billschnieder said:
You are the one confused. A dataset of triples means just that.
Bell's proof does not assume a "dataset of triples" if by "dataset" you mean the experimental data that each term in the inequality is assumed to be based on. In some variants of the proof it may assume there is some objective truth about all three members of the triple even if we can't measure them all, but the inequality only deals with measurable pairs.
billschnieder said:
If you know only pairs you have a dataset of pairs even if you assume that there was a third value for each pair which you do not know.
Yes, exactly! And the Bell inequality is a prediction about the statistics on such a dataset of pairs, given some assumptions about how they were gathered and the laws of physics that determine their values.
billschnieder said:
Simply because you can not directly calculate the LHS of Bell's inequality without the a third value and if you are calculating the LHS using a separate experiment for each term, you can not claim to have a dataset of triples. If you assume that the three values exist and you would like to consider them together theoretically as triples (like Bell did), then you have a dataset of triples not pairs.
Not sure what you mean by "consider them together theoretically as triples", if this is an important part of your argument you'll have to explain in more detail. We may be assuming theoretically the pairs are sampled from triples, but a term in the inequality like (Fraction of A,B samples which gave result A+, B-) still deals with a collection of measured pairs (specifically the pairs where we measured A,B). Do you disagree?
billschnieder said:
So for all your explanations, you have not provided anything of contrary to my claim. Claim (1) is dealing with datasets of triples not pairs despite your wishes. Again if you agree with it just say you do. If you disagree say so as well.
Based on your comment above I no longer know what you mean when you say "datasets of triples", you seem to be using that phrase in a rather odd way that you have never defined. According to
my commonsense use of the term, you only have a "dataset of triples" if you actually measured three properties of each "object" (the 'thing' being a pair of entangled particles in most cases, or a short time interval where we can measure a SQUID ring at any of three times in the case of the Leggett-Garg inequality), if you only measured two for each "object" then by definition you have a dataset of pairs. So, for example, the inequality I mentioned earlier:
(Fraction of A,B samples which gave result A+, B-) + (Fraction of B,C samples which gave result B+, C-) greater than or equal to (Fraction of A,C samples which gave result A+,C-)
...would be an inequality dealing with a dataset of pairs, even though I explicitly assumed each pair was drawn from a well-defined triple. If you disagree, please give a careful definition of what
you mean by the phrases "dataset of pairs" and "dataset of triples".
billschnieder said:
In the theoretical experiment, the values exist as triples, the terms in the inequality are obtained from the triples and in this case the inequality can never be violated even if FTL is involved.
I don't know what you mean by "the terms in the inequality are obtained from the triples" either. In the theoretical experiment I described, only two properties were measured from each object, and a term in the inequality like (Fraction of A,B samples which gave result A+, B-) dealt
only with the subset of triples where A and B were sampled, not with the full set of triples. I showed explicitly how the inequality
was violated in this case. Do you disagree that the terms in Bell's inequality also deal only with subsets of all the entangled particle pairs that were measured, so that for example a term like P(experimenter A found spin-up at 0 degrees, experimenter B found spin-down at 45 degrees) would deal only with the particle pairs that were actually measured with detector settings of 0 for A and 45 for B? So if we can't make the theoretical assumption that the full values of the triple are uncorrelated with the choice of detector settings, it would be possible for Bell's inequality to be violated too even in a local realist universe? (for example, if the detectors are actually set in the past light cone of the source emitting the particles, it's conceivable the source would "know" which settings the particles will encounter on each trial and tailor the triple of values to that, in just the right way to violate the inequality)
billschnieder said:
Go back to Bell's original work from equation (14) onwards where he introduces the third angle and follow the derivation from there. You will realize that everything prior to that point is peripheral.
Bell's "original work" is highly condensed, written for an audience of physicists who can be expected to understand his implicit assumptions, it's silly to ignore all his later writings where he stated the assumptions more explicitly, like the paper I quoted in post #1171 where he referred to the need to assume a "random sampling hypothesis" (also, since we are dealing with scientific ideas rather than religious scriptures, it is perfectly legitimate to consider the derivation of Bell inequalities by authors other than Bell). And even in that
original paper, if you examine his equations you see he does assume that the probabilities of different hidden variables λ (which in his original proof completely determine the triplet of predtermined values for each detector setting) are not in any way correlated to the choice of detector settings a and b, even if he doesn't state this explicitly (for example, in equation (21) note that he uses the same probability distribution \rho(\lambda) in calculating P(a,b) and P(a,c)). As I mentioned way back in post #861 on
page 54 of this thread, that's what later authors have called the "no-conspiracy assumption".
billschnieder said:
So contrary to your claims, Bell's inequality is in fact an arithmetic relationship between triples.
