Re: Question for the QM experts here: quantum uncertainty of the past

[Quentin Anciaux]

2013/9/3 meekerdb 

> On 9/3/2013 6:14 AM, smi...@zonnet.nl wrote:
>
>> Yes, that's also my favorite way of thinking about this, you are
>> precisely that what you experience at any one time, and that may well
>> include memories of the past.
>>
>> What was discussed earlier in this thread about decoherence, is only
>> revelevant to explaining why you don't get macroscopic manifestations of
>> typical quantum phenomena like interference phenomena or violations of
>> certain Bell's inequalities if you take serious that there are multiple
>> histories instead of a single unique one.
>>
>> What happens is that you get decoherent histories that effectively don't
>> interfere with each other. So, we can safely say that Obama winning the
>> elections was not due to macroscopically different histories leading to
>> destructive interference in Romney's vote count in Ohio.
>>
>> What one cannot say is that decoherence somehow leads to a single history
>> being selected (unless you a priori asume a collapse theory). What you get
>> is a set of macroscopically distinct histories that are decoherent relative
>> to each other, but with sufficient lack of knowledge you can be in many of
>> them simultaneously.
>>
>
> That's where this account gets muddled.  Who lacks knowledge?  There is no
> "you".


There is, the one experiencing things here and now.


>
>  This effect will not lead to probabilities behaving in a different way
>> than what you would get from classical probability theory assuming that the
>> uncertainty is due to a lack of knowledge and that in reality only ione
>> history really exists.
>>
>
> The very concept of probabilities implies there is some "you" that
> experiences them.


We don't experience the past, we remember it here and now, the only
experience an experiencer has is the here and now.

>
>
>> So, you then can't see the difference between all these histories
>> copatible with your knowledge really existing and that they don't exist.
>> But that's not a good argument (by itself) to say that they in fact don't
>> exist.
>>
>
> But if there are "all these histories" then there is no "you".
>

There is, the one experiencing things here and now.

Quentin


>
> Brent
>
>
>
>> Saibal
>>
>>
>> Citeren Dennis Ochei :
>>
>>  Given that we are elements that might belong to multiple sequences, there
>>> is no fact of the matter as to which sequence we belong to.
>>>
>>>
>>> On Tue, Sep 3, 2013 at 12:23 AM, Dennis Ochei *
>>> *wrote:
>>>
>>>  Yes, exactly.

 > But then there are no "experiencers"...

 I prefer to say that experiencers are their experiences than to say
 there
 are no experiencers (I'm explaining my phrasing more than anything)


 On Mon, Sep 2, 2013 at 11:50 PM, meekerdb  wrote:

   You mean experiences are purely qualitative, so there cannot be two
> identical experiences rather, if identical they must be one (by
> Leibniz's
> identity of indiscernibles) and not two.  But then there are no
> "experiencers", only sequences of experiences which may have some
> unifying
> property and which may share elements with other sequences.
>
> Brent
>
>
> On 9/2/2013 8:55 PM, Dennis Ochei wrote:
>
> "Qualitatively identical experiencers are also numerically identical"
> is
> how i sum this position up
>
> On Wednesday, August 14, 2013 4:39:27 PM UTC-5, Brent wrote:
>
>>
>> On 8/14/2013 7:48 AM, smi...@zonnet.nl wrote:
>> > Citeren Russell Standish :
>> >
>> >> On Tue, Aug 13, 2013 at 05:26:41PM -0700, Pierz wrote:
>> >>> I need clarification of the significance of quantum theory to
>> determining
>> >>> the *past*. I remember having read or heard that the past itself
>> is
>> subject
>> >>> to quantum uncertainty. Something like the idea that the past is
>> determined
>> >>> only to to the extent that it is forced to be so by the state of
>> the
>> >>> present, if that makes sense. In other words, there may be more
>> than
>> one
>> >>> history that could lead to the current state of the world. Let's
>> say
>> it
>> >>> might have been one way or another and then we make a measurement
>> which
>> >>> resolves this question, we are 'forcing' the past to be one way or
>> another.
>> >>> In MWI, that would be saying my 'track' through the multiverse is
>> ambiguous
>> >>> in both directions, both into the future and 'behind me' so to
>> speak. I'm
>> >>> unclear on this and what it precisely means. I seem to recall that
>> it was
>> >>> critical in calculations Hawking made about the early universe -
>> at
>> a
>> >>> certain point these uncertainties became critical and it meant
>> that
>> it was
>> >>> no longer possible to say that the universe had definitely been
>> one
>> way or
>> >>> another. Can someone clarify this for m

Re: Question for the QM experts here: quantum uncertainty of the past

[meekerdb]

On 9/3/2013 6:14 AM, smi...@zonnet.nl wrote:
Yes, that's also my favorite way of thinking about this, you are precisely that what you 
experience at any one time, and that may well include memories of the past.


What was discussed earlier in this thread about decoherence, is only revelevant to 
explaining why you don't get macroscopic manifestations of typical quantum phenomena 
like interference phenomena or violations of certain Bell's inequalities if you take 
serious that there are multiple histories instead of a single unique one.


What happens is that you get decoherent histories that effectively don't interfere with 
each other. So, we can safely say that Obama winning the elections was not due to 
macroscopically different histories leading to destructive interference in Romney's vote 
count in Ohio.


What one cannot say is that decoherence somehow leads to a single history being selected 
(unless you a priori asume a collapse theory). What you get is a set of macroscopically 
distinct histories that are decoherent relative to each other, but with sufficient lack 
of knowledge you can be in many of them simultaneously. 


That's where this account gets muddled.  Who lacks knowledge?  There is no 
"you".

This effect will not lead to probabilities behaving in a different way than what you 
would get from classical probability theory assuming that the uncertainty is due to a 
lack of knowledge and that in reality only ione history really exists.


The very concept of probabilities implies there is some "you" that experiences 
them.


So, you then can't see the difference between all these histories copatible with your 
knowledge really existing and that they don't exist. But that's not a good argument (by 
itself) to say that they in fact don't exist.


But if there are "all these histories" then there is no "you".

Brent



Saibal


Citeren Dennis Ochei :


Given that we are elements that might belong to multiple sequences, there
is no fact of the matter as to which sequence we belong to.


On Tue, Sep 3, 2013 at 12:23 AM, Dennis Ochei wrote:


Yes, exactly.

> But then there are no "experiencers"...

I prefer to say that experiencers are their experiences than to say there
are no experiencers (I'm explaining my phrasing more than anything)


On Mon, Sep 2, 2013 at 11:50 PM, meekerdb  wrote:


 You mean experiences are purely qualitative, so there cannot be two
identical experiences rather, if identical they must be one (by Leibniz's
identity of indiscernibles) and not two.  But then there are no
"experiencers", only sequences of experiences which may have some unifying
property and which may share elements with other sequences.

Brent


On 9/2/2013 8:55 PM, Dennis Ochei wrote:

"Qualitatively identical experiencers are also numerically identical" is
how i sum this position up

On Wednesday, August 14, 2013 4:39:27 PM UTC-5, Brent wrote:


On 8/14/2013 7:48 AM, smi...@zonnet.nl wrote:
> Citeren Russell Standish :
>
>> On Tue, Aug 13, 2013 at 05:26:41PM -0700, Pierz wrote:
>>> I need clarification of the significance of quantum theory to
determining
>>> the *past*. I remember having read or heard that the past itself is
subject
>>> to quantum uncertainty. Something like the idea that the past is
determined
>>> only to to the extent that it is forced to be so by the state of the
>>> present, if that makes sense. In other words, there may be more than
one
>>> history that could lead to the current state of the world. Let's say
it
>>> might have been one way or another and then we make a measurement
which
>>> resolves this question, we are 'forcing' the past to be one way or
another.
>>> In MWI, that would be saying my 'track' through the multiverse is
ambiguous
>>> in both directions, both into the future and 'behind me' so to
speak. I'm
>>> unclear on this and what it precisely means. I seem to recall that
it was
>>> critical in calculations Hawking made about the early universe - at
a
>>> certain point these uncertainties became critical and it meant that
it was
>>> no longer possible to say that the universe had definitely been one
way or
>>> another. Can someone clarify this for me?
>>>
>>
>> This idea of the past not being determinate until such a time as a
>> measurement in the present forces the issue is fundamental to my
>> interpretation of QM. It is also related to the Quantum Eraser.
Saibal
>> Mitra has written some stuff on this too - maybe he'd like to
comment?
>>
>> On the other hand, I don't think this view is particularly
>> mainstream. Even many worlds people tend to think that the multiverse
>> has decohered in the past, and that there is a matter of fact which
>> branch we are in, even if we're ignorant of that fact.
>>
>> I can't comment on Hawking's work, unfortunately, as I'm not aware of
that.
>>
>> Cheers
>> --
>
>
> Yes, I would agree with the view taken by Russell here. It has
interesting consequences
> for any future artificial intelligence who can reset its memory, as I

Re: Question for the QM experts here: quantum uncertainty of the past

[smitra]

Yes, that's also my favorite way of thinking about this, you are 
precisely that what you experience at any one time, and that may well 
include memories of the past.


What was discussed earlier in this thread about decoherence, is only 
revelevant to explaining why you don't get macroscopic manifestations 
of typical quantum phenomena like interference phenomena or violations 
of certain Bell's inequalities if you take serious that there are 
multiple histories instead of a single unique one.


What happens is that you get decoherent histories that effectively 
don't interfere with each other. So, we can safely say that Obama 
winning the elections was not due to macroscopically different 
histories leading to destructive interference in Romney's vote count in 
Ohio.


What one cannot say is that decoherence somehow leads to a single 
history being selected (unless you a priori asume a collapse theory). 
What you get is a set of macroscopically distinct histories that are 
decoherent relative to each other, but with sufficient lack of 
knowledge you can be in many of them simultaneously. This effect will 
not lead to probabilities behaving in a different way than what you 
would get from classical probability theory assuming that the 
uncertainty is due to a lack of knowledge and that in reality only ione 
history really exists.


So, you then can't see the difference between all these histories 
copatible with your knowledge really existing and that they don't 
exist. But that's not a good argument (by itself) to say that they in 
fact don't exist.


Saibal


Citeren Dennis Ochei :


Given that we are elements that might belong to multiple sequences, there
is no fact of the matter as to which sequence we belong to.


On Tue, Sep 3, 2013 at 12:23 AM, Dennis Ochei wrote:


Yes, exactly.

> But then there are no "experiencers"...

I prefer to say that experiencers are their experiences than to say there
are no experiencers (I'm explaining my phrasing more than anything)


On Mon, Sep 2, 2013 at 11:50 PM, meekerdb  wrote:


 You mean experiences are purely qualitative, so there cannot be two
identical experiences rather, if identical they must be one (by Leibniz's
identity of indiscernibles) and not two.  But then there are no
"experiencers", only sequences of experiences which may have some unifying
property and which may share elements with other sequences.

