecule? When I think of 
entanglement, I think of some special process to it.create it. How does it 
happen spontaneously? Is it stable or does it decay rapidly, and if so into 
what? TIA.

>
> On 11/15/2017 5:56 PM, agrays...@gmail.com  wrote:
>
> Consider a baseball. Is it in some kind of composite state, however 
> defined, of its constituents? Are all its constituents entangled with the 
> environment? If some are not, are they in a superposition of states? I pose 
> these questions because in my discussions with Clark on another thread, 
> it's unclear what state, if any, a macro object is in, assuming that state 
> fluctuates. TIA.
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Re: What is the quantum state of a macro object?

[Brent Meeker]

Interesting questions.  Whenever we talk about a system being in a 
quantum state, we're thinking of the "system" as some degrees of freedom 
that are isolated, so they are not interacting with and becoming 
entangled with other things.  An SG experiment typically uses silver 
atoms and refers to their state as UP or DOWN or LEFT or RIGHT.  But 
that's not a complete description of the silver atom. It has other 
degrees of freedom, which we ignore as irrelevant to the SG 
measurement.  So a "system" which we describe as having a state, isn't 
necessarily the same as an object, like a baseball or even an atom.  A 
classical object like a baseball has lots of degrees of freedom and they 
are interacting with the environment, so they are entangled with states 
of the environment.  Only certain collective variables, e.g. the 
conserved ones like momentum, are stable in the stat mech sense.  These 
ones that are stable against interaction with the environment are the 
einselected values we can measure classically.   So we could write a 
wave-function for the baseball as if it were an isolated particle, like 
the silver atom, and ignore all the internal dof which are not in any 
definite state because they're entangled with atmospheric molecules and 
IR photons, etc.


Whether something is in a superposition of states isn't an interesting 
question because the answer is always "Yes...relative to some basis."  
The interesting point is that since constituents in the baseball have 
interacted with and are now entangled with air molecules, those 
constituents of the baseball are not in any definite state.  Only the 
constituent PLUS the molecules it is entangled with has a definite 
state.  In any basis we can imagine measuring, they will be in a 
superposition relative to that basis. But in theory there would some 
basis in which the isolated baseball plus molecules would be an 
eigenstate; it's just so complicated we could never measure in that 
basis.   But if were to consider a very simple system, like a few 
electrons then we might be able to measure in the eigenbasis.


Brent

On 11/15/2017 5:56 PM, agrayson2...@gmail.com wrote:
Consider a baseball. Is it in some kind of composite state, however 
defined, of its constituents? Are all its constituents entangled with 
the environment? If some are not, are they in a superposition of 
states? I pose these questions because in my discussions with Clark on 
another thread, it's unclear what state, if any, a macro object is in, 
assuming that state fluctuates. TIA.

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What is the quantum state of a macro object?

[agrayson2000]

Consider a baseball. Is it in some kind of composite state, however 
defined, of its constituents? Are all its constituents entangled with the 
environment? If some are not, are they in a superposition of states? I pose 
these questions because in my discussions with Clark on another thread, 
it's unclear what state, if any, a macro object is in, assuming that state 
fluctuates. TIA.

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Re: Consistency of Postulates of QM

[agrayson2000]

On Wednesday, November 15, 2017 at 5:19:50 PM UTC-7, Brent wrote:
>
>
>
> On 11/15/2017 2:40 PM, agrays...@gmail.com  wrote:
>
>
>
> On Wednesday, November 15, 2017 at 2:37:02 PM UTC-7, Brent wrote: 
>>
>>
>>
>> On 11/15/2017 12:06 PM, agrays...@gmail.com wrote: 
>> > 
>> > But if it tunnels into existence at t=0, how can it be infinite in 
>> > extent? I find that egregiously hard to imagine, plus the fact that 
>> > one has to use QM to explain the tunneling, and that, ipso facto, 
>> > seems to imply it's infinitesimally small in spatial extent t=0 at 
>>
>> A limitation of imagination.  Nothing about tunneling assumes a size. 
>>
>> Brent 
>>
>
> Agreed. My imagination is not the be-all, or end-all of anything. But 
> isn't it claimed that Einstein's field equations breakdown earlier than 
> Planck time, and this is where QM must be invoked, when the universe is 
> presumably very small in spatial extent?  
>
>
> The part of the universe visible to us now (and any other finite patch) 
> was very small.
>

OK, but if everything we can measure, aka the visible universe, was hugely 
smaller in the past, what's the compelling reason to assume that the 
UN-observable universe was hugely larger at t=0, in fact infinite? It seems 
like an unwarranted conclusion when confronted with what measurements of 
the visible universe indicate. AG 

>
> Alternatively, doesn't tunneling assume QM, which is a theory about the 
> micro world. As I recall the concept is limited to QM. AG
>
>
> No.  It's  theory about the energy barrier between states.  It can be 
> states of anything.
>
> Brent
>

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Re: Consistency of Postulates of QM

[Brent Meeker]

On 11/15/2017 3:20 PM, Bruce Kellett wrote:

On 16/11/2017 9:14 am, Russell Standish wrote:

On Wed, Nov 15, 2017 at 10:54:51PM +1100, Bruce Kellett wrote:

On 15/11/2017 5:02 pm, Russell Standish wrote:

but be that as it may, I can't see how it solves the
preferred basis problem. Consider an experiment where the experimenter
may choose between inserting a circularly polarised file, or a
linearly polarised one. The preferred basis (selected by einselection)
will depend on that choice.

That is a common misconception, but the angle selected for the polarizer, or
the S-G magnet in a spin measurement, is not a selection of a measurement
basis. The measurement is actually the observation whether or not the
photon/particle passes the filter. It is then an inference from the
observation of a point on a screen, or the firing (or failing to fire) of a
detector of some sort, that the polarization/spin-component was such and
such. You don't actually measure anything in the selected orientation, you
only ever measure whether the particle passed the filter or not. So the
actual measurement is just a position measurement (position on a screen),
and the measurement basis is the position (pointer) basis.


But not all measurements are measurements of the position of
something. What about measuring the voltage of a circuit using an A->D
converter?


A surrogate measurement of the position of a pointer on a voltmeter.


When I've tried to think of measurements that are not position 
measurements, I come up with looking an emitter and seeing what color 
the photons are...a momentum measurement.


Brent




  Or the measurement of the momentum of a charged particle in
an electron multier?


Do you mean "electron multiplier"? Would than not be an energy 
measurement? Momentum of a charged particle is often measured by 
tracking the path of the charged particle in a magnetic field.



In MWI, we normally assume that there are
two branches of the universe with different choices made by the
experimenter.

That is really an oversimplification. It is done because it is simpler to
work with two-state systems, and position measurements are of a continuous
variable, so are not neatly two-valued.


The choice between circularly polarised filter and linear polarised
filters is binary. Obviously, there follows the choice of orientation,
which is continuous...


Whatever the choice of orientation, the outcome is binary, pass or not 
pass.




Unless there is some sort of superdeterminism in play,
where the experimenter does not have the freedom to choose. But
superdeterminism is certainly not a popular idea.

No, superdeterminism does not have many advocates.


Observers have nothing to do with it. In Zurek's account, it is the fact
that the results of interactions, be they measurements or not, are recorded
multiple times in the environment via decoherence, that is the mark of an
irreversible quantum event.

If you put a system in contact with a completely symmetric heat bath,
there will be no preferred basis selected by einselection.

The environment of a measurement or an interaction is not generally a
symmetric heat bath.

If there is no experimenter, just an environment, then we must
consider all possible environments in superposition. That will have
maximal symmetry.


"All possible environments in superposition"? That is seriously 
under-defined. Besides, that would only have a pseudo-symmetry.




If you measure a spin component (space quantization)
you get one of two spots on a screen downstream of the S-G magnet. These are
not symmetric wrt the rest of the environment.

That is because we're considering an SG experiment, with an SG
experimenter. That breaks the symmetry.


The environment breaks the symmetry. The environment may contain an 
experimenter, but need not. A camera would do the job.



In one world the irreversible
record is of an upper spot. In the other world it is of the lower spot. The
distinction is not lost because of symmetry. The basis for the measurement
is the position basis, because that is stable against further decoherence.
The angle of the S-G magnet is not the measurement basis.


The only
way for a basis to emerge is if there are system constraints of some
sort. I would argue that the only way these constraints could arise in
a Multiverse (which is symmetric by construction) is by considering
the environment from the point of view of some observer, ie the basic
symmetry breaking mechanism.

The observer is not a general symmetry breaking mechanism.

I would argue that observation in a multiverse is a symmetry breaking
mechanism. In the multiverse, all possible outcomes of a measurement
exist as separate branches, and if all outcomes are equally likely,
there is a fundamental symmetry along that measurement axis. But the
action of observation fixes the outcome for a particular observer,
breaking that symmetry.


In the first place, it is unlikely that all possible outcomes of an 
experiment are 

Re: Consistency of Postulates of QM

[Russell Standish]

On Thu, Nov 16, 2017 at 10:20:45AM +1100, Bruce Kellett wrote:
> On 16/11/2017 9:14 am, Russell Standish wrote:
> > But not all measurements are measurements of the position of
> > something. What about measuring the voltage of a circuit using an A->D
> > converter?
> 
> A surrogate measurement of the position of a pointer on a voltmeter.
>

There is no d'Arsenval style meter here with a pointer, just an A->D
converter + whatever recording device you want to attach to it.

Where is the position measurement in that case?

> >   Or the measurement of the momentum of a charged particle in
> > an electron multier?
> 
> Do you mean "electron multiplier"? Would than not be an energy measurement?

The direction component of the momentum can be determined by the
orientation of the multiplier tube. At least that is the sort of setup
I seem to remember using during my honours thesis - of course at 30+
years ago, my memory of the details could be a bit unreliable.

> Momentum of a charged particle is often measured by tracking the path of the
> charged particle in a magnetic field.
> 
> > > > In MWI, we normally assume that there are
> > > > two branches of the universe with different choices made by the
> > > > experimenter.
> > > That is really an oversimplification. It is done because it is simpler to
> > > work with two-state systems, and position measurements are of a continuous
> > > variable, so are not neatly two-valued.
> > > 
> > The choice between circularly polarised filter and linear polarised
> > filters is binary. Obviously, there follows the choice of orientation,
> > which is continuous...
> 
> Whatever the choice of orientation, the outcome is binary, pass or not pass.
>

Yes - but I was referring to what is the preferred basis, not the
experimental outcome.

