why is superdeterminism not the universally accepted explanation of nonlocality?

lugita15

Quote by zonde

I would like to see this. Hmm, my guess would be that you are assuming perfect (anti-)correlations for matching measurement settings.

You're right, I am assuming that. But that's a harmless assumption to make. Perfect correlations for matching measurement settings is a consequence of quantum mechanics, so surely if a local realist theory wanted to match the predictions of QM then it would have to have perfect correlations for matching measurement settings. I highly doubt this is what ThomasT is disputing.

(You can, of course, be the fringe type of local realist who has a theory making predictions contrary to QM, but who believes that the only reason the experiments have proven QM right is that they're subject to various flaws, loopholes, and systematic biases. But as Bell tests become more sophisticated, that becomes an increasingly untenable positon, arguably even more so than superdeterminism.)

lugita15

Quote by ThomasT

I didn't get that. How does it prove it?

The whole point of the entire proof is to show that the correlation is linear, but if you want the step that directly leads to it, look at 11: "So 75% of the time, P(-30)=P(0), and 75% of the time P(0)=P(30), so there's no way that P(-30)≠P(30) 75% of the time." But this is pretty much an indisputable step, because it's just math, not physics: if A has a 25% chance of occurring, and B has a 25% chance of occurring, then the probability that at least one of them occurs is at most 50%. It's definitely not possible for A to have a 25% chance of occurring, B to have a 25% chance of occurrring, but a 75% chance that at least one of them occurs.

Presumably you don't disagree with the straightforward math of step 11, so if you reject the conclusion that local realism implies linear correlation you must reject one of the earlier steps.

*ThomasT*

Quote by lugita15

The whole point of the entire proof is to show that the correlation is linear, but if you want the step that directly leads to it, look at 11: "So 75% of the time, P(-30)=P(0), and 75% of the time P(0)=P(30), so there's no way that P(-30)≠P(30) 75% of the time." But this is pretty much an indisputable step, because it's just math, not physics: if A has a 25% chance of occurring, and B has a 25% chance of occurring, then the probability that at least one of them occurs is at most 50%. It's definitely not possible for A to have a 25% chance of occurring, B to have a 25% chance of occurrring, but a 75% chance that at least one of them occurs.

Presumably you don't disagree with the straightforward math of step 11, so if you reject the conclusion that local realism implies linear correlation you must reject one of the earlier steps.

I don't understand your notation. For example, what does this mean? "So 75% of the time, P(-30)=P(0), and 75% of the time P(0)=P(30), so there's no way that P(-30)≠P(30) 75% of the time." I'm assuming that P(-30) refers to the probability of coincidental detection while keeping the setting of the A polarizer vertical and offsetting B, to the left, 30 degrees. And that P(30) refers to the probability of coincidental detection while keeping the setting of A vertical and offsetting B, to the right, 30 degrees. If so, then what? I don't get what "75% of the time, P(-30)=P(0)" is supposed to mean. Or what "75% of the time P(0)=P(30)" is supposed to mean.

Do you just mean that the probability of coincidental detection at θ=30 degrees is .75?

I think that's what you mean, so lets go with that. But wait, where did that come from? The polarizers were actually set that way, and you noted the result? Right?

Ok, so we have a probability of coincidental detection at θ=30 of .75 .

Then we set A 30 degrees to the left and B 30 degrees to the right, so now we have a θ of 60 degrees.

So now do we do some runs to see what the rate of coincidental detection at θ=60 degrees is, or do we first assume something about what that rate should be? And if we assume something about what that rate should be, then what's that assumption based on?

lugita15

ThomasT, I define P(θ) in step 2: "A local realist would say that the photon doesn't just randomly go through or not go through the detector oriented at an angle θ; he would say that each unpolarized photon has its own function P(θ) which is guiding it's behavior: it goes through if P(θ)=1 and it doesn't go through it P(θ)=0."

Let's get right to the heart of the matter. If P(-30)=P(0) and P(0)=P(30), then P(-30) must equal P(30). Thus if P(-30) does not equal P(30), either P(-30)≠P(0) or P(0)≠P(30) (or both). Since there is a 25% error rate whenever there is a thirty degree seperation, we know that the probabilities that P(-30)≠P(0) is 25%, and the probability that P(0)≠P(30) is 25%, and the probability that at least one of these two statements is true is at most 25%+25%=50%. This is not a physical assumption or constraint, it's just math. If event A happens 25% of the time and event B happens 25% of the time, then it's guaranteed that at least 50% of the time neither one of them occurs. If taxis are available in New York City a quarter of the time, and buses are available a quarter of the time, then you know that transportation is available at most 50% of the time. I hope you don't dispute this.