Brent


On 9/2/2013 8:55 PM, Dennis Ochei wrote:

"Qualitatively identical experiencers are also numerically identical" is
how i sum this position up

On Wednesday, August 14, 2013 4:39:27 PM UTC-5, Brent wrote:


On 8/14/2013 7:48 AM, smi...@zonnet.nl wrote:
> Citeren Russell Standish :
>
>> On Tue, Aug 13, 2013 at 05:26:41PM -0700, Pierz wrote:
>>> I need clarification of the significance of quantum theory to
determining
>>> the *past*. I remember having read or heard that the past itself is
subject
>>> to quantum uncertainty. Something like the idea that the past is
determined
>>> only to to the extent that it is forced to be so by the state of the
>>> present, if that makes sense. In other words, there may be more than
one
>>> history that could lead to the current state of the world. Let's say
it
>>> might have been one way or another and then we make a measurement
which
>>> resolves this question, we are 'forcing' the past to be one way or
another.
>>> In MWI, that would be saying my 'track' through the multiverse is
ambiguous
>>> in both directions, both into the future and 'behind me' so to
speak. I'm
>>> unclear on this and what it precisely means. I seem to recall that
it was
>>> critical in calculations Hawking made about the early universe - at
a
>>> certain point these uncertainties became critical and it meant that
it was
>>> no longer possible to say that the universe had definitely been one
way or
>>> another. Can someone clarify this for me?
>>>
>>
>> This idea of the past not being determinate until such a time as a
>> measurement in the present forces the issue is fundamental to my
>> interpretation of QM. It is also related to the Quantum Eraser.
Saibal
>> Mitra has written some stuff on this too - maybe he'd like to
comment?
>>
>> On the other hand, I don't think this view is particularly
>> mainstream. Even many worlds people tend to think that the multiverse
>> has decohered in the past, and that there is a matter of fact which
>> branch we are in, even if we're ignorant of that fact.
>>
>> I can't comment on Hawking's work, unfortunately, as I'm not aware of
that.
>>
>> Cheers
>> --
>
>
> Yes, I would agree with the view taken by Russell here. It has
interesting consequences
> for any future artificial intelligence who can reset its memory, as I
explain here:
>
> http://arxiv.org/abs/0902.3825
>
> So, if you reset your memory at random with some probability p and you
also do that in
> case of an impending disaster, then if you find yourself in a state
where you know that
> your memory has been reset and you need to reload your 

Re: Question for the QM experts here: quantum uncertainty of the past

[Dennis Ochei]

Given that we are elements that might belong to multiple sequences, there
is no fact of the matter as to which sequence we belong to.


On Tue, Sep 3, 2013 at 12:23 AM, Dennis Ochei wrote:

> Yes, exactly.
>
> > But then there are no "experiencers"...
>
> I prefer to say that experiencers are their experiences than to say there
> are no experiencers (I'm explaining my phrasing more than anything)
>
>
> On Mon, Sep 2, 2013 at 11:50 PM, meekerdb  wrote:
>
>>  You mean experiences are purely qualitative, so there cannot be two
>> identical experiences rather, if identical they must be one (by Leibniz's
>> identity of indiscernibles) and not two.  But then there are no
>> "experiencers", only sequences of experiences which may have some unifying
>> property and which may share elements with other sequences.
>>
>> Brent
>>
>>
>> On 9/2/2013 8:55 PM, Dennis Ochei wrote:
>>
>> "Qualitatively identical experiencers are also numerically identical" is
>> how i sum this position up
>>
>> On Wednesday, August 14, 2013 4:39:27 PM UTC-5, Brent wrote:
>>>
>>> On 8/14/2013 7:48 AM, smi...@zonnet.nl wrote:
>>> > Citeren Russell Standish :
>>> >
>>> >> On Tue, Aug 13, 2013 at 05:26:41PM -0700, Pierz wrote:
>>> >>> I need clarification of the significance of quantum theory to
>>> determining
>>> >>> the *past*. I remember having read or heard that the past itself is
>>> subject
>>> >>> to quantum uncertainty. Something like the idea that the past is
>>> determined
>>> >>> only to to the extent that it is forced to be so by the state of the
>>> >>> present, if that makes sense. In other words, there may be more than
>>> one
>>> >>> history that could lead to the current state of the world. Let's say
>>> it
>>> >>> might have been one way or another and then we make a measurement
>>> which
>>> >>> resolves this question, we are 'forcing' the past to be one way or
>>> another.
>>> >>> In MWI, that would be saying my 'track' through the multiverse is
>>> ambiguous
>>> >>> in both directions, both into the future and 'behind me' so to
>>> speak. I'm
>>> >>> unclear on this and what it precisely means. I seem to recall that
>>> it was
>>> >>> critical in calculations Hawking made about the early universe - at
>>> a
>>> >>> certain point these uncertainties became critical and it meant that
>>> it was
>>> >>> no longer possible to say that the universe had definitely been one
>>> way or
>>> >>> another. Can someone clarify this for me?
>>> >>>
>>> >>
>>> >> This idea of the past not being determinate until such a time as a
>>> >> measurement in the present forces the issue is fundamental to my
>>> >> interpretation of QM. It is also related to the Quantum Eraser.
>>> Saibal
>>> >> Mitra has written some stuff on this too - maybe he'd like to
>>> comment?
>>> >>
>>> >> On the other hand, I don't think this view is particularly
>>> >> mainstream. Even many worlds people tend to think that the multiverse
>>> >> has decohered in the past, and that there is a matter of fact which
>>> >> branch we are in, even if we're ignorant of that fact.
>>> >>
>>> >> I can't comment on Hawking's work, unfortunately, as I'm not aware of
>>> that.
>>> >>
>>> >> Cheers
>>> >> --
>>> >
>>> >
>>> > Yes, I would agree with the view taken by Russell here. It has
>>> interesting consequences
>>> > for any future artificial intelligence who can reset its memory, as I
>>> explain here:
>>> >
>>> > http://arxiv.org/abs/0902.3825
>>> >
>>> > So, if you reset your memory at random with some probability p and you
>>> also do that in
>>> > case of an impending disaster, then if you find yourself in a state
>>> where you know that
>>> > your memory has been reset and you need to reload your memory, the
>>> reason why the memory
>>> > has been reset  (routine random memory reset or you were facing an
>>> impending disaster),
>>> > is no longer determined, you are identical in the different branches
>>> until you find out
>>> > the reason.
>>> >
>>> > So, while you are firmly in the classical regime and therefore you
>>> won't see any changes
>>> > in the probabilities of the outcomes of these sorts of experiments
>>> relative to what you
>>> > would expect classically, the interpretation of how these
>>> probabilities arise is
>>> > different; while it is worthwhile to do these memory resettings in a
>>> "single classical
>>> > world" it wouldn't be worthwhile.
>>> >
>>> > The article I wrote (it was just an essay for FQXI competition which
>>> got the attention
>>> > from New Scientist), is actually rather simple, it treats the problem
>>> in a
>>> > non-relativistic way, which is a bit unnatural (the times at which
>>> things happen in the
>>> > different different branches seems to matter). You can easily
>>> generalize this, also you
>>> > can consider thought experiments involving false memories that may be
>>> correct memories
>>> > in different branches etc. etc.
>>>
>>> Hmm.  It seems that "erasing your memory" would encompass a lot more
>>> than what is com

Re: Question for the QM experts here: quantum uncertainty of the past

[Dennis Ochei]

Yes, exactly.

> But then there are no "experiencers"...

I prefer to say that experiencers are their experiences than to say there
are no experiencers (I'm explaining my phrasing more than anything)


On Mon, Sep 2, 2013 at 11:50 PM, meekerdb  wrote:

>  You mean experiences are purely qualitative, so there cannot be two
> identical experiences rather, if identical they must be one (by Leibniz's
> identity of indiscernibles) and not two.  But then there are no
> "experiencers", only sequences of experiences which may have some unifying
> property and which may share elements with other sequences.
>
> Brent
>
>
> On 9/2/2013 8:55 PM, Dennis Ochei wrote:
>
> "Qualitatively identical experiencers are also numerically identical" is
> how i sum this position up
>
> On Wednesday, August 14, 2013 4:39:27 PM UTC-5, Brent wrote:
>>
>> On 8/14/2013 7:48 AM, smi...@zonnet.nl wrote:
>> > Citeren Russell Standish :
>> >
>> >> On Tue, Aug 13, 2013 at 05:26:41PM -0700, Pierz wrote:
>> >>> I need clarification of the significance of quantum theory to
>> determining
>> >>> the *past*. I remember having read or heard that the past itself is
>> subject
>> >>> to quantum uncertainty. Something like the idea that the past is
>> determined
>> >>> only to to the extent that it is forced to be so by the state of the
>> >>> present, if that makes sense. In other words, there may be more than
>> one
>> >>> history that could lead to the current state of the world. Let's say
>> it
>> >>> might have been one way or another and then we make a measurement
>> which
>> >>> resolves this question, we are 'forcing' the past to be one way or
>> another.
>> >>> In MWI, that would be saying my 'track' through the multiverse is
>> ambiguous
>> >>> in both directions, both into the future and 'behind me' so to speak.
>> I'm
>> >>> unclear on this and what it precisely means. I seem to recall that it
>> was
>> >>> critical in calculations Hawking made about the early universe - at a
>> >>> certain point these uncertainties became critical and it meant that
>> it was
>> >>> no longer possible to say that the universe had definitely been one
>> way or
>> >>> another. Can someone clarify this for me?
>> >>>
>> >>
>> >> This idea of the past not being determinate until such a time as a
>> >> measurement in the present forces the issue is fundamental to my
>> >> interpretation of QM. It is also related to the Quantum Eraser. Saibal
>> >> Mitra has written some stuff on this too - maybe he'd like to comment?
>> >>
>> >> On the other hand, I don't think this view is particularly
>> >> mainstream. Even many worlds people tend to think that the multiverse
>> >> has decohered in the past, and that there is a matter of fact which
>> >> branch we are in, even if we're ignorant of that fact.
>> >>
>> >> I can't comment on Hawking's work, unfortunately, as I'm not aware of
>> that.
>> >>
>> >> Cheers
>> >> --
>> >
>> >
>> > Yes, I would agree with the view taken by Russell here. It has
>> interesting consequences
>> > for any future artificial intelligence who can reset its memory, as I
>> explain here:
>> >
>> > http://arxiv.org/abs/0902.3825
>> >
>> > So, if you reset your memory at random with some probability p and you
>> also do that in
>> > case of an impending disaster, then if you find yourself in a state
>> where you know that
>> > your memory has been reset and you need to reload your memory, the
>> reason why the memory
>> > has been reset  (routine random memory reset or you were facing an
>> impending disaster),
>> > is no longer determined, you are identical in the different branches
>> until you find out
>> > the reason.
>> >
>> > So, while you are firmly in the classical regime and therefore you
>> won't see any changes
>> > in the probabilities of the outcomes of these sorts of experiments
>> relative to what you
>> > would expect classically, the interpretation of how these probabilities
>> arise is
>> > different; while it is worthwhile to do these memory resettings in a
>> "single classical
>> > world" it wouldn't be worthwhile.
>> >
>> > The article I wrote (it was just an essay for FQXI competition which
>> got the attention
>> > from New Scientist), is actually rather simple, it treats the problem
>> in a
>> > non-relativistic way, which is a bit unnatural (the times at which
>> things happen in the
>> > different different branches seems to matter). You can easily
>> generalize this, also you
>> > can consider thought experiments involving false memories that may be
>> correct memories
>> > in different branches etc. etc.
>>
>> Hmm.  It seems that "erasing your memory" would encompass a lot more than
>> what is commonly
>> referred to as memory.  Quantum erasure requires erasing all the
>> information that is
>> diffused into the environment.  So erasing one's memory would imply
>> quantum erasure of all
>> the information about your past - not just the infinitesimal bit that you
>> can consciously
>> recall.
>>
>> Brent
>>
>>  --
> Y

Re: Question for the QM experts here: quantum uncertainty of the past

[meekerdb]

You mean experiences are purely qualitative, so there cannot be two identical experiences 
rather, if identical they must be one (by Leibniz's identity of indiscernibles) and not 
two.  But then there are no "experiencers", only sequences of experiences which may have 
some unifying property and which may share elements with other sequences.