> 
> > > > Unless there is some sort of superdeterminism in play,
> > > > where the experimenter does not have the freedom to choose. But
> > > > superdeterminism is certainly not a popular idea.
> > > No, superdeterminism does not have many advocates.
> > > 
> > > > > Observers have nothing to do with it. In Zurek's account, it is the 
> > > > > fact
> > > > > that the results of interactions, be they measurements or not, are 
> > > > > recorded
> > > > > multiple times in the environment via decoherence, that is the mark 
> > > > > of an
> > > > > irreversible quantum event.
> > > > If you put a system in contact with a completely symmetric heat bath,
> > > > there will be no preferred basis selected by einselection.
> > > The environment of a measurement or an interaction is not generally a
> > > symmetric heat bath.
> > If there is no experimenter, just an environment, then we must
> > consider all possible environments in superposition. That will have
> > maximal symmetry.
> 
> "All possible environments in superposition"? That is seriously
> under-defined. Besides, that would only have a pseudo-symmetry.
>

What is pseudosymmetry in this context? The only meaning that term
seems to have on the internet relates to when two crystals intergrow
(or "twin") giving rise to an apparent crystal symmetry. That doesn't
seem applicable here.

> 
> > > If you measure a spin component (space quantization)
> > > you get one of two spots on a screen downstream of the S-G magnet. These 
> > > are
> > > not symmetric wrt the rest of the environment.
> > That is because we're considering an SG experiment, with an SG
> > experimenter. That breaks the symmetry.
> 
> The environment breaks the symmetry. The environment may contain an
> experimenter, but need not. A camera would do the job.

The camera merely decoheres the system, which remains in a superposition
of the two possible outcomes of the SG experiment. To break that
symmetry requires an observer looking at the photo plate, or
downloading the image from the camera's CCD and observing it on a screen.

> 
> In the first place, it is unlikely that all possible outcomes of an
> experiment are equally likely. But I think you are confusing symmetry
> breaking with the observer self-locating in one of the possible outcome
> worlds.

Where is the confusion? Prior to self-location, the observer is in all
possible worlds, afterwards in just one.

> That breaks the symmetry for him, perhaps. But he is not important
> for that, because any future developments in the separate worlds will break
> any residual symmetry. The observer is nothing more than just one
> possibility for such a future development.
>

Einselection imposes no more symmetry breaking than the asymmetry
present in the environment. For that assymetry to get into the
environment requires conscious self-location (to use your term).

> > > The many worlds
> > > in QM are not symmetric anyway.
> > > 
> > Not completely, but far more symmetric that the world we inhabit.
> 
> Only in that the many worlds of QM contain more possibilities. Observers are
> not necessary for breaking this symmetry. The bottom line is that
> observation is not necessary 

Re: Consistency of Postulates of QM

[Brent Meeker]

On 11/15/2017 2:40 PM, agrayson2...@gmail.com wrote:



On Wednesday, November 15, 2017 at 2:37:02 PM UTC-7, Brent wrote:



On 11/15/2017 12:06 PM, agrays...@gmail.com  wrote:
>
> But if it tunnels into existence at t=0, how can it be infinite in
> extent? I find that egregiously hard to imagine, plus the fact that
> one has to use QM to explain the tunneling, and that, ipso facto,
> seems to imply it's infinitesimally small in spatial extent t=0 at

A limitation of imagination.  Nothing about tunneling assumes a size.

Brent


Agreed. My imagination is not the be-all, or end-all of anything. But 
isn't it claimed that Einstein's field equations breakdown earlier 
than Planck time, and this is where QM must be invoked, when the 
universe is presumably very small in spatial extent?


The part of the universe visible to us now (and any other finite patch) 
was very small.


Alternatively, doesn't tunneling assume QM, which is a theory about 
the micro world. As I recall the concept is limited to QM. AG


No.  It's  theory about the energy barrier between states.  It can be 
states of anything.


Brent

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Re: Consistency of Postulates of QM

[Brent Meeker]

On 11/15/2017 1:38 PM, Bruce Kellett wrote:

On 16/11/2017 6:52 am, Brent Meeker wrote:

On 11/15/2017 3:11 AM, Bruce Kellett wrote:

On 15/11/2017 3:12 pm, Brent Meeker wrote:

On 11/14/2017 7:46 PM, Bruce Kellett wrote:

On 15/11/2017 12:49 pm, Russell Standish wrote:

On Wed, Nov 15, 2017 at 11:05:22AM +1100, Bruce Kellett wrote:
One of the strongest arguments for MWI was that it eliminates 
the concept of

a conscious observer from the interpretation of quantum mechanics.

I disagree. The strongest argument is that it removes the need for a
mysterious nonunitary physical collapse process (that may or may not
be driven by a conscious observer).


I said "one of the strongest"! I know that you want to define QM 
from the idea of observer moments. I don't think that this will 
work, and the usual consensus is that one of the strengths of MWI 
is the elimination of the conscious observer.



A conscious observer (or rather just observer, really) is still
required to define the branches of the MWI, be that mediated by 
Zeh's

decoherence process, or otherwise. To eliminate observers entirely
requires solving the preferred basis problem without reference to an
observer or observation.


That is not true. The basis problem is solved by Zurek's 
einselection -- the preferred basis is the one that is stable 
against further decoherence. Observers have nothing to do with it. 
In Zurek's account, it is the fact that the results of 
interactions, be they measurements or not, are recorded multiple 
times in the environment via decoherence, that is the mark of an 
irreversible quantum event.


And "recorded" may not bring the right picture to mind.  It is 
recorded even if the information is radiated away into space.


True. The loss of interference due to radiation of IR photons from 
buckeyballs means that information does not have to be 'recorded' in 
a concrete sense -- it just has to be available somewhere, even if 
recovery is not practicable.


The future light cone is part of the environment.  But this makes 
me wonder if there are degrees of this entanglement information.  
Even though there are lot of copies of Alice's results in the 
immediate vicinity, at a distance of few billion light years the 
information is spread very thin, so there is uncertainty as to 
whether it is entangled or not at that distance.


There is no distance parameter in the wave function for 
entanglement! So distance makes no difference.


But decoherence is a statistical effect.


Is it? I thought it was a consequence of deterministic evolution 
according to the Schrödinger equation.


It's just the large number of entanglements which keep us from 
constructing and operator that reverses the decoherence.  That's what I 
meant by statistical, as in stat mech.




If the probability of interacting with the wave function at great 
distance becomes very small, then decoherence is operationally 
ineffective - you can't, at that distance, recover enough information 
to say which way Alice's measurement turned out.


If you build a big enough telescope and gather enough photons, you can 
look through the laboratory window and read Alice's lab book over her 
shoulder. There is nothing in current physics to say that this is 
impossible in principle.


I'm not exactly saying it's impossible in the classical ideal.  I'm 
thinking that the size of the telescope you need to collect enough 
photons becomes on the order of the Hubble sphere at the Hubble radius 
so it would be operationally impossible.  But on second thought, Alice 
could amplify her result and send a signal of arbitrary power (photon 
count).


Brent




And the reason for that (maybe) is that the foliation of spacetime 
has too much uncertainty over that interval. Maybe this is 
empirically ruled out by the lensing of distant galaxies...I'll have 
to think about it.


I think the evidence you are thinking of is the simultaneous arrival 
of all frequencies from distant gamma bursters. This casts some doubt 
on some granular models of space-time, but I doubt that it rules out 
all such possibilities.


Bruce



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Re: Consistency of Postulates of QM

[Bruce Kellett]

On 16/11/2017 9:14 am, Russell Standish wrote:

On Wed, Nov 15, 2017 at 10:54:51PM +1100, Bruce Kellett wrote:

On 15/11/2017 5:02 pm, Russell Standish wrote:

but be that as it may, I can't see how it solves the
preferred basis problem. Consider an experiment where the experimenter
may choose between inserting a circularly polarised file, or a
linearly polarised one. The preferred basis (selected by einselection)
will depend on that choice.

That is a common misconception, but the angle selected for the polarizer, or
the S-G magnet in a spin measurement, is not a selection of a measurement
basis. The measurement is actually the observation whether or not the
photon/particle passes the filter. It is then an inference from the
observation of a point on a screen, or the firing (or failing to fire) of a
detector of some sort, that the polarization/spin-component was such and
such. You don't actually measure anything in the selected orientation, you
only ever measure whether the particle passed the filter or not. So the
actual measurement is just a position measurement (position on a screen),
and the measurement basis is the position (pointer) basis.


But not all measurements are measurements of the position of
something. What about measuring the voltage of a circuit using an A->D
converter?


A surrogate measurement of the position of a pointer on a voltmeter.


  Or the measurement of the momentum of a charged particle in
an electron multier?


Do you mean "electron multiplier"? Would than not be an energy 
measurement? Momentum of a charged particle is often measured by 
tracking the path of the charged particle in a magnetic field.



In MWI, we normally assume that there are
two branches of the universe with different choices made by the
experimenter.

That is really an oversimplification. It is done because it is simpler to
work with two-state systems, and position measurements are of a continuous
variable, so are not neatly two-valued.


The choice between circularly polarised filter and linear polarised
filters is binary. Obviously, there follows the choice of orientation,
which is continuous...


Whatever the choice of orientation, the outcome is binary, pass or not pass.



Unless there is some sort of superdeterminism in play,
where the experimenter does not have the freedom to choose. But
superdeterminism is certainly not a popular idea.

No, superdeterminism does not have many advocates.


Observers have nothing to do with it. In Zurek's account, it is the fact
that the results of interactions, be they measurements or not, are recorded
multiple times in the environment via decoherence, that is the mark of an
irreversible quantum event.

If you put a system in contact with a completely symmetric heat bath,
there will be no preferred basis selected by einselection.

The environment of a measurement or an interaction is not generally a
symmetric heat bath.

If there is no experimenter, just an environment, then we must
consider all possible environments in superposition. That will have
maximal symmetry.


"All possible environments in superposition"? That is seriously 
under-defined. Besides, that would only have a pseudo-symmetry.




