billschnieder said:
So let's get this straight. The theoretical claim is only valid if all particles have the exact same variables for "a", "b", "c".
"All particles"? No, just that each member of a particle
pair must have same predetermined values as the other one, different pairs may have different predetermined values of course (for example one pair might share predetermined values [a=+1, b=+1, c=-1] while a different pair might share predetermined values [a=-1, b=+1, c=+1]). And this is not itself a starting assumption, rather it's a
conclusion that must be true
if there is a perfect correlation between measurements with the same setting (which is the prediction of QM) and
if we assume local realism.
If you disagree with this, you'd have to claim it's possible that you could have a local realist model that predicts a perfect correlation between measurements whenever the same setting is used in a Bell type experiment, but somehow
doesn't involve predetermined values for each of the three settings. Are you in fact making this claim?
billschnieder said:
They all disagree with that claim. They show that Bell's inequalities are not applicable to QM or any experiment that can ever be performed, whether or not the operating physical principles are non-local or local.
OK, assuming you've read them correctly (I don't know if you have), then they are crackpots and you shouldn't be posting such nonsense here.
billschnieder said:
We now have here the new definition for crackpot -- "any one who disagrees with Bell and his proponents".
Not Bell specifically, rather anyone who disagrees with a theoretical proof that thousands of physicists have concluded is airtight is almost certainly a crackpot. For example, if someone disagrees that according to GR it is possible to pass through the event horizon of a black hole and reach the singularity in finite proper time, they are a crackpot.
billschnieder said:
Note the absence of any specific rebuttal to the issues raised in those papers. It's been 12 years since the first one.
What, you expect people to read through them all and post detailed rebuttals? Why don't you describe a particular argument you found convincing. Incidentally, in case you've forgotten I did discuss the "Possible Experience: from Boole to Bell" paper with you in the past, see [post=2780659]this post[/post] and [post=2781956]this one[/post].
JesseM said:
It is of course conceivable that experiments will prove the "theoretical predictions of QM" wrong in the future
billschnieder said:
You are baiting and switching here.
No I'm not, I was responding to your comment which seemed to suggest the papers might have something to do with experimental loopholes: "Note that those articles are squarely focused on the applicability of Bell's inequalities to actual performable Bell-test experiments, and they all come to the conclusion that an a faithful Bell-test experiment can never be performed." Of course it is
in theory possible to perform a "faithful Bell-test experiment", if you disagree this is probably related to your delusions that it is somehow necessary to "control" the hidden variables in order to perform such an experiment. In fact all that needs to be assumed about an ideal
theoretical experiment is that the experimenters are choosing randomly between 3 detector settings, the choice of detector settings and the measurements with those settings are made at a spacelike separation (no locality loophole), all emitted particles are detected (no detector efficiency loophole), and for some versions of the proof we also assume it is verified that whenever both experimenters pick the same setting they are guaranteed to get the same result (a theoretical prediction of QM). I don't think there are any other experimental conditions needed, if you combine these assumptions about the experiment with the theoretical assumption of local realism (and the no-conspiracy assumption), then any other conclusions (like predetermined results for each particle pair) are
derived, not assumed.
billschnieder said:
The issue is not whether QM is correct or not. All of those papers acknowledge the correctness of QM. The issue is whether the data gathering requirements of Bell's inequalities can every be realized in any experiment. You have just confirmed that they can't, by your statement that "... implies each particle must have an identical set of predetermined values for a,b,c prior to a measurement".
But that doesn't need to be verified experimentally, it's an inescapable logical
conclusion given the previous assumptions I mentioned about 1) the experimental setup, 2) the perfect correlation whenever the same detector setting is chosen, and 3) local realist laws with the no-conspiracy assumption. There's no
theoretical way to satisfy 1), 2) and 3) without such predetermined values for each pair, I'm sure none of your papers provide a model which satisfy 1-3 but don't involve predetermined values.
billschnieder said:
You take three different independent terms P0(a0,b0), P1(b1,c1), P2(a2,c2) and substitute it into the inequality, and then triumphantly proclaim "non-locality! non-reality!" when a violation is obtained
Only if conditions 1-3 are satisfied would any such triumphant proclamation be made. As I pointed out in my last two comments to rlduncan it's unclear how his lists are supposed to relate to a Bell-type experimental setup or how they are supposed to guarantee that if the experimenters randomly choose the same setting, they will always get the same result.
billschnieder said:
Bell's proof relies on the idea that there exists a single probability distribution p(a,b,c) from which three distributions p(a,b), p(b,c), and p(a,c) are then extracted.
