Subatomic question: particle pairs and spin

Factual Questions
21

I’m not sure I can fit the dice analogy with actual testing methods. The variables are more complex and due to practical limitations, Alice isn’t actually able to positively identify the numbers that appear on the dice.

I think it would be better to describe an actual experiment.

Alice and Bob are at opposite ends of an optical table. Alice and Bob each have a polarizing filter. In the middle of the table, an emitter sends out a photon pair with identical polarity. If Alice and Bob’s filters are both vertical, then Alice and Bob should see the same number of photons pass through their filters and strike their detectors (within the limits of the detectors efficiency, which is statistically non-trivial with today’s technology). If their filters are perpendicular, then Alice and Bob’s results should oppose each other.

Parallel…
Bob: I see it!
Alice: So do I!

Perpendicular…
Bob: I didn’t see it.
Alice: I did.

If the two filters are at some other angle, the percentage of agreement should be roughly the squared cosine of the angle between the two detectors. eg. 45 degrees between the filter axes, should result in 50% agreement.

In experiments, the photons do follow this scheme (again within the limitations of the detection apparatus). But, when several runs of the experiment are performed, with the angles altered between runs and the results are all composed into a single probability distribution, the percentages seem to be breaking with Bell’s Inequality and by extension, must either be breaking quantum rules of ‘locality’ or ‘reality’.

The problem is, that it is incorrect to assume a single probability distribution for multiple, different configurations of the apparatus. This “Joint Measurability Assumption” (as Thomas Brody calls it) is like Alice and Bob saying "If we had left our polarizers in the 1st configuration, when whe made the 2nd run, the results would have been the same as the first run. Since there is no sound basis for that assumption, the resulting conclusion is meaningless (especially in the case of looking for small statistical anomalies in a completely random random event).

I hope that made sense, this little composition window makes proofing rough.

Stephen
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22

In reading my previous post, I realize that I passed right over an important point (possibly the important point).

If a photon’s polarity agrees well enough with the filter orientation, to actually pass through, it’s polarity is subsequently ‘adjusted’ to be truly parallel to that filter. This is why, when a single photon passes through a filter, it is always blocked by a second perpendicular filter. The EPR experiment I described above is trying to show that the twin photon acts as if it were the first photon, passing through the second filter.

The EPR idea is that this adjustment must be transferred to the twin in order for the actual number of transmitted ‘twin’ photons to differ from the number predicted by the simple difference in orientation. But, as I mentioned, you can’t statistically prove that, without changing your setup through multiple iterations

Stephen
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23

Talking about subatomic particles gives me a hadron.

24

I was wondering how long it would take before someone Lepton that one.

Stephen
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25

<font face=“arial,helvetica” color="#4040FF">Tracer</font>:

Actually, my analogy was simplified to make it easy to understand, and you picked up on a problem introduced by the simplification.

You see, if Bob is the one who looks at the coins, he makes them flip.

I should have mentioned that both Alice and Bob have identical devices. The infernal nature of the device is that you can’t look at the coins without pushing the button. Whoever pushes the button first is the person who make them flip. Once they’ve flipped, though, the other person can push his or her button and see the result.

Of course, such a device would need a second button, labelled Reset. When both people press the Reset button, they’re ready to transmit the next byte of information.

I can see that it’s not easy to design a “simple” example of the problem we’re discussing, here.

26

Add to that, the fact that he cannot know what the spin was before he detects it, he can’t “Watch his coins flip” he can only (at the very best) say "Hey, my coin was heads 3/4 of the time, when statistical analysis of my detector arrangement over thousands of coin flips, says it should have been heads 2/3 of the time!

In an ideal world, with 100% detection and amazing feats of statistical analysis, the signal to noise ratio would never be better than 8%. So, if EPR were true (and I seriously doubt it) how do you decide which 8% of those extra ‘heads’ were intended to provide information?

Stephen
Stephen’s Website
Satellite Hunting 1.1.0 visible satellite pass prediction
shareware available for download at
Satellite Hunting

27

You don’t get “extra heads”. What changes is the correlation between two observations. The results of each set of observations are random. The correlation is known only by bringing the results together in order to compare them.

Virtually yours,

J Matrix