Question about EPR experiments...
james...@gmail.com
have been of the form:
A source releases a photon which is directed through a crystal (i.e.
beta barium borate crystal for spontaneous parametric down conversion)
which fragments it into two lower frequency, entangled photons, an
entangled particle pair. This pair is then space separated and
measurements of the entangled properties of one determine what the
properties of the other will be.
Now, I know I am missing something elementary here, but couldn't the
situation just be that at the moment the two photons acquire their
opposite polarizations (i.e. immediately after exiting the crystal),
they simply maintain and "remember" their polarization all the way
until they hit the detector. Obviously, as long as they keep the same
polarization they had all along, the other particle will have the
opposite polarization when detected. There is nothing "spooky" about
it. It is the same as if you took a piece of paper, and wrote "up" on
one half and "down" on the other and then closed your eyes and spun
the paper around so you don't know which side is which, ripped it in
half so one half had "up" and the other "down" on it (but you don't
know which half is which because you aren't looking). Then you place
each half in a separate envelope, mail them to opposite sides of the
country, and then when you open one, you automatically,
instantaneously know what the other one says, even though it is far
away and space-separated beyond the light cone.
Is it that you must assume QM to be true, i.e. you must assume that
neither piece of paper is "up" or "down" until observed, in order for
this "superluminal" or "nonlocal" requirement of quantum information
to arise?
Now, I could see the situation where, after the initial entangled pair
is created and space-separated, one of the particles is changed
(further polarized) and this necessarily induces polarization of the
second particle...that would be more convincing. But to my
understanding, the Bell's test experiments don't have this
aspect...they simply space separate entangled particles and measure
the properties of one and show they match the other. There is no
attempt made to manipulate the properties of one particle after
entanglement and see what happens to the second. If I'm wrong please
point it where, as I'm sure I'm missing something here...
Oh No
also rotate the apparatus, so that one particle is not measured on the
same axis as the other. The Bell inequality concerns the correlations
between the two experiments when there are different angles between the
detectors.
We also do experiments in which the choice of the orientation of the
spin axis is made after separation of the particles (the Aspect
experiment, and following).
Regards
--
Charles Francis
moderator sci.physics.foundations.
charles (dot) e (dot) h (dot) francis (at) googlemail.com (remove spaces and
braces)
james...@gmail.com
> Thus spake jamesfen...@gmail.com
>
> - Show quoted text -
Thanks for your reply. I think that upon further reflection and
reading (esp. reading more carefully the original Aspect paper and
with some help from wikipedia's explanation of loopholes in Bell's
theorem...which has an explanation of the CSHS experimental setup), I
have figured it out (I think you missed the crux of my point...likely
because I poorly communicated it).
Basically, I was initially assuming that upon the creation of the
entangled pair (from the crystal or other source), the particles were
already polarized. In fact, they are not. They are simply
entangled. Once they are space separated, they are passed through a
polarizer (two-channel), and they strongly tend to polarize in the
opposite manner, as predicted by QM. So yes, indeed, the entangled
particles are "changed" or manipulated after space separation, and
they react to this change according to QM predictions. That is
satisfying to have that cleared up. I was second guessing the
strength of the evidence for nonlocality, but now I feel that it is
reaffirmed in my mind. I apologize for my misunderstanding at first,
I should've figured that out myself before posting the question.
Thanks for your help though.
======================================= MODERATOR'S COMMENT:
This group is not only for discussions among 'experts', but also for encouraging beginners :-)
james...@gmail.com
assumed that in these newly created (but not yet polarized) entangled
particle pairs, there is no inherent "knowledge" in each particle of
which particle in the pair it is, i.e. the particles are identical
(yet entangled). That is to say, there are two photons which exit the
crystal and it is assumed that these have fully identical properties
inherent to them. The same applies for any other source of entangled
pairs. Why is this assumption so strong? What evidence is there to
support that these two photons (or electrons, or fullerene molecules
etc.) are identical in all ways?
Can it not be possible that they retain some sort of inherent
information, from their creation, so that they will react a certain
way when confronted with a two-channel polarizer? This way the
particles already "know" how they will react to every method of
detection, and don't have to communicate with each other at all. This
way, no matter how far away from each other the particles are, there
is no need for nonlocality to be invoked.
The fact is that all of these ways in which entangled particles are
created are not under tight control at the single particle level. The
same crystal will probably give entangled photon particles with
slightly different properties every time (whether we can measure these
differences or not). The crystal is imperfect, no matter how hard we
try to make it fully symmetrical etc.
I guess my question is, more to the point, how certain can we be that
the two particles which are entangled are identical to each other in
every way (or at least with regard to their reactivity to polarizers/
detection methods)? Do we have experiment evidence to support this?
======================================= MODERATOR'S COMMENT:
I would like to recommend to consult Leibnitz' notion of 'identity'
james...@gmail.com
knowledge that the two particles have identical properties and appear
to be the same in every way.
What I am asking is how can we know the two entangled particles have
identical properties? All we can know is that the properties we are
aware of and are able to measure appear to us to be the same. Is
there not the very real chance that, with our incomplete understanding
of particle physics and physics in general, that each particle may
appear identical but in fact contains "hidden" information from its
point of creation? This "hidden" information would be stored in a yet-
to-be-discovered phenomenon or property of the particles such that it
causes the particles to react in a specific, predictable way (if we
know this "hidden" information) when they interact with polarizers.
Surely, no experiment can claim to have ruled this out, because in
order to do so you'd have to ,unequivocally, that we know of all the
properties the particles may possess, and be sure that there are no
fundamental properties that we have not yet discovered. If I were to
take a stab at what such property might be perhaps we could imagine
that upon creation of the entangled particle pair, each takes on a
certain opposite orientation to some aspect of spacetime in the
vicinity which determines its future behavior potential. Or perhaps
something equivalent to charge, angular momentum etc. that we are not
yet aware of is distributed in opposing fashion to each particle and
this property directs how the particles react with polarizers etc.
Oh No
>Leibniz' notion of identity does not apply here, as that relies on the
>knowledge that the two particles have identical properties and appear
>to be the same in every way.
>
>What I am asking is how can we know the two entangled particles have
>identical properties?
We know that particles are identical because we find real difference in
behaviour for systems containing many particles depending on the
"statistics"
see
http://en.wikipedia.org/wiki/Quantum_statistics
and also follow links to bosons, and fermions.
> All we can know is that the properties we are
>aware of and are able to measure appear to us to be the same. Is
>there not the very real chance that, with our incomplete understanding
>of particle physics and physics in general, that each particle may
>appear identical but in fact contains "hidden" information from its
>point of creation? This "hidden" information would be stored in a yet-
>to-be-discovered phenomenon or property of the particles such that it
>causes the particles to react in a specific, predictable way (if we
>know this "hidden" information) when they interact with polarizers.
>
>Surely, no experiment can claim to have ruled this out,
The purpose of Bell's theorem is to show that this would result in a
different prediction from the prediction of quantum mechanics.
Experiments support the prediction of quantum mechanics.
Oh No
>On Aug 15, 1:26 am, Oh No <N...@charlesfrancis.wanadoo.co.uk> wrote:
>> Thus spake jamesfen...@gmail.com
>>
>reading (esp. reading more carefully the original Aspect paper and
>with some help from wikipedia's explanation of loopholes in Bell's
>theorem...which has an explanation of the CSHS experimental setup), I
>have figured it out (I think you missed the crux of my point...likely
>because I poorly communicated it).
>
>Basically, I was initially assuming that upon the creation of the
>entangled pair (from the crystal or other source), the particles were
>already polarized. In fact, they are not. They are simply
>entangled. Once they are space separated, they are passed through a
>polarizer (two-channel), and they strongly tend to polarize in the
>opposite manner, as predicted by QM. So yes, indeed, the entangled
>particles are "changed" or manipulated after space separation, and
>they react to this change according to QM predictions. That is
>satisfying to have that cleared up. I was second guessing the
>strength of the evidence for nonlocality, but now I feel that it is
>reaffirmed in my mind. I apologize for my misunderstanding at first,
>I should've figured that out myself before posting the question.
>Thanks for your help though.
>
>
>======================================= MODERATOR'S COMMENT:
> This group is not only for discussions among 'experts', but also for
>encouraging beginners :-)
>
to formulate a question for the group. That is very much a purpose of
the newsgroup.
Cl.Massé
What you describe is the "hidden-variable" hypothesis. The Aspect's
experiment was specially designed to test it. So it isn't so simple, and
the Bell theorem must be applied. The polarization measurements have
diverse angles between their plane, and a sophisticated statistical analysis
of the correlation is performed, which involves at least two different
angles. It has shown that the hidden-variable hypothesis is largely
rejected, while an excellent agreement with the prediction of QM is
observed.
>>Is it that you must assume QM to be true, i.e. you must assume that
>>neither piece of paper is "up" or "down" until observed, in order for
>>this "superluminal" or "nonlocal" requirement of quantum information
>>to arise?
It is at the same time up and down, and for any other plane two. More
precisely, it is the coherent superposition of the up and the down state.
The total system is in a state without polarization, that can be written:
|up>|down> + |down>|up>.
>>Now, I could see the situation where, after the initial entangled pair
>>is created and space-separated, one of the particles is changed
>>(further polarized) and this necessarily induces polarization of the
>>second particle...that would be more convincing. But to my
>>understanding, the Bell's test experiments don't have this
>>aspect...they simply space separate entangled particles and measure
>>the properties of one and show they match the other. There is no
>>attempt made to manipulate the properties of one particle after
>>entanglement and see what happens to the second. If I'm wrong please
>>point it where, as I'm sure I'm missing something here...
There is no reason that the polarization plane of the photon be the same as
the one of the polarizer, so in some sense the particle is changed, that is,
its state is projected onto one of well defined polarization.
