Why is superdeterminism not the universally accepted explanation of nonlocality?

In summary, the conversation discusses the concept of nonlocality and entanglement in a deterministic universe, where the information about instantaneous transfer is known to the universe. The conversation also touches upon the idea of superdeterminism, which some people reject due to its conspiratorial nature and lack of a concrete scientific theory. The possibility of interpreting nonlocality as an answer rather than a problem is also mentioned, as well as the importance of keeping beliefs aligned with measured reality. The conversation concludes with the suggestion that it may be better to believe in the existence of random and non-local phenomena rather than inventing longer explanations.
  • #141
billschnieder said:
A polarization is an outcome of a physical measurement. It can not EXIST when the measurement has not been made. Realists, do not believe the outcomes of measurements exist when no measurement has been made. Three simultaneous polarization values are impossible so no realist believes it makes sense to ever contemplate three possible simultaneous polarization values, even hypothetically. In simple terms you can not measure an impossibility and it makes no sense to hypothesize an impossibility either.

see: https://www.physicsforums.com/showpost.php?p=3344159&postcount=193
billschnieder, we clearly have different definitions of what realism means. As DrChinese and ThomasT said you should start a new thread if you want to discuss your definition.
 
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  • #142
lugita15 said:
I'm not sure what this means.
It means that BI violations don't tell you anything about the reality underlying the instrumental behavior.

lugita15 said:
No, Bell did not just prove that a particular local realist model failed to match the predictions of QM. He proved that any possible local deterministic universe which is not superdeterministic must satisfy the Bell inequality.
Well, that's just an unwarranted interpretation of the meaning of Bell's theorem, imho.

lugita15 said:
If you disagree with this, look at the 12-step outline of Bell's argument I gave in a previous post and tell me what step does not apply to ALL local deterministic universes which are not superdeterministic.
I've looked at it. Your conclusion is unreasonable, imho.

If you really think you're on to something, then make a superdeterministic model of quantum entanglement.
 
  • #143
ThomasT said:
I've looked at it. Your conclusion is unreasonable, imho.
So then tell me which of the 12 steps need not hold in all (non-superdeterministic) local deterministic theories.
If you really think you're on to something, then make a superdeterministic model of quantum entanglement.
Um, I'm not sure what you're talking about. When did I say I'm on to a superdeterministic model?
 
  • #144
lugita15 said:
I'm not sure what you're talking about. When did I say I'm on to a superdeterministic model?
You didn't, afaik. But you seem to be defending the notion that superdeterminism can explain BI violations. So, I'm just suggesting, make a superdeterministic model that can be experimentally tested. Otherwise, what are you talking about?

As for your 12-step recounting of Bell's argument, the conclusion that the correlation between the angular difference of the crossed polarizers and the rate of coincidental detection should be linear given the assumption of local determinism is wrong.
 
  • #145
ThomasT said:
You didn't, afaik. But you seem to be defending the notion that superdeterminism can explain BI violations.
All I'm saying is that Bell's theorem as such does not necessarily rule out superdeterminism, but it definitely rules out all other forms of local realism.
As for your 12-step recounting of Bell's argument, the conclusion that the correlation between the angular difference of the crossed polarizers and the rate of coincidental detection should be linear given the assumption of local determinism is wrong.
If my conclusion is wrong, one of my steps must be wrong. Which one is it?
 
  • #146
lugita15 said:
All I'm saying is that Bell's theorem as such does not necessarily rule out superdeterminism, but it definitely rules out all other forms of local realism.
I basically agree with this ... with the qualifier that what Bell's theorem definitively rules out are Bell-type LR models of quantum entanglement. Whether non-Bell-type LR models can be definitively ruled out is still an open question, afaik. (Because, it's still an open question as to whether certain non-Bell-type LR models are actually LR models.)

lugita15 said:
If my conclusion is wrong, one of my steps must be wrong. Which one is it?
You're saying that the local realist would expect a linear correlation between θ and coincidental detection. Why would the local realist expect that?

My point is that if the local realist is aware of the historically documented characteristic behavior of light, then he wouldn't expect, in a local deterministic world, a linear correlation between the angular difference of the crossed polarizers and the rate of coincidental detection. He would, rather, expect a nonlinear correlation ... something approximating cos2θ.

The fact that Bell inequalities are, more or less, based on formal constraints which require the light in Bell tests to behave in an uncharacteristic way suggests that there's something in those constraints which is not corresponding to Bell test preparation and associated data processing. But not necessarily that nature is nonlocal.
 