Yes, that assumption is called the "no-conspiracy assumption", and a violation under local realism would imply that the properties of the particles which they had at some time prior to the choice of detector settings were statistically correlated with the
later choice of detector setting of the experimenters, a weird sort of foresight. See my comments to Rap about why I think it's reasonable to consider this very implausible.
billschnieder said:
Clearly, it is impossible in any experiment for all three measurement to be performed on the very same pair of particles. It is therefore impossible in any experiment to obtain p(a,b), p(b,c), and p(a,c) all drawn from a single probability distribution.
Not exactly possible, but the the probability of a significant difference gets tinier and tinier the more trials you do (so in the limit of an infinite number of trials, which is what frequentist probabilities are supposed to mean, the probability distributions become identical). To see this, suppose you and your buddy are playing a game where you can confer, then you have to go in separate rooms where you will be asked either question a, question b, or question c (analogous to the particles being measured at a spacelike separation), to which you answer "yes" or "no". This is repeated many times, and the one rule is that the two of you must always make sure that on any trial where you are both asked the same question, you
must give the same answer (analogous to the particles always giving the same result when measured with the same setting)--if two get this wrong even once over thousands of trials, you lose out on your chance to win a FABULOUS PRIZE! If you two have no way to communicate directly once you are taken into separate rooms (analogous to no nonlocal influences between particles), and you have no way to anticipate which question you will be asked (analogous to the no-conspiracy assumption), do you doubt that the only winning strategy for the two of you is to always agree on all three answers on each trial? (if the answer is no, please outline your alternate strategy) And if you agree to this, is it not obvious that whatever the fraction of
all trials where your predetermined answers include a given pair like "yes to question b, no to question c", then if we look at the subset of trials where you are asked questions b and c, the fraction of those trials where you answered "yes to b, no to c" is likely to be very close to the fraction on
all trials if the number of trials is very large? (to make it more technical, let's say that the probability p that the first fraction differs from the second fraction by more than some small amount ε can be made as small as you like by picking a sufficiently large number of trials N--this is basically just a restatement of the
law of large numbers)
billschnieder said:
I'm sure you understood this, that is probably why you said "... each particle must have an identical set of predetermined values for a,b,c prior to a measurement"
That "must" was not meant to be a condition, rather it was a logical deduction (implied by conditions 1-3 above), kind of like saying "if you have a prime number larger than 2, it must be odd".
billschnieder said:
So I ask, what has this all got to do with realism and non-locality? Is it your argument that if locality is true, and realism is true, then a single probability distribution p(a,b,c) must exist for the experimental results?
All conditions 1-3 are needed (including the fact of being guaranteed to get the same result on any trial where the same setting is used by both experimenters), but if they are all satisfied, then on every trial there must have been predetermined results for all three settings. If you grant this, then we don't even need to talk about "probability distributions" if you want to avoid getting into discussions of the definition of probability (as you know I define probabilities in terms of frequencies in the limit as the number of trials goes to infinity), we can just talk about the fraction of trials where each of the eight possible triplets of predetermined results occurred. Then if the number of trials is large, the probability of a significant difference between (fraction of trials where triplet of predetermined results included +1 for b, -1 for c) and (fraction of trials where b and c were measured, measurement of b gave +1 and measurement of c gave -1) becomes very small. And if you are willing to use a "limit frequentist" definition of probability for the sake of the argument, this should show why P(triplet of predetermined results included +1 for b, -1 for c) = P(b gave +1, c gave -1 | b and c chosen as detector settings).