--
~~~~ clmasse on free F-country
Liberty, Equality, Profitability.
noshellswill
OhNO!
I tremble to observe --- you side_step JFs point !
Namely UP/DOWN_only detectors. Description of Bells Inequality results ...
all of the many versions I have read equally de-value the UP/DOWN only
detectors as-if such results are embarrassing. Even Penrose does this...
Does my nose alone smell a polecat? To mis-analogize, if you try hammering
a square-peg into a round_hole, then who is surprised if "splinters" are
produced ?
nss
*******
Oh No
If only up/down detectors are used, there is no difference in prediction
between qm and hidden variables. It is necessary to use detectors at
different orientations to get a result.
james...@gmail.com
theory is, and I know that Bell's theorem (and subsequent experiments
supporting the QM side of Bell) more or less refute local hidden
variables theories (however, they say nothing about nonlocal hidden
variables). My question isn't at all about this, it is about the
possibility that one of the assumptions upon which Bell's theory
experiments is based: namely that the two entangled particles are
identical in all ways and do not have any information or properties
which differs between them...is not necessarily a strong assumption.
The entangled pair or particles is created in some imperfect way by a
real physical interaction, in the case of photons between a high
frequency photon and a crystal. We do not have a 100% understanding
of how those entangled photons arise and what properties they may
possess. We certainly know a lot about their properties, but there is
a good chance we do not know everything, and that leaves a loophole
for the possibility that each particle knows how it will react to a
future obstacle, and this particle knowledge is exactly opposite and
symmetrical between the entangled pair. I do not claim to know what
this knowledge might manifest itself as physically, but you could
imagine some physical property (or perhaps a large number of
properties) that we do not know of yet with our incomplete
understanding of particle physics.
Also, I don't think that statistical analysis of particle ensembles
can be used to prove that two entangled particles are identical. The
point is that you can only measure data for properties that you know
exist...I am positing that perhaps there are properties we have yet to
discover, and therefore a statistical analysis of known properties
will tell us nothing about unknown properties.
To C.I. Masse, I think you missed my point too. In fact, you make
another for me, which is that the beauty of Bell's test is that you do
not need to assume that the particles have a superposition of states.
Whether they do, or whether they exist as discrete, determinate
corpuscles, Bell's test shows that the interaction between two
identical entangled particles is inherently nonlocal. My issue, as
explained above, is that we cannot guarantee that we are testing two
identical entangled particles in these experiments.
Further, I personally continue to remain skeptical about this
superposition of states which is inherent to the Copenhagen
Interpretation and many-worlds. I am less skeptical of nonlocality
(but there is the potential loophole I have asked about above).
In fact, and anyone feel free to chime in on this and set me straight,
but my understanding is that the Heisenberg Uncertainty principle
itself stands on very shaky ground. There is essentially no
experimental evidence, that I'd consider conclusive or credible, which
supports it. In order to achieve this, one would need to show that
for a single particle you cannot locate the position and momentum (or
time-energy etc.) within the value of h. You'd need an experimental
setup that could measure sub-h resolution, and then you'd have to use
this on single particles and show, it cannot be done. Statistical
analysis of particle ensembles, as is done now and in all experiments
up to now, is inadequate. In fact, such experiments ignore Einstein's
point that QM is just a probabilitistic statistical theory for
particle ensembles and does not apply to single particles. I
understand that the appropriate experiment is an enormous
technological challenge, but considering the central importance of the
uncertainty principle to pretty much all of physics, it is a surprise
that it has almost no experimental support. For a recent paper
discussion the lack of experimental evidence for the Uncertainty
Principle see http://philsci-archive.pitt.edu/archive/00003077/01/UR_BHL2006.pdf.
I find this shocking.
Oh No
>I think you are missing my point...I know what the hidden variables
>theory is, and I know that Bell's theorem (and subsequent experiments
>supporting the QM side of Bell) more or less refute local hidden
>variables theories (however, they say nothing about nonlocal hidden
>variables). My question isn't at all about this, it is about the
>possibility that one of the assumptions upon which Bell's theory
>experiments is based: namely that the two entangled particles are
>identical in all ways and do not have any information or properties
>which differs between them...is not necessarily a strong assumption.
>The entangled pair or particles is created in some imperfect way by a
>real physical interaction, in the case of photons between a high
>frequency photon and a crystal. We do not have a 100% understanding
>of how those entangled photons arise and what properties they may
>possess. We certainly know a lot about their properties, but there is
>a good chance we do not know everything, and that leaves a loophole
>for the possibility that each particle knows how it will react to a
>future obstacle, and this particle knowledge is exactly opposite and
>symmetrical between the entangled pair.
The possibility that the future can affect the past is a known solution.
> I do not claim to know what
>this knowledge might manifest itself as physically, but you could
>imagine some physical property (or perhaps a large number of
>properties) that we do not know of yet with our incomplete
>understanding of particle physics.
This is the possibility refuted by the theorem
>
>Also, I don't think that statistical analysis of particle ensembles
>can be used to prove that two entangled particles are identical.
The statistical analysis of ensembles is just one test. In fact the
mathematical structure is well established. If the particles are not
identical, the entangled state has entirely different properties.
> The
>point is that you can only measure data for properties that you know
>exist...I am positing that perhaps there are properties we have yet to
>discover, and therefore a statistical analysis of known properties
>will tell us nothing about unknown properties.
Again, you are positing hidden variables which have been refuted (except
non-local ones).
You add nothing, Bell's theorem shows that we must either sacrifice
classical ideas of locality or of causality.
>
>To C.I. Masse, I think you missed my point too. In fact, you make
>another for me, which is that the beauty of Bell's test is that you do
>not need to assume that the particles have a superposition of states.
>Whether they do, or whether they exist as discrete, determinate
>corpuscles, Bell's test shows that the interaction between two
>identical entangled particles is inherently nonlocal. My issue, as
>explained above, is that we cannot guarantee that we are testing two
>identical entangled particles in these experiments.
>
>Further, I personally continue to remain skeptical about this
>superposition of states which is inherent to the Copenhagen
>Interpretation and many-worlds. I am less skeptical of nonlocality
>(but there is the potential loophole I have asked about above).
>
>In fact, and anyone feel free to chime in on this and set me straight,
>but my understanding is that the Heisenberg Uncertainty principle
>itself stands on very shaky ground.
The HUP is not a fundamental assumption, but rather a theorem. It is on
absolutely solid ground, both theoretically and empirically.
> There is essentially no
>experimental evidence, that I'd consider conclusive or credible, which
>supports it. In order to achieve this, one would need to show that
>for a single particle you cannot locate the position and momentum (or
>time-energy etc.) within the value of h. You'd need an experimental
>setup that could measure sub-h resolution, and then you'd have to use
>this on single particles and show, it cannot be done. Statistical
>analysis of particle ensembles, as is done now and in all experiments
>up to now, is inadequate. In fact, such experiments ignore Einstein's
>point that QM is just a probabilitistic statistical theory for
>particle ensembles and does not apply to single particles. I
>understand that the appropriate experiment is an enormous
>technological challenge, but considering the central importance of the
>uncertainty principle to pretty much all of physics, it is a surprise
>that it has almost no experimental support. For a recent paper
>discussion the lack of experimental evidence for the Uncertainty
>Principle see http://philsci-archive.pitt.edu/archive/00003077/01/UR_BH
>L2006.pdf.
>I find this shocking.
>
I have no idea what you have made of that paper, but it is quite
uncontroversial.
Ken S. Tucker
On Aug 17, 11:13 pm, jamesfen...@gmail.com wrote:
[snip]
> In fact, and anyone feel free to chime in on this and set me straight,
> but my understanding is that the Heisenberg Uncertainty principle
> itself stands on very shaky ground. There is essentially no
> experimental evidence, that I'd consider conclusive or credible, which
> supports it. In order to achieve this, one would need to show that
> for a single particle you cannot locate the position and momentum (or
> time-energy etc.) within the value of h. You'd need an experimental
> setup that could measure sub-h resolution, and then you'd have to use
> this on single particles and show, it cannot be done. Statistical
> analysis of particle ensembles, as is done now and in all experiments
> up to now, is inadequate. In fact, such experiments ignore Einstein's
> point that QM is just a probabilitistic statistical theory for
> particle ensembles and does not apply to single particles. I
> understand that the appropriate experiment is an enormous
> technological challenge, but considering the central importance of the
> uncertainty principle to pretty much all of physics, it is a surprise
> that it has almost no experimental support. For a recent paper
> discussion the lack of experimental evidence for the Uncertainty
> Principle seehttp://philsci-archive.pitt.edu/archive/00003077/01/UR_BHL2006.pdf.
> I find this shocking.
I'm working on a similiar problem, *what is the limit
of accuracy of a clock?* , such a question involves
the uncertainity of a time measurement.
Some find "Planck Time" to be that limit, however
here's a pop-sci link, doing experiments on that,
http://www.space.com/scienceastronomy/quantum_bits_030402.html
that claim to shed doubt on many fundamentals.
Regards
Ken S. Tucker
james...@gmail.com
> that claim to shed doubt on many fundamentals.
> Regards
>
> - Show quoted text -
That pop-sci article is very interesting! I too have been amazed at
the clarity of the Hubble Ultra Deep Space images, but it never dawned
on me that they should be blurry, but of course they should be. How
interesting. Well I'm happy to see others are doing this type of
research, including you and those mentioned in this article. There is
no better test tube or experimental apparatus than the whole universe
now is there?
Peter
> I think you are missing my point...I know what the hidden variables
> theory is, and I know that Bell's theorem (and subsequent experiments
> supporting the QM side of Bell) more or less refute local hidden
> variables theories (however, they say nothing about nonlocal hidden
> variables). My question isn't at all about this, it is about the
> possibility that one of the assumptions upon which Bell's theory
> experiments is based: namely that the two entangled particles are
> identical in all ways and do not have any information or properties
> which differs between them...is not necessarily a strong assumption.