If you measure a spin component (space quantization)
you get one of two spots on a screen downstream of the S-G magnet. These are
not symmetric wrt the rest of the environment.

That is because we're considering an SG experiment, with an SG
experimenter. That breaks the symmetry.


The environment breaks the symmetry. The environment may contain an 
experimenter, but need not. A camera would do the job.



In one world the irreversible
record is of an upper spot. In the other world it is of the lower spot. The
distinction is not lost because of symmetry. The basis for the measurement
is the position basis, because that is stable against further decoherence.
The angle of the S-G magnet is not the measurement basis.


The only
way for a basis to emerge is if there are system constraints of some
sort. I would argue that the only way these constraints could arise in
a Multiverse (which is symmetric by construction) is by considering
the environment from the point of view of some observer, ie the basic
symmetry breaking mechanism.

The observer is not a general symmetry breaking mechanism.

I would argue that observation in a multiverse is a symmetry breaking
mechanism. In the multiverse, all possible outcomes of a measurement
exist as separate branches, and if all outcomes are equally likely,
there is a fundamental symmetry along that measurement axis. But the
action of observation fixes the outcome for a particular observer,
breaking that symmetry.


In the first place, it is unlikely that all possible outcomes of an 
experiment are equally likely. But I think you are confusing symmetry 
breaking with the observer self-locating in one of the possible outcome 
worlds. That breaks the symmetry for him, perhaps. But he is not 
important for that, because any future 

Re: Consistency of Postulates of QM

[Bruce Kellett]

On 16/11/2017 9:14 am, Russell Standish wrote:

On Wed, Nov 15, 2017 at 10:54:51PM +1100, Bruce Kellett wrote:

On 15/11/2017 5:02 pm, Russell Standish wrote:

On Wed, Nov 15, 2017 at 02:46:21PM +1100, Bruce Kellett wrote:

I said "one of the strongest"! I know that you want to define QM from the
idea of observer moments. I don't think that this will work, and the usual
consensus is that one of the strengths of MWI is the elimination of the
conscious observer.

Where's your evidence that this is the usual concensus? Who argues for it?

Most people, indirectly if not directly. I am thinking of MWI proponents
such as Deutsch and Wallace. Wallace puts it like this "Some have argued
that he measurement problem of quantum mechanics gives us reason to abandon
the picture of science as describing an observer-independent world". He
does not accept this view. The general view of scientific realism consists
in the belief that the objective external world is independent of the
observer. The thinking is related to Bell's assertion that: "Measurement
should never be introduced as a primitive process in a fundamental
mechanical theory like classical or quantum mechanics..." Measurement,
observation, observers are all related concepts in this context.


Deutsch, I could believe would argue that. But Wheeler would be a
counter to that. I'm not that familiar with Wallace.


Wallace is a collaborator with Deutsch. I don't know what Wheeler would 
say here> I think he was a believer in scientific realism -- reality 
without an observer. But then, head counts don't really amount to much.



A conscious observer (or rather just observer, really) is still
required to define the branches of the MWI, be that mediated by Zeh's
decoherence process, or otherwise. To eliminate observers entirely
requires solving the preferred basis problem without reference to an
observer or observation.

That is not true. The basis problem is solved by Zurek's einselection -- the
preferred basis is the one that is stable against further
decoherence.

I understand that the idea of einselection is still rather
controversial,

Not really. See Schlosshauer's paper and book.


I haven't really followed the literature, but it strikes me that
problem is that ultimately einselection is not a unitary process, so
it has to be considered as the result of some sort of coarse graining
(which is, of course, due to the actions of the observer discretising
a continuous world), in much the same way as the second law of
thermodynamics emerges from a strictly reversible microscopic
dynamics.


That is not correct. einselection is entirely unitary. It is closely 
related to the nature of the interaction Hamiltonian between the system 
and the environment. There is no collapse involved. It is a question of 
stability against further decoherence rather than anything else.




I find it intriguing that the recent critique of Einselection by
Kastner is entitled "`Einselection' of Pointer Observables: the new
H-Theorem". The H-Theorem, as I'm sure you know, but for the benefit
of other lurkers is Bolzmann's mechanism of deriving the second law
from coarse graining the revrsible microscopic dynamics.


I am not familiar with this argument, but if he related einselection to 
coarse graining, then he has missed the point.


Bruce

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Re: Consistency of Postulates of QM

[agrayson2000]

On Wednesday, November 15, 2017 at 2:37:02 PM UTC-7, Brent wrote:
>
>
>
> On 11/15/2017 12:06 PM, agrays...@gmail.com  wrote: 
> > 
> > But if it tunnels into existence at t=0, how can it be infinite in 
> > extent? I find that egregiously hard to imagine, plus the fact that 
> > one has to use QM to explain the tunneling, and that, ipso facto, 
> > seems to imply it's infinitesimally small in spatial extent t=0 at 
>
> A limitation of imagination.  Nothing about tunneling assumes a size. 
>
> Brent 
>

Agreed. My imagination is not the be-all, or end-all of anything. But isn't 
it claimed that Einstein's field equations breakdown earlier than Planck 
time, and this is where QM must be invoked, when the universe is presumably 
very small in spatial extent?  Alternatively, doesn't tunneling assume QM, 
which is a theory about the micro world. As I recall the concept is limited 
to QM. AG

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Re: Consistency of Postulates of QM

[Russell Standish]

On Wed, Nov 15, 2017 at 10:54:51PM +1100, Bruce Kellett wrote:
> On 15/11/2017 5:02 pm, Russell Standish wrote:
> > On Wed, Nov 15, 2017 at 02:46:21PM +1100, Bruce Kellett wrote:

> > > I said "one of the strongest"! I know that you want to define QM from the
> > > idea of observer moments. I don't think that this will work, and the usual
> > > consensus is that one of the strengths of MWI is the elimination of the
> > > conscious observer.
> > Where's your evidence that this is the usual concensus? Who argues for it?
> 
> Most people, indirectly if not directly. I am thinking of MWI proponents
> such as Deutsch and Wallace. Wallace puts it like this "Some have argued
> that he measurement problem of quantum mechanics gives us reason to abandon
> the picture of science as describing an observer-independent world". He
> does not accept this view. The general view of scientific realism consists
> in the belief that the objective external world is independent of the
> observer. The thinking is related to Bell's assertion that: "Measurement
> should never be introduced as a primitive process in a fundamental
> mechanical theory like classical or quantum mechanics..." Measurement,
> observation, observers are all related concepts in this context.
>

Deutsch, I could believe would argue that. But Wheeler would be a
counter to that. I'm not that familiar with Wallace.

> > > > A conscious observer (or rather just observer, really) is still
> > > > required to define the branches of the MWI, be that mediated by Zeh's
> > > > decoherence process, or otherwise. To eliminate observers entirely
> > > > requires solving the preferred basis problem without reference to an
> > > > observer or observation.
> > > That is not true. The basis problem is solved by Zurek's einselection -- 
> > > the
> > > preferred basis is the one that is stable against further
> > > decoherence.
> > I understand that the idea of einselection is still rather
> > controversial,
> 
> Not really. See Schlosshauer's paper and book.
>

I haven't really followed the literature, but it strikes me that
problem is that ultimately einselection is not a unitary process, so
it has to be considered as the result of some sort of coarse graining
(which is, of course, due to the actions of the observer discretising
a continuous world), in much the same way as the second law of
thermodynamics emerges from a strictly reversible microscopic
dynamics.

I find it intriguing that the recent critique of Einselection by
Kastner is entitled "`Einselection' of Pointer Observables: the new
H-Theorem". The H-Theorem, as I'm sure you know, but for the benefit
of other lurkers is Bolzmann's mechanism of deriving the second law
from coarse graining the revrsible microscopic dynamics.

> > but be that as it may, I can't see how it solves the
> > preferred basis problem. Consider an experiment where the experimenter
> > may choose between inserting a circularly polarised file, or a
> > linearly polarised one. The preferred basis (selected by einselection)
> > will depend on that choice.
> 
> That is a common misconception, but the angle selected for the polarizer, or
> the S-G magnet in a spin measurement, is not a selection of a measurement
> basis. The measurement is actually the observation whether or not the
> photon/particle passes the filter. It is then an inference from the
> observation of a point on a screen, or the firing (or failing to fire) of a
> detector of some sort, that the polarization/spin-component was such and
> such. You don't actually measure anything in the selected orientation, you
> only ever measure whether the particle passed the filter or not. So the
> actual measurement is just a position measurement (position on a screen),
> and the measurement basis is the position (pointer) basis.
>

But not all measurements are measurements of the position of
something. What about measuring the voltage of a circuit using an A->D
converter? Or the measurement of the momentum of a charged particle in
an electron multier?

> > In MWI, we normally assume that there are
> > two branches of the universe with different choices made by the
> > experimenter.
> 
> That is really an oversimplification. It is done because it is simpler to
> work with two-state systems, and position measurements are of a continuous
> variable, so are not neatly two-valued.
>

The choice between circularly polarised filter and linear polarised
filters is binary. Obviously, there follows the choice of orientation,
which is continuous...

> > Unless there is some sort of superdeterminism in play,
> > where the experimenter does not have the freedom to choose. But
> > superdeterminism is certainly not a popular idea.
> 
> No, superdeterminism does not have many advocates.
> 
> > > Observers have nothing to do with it. In Zurek's account, it is the fact
> > > that the results of interactions, be they measurements or not, are 
> > > recorded
> > > multiple times in the environment via 

Re: Consistency of Postulates of QM

[John Clark]

On Tue, Nov 14, 2017 at 6:17 PM,  wrote:

​> ​
> Any macro object is in a definite state
>

​That is incorrect. An electron an be in a single quantum state with just
one associated wave function, 2 electrons can do the sane thing in
superconductors they're called "Cooper pairs", and the same can also be
true for several million atoms in a Bose–Einstein condensate but you have
to cool them  to less than a millionth of a degree above absolute zero; but
all the 10^25 atoms in a baseball have their own different wave function
because unlike the atoms in a Bose–Einstein condensate all the atoms in a
baseball are NOT entangled with each other, if they were a baseball would
exhibit the same weird behavior as an electron.  That would certainly make
for a more interesting game and might even be enough to turn me into a
baseball fan.