*ThomasT*

Quote by lugita15

Since there is a 25% error rate whenever there is a thirty degree seperation, we know that the probabilities that P(-30)≠P(0) is 25%, and the probability that P(0)≠P(30) is 25%, and the probability that at least one of these two statements is true is at most 25%+25%=50%.

That assumes that there's a linear correlation between θ and rate of coincidental detection. But the historically observed and documented behavior of light suggests otherwise. So, where did this assumption come from?

lugita15

Quote by ThomasT

That assumes that there's a linear correlation between θ and rate of coincidental detection. But the historically observed and documented behavior of light suggests otherwise. So, where did this assumption come from?

In step 11 we're not making any assumptions about physics, we're just doing math. If the probability of A is 25% and the probability of B is 25%, then the probability of "A or B" is at most 50%, regardlesss of what A and B are and whether they have anything to do with each other. (Note that "A or B" means at least one of them is true.) That is just a simple mathematical fact. In this case, A is "P(-30)≠P(0)" and B is "P(0)≠P(30)".

As I said, once you've gotten down to step 11 there is no room for argument left, it's just math. If you want to dispute the reasoning you'll have to find an earlier step you disagree with.

Demystifier

Lugita15, I would like to see your response to my post #127.

*jadrian*

Quote by jadrian

By the way i think you should be focusing more on simply c and d which i presume are next to the measurement devices and thus are far apart so they are the "conspirators", because they causally effect the outcome of the measurements by bumping the measurement device into whatever angle. either way a and d or c and d doesnt matter which you consider to be conspiring. There should be nothing conspiratorial about particle d being able to affect particle c and therefore effect a because in the history of the universe, the 10^10^MILLION (who can say how many?) interactions that have taken place, through causality and info exchange, HAVE PREDETERMINED that particle d was going to effect c and therefore a. you say a and d seemingly have nothing to do with eachother. THEY HAVE EVERYTHING TO DO WITH EACHOTHER! Simple logical determinism would lead you to the conclusion that d had causal effects on perhaps everything in the universe which ultimately led to the causal outcome of the measurement of a. Not only that but particle d,d1,d2,d3 d infinity not only via cause-effect cause-effect cause-effect.....eventually caused c to affect the measurement device for a, but d, d1, d2..... caused the experimenters to make the experiment take place in the first place.

i dont believe faster than light info transfer will be an issue here as it is not an issue with normal entanglement, because info transfered at the speed of light will always beat instantaneous info transfer to the punch. Sending light in opposite directions i suspect would be solvable by relativity to give the same conclusion.

dont think of it not particles all knowing about eachother, think of it as historical interactions in the universe as spreading a virus to every particle in the entire universe.

its not that every particle knows everything about every other particle. it only knows what has happened to it in the past. but the addition of all current states of particles which are in their current state because of their continuous past history traced back in time will give you the full information in the universe, and having this information, you would be able to predict it. and if you could predict it, that would mean it must be deterministic as a whole. so although we cannot predict the future, and the future isnt predictable, que sera' sera'.

let me clarify this a little bit. the "conspiracy" is simply the result of the history of the causal interactions of ALL the stuff in the universe. the affect of d on a is not just a relationship between of d and a. it is a result of d and a being the part of the sum of everything in the universe. d and a alone would not be able to affect eachother if isolated from the history of all interactions in the universes past. it requires all the information in the universe to result in determinism. there is nothing super about it.

if determinism only is effective within lightcones, in which case if outside eachothers lightcones, a and d could not affect eachother just as future events cannot effect the past, as lightcones expand at the speed of light, if there were particle a that had not yet interacted with other particles d1 d2 d-infinity, (i stated before that this should be impossible under a causally governed universe) in this hypothetical case it would be not practically, but THEORETICALLY impossible to do such an experiment or have such nonlocal effects even without an experiment. also, along with photons a and b traveling in opposite directions, so too will plenty of other EFFECTUAL information be propagated to a and d from particles locally and causally effecting the photon source, so it would make a and d effectively the same as being locally deterministic. it would be determined tho in the universe that the lightcones would eventually expand to make a and d react causally therefore deterministically.

lugita15

Quote by Demystifier

Lugita15, I would like to see your response to my post #127.