Brent

On 9/2/2013 8:55 PM, Dennis Ochei wrote:
"Qualitatively identical experiencers are also numerically identical" is how i sum this 
position up


On Wednesday, August 14, 2013 4:39:27 PM UTC-5, Brent wrote:

On 8/14/2013 7:48 AM, smi...@zonnet.nl  wrote:
> Citeren Russell Standish >:
>
>> On Tue, Aug 13, 2013 at 05:26:41PM -0700, Pierz wrote:
>>> I need clarification of the significance of quantum theory to 
determining
>>> the *past*. I remember having read or heard that the past itself is 
subject
>>> to quantum uncertainty. Something like the idea that the past is 
determined
>>> only to to the extent that it is forced to be so by the state of the
>>> present, if that makes sense. In other words, there may be more than one
>>> history that could lead to the current state of the world. Let's say it
>>> might have been one way or another and then we make a measurement which
>>> resolves this question, we are 'forcing' the past to be one way or 
another.
>>> In MWI, that would be saying my 'track' through the multiverse is 
ambiguous
>>> in both directions, both into the future and 'behind me' so to speak. 
I'm
>>> unclear on this and what it precisely means. I seem to recall that it 
was
>>> critical in calculations Hawking made about the early universe - at a
>>> certain point these uncertainties became critical and it meant that it 
was
>>> no longer possible to say that the universe had definitely been one way 
or
>>> another. Can someone clarify this for me?
>>>
>>
>> This idea of the past not being determinate until such a time as a
>> measurement in the present forces the issue is fundamental to my
>> interpretation of QM. It is also related to the Quantum Eraser. Saibal
>> Mitra has written some stuff on this too - maybe he'd like to comment?
>>
>> On the other hand, I don't think this view is particularly
>> mainstream. Even many worlds people tend to think that the multiverse
>> has decohered in the past, and that there is a matter of fact which
>> branch we are in, even if we're ignorant of that fact.
>>
>> I can't comment on Hawking's work, unfortunately, as I'm not aware of 
that.
>>
>> Cheers
>> --
>
>
> Yes, I would agree with the view taken by Russell here. It has interesting
consequences
> for any future artificial intelligence who can reset its memory, as I 
explain here:
>
> http://arxiv.org/abs/0902.3825
>
> So, if you reset your memory at random with some probability p and you 
also do
that in
> case of an impending disaster, then if you find yourself in a state where 
you know
that
> your memory has been reset and you need to reload your memory, the reason 
why the
memory
> has been reset  (routine random memory reset or you were facing an 
impending
disaster),
> is no longer determined, you are identical in the different branches 
until you
find out
> the reason.
>
> So, while you are firmly in the classical regime and therefore you won't 
see any
changes
> in the probabilities of the outcomes of these sorts of experiments 
relative to
what you
> would expect classically, the interpretation of how these probabilities 
arise is
> different; while it is worthwhile to do these memory resettings in a 
"single
classical
> world" it wouldn't be worthwhile.
>
> The article I wrote (it was just an essay for FQXI competition which got 
the
attention
> from New Scientist), is actually rather simple, it treats the problem in a
> non-relativistic way, which is a bit unnatural (the times at which things 
happen
in the
> different different branches seems to matter). You can easily generalize 
this,
also you
> can consider thought experiments involving false memories that may be 
correct
memories
> in different branches etc. etc.

Hmm.  It seems that "erasing your memory" would encompass a lot more than 
what is
commonly
referred to as memory.  Quantum erasure requires erasing all the 
information that is
diffused into the environment.  So erasing one's memory would imply quantum 
erasure
of all
the information about your past - not just the infinitesimal bit that you 
can
consciously
recall.

Brent

--
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Re: Question for the QM experts here: quantum uncertainty of the past

[Dennis Ochei]

"Qualitatively identical experiencers are also numerically identical" is 
how i sum this position up

On Wednesday, August 14, 2013 4:39:27 PM UTC-5, Brent wrote:
>
> On 8/14/2013 7:48 AM, smi...@zonnet.nl  wrote: 
> > Citeren Russell Standish >: 
> > 
> >> On Tue, Aug 13, 2013 at 05:26:41PM -0700, Pierz wrote: 
> >>> I need clarification of the significance of quantum theory to 
> determining 
> >>> the *past*. I remember having read or heard that the past itself is 
> subject 
> >>> to quantum uncertainty. Something like the idea that the past is 
> determined 
> >>> only to to the extent that it is forced to be so by the state of the 
> >>> present, if that makes sense. In other words, there may be more than 
> one 
> >>> history that could lead to the current state of the world. Let's say 
> it 
> >>> might have been one way or another and then we make a measurement 
> which 
> >>> resolves this question, we are 'forcing' the past to be one way or 
> another. 
> >>> In MWI, that would be saying my 'track' through the multiverse is 
> ambiguous 
> >>> in both directions, both into the future and 'behind me' so to speak. 
> I'm 
> >>> unclear on this and what it precisely means. I seem to recall that it 
> was 
> >>> critical in calculations Hawking made about the early universe - at a 
> >>> certain point these uncertainties became critical and it meant that it 
> was 
> >>> no longer possible to say that the universe had definitely been one 
> way or 
> >>> another. Can someone clarify this for me? 
> >>> 
> >> 
> >> This idea of the past not being determinate until such a time as a 
> >> measurement in the present forces the issue is fundamental to my 
> >> interpretation of QM. It is also related to the Quantum Eraser. Saibal 
> >> Mitra has written some stuff on this too - maybe he'd like to comment? 
> >> 
> >> On the other hand, I don't think this view is particularly 
> >> mainstream. Even many worlds people tend to think that the multiverse 
> >> has decohered in the past, and that there is a matter of fact which 
> >> branch we are in, even if we're ignorant of that fact. 
> >> 
> >> I can't comment on Hawking's work, unfortunately, as I'm not aware of 
> that. 
> >> 
> >> Cheers 
> >> -- 
> > 
> > 
> > Yes, I would agree with the view taken by Russell here. It has 
> interesting consequences 
> > for any future artificial intelligence who can reset its memory, as I 
> explain here: 
> > 
> > http://arxiv.org/abs/0902.3825 
> > 
> > So, if you reset your memory at random with some probability p and you 
> also do that in 
> > case of an impending disaster, then if you find yourself in a state 
> where you know that 
> > your memory has been reset and you need to reload your memory, the 
> reason why the memory 
> > has been reset  (routine random memory reset or you were facing an 
> impending disaster), 
> > is no longer determined, you are identical in the different branches 
> until you find out 
> > the reason. 
> > 
> > So, while you are firmly in the classical regime and therefore you won't 
> see any changes 
> > in the probabilities of the outcomes of these sorts of experiments 
> relative to what you 
> > would expect classically, the interpretation of how these probabilities 
> arise is 
> > different; while it is worthwhile to do these memory resettings in a 
> "single classical 
> > world" it wouldn't be worthwhile. 
> > 
> > The article I wrote (it was just an essay for FQXI competition which got 
> the attention 
> > from New Scientist), is actually rather simple, it treats the problem in 
> a 
> > non-relativistic way, which is a bit unnatural (the times at which 
> things happen in the 
> > different different branches seems to matter). You can easily generalize 
> this, also you 
> > can consider thought experiments involving false memories that may be 
> correct memories 
> > in different branches etc. etc. 
>
> Hmm.  It seems that "erasing your memory" would encompass a lot more than 
> what is commonly 
> referred to as memory.  Quantum erasure requires erasing all the 
> information that is 
> diffused into the environment.  So erasing one's memory would imply 
> quantum erasure of all 
> the information about your past - not just the infinitesimal bit that you 
> can consciously 
> recall. 
>
> Brent 
>
>

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Re: Question for the QM experts here: quantum uncertainty of the past

[Russell Standish]

On Wed, Aug 21, 2013 at 12:07:05PM -0700, meekerdb wrote:
> 
> But it seems to me that this reset is a magical, impossible
> operation.  If the human brain is a classical computer then that
> means it's computational state can be reset. But it also means the
> its physical state can't be reset.  The resetting operation itself,
> being a classical operation, is irreversible because of decoherence
> into the environment.  So the environment has the information about
> the state leading up to the reset and the reset operation.  So when
> you say 'you' can find yourself on another branch, it's not clear
> what 'you' refers to.  Apparently it would have to refer to an
> abstract computation (per Bruno, I guess) that happened to go
> through the same state twice (due to the 'reset') in this world AND
> also at least once in some other world.  But if it went through that
> state in some other world, there was already FPI even without the
> reset.  Right?
> 
> Brent
> 

Just a small observation. Brent is arguing essential from what Bruno
would call the Aristotelian position, ie that there is a definite
environment containing the results of past decoherence that the
observer belongs to, even if the observer is now ignorant of that due
to memory erasure. Saibal is arguing from the COMP position, that
memory erasure is sufficient to reestablish the superposition - ie
that there is no such objective environment.

ISTM that Brent's position is widely held amongst QM practitioners
today, particularly the Austrian group, but that the alternative (many
minds, or perhaps COMP?) is equally as valid, at least as far as
empirical results go.

Part of the problem is that the language of the thought experiment
encourages the Aristotelian interpretation - we are describing the
situation from a mythical 3rd person POV, which implicitly supposes an
environment that the 3rd person observer is entangled with. If we were
to make the contorted effort to describe things entirely from the 1st
person observer's POV, the environment Brent is talking about vanishes
with the memory erasure.

Cheers

-- 


Prof Russell Standish  Phone 0425 253119 (mobile)
Principal, High Performance Coders
Visiting Professor of Mathematics  hpco...@hpcoders.com.au
University of New South Wales  http://www.hpcoders.com.au


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Re: Question for the QM experts here: quantum uncertainty of the past

[Quentin Anciaux]

2013/8/21 meekerdb 

>  On 8/21/2013 3:57 AM, Quentin Anciaux wrote:
>
>
>
>
> 2013/8/21 meekerdb 
>
>>  On 8/20/2013 5:26 AM, smi...@zonnet.nl wrote:
>>
>>> Citeren meekerdb :
>>>
>>>  On 8/16/2013 4:57 PM, smi...@zonnet.nl wrote:

> Citeren meekerdb :
>
>  On 8/15/2013 6:18 AM, smi...@zonnet.nl wrote:
>>
>>> Citeren meekerdb :
>>>
>>>  On 8/14/2013 6:41 PM, smi...@zonnet.nl wrote:

>  I guess I don't understand that.   You seem to be considering a
>> simple case of amnesia - all purely classical - so I don't see how 
>> MWI
>> enters at all.  The probabilities are just ignorance uncertainty.  
>> You're
>> still in the same branch of the MWI, you just don't remember why your
>> memory was erased (although you may read about it in your diary).
>>
>
> No, you can't say that you are in the same branch. Just because
> you are in the clasical regime doesn't mean that the MWI is 
> irrelevant and
> we can just pretend that the world is described by classical physics. 
> It is
> only that classical physics will give the same answer as QM when 
> computing
> probabilities.
>

 Including the probability that I'm in the same world as before?

  With classical I mean a single world theory where you just compute
>>> the probabilities based "ignorance". This yields the same answer as
>>> assuming the MWI and then comouting the probabilities of the various
>>> outcomes.
>>>
>>>
> If what you are aware of is only described by your memory state
> which can be encoded by a finite number of bits, then after a memory
> resetting, the state of your memory and the environment (which 
> contains
> also the rest of your brain and body), is of the form:
>

 "The rest of my brain"??  Why do you suppose that some part of my
 brain is involved in my memories and not other parts? What about a 
 scar or
 a tattoo.  I don't see that "memory" is separable from the 
 environment.  In
 fact isn't that exactly what makes memory classical and makes the
 superposition you write below impossible to achieve? Your brain is a
 classical computer because it's not isolated from the environment.