So what do you think he was talking about in that quote from post #1171 where he talked about the need for a "random sampling hypothesis"?
billschnieder said:
I have provided mathematical proof by deriving the exact same equation without any other assumption than the presence of triples.
In physics, you can't assume one equation is the "exact same" as the other just because they are written in the same abstract form. For example, the two inequalities in my example:
(Fraction of all nine objects with properties A+ and B-) + (Fraction of all nine objects with properties B+ and C-) greater than or equal to (Fraction of all nine objects with properties A+ and C-)
and
(Fraction of A,B samples which gave result A+, B-) + (Fraction of B,C samples which gave result B+, C-) greater than or equal to (Fraction of A,C samples which gave result A+,C-)
Can both be written as:
F(A+,B-) + F(B+,C-) >= F(A+,C-)
...but their meaning is very different! The first is guaranteed to hold due to basic arithmetical considerations, but the second is not, and I explicitly showed it was violated in my example. If you make some
additional assumptions like the no-conspiracy assumption and the assumption of a very large number of trials, you can show that the second should hold as well, but it's clearly a different inequality than the first since it requires different assumptions to derive.
billschnieder said:
Bell also assumes the presence of triples and he obtains the same mathematical relationship. Is this a coincidence? Note also that you fail to specify the extra assumption without which Bell's inequality can not be derived, provided you already have triples like Bell assumed.
One of the extra assumptions is the no-conspiracy assumption, which is what I was referring to in the previous post when I said "But if you add some additional assumptions beyond local realism (assumptions which can themselves be justified by the details of how the experiment is conducted plus the assumption of local realism), like
the assumption that the probability of different hidden triplets is not correlated with the two you actually choose to sample"...
billschnieder said:
Now if you are ready to admit claim (1)
Nope, not if (1) includes the idea that Bell's inequality has the same meaning as the arithmetical inequality just because it can be written in the same form.
billschnieder said:
but want to argue that under certain conditions a dataset of pairs will also satisfy the inequality, but not under every condition, then that is understandable but non earth-shattering because my claim (1) already lays out the conditions under which those terms involving pairs will obey the inequality -- ie, when they are extracted from a dataset of triples!
Would you say the pairs in my example were "extracted from a dataset of triples"? The pairs were all extracted from a list of triples which would be known by an omniscient observer, though they weren't known by the experimenter so I wouldn't call them a "dataset". But if you would say that the pairs were "extracted from a datset of triples" then this is an explicit counterexample to your claim above, since the resulting pairs violated the inequality.
billschnieder said:
So you accept claim (1) but deny that the inequality so derived is Bell's inequality.
I thought it seemed to be
part of claim (1) that the "inequality so derived is Bell's inequality", since part of claim (1) was "Bell's inequality is an arithmetic relationship between triples of numbers". I did ask for clarification on this point when I said "Perhaps you did not actually mean for your claim 1) to include the subclaim 1b), in which case please clarify." When I ask for clarification I'm not being rhetorical, I can't really discuss my opinion on a statement of yours if I'm unclear on what you're actually saying.
billschnieder said:
I suggest you stick to Bell's inequality rather than your toy version):
How is mine a "toy version"? A, B and C could stand for polarizer angles, with A+ and A- meaning spin-up or spin-down at some angle, for example. In that case
(Fraction of A,B samples which gave result A+, B-) + (Fraction of B,C samples which gave result B+, C-) greater than or equal to (Fraction of A,C samples which gave result A+,C-)
...
is one of various Bell inequalities (it's exactly the one he was discussing in the quote from post #1171).
billschnieder said:
I have proven the arithmetic relationship
|ab+ac|-bc <= 1
from which it immediately follows that if you have a list of triples of numbers of any length where each number can take values (+1 or -1), the following is also true
|<ab> + <ac>| - <bc> <= 1
But it's only guaranteed to be true arithmetically if you actually know ab, ac and bc for
every member of the list. If for each member of the list you can only sample two, so <ab> only refers to the average result on the subset of the list where you actually sampled a and b, then it's no longer guaranteed to be true. Do you disagree?
billschnieder said:
Bell's variables (a,b,c) constitute a triple of variables each of which can take values (+1 or -1), each symbol in the inequality has exactly the same meaning, the same as the input to my derivation. Is it your claim that using variables with the same meaning, and properties like Bell's and obtaining the inequalities like Bell without any other assumption is accidental? Yes or No?