Hi James,
It may be helpful, (i), to discriminate
- 'identical' vs 'equal'
- particle vs state
and, (ii), to account for Leibniz's principle of the identity of the
indistinguishable (in case of interest, I can email you my publications on
these issues).
To illustrate this, consider a classical conservative system of two equal
billiard balls. Assume that only the conserved quantities total energy, total
momentum, total angular momentum are known - thus, the quantities Newton
would have used to describe the stationary states of this system. Knowing
this, can you distinguish one ball from the other?
> The entangled pair or particles is created in some imperfect
??
What is the locus of the two particles?
> Further, I personally continue to remain skeptical about this
> superposition of states which is inherent to the Copenhagen
> Interpretation and many-worlds. I am less skeptical of nonlocality
> (but there is the potential loophole I have asked about above).
>
> In fact, and anyone feel free to chime in on this and set me straight,
> but my understanding is that the Heisenberg Uncertainty principle
> itself stands on very shaky ground.
Indeed. It's just a metaphysical generalization of the uncertainty
*relations* which are a mathematical property of the Schrödinger equation.
> There is essentially no
> experimental evidence, that I'd consider conclusive or credible, which
> supports it. In order to achieve this, one would need to show that
> for a single particle you cannot locate the position and momentum (or
> time-energy etc.) within the value of h. You'd need an experimental
> setup that could measure sub-h resolution, and then you'd have to use
> this on single particles and show, it cannot be done. Statistical
> analysis of particle ensembles, as is done now and in all experiments
> up to now, is inadequate. In fact, such experiments ignore Einstein's
> point that QM is just a probabilitistic statistical theory for
> particle ensembles and does not apply to single particles. I
> understand that the appropriate experiment is an enormous
> technological challenge, but considering the central importance of the
> uncertainty principle to pretty much all of physics, it is a surprise
> that it has almost no experimental support. For a recent paper
> discussion the lack of experimental evidence for the Uncertainty
> Principle see
> http://philsci-archive.pitt.edu/archive/00003077/01/UR_BHL2006.pdf.
> I find this shocking.
Why?
One cannot disproof a mathematical property of an equation.
Analogously to near-field microscopy, one has first to find non-quantum means
of measurement (or of experimental setups), before such experiments make
sense.
Hope this helps,
Peter
Ken S. Tucker
A comment on pop-sci. There is some hype, but
science needs to compete against Hollywood,
sports, politics, the economy and so forth, and
the article provides leads to the basis papers.
When a string-bean basket ball player throws a
long ball for a sink, the world cheers, that's fine,
but when NASA tosses a satellite and takes a
picture of the far side of Uranus, a lot of people
think using a mirror is easier :-).
Seriously now: The suggestion from the article
splits QT (Quantum Theory) from the mathematically
evolved QM (Quantum Mechanics), that suggests
light follows a path with a random (probabilistic)
element, that we see is NOT evident.
Allow me to speculate a bit:
If a clock of infinite accuracy is theorized, then
something must propagate at an infinte rate !?!.
If the maximum rate of propagation is finite, for
example "c", then the accuracy of a clock is
finite.
If the accuracy of a clock is finite, then time and
length have a limit to their measuring resolution,
that we may call "uncertainty".
That "uncertainty" is defined using Plancks "h",
so it follows we should be able to relate "c" and
"h" from the same principle, maybe unit spin ??
The reasoning appears superficially valid, but I'm
short on hard core proof.
Regards
Ken S. Tucker
======================================= MODERATOR'S COMMENT:
You may consult Landau & Lifshits III for relativistic uncertainty relations
Salviati
see http://philsci-archive.pitt.edu/archive/00003077/01/UR_BHL2006.pdf.
Who did try and replaced IR by IR+?
Regards,
Salviati
james...@gmail.com
>
> - Show quoted text -- Hide quoted text -
>
> - Show quoted text -
I don't really question that the Heisenberg uncertainty principle is a
mathematical property of the Schrodinger equation. I doubt its
relevance to physical reality...similar to Einstein and others (Karl
Popper, Gerald t' Hooft etc.), I think it only applies to particle
ensembles and so does most if not all of quantum mechanics. Yet QM
and the HUP are routinely invoked to describe single particle events
in various theories ranging from the creation of antimatter and matter
out of the vacuum to string theory to black hole radiation etc. So I
don't view it as purely a philosophical debate, I think it has real
consequences with regard to theoretical approaches to understanding
physics. If you are assuming a theory which only applies to particle
ensembles applies to single particles when it does not, well then you
are starting off on the wrong track from the beginning. I fear this
may be occurring all over physics right now.
james...@gmail.com
> <jamesfen...@gmail.com> wrote:
>
> seehttp://philsci-archive.pitt.edu/archive/00003077/01/UR_BHL2006.pdf.
>
> Who did try and replaced IR by IR+?
>
> Regards,
> Salviati
I'm sorry Salviati, could you be more clear? I'm not sure what you
mean by IR.
Peter
> I don't really question that the Heisenberg uncertainty principle
not "principle", but relations!
> is a
> mathematical property of the Schrodinger equation. I doubt its
> relevance to physical reality...similar to Einstein and others (Karl
> Popper, Gerald t' Hooft etc.), I think it only applies to particle
> ensembles and so does most if not all of quantum mechanics.
but the Schrödinger equation applies to single particles => those relations do
it may be a good idea first to sort out the notions and their meaning used :-)
> Yet QM
> and the HUP are routinely invoked to describe single particle events
> in various theories ranging from the creation of antimatter and matter
> out of the vacuum to string theory to black hole radiation etc.
this (among others) I had meant with "metaphysical generalization"
...
hope this helps,
Peter
Salviati
<james...@gmail.com> schrieb im Newsbeitrag
news:34de3ee3-5899-4ba5...@n38g2000prl.googlegroups.com...
Black board R stands for the real numbers extending from
minus infinity to plus infinity while IR+ just ranges from zero
to infinity.
No matter whether we consider reality or a model of reality,
physical effects are always restricted to positive elapsed time
or expected positive elapsed time, respectively.
Therefore, complex representation is not a must in physics.
If quantum mechanics is based on it, this might be the reason
for EPR's paradox and other trouble.
By the way, I do not share the belief in Cantor's set theory.
To my understanding, any number lost the property of being
countable if it is thought to be a constituent of the continuum
of all real or positive real numbers. Weyl still imagined the
rationals like bones within the sauce of the irrationals.
If I am correct then any aleph except for aleph_0 (rationals)
and aleph_1 (uncountables) is of no use in physics.
After more than a century, there seems not to be any example
that would prove me wrong.
Regards,
Salviati
Oh No
>By the way, I do not share the belief in Cantor's set theory. To my
>understanding, any number lost the property of being countable if it is
>thought to be a constituent of the continuum of all real or positive
>real numbers. Weyl still imagined the rationals like bones within the
>sauce of the irrationals. If I am correct then any aleph except for
>aleph_0 (rationals) and aleph_1 (uncountables) is of no use in physics.
>After more than a century, there seems not to be any example that would
>prove me wrong.
>
harry
"Peter" <end...@dekasges.de> wrote in message
news:guest.20080821125520$07...@news.killfile.org...
>
>> I don't really question that the Heisenberg uncertainty principle
>
> not "principle", but relations!
>
>> is a
>> mathematical property of the Schrodinger equation. I doubt its
>> relevance to physical reality...similar to Einstein and others (Karl
>> Popper, Gerald t' Hooft etc.), I think it only applies to particle
>> ensembles and so does most if not all of quantum mechanics.
>
> but the Schrödinger equation applies to single particles => those
> relations do
>
> it may be a good idea first to sort out the notions and their meaning used
> :-)
By chance, I just came across an interesting book on this by Post:
http://www.amazon.com/Quantum-Reprogramming-Ensembles-Mechanics-Philosophy/dp/0792335651/ref=sr_1_1?ie=UTF8&s=books&qid=1215900043&sr=1-1
Regretfully I have not read it (it's also a bit costly, and probably it will
go over my head).
However, I did find a draft of a recent talk by that same author:
http://www.worldnpa.org/pdf/abstracts/postbob.pdf
If I understand it correctly, according to him the Schrödinger equation
applies to ensembles only.
Cheers,
Harald
Salviati
news:Sdw2uLMB...@charlesfrancis.wanadoo.co.uk...
> Thus spake Salviati <eckard.b...@arcor.de>
>>By the way, I do not share the belief in Cantor's set theory. To my
>>understanding, any number lost the property of being countable if it is
>>thought to be a constituent of the continuum of all real or positive
>>real numbers. Weyl still imagined the rationals like bones within the
>>sauce of the irrationals. If I am correct then any aleph except for
>>aleph_0 (rationals) and aleph_1 (uncountables) is of no use in physics.
>>After more than a century, there seems not to be any example that would
>>prove me wrong.
>>
> Nobody pretends that aleph is useful in physics.
In spr on 09.08.2008 "a student" wrote in the thread
"elements of reality and quantum complementarity":
"I am wondering if a basic property of set theory actually forces any
fundamental description of measurement to be like quantum mechanics."
Subsequently he used the notion cardinality. To my understanding, nobody
needs cardinality. In physics, we may alternatively distinguish between
either countables or reals/irrationals in the sense that reals with infinite
acuity are not approachable by counting, too. So far, mathematicians
thoughtlessly consider irrationals a subset of the reals.
They follow the illusion by Dedekind and Cantor that there must be more
irrationals as compared to the rationals. Fraenkel already in 1923
understood but denied that there is a so called 4th logical possibility.
Already Salviati (the old Galilei) clarified that one must not
quantitatively compare infinite quantities.
