subject:"No MWI"

Re: papers on probabilities & MWI

2021-02-19 Thread Bruno Marchal

> On 18 Feb 2021, at 04:39, Bruce Kellett  wrote:
> 
> On Thu, Feb 18, 2021 at 2:21 PM 'Brent Meeker' via Everything List 
> mailto:everything-list@googlegroups.com>> 
> wrote:
> On 2/17/2021 6:46 PM, Bruce Kellett wrote:
>> On Thu, Feb 18, 2021 at 1:05 PM 'Brent Meeker' via Everything List 
>> mailto:everything-list@googlegroups.com>> 
>> wrote:
>> On 2/17/2021 4:29 PM, Bruce Kellett wrote:
>>> Thus previous experience is no guide to the future in MWI. I know this is 
>>> true also in ordinary classical probability theory, but the difference is 
>>> that in MWI, one or more of your successors is bound to see the atypical 
>>> sequences -- that is not guaranteed in classical probability theory. It 
>>> *might* happen, but it is not *bound to* happen. This difference is 
>>> important.
>> 
>> I don't think it's even relevant.  It isn't "bound to happen" to you.  It's 
>> just a possibility for you, just as it is in the Kolmogorov sample space.
>> 
>> 
>> This is the problem with personal identity in many worlds -- the copies are 
>> all *you*, so your comment is without force. You are sneaking in the 
>> collapse that Sabine mentions; or you are making a dualist assumption -- 
>> only one of the copies is *really you*.
> 
> I don't think so.  Every copy post-test is some copy of you pre-test.  The 
> Everett explicitly writes the post-test wave function with all the you's in 
> it.  I don't see that as any more problematic than referring to possible 
> you's pre-test.  In any probabilistic theory only one possibility is realized
> 
> 
> That is where you keep slipping in the implicit collapse (or dualist identity 
> hypothesis). In MWI it is just not the case that only one possibility is 
> realized.

It is not the case that only one possibility is realised, in the 3p-view. But 
as the WM illustrates in a simpler (non quantum) setting, despite it is true 
that after the split “you” are both in Washington and Moscow, it is plain 
obvious that the two copies will feel differently, and will feel to see only 
one city. That is predictable using just mechanism, and the fact that they have 
no telepathic communication. The one in W will say “I see only Washington” and 
the one in Moscow will say “I see only Moscow”, and, as they bet on mechanism, 
they knew this in advance. This indeterminacy is provable, from the mechanist 
simple assumption. 

> 
>  
> ...that doesn't mean we have to assume there was some realism-spirit that got 
> passed to it.
> 
> 
> If you don't like dualism, then you are left with an implicit collapse 
> hypothesis. There are no other options in MWI.

You are left with a phenomenological collapse, entirely explainable in a monist 
theory of mind. Now if that theory is mechanism, the indeterminacy can no more 
be related to any particular sort of computation (selected by some personal or 
impersonal ontology), making obligatory to extract the wave itself from the 
measure on all computations, and this is confirmed by what the universal 
machine already deduce in arithmetic: there is just no evidence for any needed 
ontological commitment, as we infer already the MWI from observation, after 
having it deduced from simple mechanism. And then, thanks to incompleteness we 
get different mathematics for the qualia and the quanta, where the naturalist 
are known to not address this question, if not abuse of identification which 
simply cannot work (unless abandoned,dong mechanism).

I think that you are just eliminating the first person discourse. You look at 
all the diaries, without reading any particular one.