No, it's not accidental, as any proof of a Bell-type inequality like this:
(Fraction of A,B samples which gave result A+, B-) + (Fraction of B,C samples which gave result B+, C-) greater than or equal to (Fraction of A,C samples which gave result A+,C-)
...would
make use of the a more basic arithmetical inequality like this:
(Fraction of all triples with properties A+ and B-) + (Fraction of all triples with properties B+ and C-) greater than or equal to (Fraction of all triples with properties A+ and C-)
However, although proving the bottom inequality would be a
necessary condition for deriving the top one, it would not be
sufficient to derive the top one, to do so you need some
additional assumptions like the no-conspiracy assumption.
billschnieder said:
If you disagree, provide a dataset of triples which obeys Bell's inequalities but violates the one I derived or vice versa.
Of course, no collection of unchanging triples could violate a basic arithmetical inequality like the one you derived. The problem is the opposite: if we are sampling pairs of variables from a collection of triples, it is possible to see a violation of a Bell inequality (which deals with observed statistics in the pairs we sampled) even when the collection of triples does
not violate the more basic arithmetical inequality. My example was of exactly this type.
billschnieder said:
It should be easy for you to do. Since you claim there are other assumptions in Bell's inequality that makes my claim (1) inapplicable to Bell's inequalities, all you need do is use one of those assumptions to provide a dataset or even a single data point where both disagree.
I already showed that for the arithmetical inequality I was dealing with, are you saying you don't believe I can do something analogous for your inequality? In other words, are you saying I can't come up with a set of triples, along with a choice for each triple of which two variables are sampled by the experimenter, that violates this relation?
|(average value of a*b for all triples in which experimenter measured a and b) + (average value of a*c for all triples in which experimenter measured a and c)| - (average value of b*c for all triples in which experimenter measures b and c) <= 1
On the other hand, if you agree that it
is possible for the above relation to be violated, despite the fact that this arithmetic relation never can be:
|(average value of a*b for all triples) + (average value of a*c for all triples)| - (average value of b*c for all triples) <= 1
...then that's exactly the point I am making, that Bell's inequality is of the first type rather than the second, so proving the second alone isn't sufficient to prove Bell's inequality.
billschnieder said:
Huh? I'm talking about Bell's inequality not your toy version. Your version bears no resemblance to what Bell actually did
There are plenty of Bell inequalities, and the one I was talking about was in fact an inequality discussed by Bell. Again see http://cdsweb.cern.ch/record/142461/files/198009299.pdfpapers which I referred to in post #1171, where in equation (9) on p. 10 of the pdf he writes:
(The probability of being able to pass at 0 degrees and not able at 45 degrees)
plus
(The probability of being able to pass at 45 degrees and not able at 90 degrees)
is not less than
(The probability of being able to pass at 0 degrees and not able at 90 degrees)
Aside from the fact that I talked about fractions with a pair of properties and here he is talking about the probability of having a pair of properties, this is exactly the same as the inequality I wrote.
Anyway, like I said, I'd be happy to come up with a similar example tailored to your inequality if you really need it.
billschnieder said:
You will have to rephrase your objection in Bell's form or the form of what is actually done in Bell test experiments so that we can examine it if it makes any sense. The current version is just obfuscation and is far removed from what we are discussing.
You love to jump to the conclusion that I am "obfuscating", don't you? The thought doesn't even cross your mind that there
might be some gap in your knowledge and understanding of all things Bell-related (like not knowing that my inequality is one of the Bell inequalities, as explained above), so my examples and arguments might have some relevance that just hasn't occurred to you? You really are ridiculously uncharitable when it comes to interpreting other people's arguments, you always jump to the conclusion that they are saying something foolish rather than asking questions to see if you might be missing something.
billschnieder said:
As I have demonstrated and I hope you now agree, so long as you have a list of triples in hand with values restricted to (+1 or -1), whether theoretical or measured, no matter how the list was generated, Bell's inequality is never violated (claim 6).
Disagree, since once again the Bell inequalities deal with the probabilities of
measuring a given pair of values, not with the probability that
all triples have a given pair of values even if those weren't the two you measured.