We could say that infinity as well as any number with infinite acuity are
just fictions, fictions "with a fundamentum in re" as wrote Leibniz. How to
judge Hilbert who in 1925 tried to justify oo, oo+1, oo+2, ... with
repetitiously using the words "einfaches Hinueberzaehlen"?!!!!
While any natural number belongs to the countables, and millions of people
have to learn that, the complete entity of all natural numbers together is
such an uncountable fiction.
As understood by Brouwer, the TND and trichotomy, respectively, do not
apply for genuine, i.e. uncountable, reals.
The late Fraenkel admitted that mathematics would merely be "poorer" (in the
sense of less exotic) not wrong without set theory.
Indeed, it is hard to interpret physically the belief in an a priori
existing set of all numbers. Archimedes understod that there is no limit to
the possibility of adding something. So oo + or - anything = oo is a
quality, not a number.
To my knowledge the relationship between infinity and continuum was
gradually better and better understood by work of Spinoza, Leibniz, Euler,
Fourier, Meray and many others. Peirce was influenced by Leibniz when he
wrote "a continuum is something every part of which has parts".
Each cosine or Fourier transform or belonging inverse links the countables
(discrete numbers) with the fictive constituents of such genuine continuum
or vice versa. I ascribe a corresponding uncertainty to that non-linearity.
Given, v. Neumann understood in 1935 that his linear Hilbert space failed
because it relates on the belief in set theory, he was obviously unable to
find an alternative without abandoning ZFC or the like.
Regards,
salviati
james...@gmail.com
been struck by the intuitively pleasing ensemble interpretation of
quantum mechanics proposed by Einstein. I feel that this
interpretation is unfairly castigated and dismissed for a variety of
reasons that seem to miss the point or improperly characterize it.
One common misperception appears to be that opponents claim that this
is just a veiled attempt to maintain determinism when describing
quantum phenomena. Einstein himself said that he has no opinion over
whether nature is fundamentally determinate or indeterminate. The
ensemble interpretation does not say anything about determinism other
than to say the the Copenhagen (and MW) interpretations which claim
indeterminism are wrong. Nature may still be fundamentally
indeterminate, but it would be so for reasons other than what CI and
MWI propose.
Another attack is that it does not provide any ontological description
of single particle quantum systems. This is true, but does this make
it wrong? Rather, the ensemble interpretation does not claim to
provide a full description of what is going on in single quantum
systems, instead it simply claims that the CI and MWI, which
themselves do attempt to give an ontological description, are wrong
because QM only applies to ensembles and any claims made about single
particles are de facto unsupported.
The ensemble interpretation is basically an admittance that we do not
know what is going on with single particles, but what can provide a
statistical description of what occurs when these particles are
measured in ensembles (i.e. multiple measurements of single particles
in repeated experiments/measurements). What we don't know about
single particle behaviour is explained by currently unknown nonlocal
"hidden variables" (we know they are nonlocal because QM is inherently
nonlocal as shown by experiments with entanglement/EPR). "Hidden
variables" is just another way of saying that there are fundamental
elements of nature that we do not yet know of or understand, but that
if we did know of them, we would be able to accurately describe the
behavior of single quantum particles. So the ensemble interpretation
is basically saying that we don't know what is going on with single
particle, and those other interpretation which claim to know this (CI
and MWI) are wrong. Presumably Einstein believed that a theory of
everything, which is at least a theory of quantum gravity, would
incorporate these nonlocal hidden variables and ultimately provide a
detailed ontological description of single particle behavior (which
may be determinate or indeterminate).
>From my understanding of the literature, there really is no
experimental evidence refuting the ensemble interpretation. It
matches all other interpretations fully with regard to explaining
experimental results. So why is it so easily dismissed?
I can see how it is unsatisfying to essentially waive the white flag
with regard to our ability to give an ontological description of
single particle behavior and to say that at the moment we just don't
know, but we thing we'll know when we have a theory of everything or
at least of quantum gravity. But I think it is preferable to admit
ignorance than to abandon realism as CI and MWI QM do, and CI and MWI
does this with no experimental evidence whatsoever supporting that
realism does not exist (one would think, from the macroscopic world,
that realism does exist but who knows).
I'd appreciate any thoughts on this, consenting or dissenting.
james...@gmail.com
relations if you will).
In a typical experiment (see http://www.weshow.com/us/p/29437/heisenberg_uncertainty_principle)
to demonstrate the HUP, a laser is directed through a slit. When the
slit is wide, the laser passes straight through and makes a spot on
the detection screen (or reflective surface). When the slit is
narrowed to the point where the edges of the round laser beam are cut
off and the spot gets skinnier. But when the slit is narrowed to
around the size of the wavelength of the photons, you start to see a
spreading out of the spot. This is claimed to be due to the HUP
because you are knowing the position of the photons too well when they
pass through the slit so the momentum needs to be of a greater spread.
That's all great, but why is it that no one seems to worry about the
likely photon-matter interaction which occurs between the light beam
and the material which makes up the edges of the slit? Could it not
be the case that the diffraction observed when the slit is narrowed to
within the wavelength of the photons is due to "physical" interaction
between the photon and the atoms and electrons which makes up the
edges of the slit? Couldn't there be an electrostatic or other
interaction going on which either attracts or repels the photon from
the edge of the slit, and this interaction only occurs significantly
when the slit is narrow enough to force all of the photons to interact
with the slit edges (i.e. within a wavelength)?
The point is that, lets say we are shooting charged particles through
a slit in which the edges of the slit are also charged, but have the
opposite charge than that of the particles. Wouldn't it stand to
reason, via simple classical physics, that when the slit is narrowed
enough so that most of the particles "bump into" the edges of the slit
they'll be repelled (and lets say that this repulsion force is very
strong) and the vector direction of their momentum will be altered
significantly so they high the detector screen in a large spread?
What if a similar repulsion (or attraction) occurs between other
particles such as neutrons, photons, fullerene molecules etc. and the
edges of the slit? Then wouldn't that fully explain the single-slit
diffraction experiment in a classical sense without invoking the HUP?
This seems like an obvious, intuitive question to have, but my Google
searching has found nothing about others wondering about this. Please
advise...
Oh No
variables had not been developed. I don't think he would have found them
acceptable. I certainly don't.
You will find more on the Ensemble or statistical interpretation at
http://en.wikipedia.org/wiki/Ensemble_Interpretation
I would not say it is dismissed. It certainly has proponents, as the
size of the article demonstrates. My view is that we want to be able to
describe individual systems, and that probability theory and statistics
are better founded on Bayesian rather than Frequentist ideas.
Oh No
possibility of interaction with the edges of the slit is mentioned in
introductory text book accounts of diffraction. One of the reasons for
the development of quantum mechanics was that such interactions cannot
be made to predict the effects in e.g.
http://en.wikipedia.org/wiki/Double-slit_experiment
See also
http://en.wikipedia.org/wiki/Diffraction
james...@gmail.com
> I can't give any specific reference, but my recollection is that the
> possibility of interaction with the edges of the slit is mentioned in
> introductory text book accounts of diffraction. One of the reasons for
> the development of quantum mechanics was that such interactions cannot
> be made to predict the effects in e.g.
>
> http://en.wikipedia.org/wiki/Double-slit_experiment
>
> See also
>
> http://en.wikipedia.org/wiki/Diffraction
>
> Regards
>
> --
> Charles Francis
> moderator sci.physics.foundations.
> charles (dot) e (dot) h (dot) francis (at) googlemail.com (remove spaces and
> braces)
>
>
> - Show quoted text -
I would love to be directed toward a reference for this (I know you
said you don't have one). This would alleviate a continual concern
I've had. I have never seen any mention of this. The type of
interaction I'm referring to, by the way, could include simple
absorption of the photon by an atom on the edge of the slit and
subsequent radiative emission at nearly the same wavelength as the
incident photon (with slight red shift...i.e. Stokes shift, which is
always observed with fluorescence). While this would result in a
difference in wavelength of the photons from source vs. those that hit
the screen, this difference could be very small and undetectable
(depending on how closely you look for it). Another type of
interaction could be simple reflection by the surface of the edge of
the slit, which itself may not be entirely smooth. You have to
consider that the surface of the slit is not a perfectly smooth
surface as is commonly approximated in solid state physics, rather is
a series of atoms which are arranged (if it is made out of metal) in a
certain manner which, at the atomic level, is rough. There may be
microcavities which interact with the incident photon to allow for a
wide range of direction of reflected photons. In addition, if the
surface of the slit is painted with some non-reflective organic dye
(or otherwise rendered "dark" by having microscopic pores) the surface
will not be smooth and reflection off that surface will cover a wide
range of directions. Then there are other forces involved in light-
matter interactions, some of which may be poorly defined currently.
If introductory textbooks discussing diffraction account for each of
these possibilities and show how they cannot possibly reproduce the
diffraction pattern seen, then I'd be satisfied. If any other
reference does so I would be satisfied too.
One way of doing this, experimentally, would be to make the slits out
of different types of matter and show that in all cases the
diffraction pattern looks the same. This means that the exact
distribution of photons on the detector/plate is wholly independent of
the atomic makeup of the slit edges. But, realistically, even if the
HUP is a true physical phenomenon of nature, there will likely still
be at least small effects in the diffraction pattern which are
dependend on the atomic makeup of the slit edges, and uncoupling these
experimentally could be intractable. And of course, the problem is
that the HUP simply places an upper limit on the resolution with which
you can know the position and momentum of the particle, when in
reality in experiments the measured resolution of both observables
does not approach the HUP (correct me if I'm wrong here).
Oh No
>On Aug 27, 3:01 am, Oh No <N...@charlesfrancis.wanadoo.co.uk> wrote:
>> I can't give any specific reference, but my recollection is that the
>> possibility of interaction with the edges of the slit is mentioned in
>> introductory text book accounts of diffraction. One of the reasons for
>> the development of quantum mechanics was that such interactions cannot
>> be made to predict the effects in e.g.
