# Non-locality

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Have you ever considered the answer requires understanding the mathematics? Or literally understanding a sinusoidal waveform itself ? IE on an oscilloscope?

Let me ask a relevant question. Have you ever studied Antenna basics for radios? If you cut the antenna at the wrong length you get a reflected wave that decreases the wattage. The antenna must be cut to a length to correspond to a 1/4 wave if you cut it at 1/2 a wave you will get zero wattage.  It is literally the same fundamental process with a beam splitter. Both involve constructive and destructive interference.

Both involve polarization. Both signals are dipolar meaning there is not one but two (di) (polar) angles to the signal. One positive the other negative.

in a beam splitter the angle will affect one polarity angle ( transmit )while reflecting the other polarity.

Now ask yourself how can we explain how this works in a 50-50 lossless beamsplitter when you don't understand the math (the fully accurate answer requires the use of an RR-TT matrix. Which correlates to a Pauli matrix. ie taught in QM basics.

Edited by Mordred

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42 minutes ago, swansont said:

Any given polarization direction has some probability of transmission given by Malus's law. It's just like half of the beams being vertical, and half being horizontal. So half get transmitted, and half absorbed.

No, it's not. It's about entangled states.

It was explained to you, but the fact that you don't understand doesn't mean nobody else does.

Because they understand the physics involved.

Not being able to give that account is a crucial part of entanglement. Again, the people doing the physics understand the physics.

The authors of an advanced text probably assume you understand any prerequisite material; they are not going to reinvent the wheel. Similarly, when you show up wishing to discuss and advanced topic like non-locality, there is the expectation that you understand some basic physics.

Sadly, that doesn't always happen, and we get the same, predictable behavior that we see here. (This is nowhere near the first time for this)

If you have deficiencies in your background (and you obviously do), you need to remedy that. Nothing is keeping you from starting a thread to ask about polarization. If you persist with more advanced topics, you are going to be wrong, and post nonsense. That, coupled with showing an attitude when people correct your mistakes, is an untenable situation.

".

Malus's law /məˈls/, which is named after Étienne-Louis Malus, says that when a perfect polarizer is placed in a polarized beam of light, the irradiance, I, of the light that passes through is given by

I=I_{0}\cos ^{2}\theta _{i},}

where I0 is the initial intensity and θi is the angle between the light's initial polarization direction and the axis of the polarizer.

A beam of unpolarized light can be thought of as containing a uniform mixture of linear polarizations at all possible angles. Since the average value of  \cos ^{2}\theta } is 1/2, the transmission coefficient becomes

Here is what I do not understand. This law explains perfectly why, mathematically speaking, 50% of the light is transmitted or absorbed. But the laws speaks of an average direction, so only directions close to (there is no perfect polarizer), should be transmitted or absorbed.

Let us say that 5 is the average of 1-10. According to Malus, in one case 1,2,3,4,5 are transmitted,  and 6,7,8,9,10 are absorbed, and vice versa. [or 4,5,6,7,8, or some such combination)

That is a very generous interpretation of "average", especially if we consider that the second filter is much more critical. There, no "average" is allowed, either you belong to one direction or you are refused entrance.

Did I also understand it wrong? In that case, please bear with me and explain it to me.

Concerning your other remarks, I will abstain from any comment.

Edited by Dalo

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Thinking of polarisation as just direction is wrong, I would suggest at this point you look at the derivation of Malus's law, when you come across something in the derivation you don't understand, such as elliptical polarisation then you can read there. That's pretty much the reverse of the most efficient way to learn a complex subject and will result in massive holes in understanding but would be better when where we currently are.

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2 minutes ago, Klaynos said:

Thinking of polarisation as just direction is wrong, I would suggest at this point you look at the derivation of Malus's law, when you come across something in the derivation you don't understand, such as elliptical polarisation then you can read there. That's pretty much the reverse of the most efficient way to learn a complex subject and will result in massive holes in understanding but would be better when where we currently are.

As my previous remarks show, it is the difference between how the first polarizer reacts compared to the second.

edit: Maybe I should, as suggested, start a thread dealing exclusively with polarization.

But may I remind you all that I have used the results as given By Maudlin. And, yes, I understand them! I did not use my own ideas about polarization for the simple reason that I do not have any. So, even if you think I am ignorant of some necessary laws, all you have to do is show that I misunderstood Maudlin.

Also, remember that I was the one who admitted that I did not understand the 50-50 of the first filter, and I still don't. That didn't stop me from analyzing Maudlin's arguments and expressing my claim.

Which nobody has proven wrong. Everybody is happy to hammer on my ignorance. An ignorance I admitted.

So, why no go back to the subject of the thread, or is it too "metaphysical" for this forum?

Edited by Dalo

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5 minutes ago, Dalo said:

Here is what I do not understand. This law explains perfectly why, mathematically speaking, 50% of the light is transmitted or absorbed. But the laws speaks of an average direction, so only directions close to (there is no perfect polarizer), should be transmitted or absorbed.