Two atoms are quantum entangled entangled if they have the same wave
function but it's a delicate condition and must be carefully isolated from
the environment, the more atoms the more delicate it is, 10^25 atoms is so
delicate we never see it.

​>​
> Multiverse arose in the context of string theory, after Everett's MWI. The
> difference between Multiverse and MWI is striking and obvious.
>

​Explain to me how ​
Everett's MWI
​ can work without the Multiverse.​ The fact that string theory also needs
a Multiverse just give more support to Everett, or at least it would if
there were any experimental evidence to indecate string theory was true,

​>
>>> ​>>​
>>> ​
>>> For example, we know that irrational numbers exist
>>>
>>
>> ​>> ​
>> Do we?
>>
>
> ​> ​
> O
> ​​
> f course. It has been proven that pi and e are not rational.
>

​Yes, in the language of mathematics there are stories about rational and
irrational numbers and there are also stories about pi and e and you can
prove that the stories abut irrationality are consistent with pi and e. And
in the language of English there are stories about Harry Potter and it can
be proven that Harry's aunt is named Petunia, but there is no proof that
harry or Petunia exist in the physical world and there is no proof
pi or e (not to be confused with the approximations of pi and e) have any
effect on the laws of physics.  ​



> It's also been proven that the irrationals are dense in the reals; that
> is, many "more" irrationals than rationals;
>

​And the stories also say there are many more  non-computable Real numbers ​
​than computable Real numbers, the set of computable numbers is not dense
on the reals, its countably infinite with a cardinality of
Aleph-naught
​. If a number is not computable, ​that is to say  unlike pi or e then is
no procedure for even approximating it then I don't see how it cold be of
any importance to physics. And I say again Many Worlds is a theory about
physics not mathematics.

What about the rational numbers, does physics need all of them?
 The answer in not certain but we already have good reason to suspect that
neither time nor space is continuous, although although we won't know for
sure until we understand quantum gravity.  ​


> ​>> ​
>> there might be a infinite number of Turing Machines in the Multiverse but
>> they couldn't communicate with each other and none of them would have a
>> infinite amount of tape. So any real Turing Machine in the Multiverse is
>> certain to eventually stop, not for any software reason but because of
>> hardware failure. Eventual any real Turing machine will get a command like
>> "move the read/wright head one box to the left write a 1 in the box and
>> then change to state 6.02*10^23" but it will be unable to move one box to
>> the left became it is already at the end of the tape and there is no more
>> matter in the observable universe to extend it. If no physical process can
>> produce them that
>> seems to me a pretty good indication that the physical universe doesn't
>> need irrational numbers (or even real numbers). Many Worlds is a theory
>> about physics not mathematics so the philosophic debate about the existence
>> or nonexistence of irrational numbers ​
>> has no bearing on existence or nonexistence of
>> ​ Many Worlds.​
>>
>
> ​> ​
> I am not sufficiently knowledgeable about Turing machines to comment.
>

​All you need to know is that a Turing Machine is the simplest most
fundamental form of computer that operates according to the known laws of
physics, so if a Turning Machine can't do something then no computer can,
and a Turing Machine can't calculate a single irrational number, not even
if it makes use of all the matter in the observable universe, not even if
it has infinite time to work on it. And that makes me think irrational
numbers are not fundamentally important to the laws of physics or to our
physical world.


> ​> ​
> HOWEVER, if you prefer, forget about number theory and consider the FINITE
> AGE of our universe, the observable and unobservable regions. It's been
> expanding for 13.8 billion years, so its spatial extent must be
> 

Re: Consistency of Postulates of QM

[Bruce Kellett]

On 16/11/2017 6:52 am, Brent Meeker wrote:

On 11/15/2017 3:11 AM, Bruce Kellett wrote:

On 15/11/2017 3:12 pm, Brent Meeker wrote:

On 11/14/2017 7:46 PM, Bruce Kellett wrote:

On 15/11/2017 12:49 pm, Russell Standish wrote:

On Wed, Nov 15, 2017 at 11:05:22AM +1100, Bruce Kellett wrote:
One of the strongest arguments for MWI was that it eliminates the 
concept of

a conscious observer from the interpretation of quantum mechanics.

I disagree. The strongest argument is that it removes the need for a
mysterious nonunitary physical collapse process (that may or may not
be driven by a conscious observer).


I said "one of the strongest"! I know that you want to define QM 
from the idea of observer moments. I don't think that this will 
work, and the usual consensus is that one of the strengths of MWI 
is the elimination of the conscious observer.



A conscious observer (or rather just observer, really) is still
required to define the branches of the MWI, be that mediated by Zeh's
decoherence process, or otherwise. To eliminate observers entirely
requires solving the preferred basis problem without reference to an
observer or observation.


That is not true. The basis problem is solved by Zurek's 
einselection -- the preferred basis is the one that is stable 
against further decoherence. Observers have nothing to do with it. 
In Zurek's account, it is the fact that the results of 
interactions, be they measurements or not, are recorded multiple 
times in the environment via decoherence, that is the mark of an 
irreversible quantum event.


And "recorded" may not bring the right picture to mind.  It is 
recorded even if the information is radiated away into space.


True. The loss of interference due to radiation of IR photons from 
buckeyballs means that information does not have to be 'recorded' in 
a concrete sense -- it just has to be available somewhere, even if 
recovery is not practicable.


The future light cone is part of the environment.  But this makes me 
wonder if there are degrees of this entanglement information.  Even 
though there are lot of copies of Alice's results in the immediate 
vicinity, at a distance of few billion light years the information 
is spread very thin, so there is uncertainty as to whether it is 
entangled or not at that distance.


There is no distance parameter in the wave function for entanglement! 
So distance makes no difference.


But decoherence is a statistical effect.


Is it? I thought it was a consequence of deterministic evolution 
according to the Schrödinger equation.


If the probability of interacting with the wave function at great 
distance becomes very small, then decoherence is operationally 
ineffective - you can't, at that distance, recover enough information 
to say which way Alice's measurement turned out.


If you build a big enough telescope and gather enough photons, you can 
look through the laboratory window and read Alice's lab book over her 
shoulder. There is nothing in current physics to say that this is 
impossible in principle.


And the reason for that (maybe) is that the foliation of spacetime has 
too much uncertainty over that interval. Maybe this is empirically 
ruled out by the lensing of  distant galaxies...I'll have to think 
about it.


I think the evidence you are thinking of is the simultaneous arrival of 
all frequencies from distant gamma bursters. This casts some doubt on 
some granular models of space-time, but I doubt that it rules out all 
such possibilities.


Bruce

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Re: Consistency of Postulates of QM

[Brent Meeker]

On 11/15/2017 12:06 PM, agrayson2...@gmail.com wrote:


But if it tunnels into existence at t=0, how can it be infinite in 
extent? I find that egregiously hard to imagine, plus the fact that 
one has to use QM to explain the tunneling, and that, ipso facto, 
seems to imply it's infinitesimally small in spatial extent t=0 at


A limitation of imagination.  Nothing about tunneling assumes a size.

Brent

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Re: Consistency of Postulates of QM

[Bruce Kellett]

On 16/11/2017 1:55 am, Bruno Marchal wrote:

On 15 Nov 2017, at 00:55, Bruce Kellett wrote:

On 15/11/2017 12:47 am, Stathis Papaioannou wrote:
On Mon, 13 Nov 2017 at 8:54 am, Bruce Kellett 
 wrote:



I don't think you have fully understood the scenario I have
outlined.
There is no collapse, many worlds is assumed throughout. Alice
splits
according to her measurement result. Both copies of Alice go to meet
Bob, carrying the other particle of the original pair. Since
they both
have now met Bob, the split that Alice occasioned has now spread to
entangle Bob as well as the rest of her environment. So there
are now
two worlds, each of which has a copy of Bob, and an Alice, who has a
particular result. Locality says that Bob's particle is
unchanged from
production, so when he measure its spin, he splits into two copies,
according to spin up or spin down. Since Alice is standing
beside him,
she also becomes entangled with his result. But Alice already has a
definite result in each branch, so we now have four branches: with
results 'up-up', 'up-down', 'down-up', and 'down-down'. However,
only
the 'up-down' and 'down-up' branches conserve angular momentum.
How do
you rule out the other branches?


When you put something in the cupboard and come back later to get 
it, why, under MWI, is it still there?


I don't understand the significance of your question. Why wouldn't 
things remain stable in MWI? After all, the whole world, as it is, 
becomes entangled with the particular branching event.


OK, but not instantaneously. This might be the point where we disagree 
in the interpretation of the Non-collapse theory.


I think that the general idea is that the entanglement with the result 
spreads at the velocity of light -- inside the forward light cone. This 
spread of entanglement does not require that all objects in the forward 
light cone have explicitly interacted with the original event. The 
mathematics are quite clear on this point.


Bruce

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Re: R: Re: Consistency of Postulates of QM

[Bruce Kellett]

On 16/11/2017 12:35 am, 'scerir' via Everything List wrote:

And "recorded" may not bring the right picture to mind.  It is

[Bruce, I guess]

True. The loss of interference due to radiation of IR photons from
buckeyballs means that information does not have to be 'recorded' in a
concrete sense -- it just has to be available somewhere, even if
recovery is not practicable.

"The superposition of amplitudes is only valid if there is no way to know,
even in
principle, which path the particle took. It is important to realize that this
does not
imply that an observer actually takes note of what happens. It is sufficient
to destroy
the interference pattern, if the path information is accessible in principle
from the
experiment or even if it is dispersed in the environment and beyond any
technical
possibility to be recovered, but in principle 'still out there'."
--Anton Zeilinger, (Rev. Mod. Phys., 1999, p. S-288)


Yes, there is a considerable body of experimental evidence to this 
effect. It is not necessary to observe or record some information for 
that to have observable quantum effects, as long it is "out there" 
somewhere. Conscious observers are definitely secondary.


Bruce

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Re: Consistency of Postulates of QM

[Brent Meeker]

On 11/15/2017 7:04 AM, Bruno Marchal wrote:


On 14 Nov 2017, at 21:15, Brent Meeker wrote:




On 11/14/2017 6:18 AM, Bruno Marchal wrote:


On 13 Nov 2017, at 22:40, Bruce Kellett wrote:


On 14/11/2017 2:07 am, Bruno Marchal wrote:

On 12 Nov 2017, at 23:05, Bruce Kellett wrote:

What really annoys me is the continued claim that many worlds 
eliminates the need for non-locality. It does not, and neither 
Bruno nor anyone else has ever produced a valid argument as to 
how many worlds might restore locality.


