| Topic: |
Science > Physics |
| User: |
"nightlight" |
| Date: |
20 Oct 2005 12:25:19 PM |
| Object: |
Is there Bell's Theorem? |
Continued from sci.physics.research thread:
photoelectric effect : hypothetical experiment
http://groups.google.com/group/sci.physics.research/msg/80cabf211dfe2629
------------------------------------------------------------------------
Caroline Thompson wrote:
... Aspect's time-varying experiment. This was surely from
the start a "no-go" as far as any reasonable physical
explanation was concerned?
As Trevor Marshall has said about it, they were "slaying a minor
dragon" (to divert attention of physicists from the real dragon of
Quantum Optics experiments, the rejected data: the unpaired singles +
the accidental coincidences). The same kind of gimmick was amplified
and elaborated to ridiculous lengths over decades through adding
kilometers after kilometers to the fiber cables in Geneva experiments,
which as you note is pointless diversion. A less generous comparison
than Trevor's would be to the misdirection by a stage magician -- look
at this hand I raised, look carefully at the front, back, sides,
sleave,... no card here at all.
What physical cause could make one detector send signals to
the other in such a way as to lead to the exact QM prediction?
You're conceding here a critical point inside the vague term
"prediction". There is no QM or QED/QO prediction of Bell inequality
violation. There are two predictions hiding under "prediction" in your
statement:
P1. The detector counts will show no Bell Inequality violations.
P2. There is a _subset_ of detector counts showing cos^2(theta)
pair counts dependency on the angle theta between polarizers.
The two predictions are not mutually exclusive. The QM magic show
performers pretend there is just one "prediction" FP2, which is a
Fuzzied up P2, with the critical "subset" qualification omitted (when
pushed, they will admit it, but only after implying, _incorrectly_,
that it is a minor and temporary technological imperfection not worth
mentioning, a "loophole"). The FP2 is then wishfully rebranded into the
"Bell theorem" (Bell never called it a "theorem" since it isn't) after
showing that cos^2(theta) relation, _if one were to extrapolate_ it
from the subset to the full set of pairs (qualification known as "fair
sampling" hypothesis, often left unmentioned by the magicians, the
"theorem" popularizers and pedagogues), then the extrapolated data
would violate Bell inequalities. By omitting to mention the necessary
extrapolation step, their little (7th grade algebra) excercise is taken
to mean that QM predicts B.I. violations.
As explained in the few previous posts, the _general QM postulates_
lack the sufficient quantitative precision, the level of precision
required by the Bell inequality constraints (such as allowing at most
17% data rejections) to say what kind of "subset" is involved in P2.
The magicians and their magic show salesmen, leap from this QM lack of
precision in P2 to FP2, pretending that if general QM postulates can't
say what kind of "subset" is in P2, then they are free to declare the
subset to be the full set (or at least larger than 83% of the full
set). There is _no QM postulate_ which would (or possibly could)
guarantee the size of the subset in P2, hence there is no "Bell
theorem" (the alleged QM prediction of B.I. violations). The QM
postulates can only claim the existence of algorithms which map the
readouts of the instruments to the eigenvalues of observables (the
"operational procedures" of QM), but they can't declare detailed
quantitative properties of such algorithms (such as for example, that
the percentage of pairs kept is going to be above 83%; there isn't any
QM postulate which says, or could conceivably say, anything of the
sort).
To make the "subset" in P2 precise enough for the B.I. violation
claims, one needs a more specific model and theory of the phenomenon
being used in a particular kind of experiment. For optical photons,
such theory and model is provided by the Glauber's n detector theory,
which is an application of the Old QED (the 1920s QED of Dirac,
Heisenberg and Jordan, minus the matter field quantization) to the n
photodetectors plus the incident EM field. This is the approach taken
by Ou & Mandel in their 1988 B.I. "violation" experiment (the mother of
all present day QM magic shows based on PDC). As explained in the two
earlier posts:
http://groups.google.com/group/sci.physics.research/msg/7ee770990a31bd3f
http://groups.google.com/group/sci.physics.research/msg/fbd9858ee710e27a
there is no QED/QO prediction of B.I. violations either, except that
the sleight of hand is shamelessly naked in the QED/QO model of the
experiment (which is probably why Mandel, in his massive QO textbook,
had paradoxically reverted back to the QM version of the "Bell theorem"
instead of using the QED/QO "prediction" of B.I. violation from his
1988 paper, and has dropped entirely the Glauber's derivation of the n
detector theory he used in the 1988 paper, even though there is a whole
chapter on QED theory of photodetection; he mentions there Glauber's
derivation but then chooses to skip it and handwave instead the
critical case of the so-called 'nonclassical' light via analogy from
the coherent state case, which even the QO magicians acknowledge as
perfectly classical).
In short, there is neither QM nor QED prediction of B.I. violations in
any setup that has been theoretically analyzed and modelled to date:
the general QM postulates are not precise enough to make such
prediction and the specific QED/QO models for optical photons &
detectors, which do predict correctly all that is being observed here
(the P1 and P2) show no violation either.