Bruno

> 
> 
>> 
>> <>
>>> 
>>> Yes. I think that the idea that Bob has been pursuing is a definite 
>>> non-starter. Carroll is smart enough to see this, even though he does want 
>>> to finally reduce probability to branch counting. The real trouble I see 
>>> with Sean's approach is that he has to call on Born rule insights to know 
>>> how many additional branches to manufacture. His approach is irreducibly 
>>> circular.
>> 
>> But then he could just postulate the Born rule as the way to partition, or 
>> create, branches and it would work; which is what Sabine says.  And that 
>> tells me that the Hemmo and Pitkowsky objection is wrong.
>> 
>> 
>> That is what Carroll and Bob are doing. But that rather defeats the purpose 
>> of deriving the Born rule from the Schrodinger equation alone. All such 
>> arguments are inherently circular.
> 
> I agree with that.  Do you agree that it would work to simply add the Born 
> rule to MWI as a postulate?
> 
> 
> I have difficulty seeing how t

Re: papers on probabilities & MWI

2021-02-19 Thread Bruno Marchal


> On 18 Feb 2021, at 03:05, 'Brent Meeker' via Everything List 
>  wrote:
> 
> 
> 
> On 2/17/2021 4:29 PM, Bruce Kellett wrote:
>> On Thu, Feb 18, 2021 at 10:51 AM 'Brent Meeker' via Everything List 
>> mailto:everything-list@googlegroups.com>> 
>> wrote:
>> On 2/17/2021 2:07 PM, Bruce Kellett wrote:
>>> On Thu, Feb 18, 2021 at 7:26 AM 'scerir' via Everything List 
>>> >> <mailto:everything-list@googlegroups.com>> wrote:
>>> just few links!
>>> 
>>> http://users.ox.ac.uk/~everett/docs/Hemmo%20Pitowsky%20Quantum%20probability.pdf
>>>  
>>> <http://users.ox.ac.uk/~everett/docs/Hemmo%20Pitowsky%20Quantum%20probability.pdf>
>>> 
>>> This is an interesting paper. I was amused to see that after a long 
>>> discussion, their conclusions section says essentially the things I have 
>>> been saying for ages.
>>> 
>>> Bruce
>> 
>> Yes it says what you've been saying, but it's the thing that I think 
>> Hossenfelder said better.
>> 
>> 
>> That might be a matter of opinion. Sabine talks about MWI introducing 
>> something equivalent to collapse in the measurement process, I have said 
>> that asking the question "which branch will I end up on?" introduces a 
>> dualist notion of personal identity. This is exactly the 'collapse' that 
>> Sabine sees in MWI.
>> 
>> 
>> Hemmo and Pitowsky write:
>> 
>>  if probability is supposed to do its
>> job, it must be related at least a-posteriori to the statistical pattern in 
>> which
>> events occur in our world in such a way that the relative frequencies that 
>> actually
>> occur in our world turn out to be typical. We take this as a necessary 
>> condition
>> on whatever it is that plays the role of probability in our physical theory. 
>> Now,
>> the quantum probability rule cannot satisfy this condition in the many worlds
>> theory (nor can any other non-trivial probability rule), since in this theory
>> the dynamics logically entails that any combinatorially possible sequence of
>> outcomes occurs with complete certainty, regardless of its quantum 
>> probability.
>> 
>> But Hossenfelder notes, correctly, that advocates of MWI say you must take 
>> the probability of an outcome to be it's relative frequency as single 
>> outcome among all the branches, not just whether of not it occurred.  To may 
>> it must be "typical" is ambigous.  Flipping a 100 head in a row, isn't 
>> typical, but it's possible and we have a theory of how to assign a 
>> probability to it and how to test whether that assignment is consistent.  
>> It's a possible sequence, and it "occurs" in the sample space, but that 
>> doesn't make its probability=1.
>> 
>> 
>> That is to confuse ordinary probability in a chancy universe with the fact 
>> that these outlying branches certainly occur in MWI. I thought the point 
>> made by Hemmo and Pitowsky was relevant. They pointed out that no matter 
>> what sequence you have observed up to this time, you have no guarantee that 
>> the next N results you observe won't be contrary to Born rule expectations.
> 
> You have not guarantee in one world...if it's probabilistic.
> 
>> Thus previous experience is no guide to the future in MWI. I know this is 
>> true also in ordinary classical probability theory, but the difference is 
>> that in MWI, one or more of your successors is bound to see the atypical 
>> sequences -- that is not guaranteed in classical probability theory. It 
>> *might* happen, but it is not *bound to* happen. This difference is 
>> important.
> 
> I don't think it's even relevant.  It isn't "bound to happen" to you.  It's 
> just a possibility for you, just as it is in the Kolmogorov sample space.
> 
>> And the statistical limiting theorems that David Albert quotes point to the 
>> significance of this difference.
> 
> The statistics are the same the same as the probabilities in the N->oo limit.
> 
>> 
>> 
>> In Sean Carroll's monthly "Ask me anything" blog he wrote this:
>> 
>> 0:40:16.3 SC: Sherman Flips says, "How does the weight assigned to a given 
>> branch of the wave function correspond to the number of micro-states that 
>> are in superposition in that branch?" So, you gotta be a little bit careful. 
>> Basically, it is that number, but I wanna be careful here because number of 
>> micro-states is a slightly ambiguous concept in quantum mechanics. If what 
>> you mean is the number of dime