But nobody has proved that there is non locality in the MWI. 
EPR-BELL proves non-locality apparant in each branch, but the MWI 
avoids the needs of action at a distance to explains them. Once 
Alice and Bob are space-separated, their identity are independent. 
It makes no sense to talk of each of them like if they were 
related, (unless you correlate them with a third observer, etc) If 
they do measurement, some God could see that they are indeed no 
more related, but if they decide to come back to place where they 
can compared locally their spin, they will always get contact to 
the corresponding observer with the well correlated spin. The 
independent Alice and Bob will never meet because they can't 
belong to the same branch of the multiverse, by the MWI of the 
singlet state. So Mitra is right. Although Bertlmann's socks are 
tyically not working for Bell's violation in a MONO-universe, it 
works again in the MWI, applied in this case to the whole singlet 
state.


Bell has proved non-locality in MWI, every bit as much as in each 
branch separately. You appear not to have grasped the significance 
of the scenario I have argued carefully. Alice and Bob are not 
space-like separated in the scenario I outlined. Alice and Bob are 
together in the same laboratory when the second measurement is 
made. They are necessarily in the same world before, and branch in 
together according to Bob's result. Your mumbo-jumbo about them 
only being able to meet in appropriate matching branches does not 
work here, because they are always in the same branch. And there is 
no reason to suppose that their results in some of those branches 
do not violate conservation of angular momentum.


I have no clue what you mean. The singlet state guaranties the 
conservation of angular momentum in all worlds. The singlet state 
describes an infinity of "worlds",  and in each of them there is 
conservation of angular momentum, and it has a local common cause 
origin, the same in all worlds.


But it's not a sufficient 'hidden' variable to explain the space-like 
correlation of measurements.


If the the explanation is based on hidden variable, per branch, then 
there will be non-locality. But the many universe are not really 
hidden variable in the sense of EPR-Bell's, which assumes Alice and 
Bob have the same identity and keep it, when they do the space-like 
measurement, but it seems to me that this is a wrong interpretation of 
the singlet state when we suppress any possible collapse. If Alice and 
Bob are space-like separated, they will later only access to the Bob 
and Alice they will locally be able to interact with, and those are 
"new" people, not the original couple.


But that's the point of Bruce's version in which the measurements are 
time-like.  Alice and Bob will have continuity of identity and, as he 
argues, the explanation for the correlation of results being stronger 
than classical must be the same.


Brent

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Re: David Bohm: Thought as a System

[agrayson2000]

On Friday, September 6, 2013 at 2:53:10 PM UTC-6, Brent wrote:
>
> On 9/6/2013 1:02 PM, John Mikes wrote:
>
> Evgeniy, it was a while ago when I read (and enjoyed) David Bohm. 
> Since then I modified many of my ideas and included 'newer' ideas into 
> them. I cannot resort to ancient (?) thinkers: our knowledge is evolving.�
> Random is (IMO) out: how would you justify ANY of the physical laws and 
> their consequences if 'random' occurrences may intrude - and change the 
> continuation of anything? 
>
>
> They are justified by their success in prediction.� "Random" doesn't 
> mean "anything can happen".� In the successful theories the randomness is 
> narrowly constrained and random distributions are accurately predicted.
>

We've discussed this before. Yes, distributions accurately determined; 
individual outcomes, No. So at some point God DOES play dice with the 
universe. And considering that any rule determining individual outcomes 
would wreak havoc with physics as we know it, I think QM is "the End of the 
Road". Should we lament or rejoice? AG 

>
> It all comes from my agnosticism: we know so little and don't knwo so 
> much. Some newer knowledge infiltrates our base - in adjusted format, of 
> course, how our primitive mindset of today can apply it - but our 
> knowledge-base does grow.�
> That means my disregard for 'older' thoughts (e.g. of yesterday...).�
> I am on the basis of "I don't know".�
>
> In another line there was mention of statistical analysis.�
> *Statistics* is (IMO) a no-no, it is upon our arbitrary (present?) 
> norderlines within which we COUNT te appropriate items. As we gather new 
> information the borderlines change and our statistics becomes irrelevant. 
>
>
> It has been very successful in explaining thermodynamics by statistical 
> mechanics.
>
> Brent
>
> *Analytics*, however, is restricted to the (present?) inventory of 
> structural etc. parts in our (statistically applied?) system of a presently 
> KNOWN composition. The real results may be ingenious, but insufficient: 
> restsricted to today's knowledge.�
>
> I leave my doubts on the 'anticipatory' for tomorrow.�
>
> Regards
> John M
>
>
>

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Re: Consistency of Postulates of QM

[agrayson2000]

On Wednesday, November 15, 2017 at 12:55:18 PM UTC-7, Russell Standish 
wrote:
>
> On Wed, Nov 15, 2017 at 07:33:12AM -0800, agrays...@gmail.com 
>  wrote: 
> > 
> > 
> > On Wednesday, November 15, 2017 at 7:51:09 AM UTC-7, Bruno Marchal 
> wrote: 
> > > 
> > > 
> > > On 15 Nov 2017, at 00:17, agrays...@gmail.com  wrote: 
> > > 
> > > 
> > > Multiverse arose in the context of string theory, after Everett's MWI. 
> The 
> > > difference between Multiverse and MWI is striking and obvious. 
> > > 
> > > 
> > > 
> > > To my knowledge, "multiverse" is the terming given by David Deutsch 
> for 
> > > the Many-Worlds. Then, String Theory has used that terming in its 
> context, 
> > > but it could have used "many-World". String theory is a special 
> application 
> > > of QM. 
> > > 
> > 
> > *As "Multiverse" is now usually used, it refers to the multitude of 
> > possible universes with different basic parameters that might exist in 
> > parallel as claimed by String Theory, whereas the way Many Worlds is 
> used 
> > it refers to the (uncountable!) universes allegedly automatically 
> created 
> > when Joe the Plumber goes into a lab and shoots an electron at, say, a 
> > double slit. The two types of multiple worlds are conceptually 
> different, 
> > hugely different, and that was all I was asserting. To claim that the 
> two 
> > concepts are somehow the same is a common error, and egregiously 
> misleading 
> > to equate them. * 
> > 
>
> Multiverse can refer to any of the ensembles, depending on the 
> author. String theorists will be referring to the string lanscape, as 
> you observe, but for say someone like David Deutsch, Multiverse refers 
> to the Many Wolds of MWI. I think Deutsch coined the term originally. 
>

 Yes, Deutsch. AG

>
> Yes it is important to distinguish the difference ensembles, as in 
> Tegmark's classification of multiverses. IIRC, the string landscape 
> is a level 2 multiverse and the many worlds a level  3 multiverse.   
>
>
>
> > 
> > *I am  interested in your opinion that, as I contend,  the universe we 
> > inhabit, must be finite in spatial extent since it is finite in age. 
> This 
> > is the elephant in the room that no one wants to discuss, apparently. * 
> > 
>
> As Brent explained, if the universe is infinite in extent at t=0, it 
> remains infinite in extent at finite times. 
>

But if it tunnels into existence at t=0, how can it be infinite in extent? 
I find that egregiously hard to imagine, plus the fact that one has to use 
QM to explain the tunneling, and that, ipso facto, seems to imply it's 
infinitesimally small in spatial extent t=0 at . AG 

>
> -- 
>
>  
>
> Dr Russell StandishPhone 0425 253119 (mobile) 
> Principal, High Performance Coders 
> Visiting Senior Research Fellowhpc...@hpcoders.com.au 
>  
> Economics, Kingston University http://www.hpcoders.com.au 
>  
>
>

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Re: Consistency of Postulates of QM

[Russell Standish]

On Wed, Nov 15, 2017 at 07:33:12AM -0800, agrayson2...@gmail.com wrote:
> 
> 
> On Wednesday, November 15, 2017 at 7:51:09 AM UTC-7, Bruno Marchal wrote:
> >
> >
> > On 15 Nov 2017, at 00:17, agrays...@gmail.com  wrote:
> >
> >
> > Multiverse arose in the context of string theory, after Everett's MWI. The 
> > difference between Multiverse and MWI is striking and obvious.
> >
> >
> >
> > To my knowledge, "multiverse" is the terming given by David Deutsch for 
> > the Many-Worlds. Then, String Theory has used that terming in its context, 
> > but it could have used "many-World". String theory is a special application 
> > of QM.
> >
> 
> *As "Multiverse" is now usually used, it refers to the multitude of 
> possible universes with different basic parameters that might exist in 
> parallel as claimed by String Theory, whereas the way Many Worlds is used 
> it refers to the (uncountable!) universes allegedly automatically created 
> when Joe the Plumber goes into a lab and shoots an electron at, say, a 
> double slit. The two types of multiple worlds are conceptually different, 
> hugely different, and that was all I was asserting. To claim that the two 
> concepts are somehow the same is a common error, and egregiously misleading 
> to equate them. * 
> 

Multiverse can refer to any of the ensembles, depending on the
author. String theorists will be referring to the string lanscape, as
you observe, but for say someone like David Deutsch, Multiverse refers
to the Many Wolds of MWI. I think Deutsch coined the term originally.

Yes it is important to distinguish the difference ensembles, as in
Tegmark's classification of multiverses. IIRC, the string landscape
is a level 2 multiverse and the many worlds a level  3 multiverse.  



> 
> *I am  interested in your opinion that, as I contend,  the universe we 
> inhabit, must be finite in spatial extent since it is finite in age. This 
> is the elephant in the room that no one wants to discuss, apparently. *
> 

As Brent explained, if the universe is infinite in extent at t=0, it
remains infinite in extent at finite times.

-- 


Dr Russell StandishPhone 0425 253119 (mobile)
Principal, High Performance Coders
Visiting Senior Research Fellowhpco...@hpcoders.com.au
Economics, Kingston University http://www.hpcoders.com.au


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Re: Consistency of Postulates of QM

[Brent Meeker]

On 11/15/2017 3:11 AM, Bruce Kellett wrote:

On 15/11/2017 3:12 pm, Brent Meeker wrote:

On 11/14/2017 7:46 PM, Bruce Kellett wrote:

On 15/11/2017 12:49 pm, Russell Standish wrote:

On Wed, Nov 15, 2017 at 11:05:22AM +1100, Bruce Kellett wrote:
One of the strongest arguments for MWI was that it eliminates the 
concept of

a conscious observer from the interpretation of quantum mechanics.