By conceding that there is a QM "prediction" of B.I. violations, you
open yourself to the cheap shots from the "believers" that will
automatically follow, as nicely illustrated by the reflexive attack on
your post by Paul Kinsler. By conceding their false claim that "QM
predicts B.I. violations", you get cornered into defending a generic
position "QM is wrong" even though the only wrong thing in this context
is the wishful leap by the "believers" that the absence of the general
QM prediction about the "subset" size in P2 means they can take it to
be whatever they wish (such as > 83%).
Only their wishful leap is wrong, while the QM and QED/QO, as far as
their predictions go (P1 & P2), are perfectly fine. The QM (via QED/QO)
predictions are P1 and P2 -- they are both correct and are perfectly
harmonious with each other and with the experiments. Emilio Santos has
recently taken this exact position (the QM/QO and the experiments are
right, they agree and neither predict nor demonstrate any B.I.
violations) as explained in his recent preprint (where he also notes on
page 20 that Bell didn't call his heuristic sketch of P2, without the
"subset" evaluation, a "theorem" about QM violations of his
inequalities):
E.Santos "Bell's theorem and the experiments: Increasing empirical
support to local realism"
quant-ph/0410193 http://arxiv.org/abs/quant-ph/0410193
Although the history will eventually show this to be the correct view,
that won't be acknowledged, logic and experimental facts be damned, by
the QO magicians until they have another magic show ready for the road.
The same phenomenon happened during the 1950s Hanbury Brown and Twiss
"controversy", which was accepted as genuine experimental fact only
after Purcell (in 1956), and then finally Glauber (in 1963) explained
it within QED while _simultaneously_ promising the existence of the
"non-classical" light which would show the opposite effect (the
sub-Poissonian counts, in contrast to the HBT's super-Poissonian
counts). As you know, this promised phenomenon has been the "holy
grail" of the magic branch of Quantum Optics ever since (yet, the best
they can show as of year 2004, is the cheap magic trick in the AJP-2004
paper by Thorn et al., which was the "improvement" of Grangier et al.
1986 experiment).
The second important instance of the similar denial of facts (and
censoring of anyone pointing them out) by the magic show branch of the
QM/QO, until the new magic show was conceived, was the history of the
von Neumann's Hidden Variables impossibility "proof" of 1932. This
"proof" served for decades as the sledgehammer to pound down and
silence the "heretics" (including Einstein, de Broglie and
Schrodinger). Even after 1952, when Bohm produced a plain, direct
counter-example (the Bohmian Mechanics) to the von Neumann's "theorem",
the von Neumann's "proof" stood for another decade (with a bit of a
formal face-lift as the Kochen-Specker theorem, which retained the von
Neumann's "proof" flaw of making groundless leap in the QM operational
mapping, the same flaw affecting the so-called Bell's "theorem" today),
until Bell found a little, obscure and windy goatpath to the next QM
magic promised land, the Local HV impossibility via potential Bell
inequality violations. Well, only then the von Neumann's "proof" was
officially declared as flawed (by Bell himself) and dropped as if it
never was.
The history lesson is that this little mutual back-patting society of
QO magicians, won't budge an inch on the so-called Bell's "theorem" and
the claims of B.I. violations they allegedly observed, until someone
stumbles upon some little hidden path to the next magic show promised
land. Until then, the logic and the facts are officially (in their
little circle, which is much too loud for its real size) just a
loophole imagined by a handful of obsessed diehards.
.
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| User: "" |
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| Title: Re: Is there Bell's Theorem? |
24 Oct 2005 03:42:37 PM |
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nightlight wrote:
Continued from sci.physics.research thread:
photoelectric effect : hypothetical experiment
http://groups.google.com/group/sci.physics.research/msg/80cabf211dfe2629
------------------------------------------------------------------------
Caroline Thompson wrote:
... Aspect's time-varying experiment. This was surely from
the start a "no-go" as far as any reasonable physical
explanation was concerned?
As Trevor Marshall has said about it, they were "slaying a minor
dragon" (to divert attention of physicists from the real dragon of
Quantum Optics experiments, the rejected data: the unpaired singles +
the accidental coincidences).
You're right, of course, but I'm afraid I haven't time to study the
whole of your response. You're also right about my assuming Bell was
correct in stating the QM "prediction". I'm not qualified to check
this, but have always taken it that he was saying the prediction
applied only to perfect experiments. It has therefore (in view of the
various loopholes) never actually been tested. At the same time, I've
always had my doubts about whether every variant of QM made this
prediction.
Anyway, great minds think alike, nightlight! I entitled one of my
talks on the Bell test loopholes "Behind the Scenes at the EPR Magic
Show". It was published in the the conference proceedings
(incidentally, accompanied by a number of other interesting articles):
"Open questions in relativistic physics". Franco Selleri (ed.).
Proceedings of Athens conference, June 25-28, 1997, on "Relativistic
Physics and some of its Applications".
Several similar articles can be found on my web site:
http://freespace.virgin.net/ch.thompson1/
Caroline
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