Let us say that 5 is the average of 1-10. According to Malus, in one case 1,2,3,4,5 are transmitted,  and 6,7,8,9,10 are absorbed, and vice versa.

That is a very generous interpretation of "average", especially if we consider that the second filter is much more critical. There, no "average" is allowed, either you belong to one direction or you are refused entrance.

Did I also understand it wrong? In that case, please bear with me and explain it to me.

Concerning your other remarks, I will abstain from any comment.

Polarizations can be thought of as superpositions of the orthogonal polarization states. The amplitude of each state depends on the angle of polarization. e.g. light polarized at 45º has equal components of both. The amplitude tells you the probability it will count as a vertical or horizontal contribution.

This means that light polarized at 10º to the vertical will be mostly vertical, but some small fraction is horizontal.

1 minute ago, Dalo said:

As my previous remarks show, it is the difference between how the first polarizer reacts compared to the second.

Normally, the behavior of each polarizer can be applied independently. An exception is for entangled states.

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6 minutes ago, swansont said:

Normally, the behavior of each polarizer can be applied independently. An exception is for entangled states.

Good. Let us get back to what is the main point of this thread. You were right to say that it is not about polarization. But when I said that I simply meant that the example used by Maudlin and that I was analyzing concerned polarization.

10 minutes ago, swansont said:

Polarizations can be thought of as superpositions of the orthogonal polarization states. The amplitude of each state depends on the angle of polarization. e.g. light polarized at 45º has equal components of both. The amplitude tells you the probability it will count as a vertical or horizontal contribution.

I repeat my previous remark to Klaynos: I have no trouble understand this. What I still do not understand is why it holds only for the first filter, and not for the second one.

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6 minutes ago, Dalo said:

Good. Let us get back to what is the main point of this thread. You were right to say that it is not about polarization. But when I said that I simply meant that the example used by Maudlin and that I was analyzing concerned polarization.

I repeat my previous remark to Klaynos: I have no trouble understand this. What I still do not understand is why it holds only for the first filter, and not for the second one.

Because you have a different polarisation state (and depending on the situation entanglement) which changes the maths. You really need to derive the maths to understand this.

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Here is what your asking us to explain to you in simple terms without teaching you the math.

This is the formulas involving a 50 50 beam splitter. Yes the link includes single particle states.

This is the application of Malus law in practicum.

Edited by Mordred

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6 minutes ago, Mordred said:

Here is what your asking us to explain to you in simple terms without teaching you the math.

This is the formulas involving a 50 50 beam splitter. Yes the link includes single particle states.

Thank you. Your link does not help much, it is too mathematical for me. I withdraw my question concerning the 50-50 rule. I suggest we get back to the main subject of this thread and I apologize for the waste of time.

Edited by Dalo

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1 minute ago, Dalo said:

Thank you. Your link does not help much, it is too mathematical for me. I withdraw my question concerning the 50-50 rule. I suggest we get back to the main subject of this thread and I apologize for the waste of time.

Without the maths you cannot speak the language of physics and this discussion is probably pointless.

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17 minutes ago, Dalo said:

Good. Let us get back to what is the main point of this thread. You were right to say that it is not about polarization. But when I said that I simply meant that the example used by Maudlin and that I was analyzing concerned polarization.

From Maudlin's description he is describing entanglement, and not simply polarization. Which makes sense in a discussion of non-locality and the Bell test.

17 minutes ago, Dalo said:

I repeat my previous remark to Klaynos: I have no trouble understand this. What I still do not understand is why it holds only for the first filter, and not for the second one.

Because there has been almost no discussion of entanglement, and the implications of it.

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11 hours ago, Dalo said:
11 hours ago, studiot said:

There is a further twist to this story, that applies to relativity.

I do not doubt the validity of what you are saying, only its relevance to the subject of the thread. Non-locality in QT is not what you are describing.

In the first place you introduced relativity as well as QM.

In the second I suggest you read Klaynos' last post again.

Your posted questions would come over much better if they actually were questions rather than flat contradictions about something you also state you don't understand/know little about.

So a simple "would you explain / expand on why you brought such and such up please" would earn many brownie points.

Or "does this also have relevance to QM ?" (it does).

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Just now, Klaynos said:

Without the maths you cannot speak the language of physics and this discussion is probably pointless.

As a philosopher I can assure you that it is the most absurd affirmation you could ever express. Feel free to ask specialists in the philosophy of Physics.

It is also an avoidance strategy that does not do honor to the members of this forum.

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2 hours ago, Klaynos said:

This is why the discussions you start don't seem to go anywhere.

As a prerequisite to a discussion on entanglement is a knowledge of polarisation. You don't have that knowledge so don't know the bits of information you're missing when reading about the details.

Polarisation isn't just the linear orientation of fields. It's more complicated than that. No one wants to spend the time teaching you the basics when you're wandered in out of your depth insisting you're correct. Sorry to be blunt but that's the way it is.