I disagree. The strongest argument is that it removes the need for a
mysterious nonunitary physical collapse process (that may or may not
be driven by a conscious observer).


I said "one of the strongest"! I know that you want to define QM 
from the idea of observer moments. I don't think that this will 
work, and the usual consensus is that one of the strengths of MWI is 
the elimination of the conscious observer.



A conscious observer (or rather just observer, really) is still
required to define the branches of the MWI, be that mediated by Zeh's
decoherence process, or otherwise. To eliminate observers entirely
requires solving the preferred basis problem without reference to an
observer or observation.


That is not true. The basis problem is solved by Zurek's 
einselection -- the preferred basis is the one that is stable 
against further decoherence. Observers have nothing to do with it. 
In Zurek's account, it is the fact that the results of interactions, 
be they measurements or not, are recorded multiple times in the 
environment via decoherence, that is the mark of an irreversible 
quantum event.


And "recorded" may not bring the right picture to mind.  It is 
recorded even if the information is radiated away into space.


True. The loss of interference due to radiation of IR photons from 
buckeyballs means that information does not have to be 'recorded' in a 
concrete sense -- it just has to be available somewhere, even if 
recovery is not practicable.


The future light cone is part of the environment.  But this makes me 
wonder if there are degrees of this entanglement information.  Even 
though there are lot of copies of Alice's results in the immediate 
vicinity, at a distance of few billion light years the information is 
spread very thin, so there is uncertainty as to whether it is 
entangled or not at that distance.


There is no distance parameter in the wave function for entanglement! 
So distance makes no difference.


But decoherence is a statistical effect.  If the probability of 
interacting with the wave function at great distance becomes very small, 
then decoherence is operationally ineffective - you can't, at that 
distance, recover enough information to say which way Alice's 
measurement turned out.  And the reason for that (maybe) is that the 
foliation of spacetime has too much uncertainty over that interval. 
Maybe this is empirically ruled out by the lensing of  distant 
galaxies...I'll have to think about it.


Brent



So, if you are sufficiently far away, is there no longer any fact of 
the matter about which result Alice got?  This might be a connection 
to the quantization of spacetime, since at sufficiently time-like 
separated points the propagation of from one superspace foliation to 
another must satisfy an uncertainty principle.


Why? I don't see a particular connection here.

Bruce



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Re: David Bohm: Thought as a System

[Nicki LovesDogs]

Fantastic group. Been looking for people to continue those valuable 
conversations. I'm listening to them every single day sometimes all day 
long and deep into the night. Jiddu Krishnamurti is The ultimate 
philosopher. David Bohm is the only one during his life time who understood 
him. 



On Sunday, September 1, 2013 at 6:39:32 AM UTC-7, Evgenii Rudnyi wrote:
>
> I am reading David Bohm, Thought as a System. A few quotes below to the 
> theme that is quite often under discussion here. 
>
> Evgenii 
>
> p.  72 “We have to be able to think on this clearly; even though, as I 
> said, that by itself won’t really change the reflexes. But if we don’t 
> think of it clearly then all our attempts to get into this will go 
> wrong. Clear thinking implies that we are in some way awakened a little 
> bit. Perhaps there is something beyond the reflex which is at work – in 
> other words, something unconditioned.” 
>
> p. 72 “The question is really: is there the unconditioned? If everything 
> is conditioned, then there’s no way out. But the very fact that we are 
> sometimes able to see new things would suggest that there is 
> unconditioned. Maybe the deeper material structure of the brain is 
> unconditioned, or maybe beyond.” 
>
> p. 72 “If there is the unconditioned, which could be the movement of 
> intelligence, then there is some possibility of getting into this.” 
>
> p. 73 “If we say that there cannot be the unconditioned, then it would 
> be foolish for us to try to do anything with the conditioning. Is that 
> clear?” 
>
> p. 72 “If we once assume that there cannot be the unconditioned, then 
> we’re stuck. On the other hand, if we assume that there is the 
> unconditioned, again we are going to be stuck – we will produce an image 
> of the unconditioned in the system of conditioning, and mistake the 
> image for the unconditioned. Therefore, let’s say that there may be the 
> unconditioned. We leave room for that. We have to leave room in our 
> thought for possibilities.” 
>

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Re: Consistency of Postulates of QM

[agrayson2000]

On Wednesday, November 15, 2017 at 7:51:09 AM UTC-7, Bruno Marchal wrote:
>
>
> On 15 Nov 2017, at 00:17, agrays...@gmail.com  wrote:
>
>
>
> On Tuesday, November 14, 2017 at 3:32:08 PM UTC-7, John Clark wrote:
>>
>> On Mon, Nov 13, 2017 at 11:52 PM,  wrote:
>>
>> ​> ​
>>> I think every macro system, although comprised of a huge number of 
>>> individual constituents, is in one definite state;
>>
>>
>> ​No object large enough to see with ​
>> your unaided ​can is in one definite state, that is to say can be 
>> described with a single quantum wave function, with the possible exception 
>> of a 
>> Bose–Einstein condensate
>> ​, and even then it would be so small ​it would be at the limits of 
>> visibility. And you're not going to see one in everyday life unless you 
>> visit a lab that can cool things down to less than a millionth of a degree 
>> above absolute zero that is needed to make a 
>> Bose–Einstein condensate
>> ​.​
>>   Incidentally 
>> unless  ​
>> ET 
>> ​exists and is also interested in physics research that lab you're 
>> visiting is
>>  the coldest place in the universe
>> ​.​
>>  
>>
>  
> Any macro object is in a definite state -- not a superposition of states 
> -- at every moment in time, but obviously the state is constantly 
> fluctuating due to interactions with its constituents and entities external 
> to it. Due to the huge number of constituents, we can't write it down 
> explicitly,
>  
>
>>
>> ​> ​
>>> the lack of ISOLATION is the condition for the existence of this macro 
>>> definite state.
>>
>>
>> ​A baseball made of 10^25 atoms ​has 10^25 times more ways to interact 
>> with the environment than a single atom does, so we'd expect to see a 
>> baseball in just one state about 
>>  
>> ​10^25 times less often than we do in a single atom.​
>>  
>>
>>> ​> ​
>>> The concept of Multiverse and Many Worlds come from entirely different 
>>> contexts and theories,
>>>
>>
>> ​I don't think anybody was even talking about the Multiverse before 1957 
>> when Hugh Everett introduced the idea of Many Worlds, and Evert's idea 
>> won't work without the Multiverse. ​ That doesn't sound entirely different 
>> to me.
>>
>
> Multiverse arose in the context of string theory, after Everett's MWI. The 
> difference between Multiverse and MWI is striking and obvious.
>
>
>
> To my knowledge, "multiverse" is the terming given by David Deutsch for 
> the Many-Worlds. Then, String Theory has used that terming in its context, 
> but it could have used "many-World". String theory is a special application 
> of QM.
>

*As "Multiverse" is now usually used, it refers to the multitude of 
possible universes with different basic parameters that might exist in 
parallel as claimed by String Theory, whereas the way Many Worlds is used 
it refers to the (uncountable!) universes allegedly automatically created 
when Joe the Plumber goes into a lab and shoots an electron at, say, a 
double slit. The two types of multiple worlds are conceptually different, 
hugely different, and that was all I was asserting. To claim that the two 
concepts are somehow the same is a common error, and egregiously misleading 
to equate them. * 

>
>
>
> For example, the former has nothing to do with Joe the Plumber shooting an 
> electron at a slit in a lab and creating an awesome (uncountable!) number 
> of NEW universes.
>
>>  
>>
>>> ​> ​
>>> For example, we know that irrational numbers exist
>>>
>>
>> Do we? 
>>
>
> Of course. It has been proven that pi and e are not rational. It's also 
> been proven that the irrationals are dense in the reals; that is, many 
> "more" irrationals than rationals; the difference between countable and 
> uncountable infinities. 
>
>
> The rational are dense, but countable. The real are not countable. But 
> this is mathematics, not physics. You need some metaphysical or theological 
> hypothesis to talk about the existence or non-existence of a mathematical 
> object in a physucal reality, or vice versa. See my work for an explanation 
> that if Mechanism is true in cognitive science, then, there is 0 physical 
> universe, as arithmetic emulate all dreams, and the physical apperances 
> emerges from "number's dream" statistic. It seems you assume Aristotle 
> metaphysics, which assumes that there is a primary/primitive/non-derivable 
> Physical Universe.
>

*Why are you splitting hairs? Clark questioned whether irrational numbers 
exist. I asserted their existence has been proven, obviously in the context 
of mathematics and mathematical logic. I didn't assert, and wouldn't, that 
they exist in the physical world, any more than I would assert you can find 
a perfect triangle in the physical world.  *

*I am  interested in your opinion that, as I contend,  the universe we 
inhabit, must be finite in spatial extent since it is finite in age. This 
is the elephant in the room that no one wants to discuss, apparently. *

>
> Bruno
>
>
>
>
>
>  
>
>> We know that mathematicians 

Re: Consistency of Postulates of QM

[Bruno Marchal]

On 15 Nov 2017, at 01:05, Bruce Kellett wrote:


On 15/11/2017 12:44 am, smitra wrote:

On 14-11-2017 09:23, Bruce Kellett wrote:

On 14/11/2017 5:51 pm, smitra wrote:

Within this model, Bob does not decohere until that time he is  
told what Alice has found.


That is simply not true. Decoherence is not subject to a particular
person's knowledge. When Alice and Bob are next to each other, they
are jointly entangled with a particular result.


I think that this needs to be discussed in more detail. Decoherence  
does not cause a superposition to get reduced to either one of the  
two possible outcomes. Given what Bob knows, he cannot locate  
himself in either sector. If this were not true then given  
everything Bob is aware of, he could get to better odds than 50-50  
for guessing the spin. But that implies information transfer to  
something his brain can access.


One of the strongest arguments for MWI was that it eliminates the  
concept of a conscious observer from the interpretation of quantum  
mechanics. This is seen to be particularly important in quantum  
cosmology, but it is relevant everywhere. You seem to be wanting to  
turn the clock back and make consciousness, and conscious knowledge  
of events, central to your interpretation.