Re: papers on probabilities & MWI

2021-02-17 Thread Bruce Kellett

On Thu, Feb 18, 2021 at 2:21 PM 'Brent Meeker' via Everything List <
everything-list@googlegroups.com> wrote:

> On 2/17/2021 6:46 PM, Bruce Kellett wrote:
>
> On Thu, Feb 18, 2021 at 1:05 PM 'Brent Meeker' via Everything List <
> everything-list@googlegroups.com> wrote:
>
>> On 2/17/2021 4:29 PM, Bruce Kellett wrote:
>>
>> Thus previous experience is no guide to the future in MWI. I know this is
>> true also in ordinary classical probability theory, but the difference is
>> that in MWI, one or more of your successors is bound to see the atypical
>> sequences -- that is not guaranteed in classical probability theory. It
>> *might* happen, but it is not *bound to* happen. This difference is
>> important.
>>
>>
>> I don't think it's even relevant.  It isn't "bound to happen" to you.
>> It's just a possibility for you, just as it is in the Kolmogorov sample
>> space.
>>
>
>
> This is the problem with personal identity in many worlds -- the copies
> are all *you*, so your comment is without force. You are sneaking in the
> collapse that Sabine mentions; or you are making a dualist assumption --
> only one of the copies is *really you*.
>
>
> I don't think so.  Every copy post-test is some copy of you pre-test.  The
> Everett explicitly writes the post-test wave function with all the you's in
> it.  I don't see that as any more problematic than referring to possible
> you's pre-test.  In any probabilistic theory only one possibility is
> realized
>


That is where you keep slipping in the implicit collapse (or dualist
identity hypothesis). In MWI it is just not the case that only one
possibility is realized.



> ...that doesn't mean we have to assume there was some realism-spirit that
> got passed to it.
>


If you don't like dualism, then you are left with an implicit collapse
hypothesis. There are no other options in MWI.


>
> <>
>
>>
>> Yes. I think that the idea that Bob has been pursuing is a
>> definite non-starter. Carroll is smart enough to see this, even though he
>> does want to finally reduce probability to branch counting. The real
>> trouble I see with Sean's approach is that he has to call on Born rule
>> insights to know how many additional branches to manufacture. His
>> approach is irreducibly circular.
>>
>>
>> But then he could just postulate the Born rule as the way to partition,
>> or create, branches and it would work; which is what Sabine says.  And that
>> tells me that the Hemmo and Pitkowsky objection is wrong.
>>
>
>
> That is what Carroll and Bob are doing. But that rather defeats the
> purpose of deriving the Born rule from the Schrodinger equation alone. All
> such arguments are inherently circular.
>
>
> I agree with that.  Do you agree that it would work to simply add the Born
> rule to MWI as a postulate?
>


I have difficulty seeing how that could work. For the Born rule to work,
the dynamics have to 'see' the amplitudes rather than just the eigenstate
basis vectors. But this does not happen in Everett. The set of histories
arising in N repetitions of the spin measurement is the same for any
two-component initial state -- there is no differentiation of the histories
according to the Born probabilities.