>>>
>>> What matter is that the state is of the form:
>>>
>>> |memory_1>|environment_1> + |memory_2>|environment_2>+..
>>>
>>> with the |memory_j> orthonormal and the |environment_j> orthogonal.
>>> Such a completely correlated state will arise due to decoherence, the
>>> probabilities which are the squared norms of the |environment_j>'s are 
>>> the
>>> probabilities. They behave in a purely classical way due this 
>>> decomposition.
>>>
>>> The brain is never isolated from the environment; if project onto an
>>> |environment_j> you always get a definite classical memory state, never 
>>> a
>>> supperposition of different bitstrings. But it's not the case that
>>> projecting onto a ddefinite memory state will always yield a definite
>>> classical environment state (this is at the heart of the  Wigner's 
>>> friend
>>> thought experiment).
>>>
>>
>> I think Wigner's friend has been overtaken by decoherence. While I
>> agree with what you say above, I disagree that the |environment_i> are
>> macroscopically different.  I think you are making inconsistent
>> assumptions: that "memory" is something that can be "reset" without
>> "resetting" its physical environment and yet still holding that memory is
>> classical.
>>
>>
> The |environment_i> have to be different as they are entangled with
> different memory states, precisely due to rapid decoherence. The
> environment always "knows" exactly what happened. So, the assumption is 
> not
> that the environment "doesn't know" what has been done (decoherence 
> implies
> that the environment does know), rather that the the person whose memory 
> is
> reset doesn't know why the memory was reset.
>
> So, if you have made a copy of the memory, the system files etc.,
> there is no problem to reboot the system later based on these copies.
> Suppose that the computer is running an artificially intelligent system in
> a virtual environment, but such that this virtual environment is modeled
> based on real world data. This is actually quite similar to how the brain
> works, what you experience is a virtual world that the brain creates, 
> input
> from your senses is used to update this model, but in the end it's the
> model of reality that you experience (which leaves quite a lot of room for
> magicians to fool you).
>
> Then immediately after rebooting, you 

Re: Question for the QM experts here: quantum uncertainty of the past

[meekerdb]

On 8/21/2013 3:57 AM, Quentin Anciaux wrote:




2013/8/21 meekerdb mailto:meeke...@verizon.net>>

On 8/20/2013 5:26 AM, smi...@zonnet.nl  wrote:

Citeren meekerdb mailto:meeke...@verizon.net>>:

On 8/16/2013 4:57 PM, smi...@zonnet.nl  
wrote:

Citeren meekerdb mailto:meeke...@verizon.net>>:

On 8/15/2013 6:18 AM, smi...@zonnet.nl 
 wrote:

Citeren meekerdb mailto:meeke...@verizon.net>>:

On 8/14/2013 6:41 PM, smi...@zonnet.nl
 wrote:

I guess I don't understand that.   You seem 
to be
considering a simple case of amnesia - all 
purely
classical - so I don't see how MWI enters 
at all.
 The probabilities are just ignorance 
uncertainty.
 You're still in the same branch of the 
MWI, you
just don't remember why your memory was 
erased
(although you may read about it in your 
diary).


No, you can't say that you are in the same 
branch. Just
because you are in the clasical regime doesn't 
mean that
the MWI is irrelevant and we can just pretend 
that the
world is described by classical physics. It is 
only that
classical physics will give the same answer as 
QM when
computing probabilities.


Including the probability that I'm in the same 
world as before?

With classical I mean a single world theory where you 
just
compute the probabilities based "ignorance". This 
yields the
same answer as assuming the MWI and then comouting the
probabilities of the various outcomes.


If what you are aware of is only described by 
your
memory state which can be encoded by a finite 
number of
bits, then after a memory resetting, the state 
of your
memory and the environment (which contains also 
the rest
of your brain and body), is of the form:


"The rest of my brain"??  Why do you suppose that 
some part
of my brain is involved in my memories and not 
other parts?
What about a scar or a tattoo.  I don't see that 
"memory" is
separable from the environment.  In fact isn't that 
exactly
what makes memory classical and makes the 
superposition you
write below impossible to achieve? Your brain is a 
classical
computer because it's not isolated from the 
environment.


What matter is that the state is of the form:

|memory_1>|environment_1> + |memory_2>|environment_2>+..

with the |memory_j> orthonormal and the |environment_j>
orthogonal. Such a completely correlated state will 
arise due to
decoherence, the probabilities which are the squared 
norms of
the |environment_j>'s are the probabilities. They 
behave in a
purely classical way due this decomposition.

The brain is never isolated from the environment; if 
project
onto an |environment_j> you always get a definite 
classical
memory state, never a supperposition of different 
bitstrings.
But it's not the case that projecting onto a ddefinite 
memory
state will always yield a definite classical 
environment state
(this is at the heart of the  Wigner's friend thought 
experiment).


I think Wigner's friend has been overtaken by decoherence. 
While I
agree with what you say above, I disagree that the 
|environment_i>
are macroscopically different.  I think you are making 
inconsistent
assumptions: that "memory" is something that can be "reset" 
without
"resetting" its physical environment and yet still holding 
that
memory is classical.


The |environment_i> have to be different as they are entangled 
with
different memory states, precisely due to rapid decoherence. The

Re: Question for the QM experts here: quantum uncertainty of the past

[smitra]

Citeren Quentin Anciaux :


2013/8/21 meekerdb 


On 8/20/2013 5:26 AM, smi...@zonnet.nl wrote:


Citeren meekerdb :

 On 8/16/2013 4:57 PM, smi...@zonnet.nl wrote:



Citeren meekerdb :

 On 8/15/2013 6:18 AM, smi...@zonnet.nl wrote:



Citeren meekerdb :

 On 8/14/2013 6:41 PM, smi...@zonnet.nl wrote:



I guess I don't understand that.   You seem to be considering a
simple case of amnesia - all purely classical - so I don't 
see how MWI
enters at all.  The probabilities are just ignorance 
uncertainty.  You're
still in the same branch of the MWI, you just don't remember 
why your

memory was erased (although you may read about it in your diary).



No, you can't say that you are in the same branch. Just because you
are in the clasical regime doesn't mean that the MWI is 
irrelevant and we
can just pretend that the world is described by classical 
physics. It is
only that classical physics will give the same answer as QM 
when computing

probabilities.



Including the probability that I'm in the same world as before?

 With classical I mean a single world theory where you just compute

the probabilities based "ignorance". This yields the same answer as
assuming the MWI and then comouting the probabilities of the various
outcomes.



If what you are aware of is only described by your memory state
which can be encoded by a finite number of bits, then after a memory
resetting, the state of your memory and the environment 
(which contains

also the rest of your brain and body), is of the form:



"The rest of my brain"??  Why do you suppose that some part of my
brain is involved in my memories and not other parts? What 
about a scar or
a tattoo.  I don't see that "memory" is separable from the 
environment.  In

fact isn't that exactly what makes memory classical and makes the
superposition you write below impossible to achieve? Your brain is a
classical computer because it's not isolated from the environment.



What matter is that the state is of the form:

|memory_1>|environment_1> + |memory_2>|environment_2>+..

with the |memory_j> orthonormal and the |environment_j> orthogonal.
Such a completely correlated state will arise due to decoherence, the
probabilities which are the squared norms of the 
|environment_j>'s are the
probabilities. They behave in a purely classical way due this 
decomposition.


The brain is never isolated from the environment; if project onto an
|environment_j> you always get a definite classical memory 
state, never a

supperposition of different bitstrings. But it's not the case that
projecting onto a ddefinite memory state will always yield a definite
classical environment state (this is at the heart of the  
Wigner's friend

thought experiment).



I think Wigner's friend has been overtaken by decoherence. While I
agree with what you say above, I disagree that the |environment_i> are
macroscopically different.  I think you are making inconsistent
assumptions: that "memory" is something that can be "reset" without
"resetting" its physical environment and yet still holding that 
memory is

classical.



The |environment_i> have to be different as they are entangled with
different memory states, precisely due to rapid decoherence. The
environment always "knows" exactly what happened. So, the 
assumption is not
that the environment "doesn't know" what has been done 
(decoherence implies
that the environment does know), rather that the the person whose 
memory is

reset doesn't know why the memory was reset.

So, if you have made a copy of the memory, the system files etc., there
is no problem to reboot the system later based on these copies. Suppose
that the computer is running an artificially intelligent system in a
virtual environment, but such that this virtual environment is modeled
based on real world data. This is actually quite similar to how the brain
works, what you experience is a virtual world that the brain 
creates, input

from your senses is used to update this model, but in the end it's the
model of reality that you experience (which leaves quite a lot of 
room for

magicians to fool you).

Then immediately after rebooting, you won't yet have any information
that is in the environment about why you decided to reboot. You then have
macroscopically different environments where the reason for rebooting is
different but where you are identical.



But that's where I disagree - not about the conclusion, but about the
possibility of the premise.  I don't think it's possible to erase, in the
quantum sense, just your memory.  Of course you can given a drug that
erases short term memory and so it may be possible to create a drug that
erases long term memory too, i.e. induces amnesia.  But what you 
require is

to erase long term memory in a quantum sense so that all the informational
entanglements with the environment are erased too.  So I don't think you
can be to the "erased memory" state you  need.

Brent




But then, there is no problem restoring the original configura

Re: Question for the QM experts here: quantum uncertainty of the past

[Quentin Anciaux]

2013/8/21 meekerdb 

> On 8/20/2013 5:26 AM, smi...@zonnet.nl wrote:
>
>> Citeren meekerdb :
>>
>>  On 8/16/2013 4:57 PM, smi...@zonnet.nl wrote:
>>>
 Citeren meekerdb :

  On 8/15/2013 6:18 AM, smi...@zonnet.nl wrote:
>
>> Citeren meekerdb :
>>
>>  On 8/14/2013 6:41 PM, smi...@zonnet.nl wrote:
>>>
 I guess I don't understand that.   You seem to be considering a
> simple case of amnesia - all purely classical - so I don't see how MWI
> enters at all.  The probabilities are just ignorance uncertainty.  
> You're
> still in the same branch of the MWI, you just don't remember why your
> memory was erased (although you may read about it in your diary).
>

 No, you can't say that you are in the same branch. Just because you
 are in the clasical regime doesn't mean that the MWI is irrelevant and 
 we
 can just pretend that the world is described by classical physics. It 
 is
 only that classical physics will give the same answer as QM when 
 computing
 probabilities.

>>>
>>> Including the probability that I'm in the same world as before?
>>>
>>>  With classical I mean a single world theory where you just compute
>> the probabilities based "ignorance". This yields the same answer as
>> assuming the MWI and then comouting the probabilities of the various
>> outcomes.
>>
>>
 If what you are aware of is only described by your memory state
 which can be encoded by a finite number of bits, then after a memory
 resetting, the state of your memory and the environment (which contains
 also the rest of your brain and body), is of the form:

>>>
>>> "The rest of my brain"??  Why do you suppose that some part of my
>>> brain is involved in my memories and not other parts? What about a scar 
>>> or
>>> a tattoo.  I don't see that "memory" is separable from the environment. 
>>>  In
>>> fact isn't that exactly what makes memory classical and makes the
>>> superposition you write below impossible to achieve? Your brain is a
>>> classical computer because it's not isolated from the environment.
>>>
>>
>> What matter is that the state is of the form:
>>
>> |memory_1>|environment_1> + |memory_2>|environment_2>+..
>>
>> with the |memory_j> orthonormal and the |environment_j> orthogonal.
>> Such a completely correlated state will arise due to decoherence, the
>> probabilities which are the squared norms of the |environment_j>'s are 
>> the
>> probabilities. They behave in a purely classical way due this 
>> decomposition.
>>
>> The brain is never isolated from the environment; if project onto an
>> |environment_j> you always get a definite classical memory state, never a
>> supperposition of different bitstrings. But it's not the case that
>> projecting onto a ddefinite memory state will always yield a definite
>> classical environment state (this is at the heart of the  Wigner's friend
>> thought experiment).
>>
>
> I think Wigner's friend has been overtaken by decoherence. While I
> agree with what you say above, I disagree that the |environment_i> are
> macroscopically different.  I think you are making inconsistent
> assumptions: that "memory" is something that can be "reset" without
> "resetting" its physical environment and yet still holding that memory is
> classical.
>
>
 The |environment_i> have to be different as they are entangled with
 different memory states, precisely due to rapid decoherence. The
 environment always "knows" exactly what happened. So, the assumption is not
 that the environment "doesn't know" what has been done (decoherence implies
 that the environment does know), rather that the the person whose memory is
 reset doesn't know why the memory was reset.

 So, if you have made a copy of the memory, the system files etc., there
 is no problem to reboot the system later based on these copies. Suppose
 that the computer is running an artificially intelligent system in a
 virtual environment, but such that this virtual environment is modeled
 based on real world data. This is actually quite similar to how the brain
 works, what you experience is a virtual world that the brain creates, input
 from your senses is used to update this model, but in the end it's the
 model of reality that you experience (which leaves quite a lot of room for
 magicians to fool you).