>>
>> http://en.wikipedia.org/wiki/Double-slit_experiment
>>
>> See also
>>
>> http://en.wikipedia.org/wiki/Diffraction
>>
>> Regards
>>
>> --
>> Charles Francis
>> moderator sci.physics.foundations.
>> charles (dot) e (dot) h (dot) francis (at) googlemail.com (remove spaces and
>> braces)
>>
>> http://www.teleconnection.info/rqg/MainIndex- Hide quoted text -
>>
>> - Show quoted text -
>
>I would love to be directed toward a reference for this (I know you
>said you don't have one). This would alleviate a continual concern
>I've had. I have never seen any mention of this.
I'm afraid its 35 yrs since I did diffraction in school physics. The
text book we used was Nelkon, Advanced Level Physics. I have a copy but
its in storage. I can't specifically remember a passage, but I seem to
remember it being discussed around that time. There have also been
discussions on s.p.r. over the years, and it is likely one of those
contains a reference if you are good at searches.
Diffraction experiments have been done in vast ranges of different ways,
different materials, different particles. We get the same results for
photons, electrons, neutrons, buckminsterfullerene molecules .... These
particles have entirely different interactions with other matter, and
all diffract in the same way.
>But, realistically, even if the
>HUP is a true physical phenomenon of nature, there will likely still
>be at least small effects in the diffraction pattern which are
>dependend on the atomic makeup of the slit edges, and uncoupling these
>experimentally could be intractable. And of course, the problem is
>that the HUP simply places an upper limit on the resolution with which
>you can know the position and momentum of the particle, when in
>reality in experiments the measured resolution of both observables
>does not approach the HUP (correct me if I'm wrong here).
>
Ken S. Tucker
On Aug 27, 2:50 pm, jamesfen...@gmail.com wrote:
> On Aug 27, 3:01 am, Oh No <N...@charlesfrancis.wanadoo.co.uk> wrote:
> > I can't give any specific reference, but my recollection is that the
> > possibility of interaction with the edges of the slit is mentioned in
> > introductory text book accounts of diffraction. One of the reasons for
> > the development of quantum mechanics was that such interactions cannot
> > be made to predict the effects in e.g.
>
> >http://en.wikipedia.org/wiki/Double-slit_experiment
>
> > See also
>
> >http://en.wikipedia.org/wiki/Diffraction
>
> > Regards
>
> > --
> > Charles Francis
> > moderator sci.physics.foundations.
> > charles (dot) e (dot) h (dot) francis (at) googlemail.com (remove spaces and
> > braces)
>
> >http://www.teleconnection.info/rqg/MainIndex-Hide quoted text -
My office is 20' long with a white wall at the far end.
I used a laser pointer going threw a single slit of
thin cardboard, and eventually got a pattern somewhat
like this,
o o O o o
which *looks* like an interference pattern from a single
slit.
If anyone cares to try it, post your observations please.
Regards
Ken S. Tucker
...
Rich L.
...
> That's all great, but why is it that no one seems to worry about the
> likely photon-matter interaction which occurs between the light beam
> and the material which makes up the edges of the slit? Could it not
> be the case that the diffraction observed when the slit is narrowed to
> within the wavelength of the photons is due to "physical" interaction
> between the photon and the atoms and electrons which makes up the
> edges of the slit?
Undoubtedly. In the case of radio waves, currents are generated in
the walls of the slit (if conducting, which it must be to block the
radio waves). At higher frequencies (e.g. light) you may not observe
the currents so easily, but the electromagnetic calculations still
predict them to be there. The electromagnetic theory requires these
currents to block the waves incident on the back of the slit, or else
some of the incident waves would leak through the walls of the slit.
The electromagnetic fields in the slit, and past it, are the
superposition of the incident wave (i.e. particle) and the fields
radiated by the moving charges in the slit induced by the incident
field.
When the particles show diffraction they are interacting with the slit
as a single entity. There is momentum transferred from the diffracted
particle to the slit. This is related to the Mossbauer effect where
the nuclear recoil due to an emitted or absorbed gamma ray is taken up
not by the single nucleus, but by the entire bulk of material the
nucleus is a part of. In practice the momentum transferred when
something like a photon diffracts through a slit is so small that it
is completely unmeasurable. If the slit was made light enough that it
COULD be measured, the reaction of the slit during diffraction would
wipe out the diffraction pattern itself.
It is less clear what is happening in the case of electrons, neutrons,
etc. that also show diffraction. They are required to interact with
the walls of the slit, or else there would be no slit to cause
diffraction! What I find remarkable is that for an individual
particle (matter or photon) they can either diffract as expected, or
be absorbed in the wall of the slit. In the latter case all the
photon energy ends up very localized in an excited electron (or
something). In the former case there is some sort of collective
interaction with the entire slit. In this case there is still
momentum transfer to the slit, of an amount and direction that
conserves momentum for the system. That is, if the photon (say) is
diffracted to the left, there is some "right" momentum transfered to
the slit from the photon, and visa versa for a photon diffracted to
the right. Somehow the photon has interacted with the entire slit,
not with one or a few isolated electrons. If it had, it would not end
up as part of the diffraction pattern because in principle you could
determine which slit it passed through.
...
> The point is that, lets say we are shooting charged particles through
> a slit in which the edges of the slit are also charged, but have the
> opposite charge than that of the particles. Wouldn't it stand to
> reason, via simple classical physics, that when the slit is narrowed
> enough so that most of the particles "bump into" the edges of the slit
> they'll be repelled...
You are trying to think of the particles as tiny bullets that only
interact with the edges of the slit if they are very, very, close to
the walls. If this was the case, we would see a bright image of the
slit with a dim halo of a diffraction pattern around it. A fairly
simple observation (e.g. diffraction pattern photographs on the web)
will show that this is not the case. There is a more comprehensive
interaction between the particles and the slit, even if they are
matter particles.
You might try reading up about Fourier Optics, or an engineering
oriented book on electromagnetism. Good luck,
...
> This seems like an obvious, intuitive question to have, but my Google
> searching has found nothing about others wondering about this. Please
> advise...
Physics text books are mostly written by physicists with a
mathematical orientation. It takes quite a bit of meditation to
figure out what the math is saying about the physics. It is worth the
effort, however. I've seen some pretty stupid things said by people
that only knew the math, and were misinterpreting it.
Rich L.
Oh No
I don't accept this interpretation. We might be able to say that the
particle interacts with the material of the slits if this was the case
according to a clear, accepted, interpretation of quantum mechanics, but
actually there is no such thing. As it is there is no known form of
interaction which leads to the result. We are looking at the issues of
the interpretation of qm, not those of the interactions of matter. I
would say that the reason for the change of momentum as the particle
refracts is not to do with interaction, but rather to do with the
structure of spacetime. If, as we often discuss on s.p.f. the structure
of spacetime is an emergent quantity which depends on the configuration
of matter, then we can have an explanation for the appearance of fringes
which does not depend on an interaction between particle and slits.
Cl.Massé
news:f9726ee3-d286-4071...@v16g2000prc.googlegroups.com...
> Here's another question, relating to the uncertainty principle (or
> relations if you will).
>
> In a typical experiment (see
> http://www.weshow.com/us/p/29437/heisenberg_uncertainty_principle)
> to demonstrate the HUP, a laser is directed through a slit. When the
> slit is wide, the laser passes straight through and makes a spot on
> the detection screen (or reflective surface). When the slit is
> narrowed to the point where the edges of the round laser beam are cut
> off and the spot gets skinnier. But when the slit is narrowed to
> around the size of the wavelength of the photons, you start to see a
> spreading out of the spot. This is claimed to be due to the HUP
> because you are knowing the position of the photons too well when they
> pass through the slit so the momentum needs to be of a greater spread.
>
> That's all great, but why is it that no one seems to worry about the
> likely photon-matter interaction which occurs between the light beam
> and the material which makes up the edges of the slit? Could it not
> be the case that the diffraction observed when the slit is narrowed to
> within the wavelength of the photons is due to "physical" interaction
> between the photon and the atoms and electrons which makes up the
> edges of the slit?
Absolutely. But then, you'll see a spreading also when the slit is wide.
> Couldn't there be an electrostatic or other
> interaction going on which either attracts or repels the photon from
> the edge of the slit, and this interaction only occurs significantly
> when the slit is narrow enough to force all of the photons to interact
> with the slit edges (i.e. within a wavelength)?
There is always one, otherwise the beam wouldn't be cut off.
--
~~~~ clmasse on free F-country
Liberty, Equality, Profitability.
james...@gmail.com
ahead an copy and paste that post into this thread. I can't seem to
locate those posts anywhere (I think there are at least two which were
responses to posts in this thread). Thanks!
james...@gmail.com
people's emails (I hit "reply to author" instead of "reply" by
accident). Here's one (and the response from Rich L., who kindly
pointed out my error):
In all other cases I know of in physics and
chemistry, local matter/light interacts locally, at least initially
(this interaction may cause a cascade effect with distant results in
some cases).
>>This is one of the mysteries of quantum mechanics, and one of the ways in
which subatomic particle behave very differently from the macroscopic
particles we are all familiar with. One flagrant example is the
Mossbauer
effect. If you have a crystal of radioactive atoms (e.g. Iron-57)
that
emits 14KEV gamma rays, sometimes a gamma ray will be emitted without
the
expected recoil of the nucleus. Instead of the emitting nucleus
recoiling
the entire crystal recoils. The result is that the emitted gamma ray
has a
slightly higher energy than more ordinary gamma rays. This is very
hard to
understand, I know of no mechanism to explain how the recoil momentum
from
the gamma ray can be distributed apparently instantaneously over the
crystal, but it is observed and is a fact of nature.