You have attempted to remedy this by assuming that the number of branches
on each trial splits in the Born rule ratios. But this is inconsistent with
unitary evolution and the MWI. You might be able to construct a many worlds
theory that has the Born rule as an independent postulate -- but  the
resultant theory will not be quantum mechanics as we know it. I doubt that
it can even be unitary.

Bruce

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Re: papers on probabilities & MWI

2021-02-17 Thread 'Brent Meeker' via Everything List

On 2/17/2021 6:46 PM, Bruce Kellett wrote:
On Thu, Feb 18, 2021 at 1:05 PM 'Brent Meeker' via Everything List
<mailto:everything-list@googlegroups.com>> wrote:

On 2/17/2021 4:29 PM, Bruce Kellett wrote:

Thus previous experience is no guide to the future in MWI. I know
this is true also in ordinary classical probability theory, but
the difference is that in MWI, one or more of your successors is
bound to see the atypical sequences -- that is not guaranteed in
classical probability theory. It *might* happen, but it is not
*bound to* happen. This difference is important.

I don't think it's even relevant. It isn't "bound to happen" to
you. It's just a possibility for you, just as it is in the
Kolmogorov sample space.

This is the problem with personal identity in many worlds -- the
copies are all *you*, so your comment is without force. You are
sneaking in the collapse that Sabine mentions; or you are making a
dualist assumption -- only one of the copies is *really you*.

I don't think so. Every copy post-test is some copy of you pre-test.
The Everett explicitly writes the post-test wave function with all the
you's in it. I don't see that as any more problematic than referring to
possible you's pre-test. In any probabilistic theory only one
possibility is realized...that doesn't mean we have to assume there was
some realism-spirit that got passed to it.

Yes. I think that the idea that Bob has been pursuing is a
definite non-starter. Carroll is smart enough to see this, even
though he does want to finally reduce probability to branch
counting. The real trouble I see with Sean's approach is that he
has to call on Born rule insights to know how many additional
branches to manufacture. His approach is irreducibly circular.

But then he could just postulate the Born rule as the way to
partition, or create, branches and it would work; which is what
Sabine says. And that tells me that the Hemmo and Pitkowsky
objection is wrong.

That is what Carroll and Bob are doing. But that rather defeats the
purpose of deriving the Born rule from the Schrodinger equation alone.
All such arguments are inherently circular.

I agree with that. Do you agree that it would work to simply add the
Born rule to MWI as a postulate?

Brent

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Re: papers on probabilities & MWI

2021-02-17 Thread Bruce Kellett

On Thu, Feb 18, 2021 at 1:05 PM 'Brent Meeker' via Everything List <
everything-list@googlegroups.com> wrote:

> On 2/17/2021 4:29 PM, Bruce Kellett wrote:
>
> Thus previous experience is no guide to the future in MWI. I know this is
> true also in ordinary classical probability theory, but the difference is
> that in MWI, one or more of your successors is bound to see the atypical
> sequences -- that is not guaranteed in classical probability theory. It
> *might* happen, but it is not *bound to* happen. This difference is
> important.
>
>
> I don't think it's even relevant.  It isn't "bound to happen" to you.
> It's just a possibility for you, just as it is in the Kolmogorov sample
> space.
>


This is the problem with personal identity in many worlds -- the copies are
all *you*, so your comment is without force. You are sneaking in the
collapse that Sabine mentions; or you are making a dualist assumption --
only one of the copies is *really you*.


<>

>
> Yes. I think that the idea that Bob has been pursuing is a
> definite non-starter. Carroll is smart enough to see this, even though he
> does want to finally reduce probability to branch counting. The real
> trouble I see with Sean's approach is that he has to call on Born rule
> insights to know how many additional branches to manufacture. His
> approach is irreducibly circular.
>
>
> But then he could just postulate the Born rule as the way to partition, or
> create, branches and it would work; which is what Sabine says.  And that
> tells me that the Hemmo and Pitkowsky objection is wrong.
>


That is what Carroll and Bob are doing. But that rather defeats the purpose
of deriving the Born rule from the Schrodinger equation alone. All such
arguments are inherently circular.