 Then immediately after rebooting, you won't yet have any information
 that is in the environment about why you decided to reboot. You then have
 macroscopically different environments where the reason for rebooting is
 different but where you are identical.

>>>
>>> But tha

Re: Question for the QM experts here: quantum uncertainty of the past

[meekerdb]

On 8/20/2013 5:26 AM, smi...@zonnet.nl wrote:

Citeren meekerdb :


On 8/16/2013 4:57 PM, smi...@zonnet.nl wrote:

Citeren meekerdb :


On 8/15/2013 6:18 AM, smi...@zonnet.nl wrote:

Citeren meekerdb :


On 8/14/2013 6:41 PM, smi...@zonnet.nl wrote:
I guess I don't understand that.   You seem to be considering a simple case of 
amnesia - all purely classical - so I don't see how MWI enters at all.  The 
probabilities are just ignorance uncertainty.  You're still in the same branch of 
the MWI, you just don't remember why your memory was erased (although you may 
read about it in your diary).


No, you can't say that you are in the same branch. Just because you are in the 
clasical regime doesn't mean that the MWI is irrelevant and we can just pretend 
that the world is described by classical physics. It is only that classical 
physics will give the same answer as QM when computing probabilities.


Including the probability that I'm in the same world as before?

With classical I mean a single world theory where you just compute the probabilities 
based "ignorance". This yields the same answer as assuming the MWI and then 
comouting the probabilities of the various outcomes.




If what you are aware of is only described by your memory state which can be 
encoded by a finite number of bits, then after a memory resetting, the state of 
your memory and the environment (which contains also the rest of your brain and 
body), is of the form:


"The rest of my brain"??  Why do you suppose that some part of my brain is involved 
in my memories and not other parts? What about a scar or a tattoo.  I don't see 
that "memory" is separable from the environment.  In fact isn't that exactly what 
makes memory classical and makes the superposition you write below impossible to 
achieve? Your brain is a classical computer because it's not isolated from the 
environment.


What matter is that the state is of the form:

|memory_1>|environment_1> + |memory_2>|environment_2>+..

with the |memory_j> orthonormal and the |environment_j> orthogonal. Such a 
completely correlated state will arise due to decoherence, the probabilities which 
are the squared norms of the |environment_j>'s are the probabilities. They behave in 
a purely classical way due this decomposition.


The brain is never isolated from the environment; if project onto an |environment_j> 
you always get a definite classical memory state, never a supperposition of 
different bitstrings. But it's not the case that projecting onto a ddefinite memory 
state will always yield a definite classical environment state (this is at the heart 
of the  Wigner's friend thought experiment).


I think Wigner's friend has been overtaken by decoherence. While I agree with what 
you say above, I disagree that the |environment_i> are macroscopically different.  I 
think you are making inconsistent assumptions: that "memory" is something that can be 
"reset" without "resetting" its physical environment and yet still holding that 
memory is classical.




The |environment_i> have to be different as they are entangled with different memory 
states, precisely due to rapid decoherence. The environment always "knows" exactly 
what happened. So, the assumption is not that the environment "doesn't know" what has 
been done (decoherence implies that the environment does know), rather that the the 
person whose memory is reset doesn't know why the memory was reset.


So, if you have made a copy of the memory, the system files etc., there is no problem 
to reboot the system later based on these copies. Suppose that the computer is running 
an artificially intelligent system in a virtual environment, but such that this 
virtual environment is modeled based on real world data. This is actually quite 
similar to how the brain works, what you experience is a virtual world that the brain 
creates, input from your senses is used to update this model, but in the end it's the 
model of reality that you experience (which leaves quite a lot of room for magicians 
to fool you).


Then immediately after rebooting, you won't yet have any information that is in the 
environment about why you decided to reboot. You then have macroscopically different 
environments where the reason for rebooting is different but where you are identical.


But that's where I disagree - not about the conclusion, but about the possibility of 
the premise.  I don't think it's possible to erase, in the quantum sense, just your 
memory.  Of course you can given a drug that erases short term memory and so it may be 
possible to create a drug that erases long term memory too, i.e. induces amnesia.  But 
what you require is to erase long term memory in a quantum sense so that all the 
informational entanglements with the environment are erased too.  So I don't think you 
can be to the "erased memory" state you  need.


Brent



But then, there is no problem restoring the original configuration of a PC (e.g. if it 
has been infected by

Re: Question for the QM experts here: quantum uncertainty of the past

[smitra]

Citeren meekerdb :


On 8/16/2013 4:57 PM, smi...@zonnet.nl wrote:

Citeren meekerdb :


On 8/15/2013 6:18 AM, smi...@zonnet.nl wrote:

Citeren meekerdb :


On 8/14/2013 6:41 PM, smi...@zonnet.nl wrote:
I guess I don't understand that.   You seem to be considering a 
simple case of amnesia - all purely classical - so I don't see 
how MWI enters at all.  The probabilities are just ignorance 
uncertainty.  You're still in the same branch of the MWI, you 
just don't remember why your memory was erased (although you 
may read about it in your diary).


No, you can't say that you are in the same branch. Just because 
you are in the clasical regime doesn't mean that the MWI is 
irrelevant and we can just pretend that the world is described 
by classical physics. It is only that classical physics will 
give the same answer as QM when computing probabilities.


Including the probability that I'm in the same world as before?

With classical I mean a single world theory where you just compute 
the probabilities based "ignorance". This yields the same answer 
as assuming the MWI and then comouting the probabilities of the 
various outcomes.




If what you are aware of is only described by your memory state 
which can be encoded by a finite number of bits, then after a 
memory resetting, the state of your memory and the environment 
(which contains also the rest of your brain and body), is of the 
form:


"The rest of my brain"??  Why do you suppose that some part of my 
brain is involved in my memories and not other parts? What about 
a scar or a tattoo.  I don't see that "memory" is separable from 
the environment.  In fact isn't that exactly what makes memory 
classical and makes the superposition you write below impossible 
to achieve? Your brain is a classical computer because it's not 
isolated from the environment.


What matter is that the state is of the form:

|memory_1>|environment_1> + |memory_2>|environment_2>+..

with the |memory_j> orthonormal and the |environment_j> 
orthogonal. Such a completely correlated state will arise due to 
decoherence, the probabilities which are the squared norms of the 
|environment_j>'s are the probabilities. They behave in a purely 
classical way due this decomposition.


The brain is never isolated from the environment; if project onto 
an |environment_j> you always get a definite classical memory 
state, never a supperposition of different bitstrings. But it's 
not the case that projecting onto a ddefinite memory state will 
always yield a definite classical environment state (this is at 
the heart of the  Wigner's friend thought experiment).


I think Wigner's friend has been overtaken by decoherence. While I 
agree with what you say above, I disagree that the |environment_i> 
are macroscopically different.  I think you are making inconsistent 
assumptions: that "memory" is something that can be "reset" without 
"resetting" its physical environment and yet still holding that 
memory is classical.




The |environment_i> have to be different as they are entangled with 
different memory states, precisely due to rapid decoherence. The 
environment always "knows" exactly what happened. So, the assumption 
is not that the environment "doesn't know" what has been done 
(decoherence implies that the environment does know), rather that 
the the person whose memory is reset doesn't know why the memory was 
reset.


So, if you have made a copy of the memory, the system files etc., 
there is no problem to reboot the system later based on these 
copies. Suppose that the computer is running an artificially 
intelligent system in a virtual environment, but such that this 
virtual environment is modeled based on real world data. This is 
actually quite similar to how the brain works, what you experience 
is a virtual world that the brain creates, input from your senses is 
used to update this model, but in the end it's the model of reality 
that you experience (which leaves quite a lot of room for magicians 
to fool you).


Then immediately after rebooting, you won't yet have any information 
that is in the environment about why you decided to reboot. You then 
have macroscopically different environments where the reason for 
rebooting is different but where you are identical.


But that's where I disagree - not about the conclusion, but about the 
possibility of the premise.  I don't think it's possible to erase, in 
the quantum sense, just your memory.  Of course you can given a drug 
that erases short term memory and so it may be possible to create a 
drug that erases long term memory too, i.e. induces amnesia.  But 
what you require is to erase long term memory in a quantum sense so 
that all the informational entanglements with the environment are 
erased too.  So I don't think you can be to the "erased memory" state 
you  need.


Brent



But then, there is no problem restoring the original configuration of a 
PC (e.g. if it has been infected by a virus, the systme may have be

Re: Question for the QM experts here: quantum uncertainty of the past

[meekerdb]

On 8/16/2013 4:57 PM, smi...@zonnet.nl wrote:

Citeren meekerdb :


On 8/15/2013 6:18 AM, smi...@zonnet.nl wrote:

Citeren meekerdb :


On 8/14/2013 6:41 PM, smi...@zonnet.nl wrote:
I guess I don't understand that.   You seem to be considering a simple case of 
amnesia - all purely classical - so I don't see how MWI enters at all.  The 
probabilities are just ignorance uncertainty.  You're still in the same branch of 
the MWI, you just don't remember why your memory was erased (although you may read 
about it in your diary).


No, you can't say that you are in the same branch. Just because you are in the 
clasical regime doesn't mean that the MWI is irrelevant and we can just pretend that 
the world is described by classical physics. It is only that classical physics will 
give the same answer as QM when computing probabilities.


Including the probability that I'm in the same world as before?

With classical I mean a single world theory where you just compute the probabilities 
based "ignorance". This yields the same answer as assuming the MWI and then comouting 
the probabilities of the various outcomes.




If what you are aware of is only described by your memory state which can be encoded 
by a finite number of bits, then after a memory resetting, the state of your memory 
and the environment (which contains also the rest of your brain and body), is of the 
form:


"The rest of my brain"??  Why do you suppose that some part of my brain is involved 
in my memories and not other parts? What about a scar or a tattoo.  I don't see that 
"memory" is separable from the environment.  In fact isn't that exactly what makes 
memory classical and makes the superposition you write below impossible to achieve? 
Your brain is a classical computer because it's not isolated from the environment.


What matter is that the state is of the form:

|memory_1>|environment_1> + |memory_2>|environment_2>+..

with the |memory_j> orthonormal and the |environment_j> orthogonal. Such a completely 
correlated state will arise due to decoherence, the probabilities which are the 
squared norms of the |environment_j>'s are the probabilities. They behave in a purely 
classical way due this decomposition.


The brain is never isolated from the environment; if project onto an |environment_j> 
you always get a definite classical memory state, never a supperposition of different 
bitstrings. But it's not the case that projecting onto a ddefinite memory state will 
always yield a definite classical environment state (this is at the heart of the  
Wigner's friend thought experiment).


I think Wigner's friend has been overtaken by decoherence. While I agree with what you 
say above, I disagree that the |environment_i> are macroscopically different.  I think 
you are making inconsistent assumptions: that "memory" is something that can be "reset" 
without "resetting" its physical environment and yet still holding that memory is 
classical.




The |environment_i> have to be different as they are entangled with different memory 
states, precisely due to rapid decoherence. The environment always "knows" exactly what 
happened. So, the assumption is not that the environment "doesn't know" what has been 
done (decoherence implies that the environment does know), rather that the the person 
whose memory is reset doesn't know why the memory was reset.


So, if you have made a copy of the memory, the system files etc., there is no problem to 
reboot the system later based on these copies. Suppose that the computer is running an 
artificially intelligent system in a virtual environment, but such that this virtual 
environment is modeled based on real world data. This is actually quite similar to how 
the brain works, what you experience is a virtual world that the brain creates, input 
from your senses is used to update this model, but in the end it's the model of reality 
that you experience (which leaves quite a lot of room for magicians to fool you).


Then immediately after rebooting, you won't yet have any information that is in the 
environment about why you decided to reboot. You then have macroscopically different 
environments where the reason for rebooting is different but where you are identical. 