Oh, I agree wholeheartedly that all of the theories listed in your blog post are viable alternatives (with the exception of Joy Christian), and that they are each in one way or another local, and even that some of them are in one way or another realistic or deterministic. But I think the only alternative out of your list that deserves the appelation "local determinism" is superdeterminism, because it is the only when where the real future states of real particles in our 3-dimensional universe are determined by the real past states and real local interactions of real particlces (whew, I think I put enough qualifications). But yes, there are several viewpoints that someone like backwards causation where some pedant could make the argument that we have a local determinist theory.

Still, it's a worthwhile task to show that local realism (unless it's superdeterministic) using the conventional definiton cannot reproduce the predictions of quantum mechanics.

Demystifier

Thanks lugita!

*jadrian*

Quote by jadrian

let me clarify this a little bit. the "conspiracy" is simply the result of the history of the causal interactions of ALL the stuff in the universe. it is a result of d and a being the part of the sum of everything in the universe. d and a alone would not be able to affect eachother if isolated from the history of all interactions in the universes past. it requires all the information in the universe to result in determinism. there is nothing super about it.

if determinism only is effective within lightcones, in which case if outside eachothers lightcones, a and d could not affect eachother just as future events cannot effect the past, as lightcones expand at the speed of light, if there were particle a that had not yet interacted with other particles d1 d2 d-infinity, (i stated before that this should be impossible under a causally governed universe) in this hypothetical case it would be not practically, but THEORETICALLY impossible to do such an experiment or have such nonlocal effects even without an experiment. also, along with photons a and b traveling in opposite directions, so too will plenty of other EFFECTUAL information be propagated to a and d from particles locally and causally effecting the photon source, so it would make a and d effectively the same as being locally deterministic. it would be determined tho in the universe that the lightcones would eventually expand to make a and d react causally therefore deterministically.

but outside our lightcone they will have their own lightcone, in which their determinism will eventually mesh precicely with our determinism leading to the same result that the future of everything is predetermined.

Delta Kilo

Wouldn't retro-casuality have exactly the same outward appearance as superdeterminism to us? It is certainly more economical (in occam sense) - the 'conspiracy' in each case only has to go back in time as far as needed to achieve correct outcomes as opposed to setting it all up just before big bang. Also laws of physics are time-symmetrical already (:those that counts anyway:).

DrChinese

Quote by jadrian

if determinism only is effective within lightcones, in which case if outside eachothers lightcones, a and d could not affect eachother just as future events cannot effect the past, as lightcones expand at the speed of light, if there were particle a that had not yet interacted with other particles d1 d2 d-infinity, (i stated before that this should be impossible under a causally governed universe) in this hypothetical case it would be not practically, but THEORETICALLY impossible to do such an experiment or have such nonlocal effects even without an experiment. also, along with photons a and b traveling in opposite directions, so too will plenty of other EFFECTUAL information be propagated to a and d from particles locally and causally effecting the photon source, so it would make a and d effectively the same as being locally deterministic. it would be determined tho in the universe that the lightcones would eventually expand to make a and d react causally therefore deterministically.

Not sure what most of this means, but would like to remind you that a and d have never existed within a common light cone. They were "born" separated and remain separated their entire existence. Yet they were made to be entangled, displaying correlations characteristic of twins. Yet other photons from the same laser sources at the same time, those not made to be entangled, show no such relationship. Further, the decision to entangle is made AFTER the photons are detected and their existence has ended.

And you are trying to say that local deterministic systems naturally display this behavior. You might want to rethink that. Clearly, you need something "super" to explain this. Because your explanation above doesn't explain why some photons show the correlations and others don't. Following your concepts, all of them should evidence Bell state statistics.

lugita15

Quote by DrChinese

And you are trying to say that local deterministic systems naturally display this behavior. You might want to rethink that. Clearly, you need something "super" to explain this. Because your explanation above doesn't explain why some photons show the correlations and others don't. Following your concepts, all of them should evidence Bell state statistics.

DrChinese, you're not a very good conspiracy theorist. Clearly the particles are always entangled with each other, but never display this entanglement unless they know that quantum mechanics would consider them to be entangled, in which case they would each try to act in exactly the right way so that everyone is fooled into thinking quantum mechanics is right. Theories are so easy to make when you abandon things like Occam's razor.

DrChinese

Quote by lugita15

DrChinese, you're not a very good conspiracy theorist. Clearly the particles are always entangled with each other, but never display this entanglement unless they know that quantum mechanics would consider them to be entangled, in which case they would each try to act in exactly the right way so that everyone is fooled into thinking quantum mechanics is right. Theories are so easy to make when you abandon things like Occam's razor.