Bruce

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Re: papers on probabilities & MWI

2021-02-17 Thread 'Brent Meeker' via Everything List




On 2/17/2021 4:29 PM, Bruce Kellett wrote:
On Thu, Feb 18, 2021 at 10:51 AM 'Brent Meeker' via Everything List 
<mailto:everything-list@googlegroups.com>> wrote:


On 2/17/2021 2:07 PM, Bruce Kellett wrote:

On Thu, Feb 18, 2021 at 7:26 AM 'scerir' via Everything List
mailto:everything-list@googlegroups.com>> wrote:

just few links!


http://users.ox.ac.uk/~everett/docs/Hemmo%20Pitowsky%20Quantum%20probability.pdf

<http://users.ox.ac.uk/~everett/docs/Hemmo%20Pitowsky%20Quantum%20probability.pdf>


This is an interesting paper. I was amused to see that after a
long discussion, their conclusions section says essentially the
things I have been saying for ages.

Bruce


Yes it says what you've been saying, but it's the thing that I
think Hossenfelder said better.



That might be a matter of opinion. Sabine talks about MWI introducing 
something equivalent to collapse in the measurement process, I have 
said that asking the question "which branch will I end up on?" 
introduces a dualist notion of personal identity. This is exactly the 
'collapse' that Sabine sees in MWI.



Hemmo and Pitowsky write:
/
// if probability is supposed to do its//
//job, it must be related at least a-posteriori to the statistical
pattern in which//
//events occur in our world in such a way that the relative
frequencies that actually//
//occur in our world turn out to be typical. We take this as a
necessary condition//
//on whatever it is that plays the role of probability in our
physical theory. Now,//
//the quantum probability rule cannot satisfy this condition in
the many worlds//
//theory (nor can any other non-trivial probability rule), since
in this theory//
//the dynamics logically entails that any combinatorially possible
sequence of//
//outcomes occurs with complete certainty, regardless of its
quantum probability./

But Hossenfelder notes, correctly, that advocates of MWI say you
must take the probability of an outcome to be it's relative
frequency as single outcome among all the branches, not just
whether of not it occurred.  To may it must be "typical" is
ambigous.  Flipping a 100 head in a row, isn't typical, but it's
possible and we have a theory of how to assign a probability to it
and how to test whether that assignment is consistent.  It's a
possible sequence, and it "occurs" in the sample space, but that
doesn't make its probability=1.



That is to confuse ordinary probability in a chancy universe with the 
fact that these outlying branches certainly occur in MWI. I thought 
the point made by Hemmo and Pitowsky was relevant. They pointed out 
that no matter what sequence you have observed up to this time, you 
have no guarantee that the next N results you observe won't be 
contrary to Born rule expectations.


You have not guarantee in one world...if it's probabilistic.

Thus previous experience is no guide to the future in MWI. I know this 
is true also in ordinary classical probability theory, but the 
difference is that in MWI, one or more of your successors is bound to 
see the atypical sequences -- that is not guaranteed in classical 
probability theory. It *might* happen, but it is not *bound to* 
happen. This difference is important.


I don't think it's even relevant.  It isn't "bound to happen" to you.  
It's just a possibility for you, just as it is in the Kolmogorov sample 
space.


And the statistical limiting theorems that David Albert quotes point 
to the significance of this difference.


The statistics are the same the same as the probabilities in the N->oo 
limit.