But that's where I disagree - not about the conclusion, but about the possibility of the 
premise.  I don't think it's possible to erase, in the quantum sense, just your memory.  
Of course you can given a drug that erases short term memory and so it may be possible to 
create a drug that erases long term memory too, i.e. induces amnesia.  But what you 
require is to erase long term memory in a quantum sense so that all the informational 
entanglements with the environment are erased too.  So I don't think you can be to the 
"erased memory" state you  need.


Brent

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Re: Question for the QM experts here: quantum uncertainty of the past

[smitra]

Citeren meekerdb :


On 8/15/2013 6:18 AM, smi...@zonnet.nl wrote:

Citeren meekerdb :


On 8/14/2013 6:41 PM, smi...@zonnet.nl wrote:
I guess I don't understand that.   You seem to be considering a 
simple case of amnesia - all purely classical - so I don't see 
how MWI enters at all.  The probabilities are just ignorance 
uncertainty.  You're still in the same branch of the MWI, you 
just don't remember why your memory was erased (although you may 
read about it in your diary).


No, you can't say that you are in the same branch. Just because 
you are in the clasical regime doesn't mean that the MWI is 
irrelevant and we can just pretend that the world is described by 
classical physics. It is only that classical physics will give the 
same answer as QM when computing probabilities.


Including the probability that I'm in the same world as before?

With classical I mean a single world theory where you just compute 
the probabilities based "ignorance". This yields the same answer as 
assuming the MWI and then comouting the probabilities of the various 
outcomes.




If what you are aware of is only described by your memory state 
which can be encoded by a finite number of bits, then after a 
memory resetting, the state of your memory and the environment 
(which contains also the rest of your brain and body), is of the 
form:


"The rest of my brain"??  Why do you suppose that some part of my 
brain is involved in my memories and not other parts?  What about a 
scar or a tattoo.  I don't see that "memory" is separable from the 
environment.  In fact isn't that exactly what makes memory 
classical and makes the superposition you write below impossible to 
achieve? Your brain is a classical computer because it's not 
isolated from the environment.


What matter is that the state is of the form:

|memory_1>|environment_1> + |memory_2>|environment_2>+..

with the |memory_j> orthonormal and the |environment_j> orthogonal. 
Such a completely correlated state will arise due to decoherence, 
the probabilities which are the squared norms of the 
|environment_j>'s are the probabilities. They behave in a purely 
classical way due this decomposition.


The brain is never isolated from the environment; if project onto an 
|environment_j> you always get a definite classical memory state, 
never a supperposition of different bitstrings. But it's not the 
case that projecting onto a ddefinite memory state will always yield 
a definite classical environment state (this is at the heart of the  
Wigner's friend thought experiment).


I think Wigner's friend has been overtaken by decoherence.  While I 
agree with what you say above, I disagree that the |environment_i> 
are macroscopically different.  I think you are making inconsistent 
assumptions: that "memory" is something that can be "reset" without 
"resetting" its physical environment and yet still holding that 
memory is classical.




The |environment_i> have to be different as they are entangled with 
different memory states, precisely due to rapid decoherence. The 
environment always "knows" exactly what happened. So, the assumption is 
not that the environment "doesn't know" what has been done (decoherence 
implies that the environment does know), rather that the the person 
whose memory is reset doesn't know why the memory was reset.


So, if you have made a copy of the memory, the system files etc., there 
is no problem to reboot the system later based on these copies. Suppose 
that the computer is running an artificially intelligent system in a 
virtual environment, but such that this virtual environment is modeled 
based on real world data. This is actually quite similar to how the 
brain works, what you experience is a virtual world that the brain 
creates, input from your senses is used to update this model, but in 
the end it's the model of reality that you experience (which leaves 
quite a lot of room for magicians to fool you).


Then immediately after rebooting, you won't yet have any information 
that is in the environment about why you decided to reboot. You then 
have macroscopically different environments where the reason for 
rebooting is different but where you are identical. If not, and you 
assume that in each environment your mental state is different, then 
that contradicts the assumption about the abilty to reboot based on the 
old system files.


So, you need to learn from the environment what happened before this 
information can affect you. This does not mean that the memory is not 
classical, rather that it's immune to noise from the environment, this 
allows it to perform reliable computations. So, while the environment, 
of course, does affect the physical state of the computer, the 
computational states of the computer are represented by macroscopic 
bits which can be kept isolated.


Saibal


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Re: Question for the QM experts here: quantum uncertainty of the past

[meekerdb]

On 8/15/2013 6:18 AM, smi...@zonnet.nl wrote:

Citeren meekerdb :


On 8/14/2013 6:41 PM, smi...@zonnet.nl wrote:
I guess I don't understand that.   You seem to be considering a simple case of 
amnesia - all purely classical - so I don't see how MWI enters at all.  The 
probabilities are just ignorance uncertainty.  You're still in the same branch of the 
MWI, you just don't remember why your memory was erased (although you may read about 
it in your diary).


No, you can't say that you are in the same branch. Just because you are in the 
clasical regime doesn't mean that the MWI is irrelevant and we can just pretend that 
the world is described by classical physics. It is only that classical physics will 
give the same answer as QM when computing probabilities.


Including the probability that I'm in the same world as before?

With classical I mean a single world theory where you just compute the probabilities 
based "ignorance". This yields the same answer as assuming the MWI and then comouting 
the probabilities of the various outcomes.




If what you are aware of is only described by your memory state which can be encoded 
by a finite number of bits, then after a memory resetting, the state of your memory 
and the environment (which contains also the rest of your brain and body), is of the 
form:


"The rest of my brain"??  Why do you suppose that some part of my brain is involved in 
my memories and not other parts?  What about a scar or a tattoo.  I don't see that 
"memory" is separable from the environment.  In fact isn't that exactly what makes 
memory classical and makes the superposition you write below impossible to achieve? 
Your brain is a classical computer because it's not isolated from the environment.


What matter is that the state is of the form:

|memory_1>|environment_1> + |memory_2>|environment_2>+..

with the |memory_j> orthonormal and the |environment_j> orthogonal. Such a completely 
correlated state will arise due to decoherence, the probabilities which are the squared 
norms of the |environment_j>'s are the probabilities. They behave in a purely classical 
way due this decomposition.


The brain is never isolated from the environment; if project onto an |environment_j> you 
always get a definite classical memory state, never a supperposition of different 
bitstrings. But it's not the case that projecting onto a ddefinite memory state will 
always yield a definite classical environment state (this is at the heart of the  
Wigner's friend thought experiment).


I think Wigner's friend has been overtaken by decoherence.  While I agree with what you 
say above, I disagree that the |environment_i> are macroscopically different.  I think you 
are making inconsistent assumptions: that "memory" is something that can be "reset" 
without "resetting" its physical environment and yet still holding that memory is classical.




So, I am assuming that the brain is 100% classical (decoherence has run its complete 
course), whatever the memory state of the brain is can also be found in the environment.


Then the assumption that I'm making is that whenever there is information in the 
environment that the observer is not aware of, 


What does "aware of" mean?...physically encoded somewhere?  present in consciousness as a 
thought?...a sentence?  You seem to be implicitly invoking a dualism whereby awareness and 
memory can be changed in ways physical things can't.


Brent

the observer will be identical as far as the description of the observer in terms of its 
memory state is concerned accross the branches where that information is different. So, 
if the initial state is:


|memory>|environment>

and in the environment something happens which has two possible outcomes, and you have 
yet to learn about that, then the state will evolve to a state of the form:


|memory>(|environment_1> + |environment_2>)

and not:

|memory_1>|environment_1> + |memory_2>|environment_2>

because the latter would imply that you could (in principle) tell what happned without 
performing a measurement, and I don't believe on psychic phenomena.


So, the "no-psychic phenomena postulate" would compel you to assume that:

|memory>(|environment_1> + |environment_2>)


is the correct description of the state and that only after you learn about the fact you 
become localized in either branch. This applied to the memory resetting implies what I 
was arguing for.


Saibal




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Re: Question for the QM experts here: quantum uncertainty of the past

[smitra]

Citeren meekerdb :


On 8/14/2013 6:41 PM, smi...@zonnet.nl wrote:
I guess I don't understand that.   You seem to be considering a 
simple case of amnesia - all purely classical - so I don't see how 
MWI enters at all.  The probabilities are just ignorance 
uncertainty.  You're still in the same branch of the MWI, you just 
don't remember why your memory was erased (although you may read 
about it in your diary).


No, you can't say that you are in the same branch. Just because you 
are in the clasical regime doesn't mean that the MWI is irrelevant 
and we can just pretend that the world is described by classical 
physics. It is only that classical physics will give the same answer 
as QM when computing probabilities.


Including the probability that I'm in the same world as before?

With classical I mean a single world theory where you just compute the 
probabilities based "ignorance". This yields the same answer as 
assuming the MWI and then comouting the probabilities of the various 
outcomes.




If what you are aware of is only described by your memory state 
which can be encoded by a finite number of bits, then after a memory 
resetting, the state of your memory and the environment (which 
contains also the rest of your brain and body), is of the form:


"The rest of my brain"??  Why do you suppose that some part of my 
brain is involved in my memories and not other parts?  What about a 
scar or a tattoo.  I don't see that "memory" is separable from the 
environment.  In fact isn't that exactly what makes memory classical 
and makes the superposition you write below impossible to achieve? 
Your brain is a classical computer because it's not isolated from the 
environment.


What matter is that the state is of the form:

|memory_1>|environment_1> + |memory_2>|environment_2>+..

with the |memory_j> orthonormal and the |environment_j> orthogonal. 
Such a completely correlated state will arise due to decoherence, the 
probabilities which are the squared norms of the |environment_j>'s are 
the probabilities. They behave in a purely classical way due this 
decomposition.


The brain is never isolated from the environment; if project onto an 
|environment_j> you always get a definite classical memory state, never 
a supperposition of different bitstrings. But it's not the case that 
projecting onto a ddefinite memory state will always yield a definite 
classical environment state (this is at the heart of the  Wigner's 
friend thought experiment).


So, I am assuming that the brain is 100% classical (decoherence has run 
its complete course), whatever the memory state of the brain is can 
also be found in the environment.


Then the assumption that I'm making is that whenever there is 
information in the environment that the observer is not aware of, the 
observer will be identical as far as the description of the observer in 
terms of its memory state is concerned accross the branches where that 
information is different. So, if the initial state is:


|memory>|environment>

and in the environment something happens which has two possible 
outcomes, and you have yet to learn about that, then the state will 
evolve to a state of the form:


|memory>(|environment_1> + |environment_2>)

and not:

|memory_1>|environment_1> + |memory_2>|environment_2>

because the latter would imply that you could (in principle) tell what 
happned without performing a measurement, and I don't believe on 
psychic phenomena.


So, the "no-psychic phenomena postulate" would compel you to assume that:

|memory>(|environment_1> + |environment_2>)


is the correct description of the state and that only after you learn 
about the fact you become localized in either branch. This applied to 
the memory resetting implies what I was arguing for.


Saibal


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Re: Question for the QM experts here: quantum uncertainty of the past

[Pierz]

Yes my understanding would be the same. Although the brain or computer's 
ability to correctly represent the information about what has happened has 
been destroyed by the reset, the information itself is still embedded in 
the environment. Resetting registers in a computer does not actually 
destroy the information, it merely disperses it into the environment in a 
way that is non-recoverable (by the computer). That's what decoherence is 
all about. So if you wanted to "teleport" yourself across the multiverse in 
such a fashion, you'd have to find a method of really destroying the 
information, which I think is impossible...This theory seems to go back to 
Schrödinger's Cat, before the solution to the paradox was understood.

The quantum eraser does show that some elements of the past can be 
"altered" by quantum measurements, but it's not clear from that that one's 
history on a macroscopic scale is not singularly defined. This is the point 
I'm trying to clarify. In a way I'm not even sure what this means - unless 
the laws of physics are such that it is in principle possible to 
reconstruct the past to an arbitrary level of precision. I think Hawking 
was showing that that isn't the case - at a certain point in very early 
history at least, the information can no longer be resolved, and therefore 
there isn't a single origin point.