>>In a very similar way particles, even matter particles, diffracted through
apertures will interact with the entire aperture instead of with just
a
single atom. If the gamma ray DOES interact with a single atom in the
aperture, then you will NOT see diffraction from that particle. It
will be
scattered over the entire range of angles possible.
I have this overriding concern that in every case where it is pointed
out, like you did that when the slit wall becomes light and small
enough to move in response to diffracting a photon (i.e. the momentum
transfer produces an observable movement in the slit wall thereby
giving "which way" info) it is claimed that this will destroy the
diffraction pattern due to the HUP (you didn't say it was due to HUP,
but most physicists do, and you may have been thinking it). Couldn't
it simply be that the diffraction pattern is destroyed because there
is a decoherence event which occurs when the wave-like properties of
the atoms and electrons which make up the wall (aka wavefunction in QM
formalism) combine with the wave-like nature of the particle passing
by in a sense that momentum is exchanged between both and perhaps the
wavefunction of the particle is immediately coupled to the
wavefunction of a variety of surrounding matter (the atoms of the
wall)...
>>I think you are describing the same mechanism. When the particle
interacts not with the entire aperture, but with some localized part
of it,
then the phase of the particle is scrambled and it will no longer end
up on
the screen with probabilities per the expected diffraction pattern.
so the diffraction pattern observed is "lost", but by "lost" I
mean it is still there, it is just far more complicated and
undecipherable...
>>Actually, talking about a diffraction pattern for a single particle
doesn't make sense. A diffraction pattern is the result of many many
particles interacting with the aperture and being detected on some
surface.
because each individual interaction between particle
and wall atoms is distinct and perhaps provides a unique disturbance
to the particle wavefunction such that the initially nearly identical
particles (with similar wave properties) are not heterogeneous to the
point that their waves have a very complex array of constructive and
destructive interference events so that it looks like there are no
more interference fringes when in reality the fringes are there they
just happen to be enormously more complex (and less intense...far
below the detection limit) than prior to the interaction between the
particles and the wall atoms.
>>One thing you may be forgetting is that you can observe diffraction
patterns even when there is only one particle in the experiment at a
time.
This has been shown conclusively by experiment many times.
In addition, the appearance of diffraction patterns from particles
passing through single slits could be due to the type of particle-
atom/
electron (of slit wall) interactions discussed above,
>>NO! Only the shape of the aperture is important. To a limited degree the
boundary conditions at the aperture may have an effect, but it is
really a
second order effect. I think you are missing the point if you try to
ascribe the diffraction pattern to the nature of the particle
interaction
with the atoms in the aperture
and these occur
based on the point in the period of the wave the particle is in when
interacting with the edge so that the strength of the interactions
varies in a way that reflects the wavenature of the particles (by the
way, I do not doubt the wave nature of particles at all, I only
question the HUP). I do not pretend to know the details of how the
culmination of these interaction reproduce the observed interference
fringes (or diffraction fringes for single slit), but I do posit that
the interactions, while probably of local nature, do have a nonlocal
component because the particle's wavefunction are clearly nonlocal in
nature (from single particle double slit experiment). I fully
recognize I'm being a little wishy washy on this particular point of
how different physical interactions between the particle and the
atoms/
electrons of the wall of the slit (which are nearby where the particle
passes through) could reproduce the observed interference fringes in
the single and double slit experiment, but I am somewhat confident
(please show me if I'm wrong) that this has not been disproven.
I really appreciate the discussion by the way! You all are really
helping me deal with some of my lingering concerns about QM and in
particular the HUP. I believe that extraordinary ideas (the HUP is
certainly one) require extraordinary experimental evidence. And so
far the experimental evidence is not extraordinary
>>I have to disagree with this statement. The issues you are questioning
are solidly established and in no doubt whatsoever.
Rich L.
BTW, this message came to me on my personal email. Did you mean to
post it
to the newsgroup for everyone to see? -ral
Rich L.
> Thus spake Rich L. <ralivings...@sbcglobal.net>
...
I'm not sure what you are not accepting. I think you have to admit
that there is SOME sort of interaction between the particles and the
slits, otherwise there would be no diffraction (the particles would
pass right through the "opaque" part of the slits!). I am quite
familiar with electromagnetic diffraction (that is what my doctoral
thesis was on). Although the general appearance of the diffraction
pattern does not depend strongly on the boundary conditions at the
walls of the slit, when studied in detail the boundary conditions do
perturb the diffraction patterns somewhat. Since the QM wavefunction
is identified with the EM fields, it seems clear to me that the
interactions of the particles with matter DO matter.
I do admit that I am struck by how much you can calculate the
diffraction patterns just based on the opacity of the aperture,
without any consideration of the nature of the interactions. However
I think you are missing something if you do not do the accounting for
conservation of momentum. The particles passing through the slits ARE
diffracted. The particle ends up traveling in a different direction
than the incident particles, so there has to be a transfer of
momentum. If the particles don't interact with the aperture, where
does the momentum go?
Rich L.
Oh No
I am suggesting that diffraction is due to spacetime structure, not to
interaction. I don't find it unreasonable that boundary conditions of
the slits may perturb the structure. My thought is that the structure is
not complete, which is why we have no answer to "which slit?" questions.
The detection of the particle is itself an event which contributes to
spacetime structure,. It is only sensible to talk of momentum in the
context of spacetime structure. I am suggesting that a small change in
spacetime structure, at the point of detection, results in a small
change in the calculation of the momentum of the slits.
Rich L.
> Thus spake Rich L. <ralivings...@sbcglobal.net>
...
> >On Aug 28, 3:55 am, Oh No <N...@charlesfrancis.wanadoo.co.uk> wrote:
> >> Thus spake Rich L. <ralivings...@sbcglobal.net>
...
> >diffracted. The particle ends up traveling in a different direction
> >than the incident particles, so there has to be a transfer of
> >momentum. If the particles don't interact with the aperture, where
> >does the momentum go?
>
> I am suggesting that diffraction is due to spacetime structure, not to
> interaction. I don't find it unreasonable that boundary conditions of
> the slits may perturb the structure. My thought is that the structure is
> not complete, which is why we have no answer to "which slit?" questions.
> The detection of the particle is itself an event which contributes to
> spacetime structure,. It is only sensible to talk of momentum in the
> context of spacetime structure. I am suggesting that a small change in
> spacetime structure, at the point of detection, results in a small
> change in the calculation of the momentum of the slits.
> - Show quoted text -
This is a VERY non-standard interpretation! I'm sure I don't fully
understand your concept. (I've looked at your teleconnection web
site, and I'm afraid I don't understand how your teleconnect concept
is materially different from the standard thought experiments common
in Relativity derivations. But perhaps I am being dense.) I am
skeptical that the diffraction effect affects the geometry of the
space (if that is what you are implying). If the geometry were being
affected, I'd expect to see other things affected, such as refraction
of light propagating across the apparatus while the diffraction is
happening. We don't see this.
On a distantly related issue, GR describes gravity as a distortion of
space from a Euclidian state. Electrostatics, on the otherhand, does
not work as a distortion of geometry because a positive and negative
charge in the same region would have to see very different
geometries. It doesn't make sense unless the two particles can
experience the same region as different geometries at the same time.
Perhaps something like this is what you are thinking, but it impresses
me as a huge conceptual complication. I'd need to see some big
advantage before I could buy into it.
Can you explain your idea more completely?
Rich L.
scerir
It seems something close to Bohr's complementarity,
that is to say the impossibility of any sharp
distinction between the behaviour of quantum objects
and the interaction with the measuring instruments
which serve to define the conditions under which the
phenomena appear.
Bohr says something more here. "However, since the discovery
of the quantum of action, we know that the classical ideal
cannot be attained in the description of atomic phenomena.
In particular, any attempt at an ordering in space-time leads
to a break in the causal chain, since such an attempt is
bound up with an essential exchange of momentum and energy
between the individuals and the measuring rods and clocks
used for observation; and just this exchange cannot be
taken into account if the measuring instruments are to
fulfil their purpose. Conversely, any conclusion, based
in an unambiguous manner upon the strict conservation
of energy and momentum, with regard to the dynamical
behaviour of the individual units obviously necessitates
a complete renunciation of following their course in space
and time."
Peter
> Bohr says something more here. "However, since the discovery
> of the quantum of action, we know that the classical ideal
Bohr didn't know the difference between Newton's and Laplace's notion of state
> cannot be attained in the description of atomic phenomena.
His 1913 statement about the CM principles of motion is wrong
> In particular, any attempt at an ordering in space-time
This seems to refer to classical orbits
> leads to a break in the causal chain, since such an attempt is
> bound up with an essential exchange of momentum and energy
> between the individuals and the measuring rods and clocks
> used for observation;
here is the differentiation between the actual and the possible observations
> and just this exchange cannot be
> taken into account if the measuring instruments are to
> fulfil their purpose. Conversely, any conclusion, based
> in an unambiguous manner upon the strict conservation
> of energy and momentum, with regard to the dynamical
> behaviour of the individual units obviously necessitates
> a complete renunciation of following their course in space
> and time."
being a physicist (contrasted to a philosopher), I just don't understand this
statement and thus ask for a popular formulation :-)
Peter
scerir
> > and just this exchange cannot be
> > taken into account if the measuring instruments are to
> > fulfil their purpose. Conversely, any conclusion, based
> > in an unambiguous manner upon the strict conservation
> > of energy and momentum, with regard to the dynamical
> > behaviour of the individual units obviously necessitates
> > a complete renunciation of following their course in space
> > and time."
Peter writes:
> being a physicist (contrasted to a philosopher), I just
> don't understand this statement and thus ask for a popular
> formulation :-)
Imagine the old two-slit interferometer and photons
arriving at the old screen, showing the interferential
pattern (because amplitudes come from both slits).