The branches form under decoherence for every quantum event. Whether  
you know about it or not, or know the result of the experiment, is  
irrelevant. Schrödinger's cat is definitely dead in one branch, and  
definitely alive in the other, whether you open the box or not.


That is MWI in standard QM. If you want to propose another theory in  
which consciousness is central, then that is up to you. But you have  
to show that your alternative theory reproduces all the observed  
results of quantum mechanics before you can say that you are right  
and everyone else is wrong.



Everett use the theory of Mechanism for consciousness, and yes, that  
is the main reason to prefer MWI than an hardly intelligible action of  
consciousness on matter, but I think Saibal was using only the usual  
first person/third person distinction, that Mechanism implied (if I  
got his point).


Bruno





So, it boils down to decoherence acting on a microscopic degrees of  
freedom, while brains and computers must be robust systems that  
would not function well if they would be affected by such effects.  
Thermal noise would make computing impossible.


If you have robust bitstrings that are only going to be affected by  
information present in the environment at a sufficiently coarse  
grained level, then that bitstring is never going to pick up any  
information about Alice's result other than via direct  
communication or any leakage of information e.g. if Bob is in to  
cold reading, or if there are other correlations at the macroscopic  
level that Bob can exploit.


So, we have two decohered parallel worlds, but Bob is mentally  
identical in the two sectors despite decoherence having split his  
body. As long as he cannot access that information, he is the same  
person in both sectors.


And the rock on the ground outside the laboratory is the same in  
both decohered worlds. That is irrelevant to the existence of such  
worlds in MWI. As I said, Bob's knowledge or lack of knowledge is  
irrelevant to the fact that locality implies there are worlds in  
which angular momentum is not conserved in the scenario that I have  
outlined.


Bruce

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Re: Consistency of Postulates of QM

[Bruno Marchal]

On 14 Nov 2017, at 21:15, Brent Meeker wrote:




On 11/14/2017 6:18 AM, Bruno Marchal wrote:


On 13 Nov 2017, at 22:40, Bruce Kellett wrote:


On 14/11/2017 2:07 am, Bruno Marchal wrote:

On 12 Nov 2017, at 23:05, Bruce Kellett wrote:

What really annoys me is the continued claim that many worlds  
eliminates the need for non-locality. It does not, and neither  
Bruno nor anyone else has ever produced a valid argument as to  
how many worlds might restore locality.


But nobody has proved that there is non locality in the MWI. EPR- 
BELL proves non-locality apparant in each branch, but the MWI  
avoids the needs of action at a distance to explains them. Once  
Alice and Bob are space-separated, their identity are  
independent. It makes no sense to talk of each of them like if  
they were related, (unless you correlate them with a third  
observer, etc) If they do measurement, some God could see that  
they are indeed no more related, but if they decide to come back  
to place where they can compared locally their spin, they will  
always get contact to the corresponding observer with the well  
correlated spin. The independent Alice and Bob will never meet  
because they can't belong to the same branch of the multiverse,  
by the MWI of the singlet state. So Mitra is right. Although  
Bertlmann's socks are tyically not working for Bell's violation  
in a MONO-universe, it works again in the MWI, applied in this  
case to the whole singlet state.


Bell has proved non-locality in MWI, every bit as much as in each  
branch separately. You appear not to have grasped the significance  
of the scenario I have argued carefully. Alice and Bob are not  
space-like separated in the scenario I outlined. Alice and Bob are  
together in the same laboratory when the second measurement is  
made. They are necessarily in the same world before, and branch in  
together according to Bob's result. Your mumbo-jumbo about them  
only being able to meet in appropriate matching branches does not  
work here, because they are always in the same branch. And there  
is no reason to suppose that their results in some of those  
branches do not violate conservation of angular momentum.


I have no clue what you mean. The singlet state guaranties the  
conservation of angular momentum in all worlds. The singlet state  
describes an infinity of "worlds",  and in each of them there is  
conservation of angular momentum, and it has a local common cause  
origin, the same in all worlds.


But it's not a sufficient 'hidden' variable to explain the space- 
like correlation of measurements.


If the the explanation is based on hidden variable, per branch, then  
there will be non-locality. But the many universe are not really  
hidden variable in the sense of EPR-Bell's, which assumes Alice and  
Bob have the same identity and keep it, when they do the space-like  
measurement, but it seems to me that this is a wrong interpretation of  
the singlet state when we suppress any possible collapse. If Alice and  
Bob are space-like separated, they will later only access to the Bob  
and Alice they will locally be able to interact with, and those are  
"new" people, not the original couple.


Bruno







Brent

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Re: Consistency of Postulates of QM

[Bruno Marchal]

On 15 Nov 2017, at 00:55, Bruce Kellett wrote:


On 15/11/2017 12:47 am, Stathis Papaioannou wrote:
On Mon, 13 Nov 2017 at 8:54 am, Bruce Kellett  wrote:


I don't think you have fully understood the scenario I have outlined.
There is no collapse, many worlds is assumed throughout. Alice splits
according to her measurement result. Both copies of Alice go to meet
Bob, carrying the other particle of the original pair. Since they  
both

have now met Bob, the split that Alice occasioned has now spread to
entangle Bob as well as the rest of her environment. So there are now
two worlds, each of which has a copy of Bob, and an Alice, who has a
particular result. Locality says that Bob's particle is unchanged  
from

production, so when he measure its spin, he splits into two copies,
according to spin up or spin down. Since Alice is standing beside  
him,

she also becomes entangled with his result. But Alice already has a
definite result in each branch, so we now have four branches: with
results 'up-up', 'up-down', 'down-up', and 'down-down'. However, only
the 'up-down' and 'down-up' branches conserve angular momentum. How  
do

you rule out the other branches?

When you put something in the cupboard and come back later to get  
it, why, under MWI, is it still there?


I don't understand the significance of your question. Why wouldn't  
things remain stable in MWI? After all, the whole world, as it is,  
becomes entangled with the particular branching event.


OK, but not instantaneously. This might be the point where we disagree  
in the interpretation of the Non-collapse theory.


Bruno





Bruce

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Re: Consistency of Postulates of QM

[Bruno Marchal]

On 15 Nov 2017, at 00:17, agrayson2...@gmail.com wrote:




On Tuesday, November 14, 2017 at 3:32:08 PM UTC-7, John Clark wrote:
On Mon, Nov 13, 2017 at 11:52 PM,  wrote:

​> ​I think every macro system, although comprised of a huge  
number of individual constituents, is in one definite state;


​No object large enough to see with ​your unaided ​can is in  
one definite state, that is to say can be described with a single  
quantum wave function, with the possible exception of a Bose– 
Einstein condensate​, and even then it would be so small ​it  
would be at the limits of visibility. And you're not going to see  
one in everyday life unless you visit a lab that can cool things  
down to less than a millionth of a degree above absolute zero that  
is needed to make a Bose–Einstein condensate​.​  Incidentally  
unless  ​ET ​exists and is also interested in physics research  
that lab you're visiting is the coldest place in the universe​.​


Any macro object is in a definite state -- not a superposition of  
states -- at every moment in time, but obviously the state is  
constantly fluctuating due to interactions with its constituents and  
entities external to it. Due to the huge number of constituents, we  
can't write it down explicitly,



​> ​the lack of ISOLATION is the condition for the existence of  
this macro definite state.


​A baseball made of 10^25 atoms ​has 10^25 times more ways to  
interact with the environment than a single atom does, so we'd  
expect to see a baseball in just one state about  ​10^25 times less  
often than we do in a single atom.​


​> ​The concept of Multiverse and Many Worlds come from entirely  
different contexts and theories,


​I don't think anybody was even talking about the Multiverse before  
1957 when Hugh Everett introduced the idea of Many Worlds, and  
Evert's idea won't work without the Multiverse. ​ That doesn't  
sound entirely different to me.


Multiverse arose in the context of string theory, after Everett's  
MWI. The difference between Multiverse and MWI is striking and  
obvious.



To my knowledge, "multiverse" is the terming given by David Deutsch  
for the Many-Worlds. Then, String Theory has used that terming in its  
context, but it could have used "many-World". String theory is a  
special application of QM.




For example, the former has nothing to do with Joe the Plumber  
shooting an electron at a slit in a lab and creating an awesome  
(uncountable!) number of NEW universes.


​> ​For example, we know that irrational numbers exist

Do we?

Of course. It has been proven that pi and e are not rational. It's  
also been proven that the irrationals are dense in the reals; that  
is, many "more" irrationals than rationals; the difference between  
countable and uncountable infinities.


The rational are dense, but countable. The real are not countable. But  
this is mathematics, not physics. You need some metaphysical or  
theological hypothesis to talk about the existence or non-existence of  
a mathematical object in a physucal reality, or vice versa. See my  
work for an explanation that if Mechanism is true in cognitive  
science, then, there is 0 physical universe, as arithmetic emulate all  
dreams, and the physical apperances emerges from "number's dream"  
statistic. It seems you assume Aristotle metaphysics, which assumes  
that there is a primary/primitive/non-derivable Physical Universe.


Bruno







We know that mathematicians can use the language of mathematics to  
write stories about irrational numbers​,​ but nobody has ever  
seen a irrational number ​of​ anything in the physical world. And  
we know that a English professor can write stories about The Lord Of  
The Rings, but noddy has ever seen ​​Frodo Baggins​ or The  
Shire.


​> ​if your conjecture were true, it would be impossible for  
irrational numbers to exist, since recurring repetitions of subset  
strings would be impossible to avoid.


