Bell experiment would somehow prove non-locality and information FTL?

[wm]

Non-locality: Getting specific

I don't really follow what you are saying, because you seem to be mixing and matching words. The result doesn't match too well with the common way of expressing polarization.

I DO NOT claim that: an unpolarized photon has a polarization, but that we don't know what it is.

1. An unpolarized photon is in a mixed state (where H is horizontal and V is vertical):

H> + V>

2. A polarized photon is in a pure state:

H> (in whatever basis you choose to observe it)

3. A pair of entangled photons are also in a mixed state:

H>V> + V>H> (assuming Type II PDC)

As far as I know, it takes an observation to cause the mixed state to collapse to a pure state.

DrChinese, Discussing photon polarisation, in the interests of advancing our understanding of non-locality:

Let's allow that I am sending you photons; one at a time, one every minute (say) on an agreed line of flight.

1. What is the wave-function (mathematically)?

2. What is the wave-function (physically, or in your own words)?

3. What is the observation that collapses the wave-function?

4. What then is the collapsed wave-function?

5. Please elaborate on any non-locality that enters your maths or your thinking.

PS: Should my terminology need clarification, I'd be happy to do that before you answer.

Thanks, wm

 

[DrChinese]

DrChinese, Discussing photon polarisation, in the interests of advancing our understanding of non-locality:

Let's allow that I am sending you photons; one at a time, one every minute (say) on an agreed line of flight.

1. What is the wave-function (mathematically)?

2. What is the wave-function (physically, or in your own words)?

3. What is the observation that collapses the wave-function?

4. What then is the collapsed wave-function?

5. Please elaborate on any non-locality that enters your maths or your thinking.

PS: Should my terminology need clarification, I'd be happy to do that before you answer.

Thanks, wm

The answers depend on the source of the photons. As I indicated, there are more or less 3 types: known entangled, known polarization, and unknown polarization. Their wave functions are as shown above. If they are in a mixed state, their wave function can be collapsed by a suitable observation.

If a photon was part of an entangled pair, then an observation on either will collapse the wave function for both. Keep in mind that entangled particles should not be considered as having separate existence until their wave function is collapsed.

Once you know a photon's polarization, it retains that value until a different polarization observation is performed.

I hope this helps.

 

[wm]

NON-LOCALITY: Getting specific.

The answers depend on the source of the photons. As I indicated, there are more or less 3 types: known entangled, known polarization, and unknown polarization. Their wave functions are as shown above. If they are in a mixed state, their wave function can be collapsed by a suitable observation.

If a photon was part of an entangled pair, then an observation on either will collapse the wave function for both. Keep in mind that entangled particles should not be considered as having separate existence until their wave function is collapsed.

Once you know a photon's polarization, it retains that value until a different polarization observation is performed.

I hope this helps.

DrC, It would really be more helpful if you answered the questions one-by-one? Is that not possible?

In the way that I specified the photons, is not the answer to the Q1 (in your terms) something like this:

(A1) |Y> = h|H> + v|V>; where you define the terms?

Does that not open the way for you to continue with your specific answers to the remaining questions?

PS: I am seeking to undertand your specific conceptualisation of non-locality. Presumably (as I understand your position) you will need to entertain (in your answers) the consequences that might follow if each photon sent to you were somehow paired with another sent to someone else. (You may exclude the possibility that they are observing them.)

Regards, wm

 

[wm]

Sorry; this was responding to another thread; though it derives from this thread so I'll leave it.

Although I tailored the short proofs I gave above to a particular thought-experiment, it's quite trivial to change a few words so they cover any situation where two people can measure one of three properties and they find that whenever they measure the same property they get opposite results. If you don't see how, I can do this explicitly if you'd like. I am interested in the physics of the situation, not in playing a sort of "gotcha" game where if we can show that Bell's original proof did not cover all possible local hidden variable explanations then the whole proof is declared null and void, even if it would be trivial to modify the proof to cover the new explanations we just thought up as well. I'll try reading his paper to see what modifications, if any, would be needed to cover the case where measurement is not merely revealing preexisting spins, but in the meantime let me ask you this: do you agree or disagree that if we have two experimenters with a spacelike separation who have a choice of 3 possible measurements which we label A,B,C that can each return two possible answers which we label + and - (note that these could be properties of socks, downhill skiers, whatever you like), then if they always get opposite answers when they make the same measurement on any given trial, and we try to explain this in terms of some event in both their past light cone which predetermined the answer they'd get to each possible measurement with no violations of locality allowed (and also with the assumption that their choice of what to measure is independent of what the predetermined answers are on each trial, so their measurements are not having a backwards-in-time effect on the original predetermining event, as well as the assumption that the experimenters are not splitting into multiple copies as in the many-worlds interpretation), then the following inequalities must hold:

1. Probability(Experimenter #1 measures A and gets +, Experimenter #2 measures B and gets +) plus Probability(Experimenter #1 measures B and gets +, Experimenter #2 measures C and gets +) must be greater than or equal to Probability(Experimenter #1 measures A and gets +, Experimenter #2 measures C and gets +)

2. On the trials where they make different measurements, the probability of getting opposite answers must be greater than or equal to 1/3

Jesse,

1. Do you see here how long you have sentences?

2. Does not my classical model (of old) refute this Bellian-Inequality easily? Are you not giving conditions which my model meets?

3. Are you not saying (as I will let you):

a. That Alice may make a countable-inifinity of detector-settings, each delivering outcome of {+1, -1}.

b. That Bob may make a countable-infinity of detector-settings, each delivering outcomes of {+1', -1'}.

4. Anyway: Down-hill skiers, dirty-socks, books and the like will satisfy your inequality. More subtle, less wholly concrete objects will sink it for some detector combinations. Yes?

5. Is my conclusion not what vanesch has shown?

wm