On Thursday, August 15, 2013 12:05:42 PM UTC+10, Brent wrote:
>
> On 8/14/2013 6:41 PM, smi...@zonnet.nl  wrote: 
> >> I guess I don't understand that.   You seem to be considering a simple 
> case of amnesia 
> >> - all purely classical - so I don't see how MWI enters at all.  The 
> probabilities are 
> >> just ignorance uncertainty.  You're still in the same branch of the 
> MWI, you just don't 
> >> remember why your memory was erased (although you may read about it in 
> your diary). 
> > 
> > No, you can't say that you are in the same branch. Just because you are 
> in the clasical 
> > regime doesn't mean that the MWI is irrelevant and we can just pretend 
> that the world is 
> > described by classical physics. It is only that classical physics will 
> give the same 
> > answer as QM when computing probabilities. 
>
> Including the probability that I'm in the same world as before? 
>
> > 
> > If what you are aware of is only described by your memory state which 
> can be encoded by 
> > a finite number of bits, then after a memory resetting, the state of 
> your memory and the 
> > environment (which contains also the rest of your brain and body), is of 
> the form: 
>
> "The rest of my brain"??  Why do you suppose that some part of my brain is 
> involved in my 
> memories and not other parts?  What about a scar or a tattoo.  I don't see 
> that "memory" 
> is separable from the environment.  In fact isn't that exactly what makes 
> memory classical 
> and makes the superposition you write below impossible to achieve? Your 
> brain is a 
> classical computer because it's not isolated from the environment. 
>
> Brent 
>
> > 
> > |memory_1>|environment_1> + |memory_2>|environment_2>+... 
> > 
> > where |environment_i> is not (necessarily) normalized. 
> > 
> > It then follows that a process that can lead to the same memory state 
> via different 
> > paths (routine resetting or resetting in case of bad news) will lead to 
> a state |psi>, 
> > such that projecting out a definite memory state gives: 
> > 
> > |memory> = 
> > 
> > |memory> sum over different |environments> 
> > 
> > where the different environments contain different information about the 
> paths that led 
> > to the memory. 
> > 
> > So, from the point of view of a memory state that has undergone a 
> resetting, the 
> > environment will be in a superposition of different states, the reason 
> why the reseting 
> > has been done is thus undetermined prior to a measurement. 
> > 
> > Saibal 
> > 
>
>

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Re: Question for the QM experts here: quantum uncertainty of the past

[meekerdb]

On 8/14/2013 6:41 PM, smi...@zonnet.nl wrote:
I guess I don't understand that.   You seem to be considering a simple case of amnesia 
- all purely classical - so I don't see how MWI enters at all.  The probabilities are 
just ignorance uncertainty.  You're still in the same branch of the MWI, you just don't 
remember why your memory was erased (although you may read about it in your diary).


No, you can't say that you are in the same branch. Just because you are in the clasical 
regime doesn't mean that the MWI is irrelevant and we can just pretend that the world is 
described by classical physics. It is only that classical physics will give the same 
answer as QM when computing probabilities.


Including the probability that I'm in the same world as before?



If what you are aware of is only described by your memory state which can be encoded by 
a finite number of bits, then after a memory resetting, the state of your memory and the 
environment (which contains also the rest of your brain and body), is of the form:


"The rest of my brain"??  Why do you suppose that some part of my brain is involved in my 
memories and not other parts?  What about a scar or a tattoo.  I don't see that "memory" 
is separable from the environment.  In fact isn't that exactly what makes memory classical 
and makes the superposition you write below impossible to achieve? Your brain is a 
classical computer because it's not isolated from the environment.


Brent



|memory_1>|environment_1> + |memory_2>|environment_2>+...

where |environment_i> is not (necessarily) normalized.

It then follows that a process that can lead to the same memory state via different 
paths (routine resetting or resetting in case of bad news) will lead to a state |psi>, 
such that projecting out a definite memory state gives:


|memory> =

|memory> sum over different |environments>

where the different environments contain different information about the paths that led 
to the memory.


So, from the point of view of a memory state that has undergone a resetting, the 
environment will be in a superposition of different states, the reason why the reseting 
has been done is thus undetermined prior to a measurement.


Saibal



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Re: Question for the QM experts here: quantum uncertainty of the past

[smitra]

Citeren meekerdb :


On 8/14/2013 4:43 PM, smi...@zonnet.nl wrote:

Citeren meekerdb :


On 8/14/2013 7:48 AM, smi...@zonnet.nl wrote:

Citeren Russell Standish :


On Tue, Aug 13, 2013 at 05:26:41PM -0700, Pierz wrote:
I need clarification of the significance of quantum theory to 
determining
the *past*. I remember having read or heard that the past itself 
is subject
to quantum uncertainty. Something like the idea that the past is 
determined

only to to the extent that it is forced to be so by the state of the
present, if that makes sense. In other words, there may be more than one
history that could lead to the current state of the world. Let's say it
might have been one way or another and then we make a measurement which
resolves this question, we are 'forcing' the past to be one way 
or another.
In MWI, that would be saying my 'track' through the multiverse 
is ambiguous
in both directions, both into the future and 'behind me' so to 
speak. I'm
unclear on this and what it precisely means. I seem to recall 
that it was

critical in calculations Hawking made about the early universe - at a
certain point these uncertainties became critical and it meant 
that it was
no longer possible to say that the universe had definitely been 
one way or

another. Can someone clarify this for me?



This idea of the past not being determinate until such a time as a
measurement in the present forces the issue is fundamental to my
interpretation of QM. It is also related to the Quantum Eraser. Saibal
Mitra has written some stuff on this too - maybe he'd like to comment?

On the other hand, I don't think this view is particularly
mainstream. Even many worlds people tend to think that the multiverse
has decohered in the past, and that there is a matter of fact which
branch we are in, even if we're ignorant of that fact.

I can't comment on Hawking's work, unfortunately, as I'm not 
aware of that.


Cheers
--



Yes, I would agree with the view taken by Russell here. It has 
interesting consequences for any future artificial intelligence 
who can reset its memory, as I explain here:


http://arxiv.org/abs/0902.3825

So, if you reset your memory at random with some probability p and 
you also do that in case of an impending disaster, then if you 
find yourself in a state where you know that your memory has been 
reset and you need to reload your memory, the reason why the 
memory has been reset  (routine random memory reset or you were 
facing an impending disaster), is no longer determined, you are 
identical in the different branches until you find out the reason.


So, while you are firmly in the classical regime and therefore you 
won't see any changes in the probabilities of the outcomes of 
these sorts of experiments relative to what you would expect 
classically, the interpretation of how these probabilities arise 
is different; while it is worthwhile to do these memory resettings 
in a "single classical world" it wouldn't be worthwhile.


The article I wrote (it was just an essay for FQXI competition 
which got the attention from New Scientist), is actually rather 
simple, it treats the problem in a non-relativistic way, which is 
a bit unnatural (the times at which things happen in the different 
different branches seems to matter). You can easily generalize 
this, also you can consider thought experiments involving false 
memories that may be correct memories in different branches etc. 
etc.


Hmm.  It seems that "erasing your memory" would encompass a lot 
more than what is commonly referred to as memory.  Quantum erasure 
requires erasing all the information that is diffused into the 
environment.  So erasing one's memory would imply quantum erasure 
of all the information about your past - not just the infinitesimal 
bit that you can consciously recall.


Brent


Yes, but then this is not "quantum erasure". If you were to reverse 
the act of a measurement then you could experimentally falsify the 
Copenhagen interpretation like e.g. in David Deutsch' thought 
experiment. However, if you simply erase part of your memory and if 
the reason why you did that is not certain (e.g. you do this 
randomly and in case of bad news), then after you find that your 
memory has been partially erased you are in the same "macro state" 
in different branches where the reason of the memory resetting is 
different.


I assume that whatever you experience is defined by some suitably 
defined macro state that can be isolated from the environment, not 
the exact micro state of the system which is always strongly 
correlated with the environment; if this is not true, then you'll 
have hard time arguing against psychics who claim to be able to feel 
what happens somehwere else from basic physics principles alone.


So, of course, the information is present in the environment, but 
you are unaware of what is in the environment, and therefore the 
outcome of the measurement is uncertain as far as you are concerned. 
The relevant physics

Re: Question for the QM experts here: quantum uncertainty of the past

[meekerdb]

On 8/14/2013 4:43 PM, smi...@zonnet.nl wrote:

Citeren meekerdb :


On 8/14/2013 7:48 AM, smi...@zonnet.nl wrote:

Citeren Russell Standish :


On Tue, Aug 13, 2013 at 05:26:41PM -0700, Pierz wrote:

I need clarification of the significance of quantum theory to determining
the *past*. I remember having read or heard that the past itself is subject
to quantum uncertainty. Something like the idea that the past is determined
only to to the extent that it is forced to be so by the state of the
present, if that makes sense. In other words, there may be more than one
history that could lead to the current state of the world. Let's say it
might have been one way or another and then we make a measurement which
resolves this question, we are 'forcing' the past to be one way or another.
In MWI, that would be saying my 'track' through the multiverse is ambiguous
in both directions, both into the future and 'behind me' so to speak. I'm
unclear on this and what it precisely means. I seem to recall that it was
critical in calculations Hawking made about the early universe - at a
certain point these uncertainties became critical and it meant that it was
no longer possible to say that the universe had definitely been one way or
another. Can someone clarify this for me?



This idea of the past not being determinate until such a time as a
measurement in the present forces the issue is fundamental to my
interpretation of QM. It is also related to the Quantum Eraser. Saibal
Mitra has written some stuff on this too - maybe he'd like to comment?

On the other hand, I don't think this view is particularly
mainstream. Even many worlds people tend to think that the multiverse
has decohered in the past, and that there is a matter of fact which
branch we are in, even if we're ignorant of that fact.

I can't comment on Hawking's work, unfortunately, as I'm not aware of that.

Cheers
--



Yes, I would agree with the view taken by Russell here. It has interesting 
consequences for any future artificial intelligence who can reset its memory, as I 
explain here:


http://arxiv.org/abs/0902.3825

So, if you reset your memory at random with some probability p and you also do that in 
case of an impending disaster, then if you find yourself in a state where you know 
that your memory has been reset and you need to reload your memory, the reason why the 
memory has been reset  (routine random memory reset or you were facing an impending 
disaster), is no longer determined, you are identical in the different branches until 
you find out the reason.


So, while you are firmly in the classical regime and therefore you won't see any 
changes in the probabilities of the outcomes of these sorts of experiments relative to 
what you would expect classically, the interpretation of how these probabilities arise 
is different; while it is worthwhile to do these memory resettings in a "single 
classical world" it wouldn't be worthwhile.


The article I wrote (it was just an essay for FQXI competition which got the attention 
from New Scientist), is actually rather simple, it treats the problem in a 
non-relativistic way, which is a bit unnatural (the times at which things happen in 
the different different branches seems to matter). You can easily generalize this, 
also you can consider thought experiments involving false memories that may be correct 
memories in different branches etc. etc.


Hmm.  It seems that "erasing your memory" would encompass a lot more than what is 
commonly referred to as memory.  Quantum erasure requires erasing all the information 
that is diffused into the environment.  So erasing one's memory would imply quantum 
erasure of all the information about your past - not just the infinitesimal bit that 
you can consciously recall.


Brent


Yes, but then this is not "quantum erasure". If you were to reverse the act of a 
measurement then you could experimentally falsify the Copenhagen interpretation like 
e.g. in David Deutsch' thought experiment. However, if you simply erase part of your 
memory and if the reason why you did that is not certain (e.g. you do this randomly and 
in case of bad news), then after you find that your memory has been partially erased you 
are in the same "macro state" in different branches where the reason of the memory 
resetting is different.


I assume that whatever you experience is defined by some suitably defined macro state 
that can be isolated from the environment, not the exact micro state of the system which 
is always strongly correlated with the environment; if this is not true, then you'll 
have hard time arguing against psychics who claim to be able to feel what happens 
somehwere else from basic physics principles alone.