​If the ​conjecture ​is​ true​ then there might be a  
infinite number of Turing Machines in the Multiverse but they  
couldn't communicate with each other and none of them would have a  
infinite amount of tape. So any real Turing Machine in the  
Multiverse is certain to eventually stop, not for any software  
reason but because of hardware failure. Eventual any real Turing  
machine will get a command like "move the read/wright head one box  
to the left write a 1 in the box and then change to state  
6.02*10^23" but it will be unable to move one box to the left became  
it is already at the end of the tape and there is no more matter in  
the observable universe to extend it. If no physical process can  
produce them that seems to me a pretty good indication that the  
physical universe doesn't need irrational numbers (or even real  
numbers). Many Worlds is a theory about physics not mathematics so  
the philosophic debate about the existence or nonexistence of  
irrational numbers ​has no bearing on 

Re: Consistency of Postulates of QM

[Bruno Marchal]

On 14 Nov 2017, at 17:47, agrayson2...@gmail.com wrote:




On Monday, November 13, 2017 at 9:52:32 PM UTC-7,  
agrays...@gmail.com wrote:



On Monday, November 13, 2017 at 9:38:54 PM UTC-7,  
agrays...@gmail.com wrote:



On Monday, November 13, 2017 at 4:22:08 PM UTC-7, John Clark wrote:
On Mon, Nov 13, 2017 at 1:24 AM,  wrote ​

​> ​You're conflating Multiverse with the MWI.

​You can't have the MWI without the Multiverse, and if there is a  
Multiverse then the MWI explains a lot.​ ​There are about 10^80  
atoms in the observable universe and obviously there is a finite  
number of ways 10^80 atoms can be arranged in a sphere with a radius  
of 13.8 billion light years; so if the ​entire ​universe (not to  
be confused with the observable universe) is infinite then at a very  
large but still finite distance things must repeat and there is a  
universe identical to our own, and at another hyper large distance  
there is a universe identical to ours except that the freckle on my  
right thumb is on my left thumb instead. And at a even greater  
distance one second after a John Clark hits send on a message  
identical to this one all the air molecules in the room he is in go  
to the other side of the room due to random thermal vibrations and  
that John Clark suffocates. Bizarre events like that are not  
impossible just very very unlikely, but if the universe is really  
infinite then everything that doesn't violate the laws of physics  
will happen, and the Many World people say that's what the wave  
function is trying to tell us, everything that can happen will happen.


The concept of Multiverse and Many Worlds come from entirely  
different contexts and theories, so the idea that they are somehow  
connected or related strikes me a patently false. Moreover, the idea  
that if the universe is infinite (in some parameter; spatial extent,  
age, whatever), then anything that can happen, will happen, is IMO  
unproven and almost certainly false. For example, we know that  
irrational numbers exist, but in an infinite string of digits  
representing some irrational number, there are no repetitions of any  
subset strings. But there should be according to your conjecture.


Or look at it this way; if your conjecture were true, it would be  
impossible for irrational numbers to exist, since recurring  
repetitions of subset strings would be impossible to avoid.


I think my conjecture above is incorrect. Although finite strings of  
any length would repeat in an infinite random string, they would not  
repeat at regular intervals that would cause the original string to  
fail to represent an irrational number. OTOH, I think we can agree  
that necessary repetitions of whatever in a FINITE universe cannot  
be expected. Thus, if our universe is finite in extent and number of  
particles, there will be no automatic or expected repeats of  
anything. I submit that our universe is, indeed, finite (observable  
and unobservable regions) because it is FINITE IN AGE.


The existence (or not) of irrational numbers is independent of the  
existence of a physical universe. Numbers are not physical objects,  
unless you postulate a vey special metaphysics making them so. But  
then you might describe it, perhaps.


Bruno




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R: Re: Consistency of Postulates of QM

['scerir' via Everything List]

>> And "recorded" may not bring the right picture to mind.  It is 

[Bruce, I guess]
>True. The loss of interference due to radiation of IR photons from 
>buckeyballs means that information does not have to be 'recorded' in a 
>concrete sense -- it just has to be available somewhere, even if 
>recovery is not practicable.

"The superposition of amplitudes is only valid if there is no way to know, 
even in
principle, which path the particle took. It is important to realize that this 
does not
imply that an observer actually takes note of what happens. It is sufficient 
to destroy
the interference pattern, if the path information is accessible in principle 
from the
experiment or even if it is dispersed in the environment and beyond any 
technical
possibility to be recovered, but in principle 'still out there'."
--Anton Zeilinger, (Rev. Mod. Phys., 1999, p. S-288)

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Re: Consistency of Postulates of QM

[Bruce Kellett]

On 15/11/2017 5:02 pm, Russell Standish wrote:

On Wed, Nov 15, 2017 at 02:46:21PM +1100, Bruce Kellett wrote:

On 15/11/2017 12:49 pm, Russell Standish wrote:

On Wed, Nov 15, 2017 at 11:05:22AM +1100, Bruce Kellett wrote:

One of the strongest arguments for MWI was that it eliminates the concept of
a conscious observer from the interpretation of quantum mechanics.

I disagree. The strongest argument is that it removes the need for a
mysterious nonunitary physical collapse process (that may or may not
be driven by a conscious observer).

I said "one of the strongest"! I know that you want to define QM from the
idea of observer moments. I don't think that this will work, and the usual
consensus is that one of the strengths of MWI is the elimination of the
conscious observer.

Where's your evidence that this is the usual concensus? Who argues for it?


Most people, indirectly if not directly. I am thinking of MWI proponents 
such as Deutsch and Wallace. Wallace puts it like this "Some have argued 
that he measurement problem of quantum mechanics gives us reason to 
abandon the picture of science as describing an observer-independent 
world". He does not accept this view. The general view of scientific 
realism consists in the belief that the objective external world is 
independent of the observer. The thinking is related to Bell's assertion 
that: "Measurement should never be introduced as a primitive process in 
a fundamental mechanical theory like classical or quantum mechanics..." 
Measurement, observation, observers are all related concepts in this 
context.



A conscious observer (or rather just observer, really) is still
required to define the branches of the MWI, be that mediated by Zeh's
decoherence process, or otherwise. To eliminate observers entirely
requires solving the preferred basis problem without reference to an
observer or observation.

That is not true. The basis problem is solved by Zurek's einselection -- the
preferred basis is the one that is stable against further
decoherence.

I understand that the idea of einselection is still rather
controversial,


Not really. See Schlosshauer's paper and book.


but be that as it may, I can't see how it solves the
preferred basis problem. Consider an experiment where the experimenter
may choose between inserting a circularly polarised file, or a
linearly polarised one. The preferred basis (selected by einselection)
will depend on that choice.


That is a common misconception, but the angle selected for the 
polarizer, or the S-G magnet in a spin measurement, is not a selection 
of a measurement basis. The measurement is actually the observation 
whether or not the photon/particle passes the filter. It is then an 
inference from the observation of a point on a screen, or the firing (or 
failing to fire) of a detector of some sort, that the 
polarization/spin-component was such and such. You don't actually 
measure anything in the selected orientation, you only ever measure 
whether the particle passed the filter or not. So the actual measurement 
is just a position measurement (position on a screen), and the 
measurement basis is the position (pointer) basis.



In MWI, we normally assume that there are
two branches of the universe with different choices made by the
experimenter.


That is really an oversimplification. It is done because it is simpler 
to work with two-state systems, and position measurements are of a 
continuous variable, so are not neatly two-valued.



Unless there is some sort of superdeterminism in play,
where the experimenter does not have the freedom to choose. But
superdeterminism is certainly not a popular idea.


No, superdeterminism does not have many advocates.


Observers have nothing to do with it. In Zurek's account, it is the fact
that the results of interactions, be they measurements or not, are recorded
multiple times in the environment via decoherence, that is the mark of an
irreversible quantum event.

If you put a system in contact with a completely symmetric heat bath,
there will be no preferred basis selected by einselection.


The environment of a measurement or an interaction is not generally a 
symmetric heat bath. If you measure a spin component (space 
quantization) you get one of two spots on a screen downstream of the S-G 
magnet. These are not symmetric wrt the rest of the environment. In one 
world the irreversible record is of an upper spot. In the other world it 
is of the lower spot. The distinction is not lost because of symmetry. 
The basis for the measurement is the position basis, because that is 
stable against further decoherence. The angle of the S-G magnet is not 
the measurement basis.



The only
way for a basis to emerge is if there are system constraints of some
sort. I would argue that the only way these constraints could arise in
a Multiverse (which is symmetric by construction) is by considering
the environment from the point of view of some observer, ie the basic
symmetry 

Re: Consistency of Postulates of QM

[Bruce Kellett]

On 15/11/2017 3:12 pm, Brent Meeker wrote:

On 11/14/2017 7:46 PM, Bruce Kellett wrote:

On 15/11/2017 12:49 pm, Russell Standish wrote:

On Wed, Nov 15, 2017 at 11:05:22AM +1100, Bruce Kellett wrote:
One of the strongest arguments for MWI was that it eliminates the 
concept of

a conscious observer from the interpretation of quantum mechanics.

I disagree. The strongest argument is that it removes the need for a
mysterious nonunitary physical collapse process (that may or may not
be driven by a conscious observer).


I said "one of the strongest"! I know that you want to define QM from 
the idea of observer moments. I don't think that this will work, and 
the usual consensus is that one of the strengths of MWI is the 
elimination of the conscious observer.



A conscious observer (or rather just observer, really) is still
required to define the branches of the MWI, be that mediated by Zeh's
decoherence process, or otherwise. To eliminate observers entirely
requires solving the preferred basis problem without reference to an
observer or observation.


That is not true. The basis problem is solved by Zurek's einselection 
-- the preferred basis is the one that is stable against further 
decoherence. Observers have nothing to do with it. In Zurek's 
account, it is the fact that the results of interactions, be they 
measurements or not, are recorded multiple times in the environment 
via decoherence, that is the mark of an irreversible quantum event.


And "recorded" may not bring the right picture to mind.  It is 
recorded even if the information is radiated away into space.


True. The loss of interference due to radiation of IR photons from 
buckeyballs means that information does not have to be 'recorded' in a 
concrete sense -- it just has to be available somewhere, even if 
recovery is not practicable.


The future light cone is part of the environment.  But this makes me 
wonder if there are degrees of this entanglement information.  Even 
though there are lot of copies of Alice's results in the immediate 
vicinity, at a distance of few billion light years the information is 
spread very thin, so there is uncertainty as to whether it is 
entangled or not at that distance.


There is no distance parameter in the wave function for entanglement! So 
distance makes no difference.


So, if you are sufficiently far away, is there no longer any fact of 
the matter about which result Alice got?  This might be a connection 
to the quantization of spacetime, since at sufficiently time-like 
separated points the propagation of from one superspace foliation to 
another must satisfy an uncertainty principle.


Why? I don't see a particular connection here.

Bruce

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