Now let me suppose we have a new, smart, nano-tubular
screen which can actually or in principle register, for
each photon arriving at the screen, both its POSITION
(the impact on the screen) and its MOMENTUM (that is to say,
which slit it chose). What do you think would be the
pattern on the screen? Interferential, because the screen
registers the position? Ot smooth, because the screen
registers the momentum (thus distinguishing the paths)?
Or both?
Well, according to Bohr, the situation, with regard to
the dynamical behaviour of the individual photons arriving
at the screen, necessitates a renunciation of following
their course in SPACE and TIME. (In other words our new
smart nano-tubular screen, because it can register the
momentum of each photon arriving at the screen, would cause
a retro-action on each photon, transforming the potential
interference pattern into an actual smooth pattern).
Rich L.
You would see the "inferential" pattern for the arrival of the
photons, but the momentum measurement on the photons would not
consistently show that the photon came from only one slit. The
momentum measurement would be uncertain enough that you could not
tell. One photon might appear to have come from one slit, or the
other, while the next photon might appear to have come from the gap
between the two slits.
>
> Well, according to Bohr, the situation, with regard to
> the dynamical behaviour of the individual photons arriving
> at the screen, necessitates a renunciation of following
> their course in SPACE and TIME.
I have not problem with this statement.
>(In other words our new
> smart nano-tubular screen, because it can register the
> momentum of each photon arriving at the screen, would cause
> a retro-action on each photon, transforming the potential
> interference pattern into an actual smooth pattern).
This I think is an unwarrented inference. Just because you cannot
determine the exact path of the photon (even asking this question
assumes that there IS such a unique path, which I think is the major
misunderstanding), does not neccessarily mean that something is
changing retroactively. This is the mystical part of the Copenhagen
interpretation that I've always objected to. It is a POSSIBLE
interpretation, it is POSSIBLE that the world actually works this way,
but I am very skeptical. For one thing, it causes HUGE problems when
you try to reconcile this idea with relativity theory. Something has
to give in one of these theories, and my choice is the mystical
"collapse of the wave function" as a physical event. I think the
"collapse" is nothing more than our knowledge of what was actually
happening, just like our knowledge(observation) that the die just
rolled a six does not change how the die bounced on the table.
Rich L.
Salviati
> Something has
> to give in one of these theories, and my choice is the mystical
> "collapse of the wave function" as a physical event. I think the
> "collapse" is nothing more than our knowledge of what was actually
Isn't collapse of the wave function synonymous to reduction
of the wave packet proposed by the standard theory of v. Neumann?
Doesn't decoherence strictly speaking suppose an infinite time?
Engineers understand that any measurement is bandlimited.
So far I do not yet understand why in 1935 - perhaps related to EPR -,
v. Neumann did no longer belief in Hilbert space.
I read that QM can be based on phase space instead of Hilbert
space if one accepts negative probabilities.
This seems not to be the solution.
If the concept of Hilbert space is to blame,
I wonder if phase space is not also inappropriate.
Regards,
Salviati:
... in ultima conclusione, gli attributi di eguale
maggiore e minore non aver luogo ne gl'infiniti,
ma solo nelle quantità terminate.
IR>|>IR+>|>IR
scerir
> You would see the "inferential" pattern for the arrival of the
> photons, but the momentum measurement on the photons would not
> consistently show that the photon came from only one slit. The
> momentum measurement would be uncertain enough that you could not
> tell. One photon might appear to have come from one slit, or the
> other, while the next photon might appear to have come from the gap
> between the two slits.
Yes that is possible. See Wootters & Zurek: "Complementarity
in the double-slit experiment: Quantum nonseparability and
a quantitative statement of Bohr's principle", PR, D-19, 1979,
p.473-484.
But even a probabilistic, or partial knowledge of the 'which slit'
would perhaps modify the interference pattern.
There is the relation P^2 + V^2 = 1, where P is the
probability for the particle taking one of the two possible
paths, and V the visibility of the interference fringes.
http://arxiv.org/abs/quant-ph/9908072
http://arxiv.org/abs/quant-ph/0311179
http://arxiv.org/abs/quant-ph/0201026
http://arxiv.org/abs/quant-ph/0404013
> I think the "collapse" is nothing more than our knowledge
> of what was actually happening, just like our knowledge
> (observation) that the die just rolled a six does not change
> how the die bounced on the table.
Here is a little collection of quotes, sometimes convergent,
sometimes divergent.
"This probability function represents a mixture of two things,
partly a fact and partly our knowledge of a fact. It represents a
fact in so far as it assigns at the initial time the probability
unity (i.e., complete certainty) to the initial situation: the
electron moving with the observed velocity at the observed position;
'observed' means observed within the accuracy of the experiment.
It represents our knowledge in so far as another observer could
perhaps know the position of the electron more accurately. The error
in the experiment does - at least to some extent - not represent a
property of the electron but a deficiency in our knowledge of the
electron. Also this deficiency of knowledge is expressed in the
probability function."
-Heisenberg, 'Physics and Philosophy'.
Heisenberg by the way goes on to say: "We can, for instance,
predict the probability for finding the electron at a later
time at a given point in the cloud chamber. It should be
emphasised, however, that the probability function does not
in itself represent a course of events in the course of time.
It represents a tendency for events and our knowledge of events."
And a little further, he says: "The observation ... breaks
the determined continuity of the probability function by changing
our knowledge of the system."
And also: "Therefore, the transition from the 'possible'
to the 'actual' takes place during the act of observation.
If we want to describe what happens in an atomic event,
we have to realize that the word 'happens' can apply only
to the observation, not to the state of affairs between two
observations. It applies to the physical, not the psychical act
of observation, and we may say that the transition from the
'possible' to the 'actual' takes place as soon as the
interaction of the object with the measuring device, and
thereby with the rest of the world, has come into play; it is not
connected with the act of registration of the result by the mind
of the observer. The discontinuous change in the probability
function, however, takes place with the act of registration,
because it is the discontinuous change of our knowledge in
the instant of registration that has its image in the discontinuous
change of the probability function."
"It is inherenly entirely correct that the measurement or
the related process of the subjective perception is a new entity
relative to the physical environment and is not reducible
to the latter. Indeed, subjective perception leads us into the
intellectual inner life of the individual, which is
extra-observational by its very nature".
-J. von Neumann, Mathematical Foundations of Quantum Mechanics,
p.418.
J. von Neumann also defined the principle of "psycho-physical
parallelism" that is to say .... "that it must be possible
to describe the extra-physical process of the subjective
perception as if it were in reality in the physical world
- i.e., to assign to its parts equivalent physical processes
in the objective environment, in ordinary space."
Personally I see some value in what Horodecki wrote here:
"If we insist that the role of the wave function is
simply to describe probabilities, we must give up the
possibility of treating the wave function as an isomorphic
image of what is actually processed in the laboratory".
Not to mention Born: "The question of whether the waves
are something 'real' or a function to describe and predict
phenomena in a convenient way is a matter of taste. I personally
like to regard a probability wave, even in 3N-dimensional space,
as a real thing, certainly as more than a tool for mathematical
calculations ... Quite generally, how could we rely on
probability predictions if by this notion we do not refer
to something real and objective?"
Cl.Massé
news:Yp6wk.143896$FR.4...@twister1.libero.it...
> Now let me suppose we have a new, smart, nano-tubular
> screen which can actually or in principle register, for
> each photon arriving at the screen, both its POSITION
> (the impact on the screen) and its MOMENTUM (that is to say,
> which slit it chose). What do you think would be the
> pattern on the screen? Interferential, because the screen
> registers the position? Ot smooth, because the screen
> registers the momentum (thus distinguishing the paths)?
> Or both?
The result won't be the one you expect. The measured momentum will be
intermediary between the two "possible" values, and the pattern will still
be there.
Oh No
>> Thus spake Rich L. <ralivings...@sbcglobal.net>
> ...
>> >On Aug 28, 3:55 am, Oh No <N...@charlesfrancis.wanadoo.co.uk> wrote:
>> >> Thus spake Rich L. <ralivings...@sbcglobal.net>
> ...
>>> The particles passing through the slits ARE
>> >diffracted. The particle ends up traveling in a different direction
>> >than the incident particles, so there has to be a transfer of
>> >momentum. If the particles don't interact with the aperture, where
>> >does the momentum go?
>>
>> I am suggesting that diffraction is due to spacetime structure, not to
>> interaction. I don't find it unreasonable that boundary conditions of
>> the slits may perturb the structure. My thought is that the structure is
>> not complete, which is why we have no answer to "which slit?" questions.
>> The detection of the particle is itself an event which contributes to
>> spacetime structure,. It is only sensible to talk of momentum in the
>> context of spacetime structure. I am suggesting that a small change in
>> spacetime structure, at the point of detection, results in a small
>> change in the calculation of the momentum of the slits.
>
>> - Show quoted text -
>
>This is a VERY non-standard interpretation!
I agree that it goes well beyond what is found in standard
"interpretations", but while many of those interpretations contain much
that is good and true, they fall short of really being interpretations,
in that, while containing some insight into the meaning of quantum
mechanics they fail to describe the actual behaviour of matter.
>I'm sure I don't fully
>understand your concept. (I've looked at your teleconnection web
>site, and I'm afraid I don't understand how your teleconnect concept
>is materially different from the standard thought experiments common
>in Relativity derivations.
Indeed, the teleconnection was discovered by taking such derivations to
their logical conclusion and by applying similar fundamental precepts in
the quantum domain.
>But perhaps I am being dense.) I am
>skeptical that the diffraction effect affects the geometry of the
>space (if that is what you are implying). If the geometry were being
>affected, I'd expect to see other things affected, such as refraction
>of light propagating across the apparatus while the diffraction is
>happening. We don't see this.
To ascertain exactly what is and what is not affected, it is necessary
to analyse the implications mathematically.