I was trying (unsuccessfully it seems

) to force jadrian to realize that the laser source must be imparting the hidden (it is a conspiracy, so something should be hidden) information to the photon at the time it is created. But that the same laser source only imparts the correct information for perfect correlations to a small subset of photons, just those that some spacelike-separated robotic observer will eventually mark as being in a Bell state (and no others).

So that means the laser source ALSO knows enough about that robotic observer to know which ones will be seen to be entangled (since the robotic observer makes that decision at a later time).

Oh, and the laser source ALSO knows which direction the polarizers for a and d are set in. That, of course, so that the Bell relationship holds. Of course, those polarizers can be set by 2 more robotic observers using let's say, 2 different random algorithms. Which of course the laser source knows this too.

Of course, there are actually 2 separate laser sources which are phase locked together. So both knows what the other is going to do. On the other hand, the photons don't even need to exist at the same time any more than they need to exist in the same location, so that the appearance of entanglement crosses both space and time if we want to set it up that way.

And so, as you say, does the theory continue on without the benefit of Occam...

zonde

Quote by lugita15

You're right, I am assuming that. But that's a harmless assumption to make.

Linear relationship between θ and correlation level follows directly from that assumption.
So your statement that "the argument does not assume it, it proves it." ... well, I wouldn't say it's very truthful.

Quote by lugita15

Perfect correlations for matching measurement settings is a consequence of quantum mechanics, so surely if a local realist theory wanted to match the predictions of QM then it would have to have perfect correlations for matching measurement settings. I highly doubt this is what ThomasT is disputing.

Local realistic theory can not reproduce all predictions of QM.

But local realistic theory can try to reproduce QM predictions in domain where they are experimentally verified. And that domain does not include (something close to) perfect correlations for matching measurement settings.

What I think ThomasT is disputing is that given Malus law it is very unreasonable conclusion that there is linear relationship between θ and correlation level.

Quote by lugita15

(You can, of course, be the fringe type of local realist who has a theory making predictions contrary to QM, but who believes that the only reason the experiments have proven QM right is that they're subject to various flaws, loopholes, and systematic biases. But as Bell tests become more sophisticated, that becomes an increasingly untenable positon, arguably even more so than superdeterminism.)

No, I am a type of local realist who tries to make falsifiable local realistic explanations agreeing with QM in a domain where it is experimentally tested.

lugita15

Quote by zonde

Linear relationship between θ and correlation level follows directly from that assumption.

You're right, it's a fairly direct route from the assumption that there is perfect correlation at identical polarizer settings to the conclusion that the local realist must believe that the correlation is linear. But ThomasT does not agree with this fairly direct line of reasoning, so I'm trying to convince him that it works.

Local realistic theory can not reproduce all predictions of QM.

If I could persuade ThomasT of this, I'd be done.

But local realistic theory can try to reproduce QM predictions in domain where they are experimentally verified. And that domain does not include (something close to) perfect correlations for matching measurement settings.

But that just has to do with practical experimental limitations. The point I'm arguing with him about is whether someone can believe that all the predictions of quantum mechanics are correct and still believe in (non-superdeterministic) local realism. I'm trying to show that the answer is no, because one experimental prediction of QM is perfect correlations at identical polarizer settings, from which the local realist is forced to believe in a linear correlation relationship, which is in contradiction with another experimental prediction of QM.

What I think ThomasT is disputing is that given Malus law it is very unreasonable conclusion that there is linear relationship between θ and correlation level.

I agree that this is the point of contention, but keep in mind that he thinks a local realist can believe in the nonlinear correlation given by Malus' law, while at the same time also believing that there is perfect correlation at identical settings. I hope you agree that he's wrong on this point.

No, I am a type of local realist who tries to make falsifiable local realistic explanations agreeing with QM in a domain where it is experimentally tested.

Out of curiosity, which experimental loophole of Bell tests do you cling onto? Detector efficiency, communication, freedom of choice, or something else?

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Demystifier Blog Entries: 19 Recognitions: Science Advisor	Lugita15, I would like to see your response to my post #127.

Delta Kilo	Wouldn't retro-casuality have exactly the same outward appearance as superdeterminism to us? It is certainly more economical (in occam sense) - the 'conspiracy' in each case only has to go back in time as far as needed to achieve correct outcomes as opposed to setting it all up just before big bang. Also laws of physics are time-symmetrical already (:those that counts anyway:).