In Sean Carroll's monthly "Ask me anything" blog he wrote this:
/
//0:40:16.3 SC: Sherman Flips says, "How does the weight assigned
to a given branch of the wave function correspond to the number of
micro-states that are in superposition in that branch?" So, you
gotta be a little bit careful. Basically, it is that number, but I
wanna be careful here because number of micro-states is a slightly
ambiguous concept in quantum mechanics. If what you mean is the
number of dimensions of Hilbert space that correspond to that
branch, that's what it means, the number of different directions
in Hilbert space that you can add together in some principled way
to make that particular vector corresponding to that branch.
Whether you wanna call a dimension of Hilbert space a micro-state
or not is up to you.//
//
//
//0:41:00.7 SC: There's another way of thinking about things if
you just had like a bunch of spins. So you have a bunch of
two-dimensional Hilbert spaces, one for each spin, spin up or spin
down, but the dimensionality of the combined Hilbert space is not
2N. If you have N spins, it's

Re: papers on probabilities & MWI

2021-02-17 Thread Bruce Kellett

On Thu, Feb 18, 2021 at 10:51 AM 'Brent Meeker' via Everything List <
everything-list@googlegroups.com> wrote:

> On 2/17/2021 2:07 PM, Bruce Kellett wrote:
>
> On Thu, Feb 18, 2021 at 7:26 AM 'scerir' via Everything List <
> everything-list@googlegroups.com> wrote:
>
>> just few links!
>>
>>
>> http://users.ox.ac.uk/~everett/docs/Hemmo%20Pitowsky%20Quantum%20probability.pdf
>>
>
> This is an interesting paper. I was amused to see that after a long
> discussion, their conclusions section says essentially the things I have
> been saying for ages.
>
> Bruce
>
>
> Yes it says what you've been saying, but it's the thing that I think
> Hossenfelder said better.
>


That might be a matter of opinion. Sabine talks about MWI introducing
something equivalent to collapse in the measurement process, I have said
that asking the question "which branch will I end up on?" introduces a
dualist notion of personal identity. This is exactly the 'collapse' that
Sabine sees in MWI.


Hemmo and Pitowsky write:
>
> * if probability is supposed to do its*
> *job, it must be related at least a-posteriori to the statistical pattern
> in which*
> *events occur in our world in such a way that the relative frequencies
> that actually*
> *occur in our world turn out to be typical. We take this as a necessary
> condition*
> *on whatever it is that plays the role of probability in our physical
> theory. Now,*
> *the quantum probability rule cannot satisfy this condition in the many
> worlds*
> *theory (nor can any other non-trivial probability rule), since in this
> theory*
> *the dynamics logically entails that any combinatorially possible sequence
> of*
> *outcomes occurs with complete certainty, regardless of its quantum
> probability.*
>
> But Hossenfelder notes, correctly, that advocates of MWI say you must take
> the probability of an outcome to be it's relative frequency as single
> outcome among all the branches, not just whether of not it occurred.  To
> may it must be "typical" is ambigous.  Flipping a 100 head in a row, isn't
> typical, but it's possible and we have a theory of how to assign a
> probability to it and how to test whether that assignment is consistent.
> It's a possible sequence, and it "occurs" in the sample space, but that
> doesn't make its probability=1.
>


That is to confuse ordinary probability in a chancy universe with the fact
that these outlying branches certainly occur in MWI. I thought the point
made by Hemmo and Pitowsky was relevant. They pointed out that no matter
what sequence you have observed up to this time, you have no guarantee that
the next N results you observe won't be contrary to Born rule expectations.
Thus previous experience is no guide to the future in MWI. I know this is
true also in ordinary classical probability theory, but the difference is
that in MWI, one or more of your successors is bound to see the atypical
sequences -- that is not guaranteed in classical probability theory. It
*might* happen, but it is not *bound to* happen. This difference is
important. And the statistical limiting theorems that David Albert quotes
point to the significance of this difference.