Edit : stuff happened whilst I was writing so this was the Klaynos post I meant.

Sorry for any confusion.

Edited by studiot

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2 minutes ago, studiot said:

"does this also have relevance to QM ?" (it does).

saying it is not enough. You have to show it. The idea that one cannot discuss QT without involving RT is really strange.

Edited by Dalo

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1 minute ago, Dalo said:

saying it is not enough. You have to show it. The idea that one cannot discuss QT without involving RT is really strange.

Well I don't know what your abbreviations QT or RT stand for and I am not minded to look them up.

Please stop stridently telling others what the have to do or not do.

I really hoped that our last exchange about locality had put all that nonsense behind us, so I am suprised that someone who claims some training in Philosophy persists in that confrontational approach.

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6 minutes ago, Dalo said:

As a philosopher I can assure you that it is the most absurd affirmation you could ever express. Feel free to ask specialists in the philosophy of Physics.

It is also an avoidance strategy that does not do honor to the members of this forum.

As you yourself said: "saying it is not enough. You have to show it. "

If you don't have any understanding of linear algebra, you will not understand the way that waves can add together, and therefore what it is that a polarizer is doing.

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Well some things cannot be correctly answered to those that won't take the time to understand the mathematics involved.

This isn't our fault its simple reality philosophy cannot address physics because physics requires understanding the math while philosophy largely ignores it.

It is precisely why I don't place any faith in metaphysics

Edited by Mordred

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13 minutes ago, Mordred said:

Well some things cannot be correctly answered to those that won't take the time to understand the mathematics involved.

This isn't our fault its simple reality philosophy cannot address physics because physics requires understanding the math while philosophy largely ignores it

Ideally philosophy should be what we engage in once we have our ducks in a row. We can then try different arrangements of the ducks and see how that works.

On the other hand it is also a philosophical question to acknowledge  what  you do not know (someone said that once) and it is also a human kindness  for those with access to knowledge to give a helpful resume to those who do not have it ( a bit self serving I know)

Edited by geordief

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Yes but the key is getting defining the ducks in the first place

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Just now, Mordred said:

Yes but the key is getting defining the ducks in the first place

When your level of knowledge is as low as mine ,it is a bit easier

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Lol at least your trying to understand. Not to imply the OP isn't. Just that some things are near impossible to explain accurately with just verbal words and images.

Edited by Mordred

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1 hour ago, Dalo said:

As a philosopher I can assure you that it is the most absurd affirmation you could ever express. Feel free to ask specialists in the philosophy of Physics.

We're trying to discuss physics here, rather than the philosophy of physics, so I don't see the relevance. The latter may not rely on math, but the former does, and there is a pretty shallow limit for how much you can discuss without it.

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On 12/16/2017 at 12:41 PM, Dalo said:

My claim will be that causality is always local, and that entanglement is the result of faulty logic and theoretical biases.

On 12/16/2017 at 3:25 PM, Dalo said:

2) both filters are identical.

In such a situation, we can say that the distance between both photons is totally irrelevant. What is important are the two identities I have just presented. Photon 2 and filter 2 can be considered as a local system in the sense that they could swap places with photon 1 and filter 1 without changing anything to the results of the experiment.

In other words, what happens with photon 2 and filter 2 is what would happen with photon 1 and filter 2 locally!

On 12/17/2017 at 10:28 AM, Dalo said:

The second photon and the second filter create together a system that is indistinguishable from the first photon and filter. It is therefore not surprising that  Bohr, who was maybe already convinced that nature was probabilistic, thought that the photons were entangled.

It is certainly ironic that Bohr did not recognize one of his main epistemological principles: the regularities were the result of the experimental setup. But then, that same epistemological principle would have indicated that the so-called "hidden variable" was in fact hidden in plain view, and that therefore a deterministic explanation could certainly not be excluded.

On 12/17/2017 at 3:16 AM, Dalo said:

The debate between von Neumann and Bell proves at least one thing to me as a philosopher. Any mathematical solution to the hidden variable theories, and therefore to quantum entanglement, is controversial,

On 12/17/2017 at 3:16 AM, Dalo said:

it is a matter of fundamental interpretation, of philosophy, and not of mathematics.

On 12/17/2017 at 3:16 AM, Dalo said:

My arguments are not mathematical, and neither statistical nor physical

On 12/16/2017 at 3:25 PM, Dalo said:

Let us recall the main points.
1) Two photons created out of the same atom have the same polarization which they keep even after going each in its direction, opposite to that of their twin.
2) When going through a polarizer they exhibit the same behavior if both filters are aligned. Otherwise the angle of misalignment between both filters determine how the second photon will react.
3) the distance between them can be theoretically infinite.

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Entanglement is an experimental result. Wishing it away doesn't solve anything. Not understanding the experiments (you need maths to do that) doesn't solve anything.

Two polarised photons and to entangled photons are not necessarily the same thing.