So, of course, the information is present in the environment, but you are unaware of 
what is in the environment, and therefore the outcome of the measurement is uncertain as 
far as you are concerned. The relevant physics here is purely classical (except for the 

Re: Question for the QM experts here: quantum uncertainty of the past

[smitra]

Citeren meekerdb :


On 8/14/2013 7:48 AM, smi...@zonnet.nl wrote:

Citeren Russell Standish :


On Tue, Aug 13, 2013 at 05:26:41PM -0700, Pierz wrote:

I need clarification of the significance of quantum theory to determining
the *past*. I remember having read or heard that the past itself 
is subject
to quantum uncertainty. Something like the idea that the past is 
determined

only to to the extent that it is forced to be so by the state of the
present, if that makes sense. In other words, there may be more than one
history that could lead to the current state of the world. Let's say it
might have been one way or another and then we make a measurement which
resolves this question, we are 'forcing' the past to be one way or 
another.
In MWI, that would be saying my 'track' through the multiverse is 
ambiguous

in both directions, both into the future and 'behind me' so to speak. I'm
unclear on this and what it precisely means. I seem to recall that it was
critical in calculations Hawking made about the early universe - at a
certain point these uncertainties became critical and it meant that it was
no longer possible to say that the universe had definitely been one way or
another. Can someone clarify this for me?



This idea of the past not being determinate until such a time as a
measurement in the present forces the issue is fundamental to my
interpretation of QM. It is also related to the Quantum Eraser. Saibal
Mitra has written some stuff on this too - maybe he'd like to comment?

On the other hand, I don't think this view is particularly
mainstream. Even many worlds people tend to think that the multiverse
has decohered in the past, and that there is a matter of fact which
branch we are in, even if we're ignorant of that fact.

I can't comment on Hawking's work, unfortunately, as I'm not aware of that.

Cheers
--



Yes, I would agree with the view taken by Russell here. It has 
interesting consequences for any future artificial intelligence who 
can reset its memory, as I explain here:


http://arxiv.org/abs/0902.3825

So, if you reset your memory at random with some probability p and 
you also do that in case of an impending disaster, then if you find 
yourself in a state where you know that your memory has been reset 
and you need to reload your memory, the reason why the memory has 
been reset  (routine random memory reset or you were facing an 
impending disaster), is no longer determined, you are identical in 
the different branches until you find out the reason.


So, while you are firmly in the classical regime and therefore you 
won't see any changes in the probabilities of the outcomes of these 
sorts of experiments relative to what you would expect classically, 
the interpretation of how these probabilities arise is different; 
while it is worthwhile to do these memory resettings in a "single 
classical world" it wouldn't be worthwhile.


The article I wrote (it was just an essay for FQXI competition which 
got the attention from New Scientist), is actually rather simple, it 
treats the problem in a non-relativistic way, which is a bit 
unnatural (the times at which things happen in the different 
different branches seems to matter). You can easily generalize this, 
also you can consider thought experiments involving false memories 
that may be correct memories in different branches etc. etc.


Hmm.  It seems that "erasing your memory" would encompass a lot more 
than what is commonly referred to as memory.  Quantum erasure 
requires erasing all the information that is diffused into the 
environment.  So erasing one's memory would imply quantum erasure of 
all the information about your past - not just the infinitesimal bit 
that you can consciously recall.


Brent


Yes, but then this is not "quantum erasure". If you were to reverse the 
act of a measurement then you could experimentally falsify the 
Copenhagen interpretation like e.g. in David Deutsch' thought 
experiment. However, if you simply erase part of your memory and if the 
reason why you did that is not certain (e.g. you do this randomly and 
in case of bad news), then after you find that your memory has been 
partially erased you are in the same "macro state" in different 
branches where the reason of the memory resetting is different.


I assume that whatever you experience is defined by some suitably 
defined macro state that can be isolated from the environment, not the 
exact micro state of the system which is always strongly correlated 
with the environment; if this is not true, then you'll have hard time 
arguing against psychics who claim to be able to feel what happens 
somehwere else from basic physics principles alone.


So, of course, the information is present in the environment, but you 
are unaware of what is in the environment, and therefore the outcome of 
the measurement is uncertain as far as you are concerned. The relevant 
physics here is purely classical (except for the many Worlds aspect, 
but this enter

Re: Question for the QM experts here: quantum uncertainty of the past

[meekerdb]

On 8/14/2013 7:48 AM, smi...@zonnet.nl wrote:

Citeren Russell Standish :


On Tue, Aug 13, 2013 at 05:26:41PM -0700, Pierz wrote:

I need clarification of the significance of quantum theory to determining
the *past*. I remember having read or heard that the past itself is subject
to quantum uncertainty. Something like the idea that the past is determined
only to to the extent that it is forced to be so by the state of the
present, if that makes sense. In other words, there may be more than one
history that could lead to the current state of the world. Let's say it
might have been one way or another and then we make a measurement which
resolves this question, we are 'forcing' the past to be one way or another.
In MWI, that would be saying my 'track' through the multiverse is ambiguous
in both directions, both into the future and 'behind me' so to speak. I'm
unclear on this and what it precisely means. I seem to recall that it was
critical in calculations Hawking made about the early universe - at a
certain point these uncertainties became critical and it meant that it was
no longer possible to say that the universe had definitely been one way or
another. Can someone clarify this for me?



This idea of the past not being determinate until such a time as a
measurement in the present forces the issue is fundamental to my
interpretation of QM. It is also related to the Quantum Eraser. Saibal
Mitra has written some stuff on this too - maybe he'd like to comment?

On the other hand, I don't think this view is particularly
mainstream. Even many worlds people tend to think that the multiverse
has decohered in the past, and that there is a matter of fact which
branch we are in, even if we're ignorant of that fact.

I can't comment on Hawking's work, unfortunately, as I'm not aware of that.

Cheers
--



Yes, I would agree with the view taken by Russell here. It has interesting consequences 
for any future artificial intelligence who can reset its memory, as I explain here:


http://arxiv.org/abs/0902.3825

So, if you reset your memory at random with some probability p and you also do that in 
case of an impending disaster, then if you find yourself in a state where you know that 
your memory has been reset and you need to reload your memory, the reason why the memory 
has been reset  (routine random memory reset or you were facing an impending disaster), 
is no longer determined, you are identical in the different branches until you find out 
the reason.


So, while you are firmly in the classical regime and therefore you won't see any changes 
in the probabilities of the outcomes of these sorts of experiments relative to what you 
would expect classically, the interpretation of how these probabilities arise is 
different; while it is worthwhile to do these memory resettings in a "single classical 
world" it wouldn't be worthwhile.


The article I wrote (it was just an essay for FQXI competition which got the attention 
from New Scientist), is actually rather simple, it treats the problem in a 
non-relativistic way, which is a bit unnatural (the times at which things happen in the 
different different branches seems to matter). You can easily generalize this, also you 
can consider thought experiments involving false memories that may be correct memories 
in different branches etc. etc.


Hmm.  It seems that "erasing your memory" would encompass a lot more than what is commonly 
referred to as memory.  Quantum erasure requires erasing all the information that is 
diffused into the environment.  So erasing one's memory would imply quantum erasure of all 
the information about your past - not just the infinitesimal bit that you can consciously 
recall.


Brent

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Re: Question for the QM experts here: quantum uncertainty of the past

[smitra]

Citeren Russell Standish :


On Tue, Aug 13, 2013 at 05:26:41PM -0700, Pierz wrote:

I need clarification of the significance of quantum theory to determining
the *past*. I remember having read or heard that the past itself is subject
to quantum uncertainty. Something like the idea that the past is determined
only to to the extent that it is forced to be so by the state of the
present, if that makes sense. In other words, there may be more than one
history that could lead to the current state of the world. Let's say it
might have been one way or another and then we make a measurement which
resolves this question, we are 'forcing' the past to be one way or another.
In MWI, that would be saying my 'track' through the multiverse is ambiguous
in both directions, both into the future and 'behind me' so to speak. I'm
unclear on this and what it precisely means. I seem to recall that it was
critical in calculations Hawking made about the early universe - at a
certain point these uncertainties became critical and it meant that it was
no longer possible to say that the universe had definitely been one way or
another. Can someone clarify this for me?



This idea of the past not being determinate until such a time as a
measurement in the present forces the issue is fundamental to my
interpretation of QM. It is also related to the Quantum Eraser. Saibal
Mitra has written some stuff on this too - maybe he'd like to comment?

On the other hand, I don't think this view is particularly
mainstream. Even many worlds people tend to think that the multiverse
has decohered in the past, and that there is a matter of fact which
branch we are in, even if we're ignorant of that fact.

I can't comment on Hawking's work, unfortunately, as I'm not aware of that.

Cheers
--



Yes, I would agree with the view taken by Russell here. It has 
interesting consequences for any future artificial intelligence who can 
reset its memory, as I explain here:


http://arxiv.org/abs/0902.3825

So, if you reset your memory at random with some probability p and you 
also do that in case of an impending disaster, then if you find 
yourself in a state where you know that your memory has been reset and 
you need to reload your memory, the reason why the memory has been 
reset  (routine random memory reset or you were facing an impending 
disaster), is no longer determined, you are identical in the different 
branches until you find out the reason.


So, while you are firmly in the classical regime and therefore you 
won't see any changes in the probabilities of the outcomes of these 
sorts of experiments relative to what you would expect classically, the 
interpretation of how these probabilities arise is different; while it 
is worthwhile to do these memory resettings in a "single classical 
world" it wouldn't be worthwhile.


The article I wrote (it was just an essay for FQXI competition which 
got the attention from New Scientist), is actually rather simple, it 
treats the problem in a non-relativistic way, which is a bit unnatural 
(the times at which things happen in the different different branches 
seems to matter). You can easily generalize this, also you can consider 
thought experiments involving false memories that may be correct 
memories in different branches etc. etc.


Saibal






Prof Russell Standish  Phone 0425 253119 (mobile)
Principal, High Performance Coders
Visiting Professor of Mathematics  hpco...@hpcoders.com.au
University of New South Wales  http://www.hpcoders.com.au


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Re: Question for the QM experts here: quantum uncertainty of the past

[Russell Standish]

On Tue, Aug 13, 2013 at 05:26:41PM -0700, Pierz wrote:
> I need clarification of the significance of quantum theory to determining 
> the *past*. I remember having read or heard that the past itself is subject 
> to quantum uncertainty. Something like the idea that the past is determined 
> only to to the extent that it is forced to be so by the state of the 
> present, if that makes sense. In other words, there may be more than one 
> history that could lead to the current state of the world. Let's say it 
> might have been one way or another and then we make a measurement which 
> resolves this question, we are 'forcing' the past to be one way or another. 
> In MWI, that would be saying my 'track' through the multiverse is ambiguous 
> in both directions, both into the future and 'behind me' so to speak. I'm 
> unclear on this and what it precisely means. I seem to recall that it was 
> critical in calculations Hawking made about the early universe - at a 
> certain point these uncertainties became critical and it meant that it was 
> no longer possible to say that the universe had definitely been one way or 
> another. Can someone clarify this for me?
> 

This idea of the past not being determinate until such a time as a
measurement in the present forces the issue is fundamental to my
interpretation of QM. It is also related to the Quantum Eraser. Saibal
Mitra has written some stuff on this too - maybe he'd like to comment?

On the other hand, I don't think this view is particularly
mainstream. Even many worlds people tend to think that the multiverse
has decohered in the past, and that there is a matter of fact which
branch we are in, even if we're ignorant of that fact.

I can't comment on Hawking's work, unfortunately, as I'm not aware of that.

Cheers
-- 


Prof Russell Standish  Phone 0425 253119 (mobile)
Principal, High Performance Coders
Visiting Professor of Mathematics  hpco...@hpcoders.com.au
University of New South Wales  http://www.hpcoders.com.au


-- 
You received this message because you are subscribed to the Google Groups 
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