In Sean Carroll's monthly "Ask me anything" blog he wrote this:
>
> *0:40:16.3 SC: Sherman Flips says, "How does the weight assigned to a
> given branch of the wave function correspond to the number of micro-states
> that are in superposition in that branch?" So, you gotta be a little bit
> careful. Basically, it is that number, but I wanna be careful here because
> number of micro-states is a slightly ambiguous concept in quantum
> mechanics. If what you mean is the number of dimensions of Hilbert space
> that correspond to that branch, that's what it means, the number of
> different directions in Hilbert space that you can add together in some
> principled way to make that particular vector corresponding to that branch.
> Whether you wanna call a dimension of Hilbert space a micro-state or not is
> up to you.*
>
>
> *0:41:00.7 SC: There's another way of thinking about things if you just
> had like a bunch of spins. So you have a bunch of two-dimensional Hilbert
> spaces, one for each spin, spin up or spin down, but the dimensionality of
> the combined Hilbert space is not 2N. If you have N spins, it's 2 to the N.
> So you don't have one dimension of Hilbert space for each dimension of the
> subspaces; you exponentiate them. That's why it depends on what you mean by
> micro-state, but basically, that is what the weight means. You're on the
> right track thinking about that.*
>
> So he's definitely branch counting, but not describing the mechanism
> whereby the amplitude of one component of a superposition is translat

Re: papers on probabilities & MWI

2021-02-17 Thread 'Brent Meeker' via Everything List




On 2/17/2021 2:07 PM, Bruce Kellett wrote:
On Thu, Feb 18, 2021 at 7:26 AM 'scerir' via Everything List 
<mailto:everything-list@googlegroups.com>> wrote:


just few links!


http://users.ox.ac.uk/~everett/docs/Hemmo%20Pitowsky%20Quantum%20probability.pdf

<http://users.ox.ac.uk/~everett/docs/Hemmo%20Pitowsky%20Quantum%20probability.pdf>


This is an interesting paper. I was amused to see that after a long 
discussion, their conclusions section says essentially the things I 
have been saying for ages.


Bruce


Yes it says what you've been saying, but it's the thing that I think 
Hossenfelder said better.  Hemmo and Pitowsky write:

/
// if probability is supposed to do its//
//job, it must be related at least a-posteriori to the statistical 
pattern in which//
//events occur in our world in such a way that the relative frequencies 
that actually//
//occur in our world turn out to be typical. We take this as a necessary 
condition//
//on whatever it is that plays the role of probability in our physical 
theory. Now,//
//the quantum probability rule cannot satisfy this condition in the many 
worlds//
//theory (nor can any other non-trivial probability rule), since in this 
theory//
//the dynamics logically entails that any combinatorially possible 
sequence of//
//outcomes occurs with complete certainty, regardless of its quantum 
probability./


But Hossenfelder notes, correctly, that advocates of MWI say you must 
take the probability of an outcome to be it's relative frequency as 
single outcome among all the branches, not just whether of not it 
occurred.  To may it must be "typical" is ambigous. Flipping a 100 head 
in a row, isn't typical, but it's possible and we have a theory of how 
to assign a probability to it and how to test whether that assignment is 
consistent.  It's a possible sequence, and it "occurs" in the sample 
space, but that doesn't make its probability=1.


In Sean Carroll's monthly "Ask me anything" blog he wrote this:
/
//0:40:16.3 SC: Sherman Flips says, "How does the weight assigned to a 
given branch of the wave function correspond to the number of 
micro-states that are in superposition in that branch?" So, you gotta be 
a little bit careful. Basically, it is that number, but I wanna be 
careful here because number of micro-states is a slightly ambiguous 
concept in quantum mechanics. If what you mean is the number of 
dimensions of Hilbert space that correspond to that branch, that's what 
it means, the number of different directions in Hilbert space that you 
can add together in some principled way to make that particular vector 
corresponding to that branch. Whether you wanna call a dimension of 
Hilbert space a micro-state or not is up to you.//

//
//
//0:41:00.7 SC: There's another way of thinking about things if you just 
had like a bunch of spins. So you have a bunch of two-dimensional 
Hilbert spaces, one for each spin, spin up or spin down, but the 
dimensionality of the combined Hilbert space is not 2N. If you have N 
spins, it's 2 to the N. So you don't have one dimension of Hilbert space 
for each dimension of the subspaces; you exponentiate them. That's why 
it depends on what you mean by micro-state, but basically, that is what 
the weight means. You're on the right track thinking about that./


So he's definitely branch counting, but not describing the mechanism 
whereby the amplitude of one component of a superposition is translated 
into a different dimensionality of the combined Hilbert space.