>On a distantly related issue, GR describes gravity as a distortion of
>space from a Euclidian state. Electrostatics, on the otherhand, does
>not work as a distortion of geometry because a positive and negative
>charge in the same region would have to see very different
>geometries. It doesn't make sense unless the two particles can
>experience the same region as different geometries at the same time.
>Perhaps something like this is what you are thinking, but it impresses
>me as a huge conceptual complication. I'd need to see some big
>advantage before I could buy into it.
>
>Can you explain your idea more completely?
That is the point of the website. I do not think there is any reasonable
half-way house between the sort of skimpy rough description that I can
put into a post and a full mathematical development.
Rich L.
> Rich L:
>
> > You would see the "inferential" pattern for the arrival of the
> > photons, but the momentum measurement on the photons would not
> > consistently show that the photon came from only one slit. The
> > momentum measurement would be uncertain enough that you could not
> > tell. One photon might appear to have come from one slit, or the
> > other, while the next photon might appear to have come from the gap
> > between the two slits.
>
> Yes that is possible. See Wootters & Zurek: "Complementarity
> in the double-slit experiment: Quantum nonseparability and
> a quantitative statement of Bohr's principle", PR, D-19, 1979,
> p.473-484.
> But even a probabilistic, or partial knowledge of the 'which slit'
> would perhaps modify the interference pattern.
> There is the relation P^2 + V^2 = 1, where P is the
> probability for the particle taking one of the two possible
>
> > I think the "collapse" is nothing more than our knowledge
> > of what was actually happening, just like our knowledge
> > (observation) that the die just rolled a six does not change
> > how the die bounced on the table.
>
> Here is a little collection of quotes, sometimes convergent,
> sometimes divergent.
>
>
The question of what IS the wave function is the crux of the issue of
interpretation. The interpretation that it is a probability implies
that it is not "real", but is a representation of our knowledge, or
lack of it. The natural thought is that the particle is "actually"
doing something definite (e.g. passing through the left slit), but we
simply don't KNOW that. This leads to the idea of wave function
collapse when we DO learn what it was doing, or at least where it
ended up.
My interest in this question is the conflict between QM and GR. To
calculate the geometry of space one needs to know, at least in
principle, the energy density. The wave function seems to be somewhat
lacking in its ability to represent the energy density, since it shows
finite probability for the particle in distant regions of space up
until the "collapse", when those probabilities suddenly go to zero.
GR requires that the energy flow at no more than the speed of light,
so an "instantaneous collapse" is a problem if there is any reality
associated with the wave function.
The idea that the particle is actually doing something definite, even
though we don't know which of the several possibilities it is
"actually" doing leads to the idea of hidden variables. It is not
unlike the ideas behind statistical physics, or thermodynamics, where
it is assumed (classically) that each particle can in principle have a
known, or at least a definite, position and momentum. This is the
idea that the Bell Inequality was derived to test. The results of the
experiments recently (last 10 years or so) have been pretty clear that
the idea of hidden variables combined with locality is not supported
by experiment.
Hidden variables and locality are two different things, however.
There can still be hidden variables if we give up locality. (Locality
is the idea that influences must propagate from one point to another
at no faster than the speed of light, in any reference frame).
Unfortunately locality is a fundamental idea of GR. If we give up on
hidden variables (which I think it is fair to say is the currently
popular opinion) then we have no way to calculate the geometry of
space during an EPR experiment, and GR becomes a problem. Curiously
(to me at least) is that the "Copenhagen Interpretation" also gives up
on locality as well. This is what leads to the concept of the
"collapse of the wave function". This interpretation of collapse is
not relatavistically consistent, however. One observer can say that
the detection at A occurs first and thus results in the wavefunction
collapse, while another observer can see the same events as the first
detection is at B and causes the wavefunction to collapse at that
time. Any mechanism that results in changes over space
"instantaneously" is not consistent with the ideas of relativity.
If we keep hidden variables, we have to modify the idea of locality.
I've mentioned this idea before (and others before me, but I don't
necessarily advocate it). If we suppose that interactions at the
speed of light are "instantaneous" in the sense that the proper
distance is zero (i.e. the two events, emission and absorbtion are on
null lines), then we can wave our hands a bit and say that both
detections at A and B are actually coupled (somehow) through the
emitting atom, and the detections are predetermined by the time the
photon is emitted. There seems to be a bit of hand waving here, but
it seems like something that might be made to work. So far I haven't
found any compelling reason to believe this. I don't see how it
allows us to do a calculation that we couldn't do before accepting
this idea.
This concept also has the unpleasant side effect that it implies that
the future is set, frozen, and there is little or nothing we can do to
influence it to be more to our liking. This is an emotional argument
that I feel has little bearing on the science, but I also admit to
some discomfort with this aspect.
Another solution would be to allow faster than light interactions.
This seems to be implied by the idea of "instantaneous collapse of the
wave function". This requires giving up the principle of relativity
(i.e. that the laws of physics are the same in all reference frames),
and I don't think very many physicists are ready to do that yet.
In anycase, I think the interpretation of the wave function is a key
issue in physics. Your quotes seem to support that important
physicists have devoted significant time to clarifying the
interpretation. The fact that some of these clarifications contradict
shows, I think, that there is still some work to do here. One thing
that does concern me, however, is that most of the effort has
approached it from only the QM side. Relativity also has something to
say about it, and in particular it is difficult for me to understand
how the so called "Copenhagen Interpretation" of the EPR/Aspect
experiments can be consistent with the principles of relativity.
Again, my two cents on the subject,
Rich L.
Oh No
>interpretation. The interpretation that it is a probability implies
>that it is not "real", but is a representation of our knowledge, or
>lack of it. The natural thought is that the particle is "actually"
>doing something definite (e.g. passing through the left slit), but we
>simply don't KNOW that. This leads to the idea of wave function
>collapse when we DO learn what it was doing, or at least where it
>ended up.
"passing through the left slit" is too strong. The thought should be
that it is doing something definite, but that the structures of
mathematics, in particular the mathematical structure of space, which we
commonly use to describe what it is doing, have broken down.
>
>My interest in this question is the conflict between QM and GR. To
>calculate the geometry of space one needs to know, at least in
>principle, the energy density. The wave function seems to be somewhat
>lacking in its ability to represent the energy density, since it shows
>finite probability for the particle in distant regions of space up
>until the "collapse", when those probabilities suddenly go to zero.
>GR requires that the energy flow at no more than the speed of light,
>so an "instantaneous collapse" is a problem if there is any reality
>associated with the wave function.
Indeed. These matters have been considered in the Eppley-Hannah
experiment, and also in the Page-Geilker experiment. Considering the
central importance of these experiments in guiding thought on quantum
gravity, I have been surprised to find remarkably little in the way of
descriptions of them on the net. I have made a few comments at
http://www.teleconnection.info/rqg/SpacetimeStructure.
>
>The idea that the particle is actually doing something definite, even
>though we don't know which of the several possibilities it is
>"actually" doing leads to the idea of hidden variables. It is not
>unlike the ideas behind statistical physics, or thermodynamics, where
>it is assumed (classically) that each particle can in principle have a
>known, or at least a definite, position and momentum. This is the
>idea that the Bell Inequality was derived to test. The results of the
>experiments recently (last 10 years or so) have been pretty clear that
>the idea of hidden variables combined with locality is not supported
>by experiment.
>
>Hidden variables and locality are two different things, however.
>There can still be hidden variables if we give up locality. (Locality
>is the idea that influences must propagate from one point to another
>at no faster than the speed of light, in any reference frame).
>Unfortunately locality is a fundamental idea of GR. If we give up on
>hidden variables (which I think it is fair to say is the currently
>popular opinion) then we have no way to calculate the geometry of
>space during an EPR experiment, and GR becomes a problem.
This is the clue. If we have no way to calculate the geometry of space,
then the geometry of space ceases to have meaning. In this case we
cannot consider under the possibilities for what the particle is
actually doing those possibilities which depend on our visualisation of
space. In particular we cannot consider possibilities like "the particle
went through the left slit".
>Curiously
>(to me at least) is that the "Copenhagen Interpretation" also gives up
>on locality as well. This is what leads to the concept of the
>"collapse of the wave function". This interpretation of collapse is
>not relatavistically consistent, however. One observer can say that
>the detection at A occurs first and thus results in the wavefunction
>collapse, while another observer can see the same events as the first
>detection is at B and causes the wavefunction to collapse at that
>time. Any mechanism that results in changes over space
>"instantaneously" is not consistent with the ideas of relativity.
On the other hand, there is no such issue with the notion that the wave
function is simply a way of expressing probability.
Yes. I have always considered that a reason for the failure of
interpretations is that they try to deal only with non-relativistic
quantum mechanics. My own approach is been relativistic from the outset.
At the root of it is the idea that we should take relativity one step
further, into full blooded relationism. IOW we should not just say that
motion is relative, but we should actually say that position is
relative. Historically relationism failed because it could not find a
mathematical way in which to describe a universe in which only relative
position is possible. Hence Newton's ideas on absolute space. However,
maths and physics are now a few generations more advanced, and I have
sought to show that quantum logic is the natural mathematical language
in which we can describe measurement in a relationist universe
(http://www.teleconnection.info/rqg/FoundationsOfQuantumTheory). It is
necessarily probabilistic, and hence, non-deterministic.
Wrt the Aspect experiment, we can only discuss the relative orientation
of Alice & Bob's measurements in the context of a spacetime structure
which contains both. At the time the measurements take place, this
structure is not complete. The correlation in the results can only be
found at a time when the measurement results are brought together to a
point in which the measurements are in the past light cone. I find this
quite consistent with the basic idea in special relativity that
spacetime coordinates are defined by two way photon exchange, and
conclude that we can only define spacetime structure after this, or
equivalent, processes have taken place.