Brent

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Re: papers on probabilities & MWI

2021-02-17 Thread Bruce Kellett

On Thu, Feb 18, 2021 at 7:26 AM 'scerir' via Everything List <
everything-list@googlegroups.com> wrote:

> just few links!
>
>
> http://users.ox.ac.uk/~everett/docs/Hemmo%20Pitowsky%20Quantum%20probability.pdf
>

This is an interesting paper. I was amused to see that after a long
discussion, their conclusions section says essentially the things I have
been saying for ages.

Bruce

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papers on probabilities & MWI

2021-02-17 Thread 'scerir' via Everything List

just few links!

https://kups.ub.uni-koeln.de/6889/

http://philsci-archive.pitt.edu/15798/

https://plato.stanford.edu/entries/qm-manyworlds/

https://www.sciencedirect.com/science/article/abs/pii/S135521980700024X

http://users.ox.ac.uk/~everett/docs/Hemmo%20Pitowsky%20Quantum%20probability.pdf

http://philsci-archive.pitt.edu/8558/

https://www.tau.ac.il/~vaidman/lvhp/m117.pdf

https://core.ac.uk/download/pdf/295730424.pdf

https://philpapers.org/rec/HEWAIT

https://hal.archives-ouvertes.fr/hal-03025703/document

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Re: MWI and time

2020-04-27 Thread Eva

Thank you! I have to admit that I like this interpretation. Some people say 
that it even explain cosmological fine-tunning

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Re: MWI and time

2020-04-24 Thread Jason Resch

Hi Eva,

The founder of this list published an interpretation of QM that embodies
both timelessness and many worlds.

He calls it: "a really simple interpretation of quantum mechanics":

http://www.weidai.com/qm-interpretation.txt

So I think you are right it isn't needed in any objective sense. As far as
why we experience it, I think the reason is thermodynamics. It takes energy
to process and record information (Landauer's Limit) and since energy can
only be expended in one direction of time, information processing systems
like life and brains evolved to process and record information as soon as
it was able to (moving through the present from the past, and into the
future). But this feeling is a subjective illusion.

Jason

On Thursday, April 23, 2020, Eva  wrote:

> Hello guys :) what do you think about time in many world interpretation?
> If there is one changless global wave function, than why we have change at
> all?
>
> All these states, different branches which emerge or are incribed in
> global wave, are not changless - we experience change.
>
> Why?
>
> Is it because they are relative?
>
> If so, everything which is relative is transitory?
>
> --
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> msgid/everything-list/0411c43f-8408-4bd3-80e5-d5b442712a09%40googlegroups.
> com.
>

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Re: MWI and time

2020-04-23 Thread Lawrence Crowell

On Thursday, April 23, 2020 at 2:21:48 PM UTC-5, Eva wrote:
>
> Hello guys :) what do you think about time in many world interpretation?
> If there is one changless global wave function, than why we have change at 
> all?
>
> All these states, different branches which emerge or are incribed in 
> global wave, are not changless - we experience change.
>
> Why?
>
> Is it because they are relative? 
>
> If so, everything which is relative is transitory?
>

In MWI there is the global wave function, and with respect to any 
observer's measurement outcome this is manifested by a projector that 
reduces observed state of the quantum system. The time any observer records 
on their clock would then be the same as the global time. Things only get a 
bit odd when we consider different eigen-branching of the system are in 
different regions of gravity so they have different proper times. 

LC 

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MWI and time

2020-04-23 Thread Eva

Hello guys :) what do you think about time in many world interpretation?
If there is one changless global wave function, than why we have change at all?

All these states, different branches which emerge or are incribed in global 
wave, are not changless - we experience change.

Why?

Is it because they are relative? 

If so, everything which is relative is transitory?

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