  • #147
ThomasT said:
You're saying that the local realist would expect a linear correlation between θ and coincidental detection. Why would the local realist expect that?
To repeat, the fact that local realism implies a linear correlation is NOT some arbitrary assumption or constraint we place on local realist theories. It is the conclusion of a careful argument, and if you're claiming the conclusion is wrong then there must be something wrong with this argument.
 
  • #148
lugita15 said:
To repeat, the fact that local realism implies a linear correlation is NOT some arbitrary assumption or constraint we place on local realist theories. It is the conclusion of a careful argument, and if you're claiming the conclusion is wrong then there must be something wrong with this argument.
Why does the argument assume that the correlation between θ and rate of coincidental detection should be linear?
 
  • #149
ThomasT said:
Why does the argument assume that the correlation between θ and rate of coincidental detection should be linear?
Argh! ThomasT, I told you, the argument does not assume it, it proves it.
 
  • #150
lugita15 said:
Argh! ThomasT, I told you, the argument does not assume it, it proves it.
I didn't get that. How does it prove it?
 
  • #151
billschnieder said:
Bah! I had hoped you will have seen problem the so called "DrChinese challenge" by now. You keep saying:

- give me a dataset with values for simultaneous polarization outcomes at 0, 120 and 240 degrees.

Don't you yet understand that "dataset with simultaneous outcomes" implies an experiment is being performed. Previously I asked you to describe the experiment and I will give you the dataset but you never described the experiment because you can not and nobody can because THERE CAN NEVER BE AN EXPERIMENT WHICH SIMULTANEOUSLY MEASURES TWO PHOTONS AT 3 ANGLES (yes I'm shouting this time).

Therefore failure of anybody to provide your purported dataset is not due to anything other than the fact that the request is nonsensical.
Under local realism cloning of entangled pair is completely valid operation. From that follows that "DrChinese challenge" is applicable to LR models.

While I am proponent of local realism I side with DrChinese in this. Have to say that you can have constructive discussions with DrChinese and I am grateful to him as discussions with him have shaped a lot my own understanding about entanglement problem.
 
  • #152
f95toli said:
I don't normally get involved in these discussions, because ultimately I don't think they are very interesting.
However, I thought I'd add my (usual) comment about experimental QM.

Whereas nearly all "conceptual" (and many practical) experiments are done using light, there are lots of examples of QM experiments that do NOT involve light, angular momentum, polarization, photon detectors etc.

People have performed experiments that are formally exactly analogues to the early (optical) tests of Bell's inequalities. We will probably see the first demonstrations in my own field pretty soon (solid-state QIP, which has nothing to do with optics but the QM formalism is obviously the same)
Hence, any attempt to explain away Bell type experiments by saying that that results are due to the fact we do not understand a specific technical detail of Aspect's original experiments is ultimately futile.

Moreover, note also that we are nowadays often -in practical- terms more concerned about OTHER inequalities that for one reason or another are better to test experimentally. A good example are tests of Legget-type inequalities which can used to test whether or not QM is local.
Can you give one good reason why your position is not subject to confirmation bias?
 
  • #153
lugita15 said:
Argh! ThomasT, I told you, the argument does not assume it, it proves it.
I would like to see this. Hmm, my guess would be that you are assuming perfect (anti-)correlations for matching measurement settings.
 
  • #154
zonde said:
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.)
 
  • #155
ThomasT said:
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.
 
  • #156
lugita15 said:
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 let's 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?
 
  • #157
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.
 
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  • #158
lugita15 said:
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?
 
  • #159
ThomasT said:
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.
 
  • #160
Lugita15, I would like to see your response to my post #127.
 
  • #161
jadrian said:
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 doesn't 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 each other. 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 don't believe faster than light info transfer will be an issue here as it is not an issue with normal entanglement, because info transferred 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 each other, 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 isn't 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 each other 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 each others lightcones, a and d could not affect each other 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.
 
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  • #162
Demystifier said:
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.
 
  • #164
jadrian said:
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 each other 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 each others lightcones, a and d could not affect each other 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.
 
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  • #165
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:).
 
  • #166
jadrian said:
if determinism only is effective within lightcones, in which case if outside each others lightcones, a and d could not affect each other 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.
 
  • #167
DrChinese said:
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.
 
  • #168
lugita15 said:
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 :smile: ) 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...
 
  • #169
lugita15 said:
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.

lugita15 said:
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.


lugita15 said:
(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.
 
  • #170
zonde said:
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?
 
  • #171
Delta Kilo said:
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:).

exactly. it shouldn't be called super determinism. it should be called universal causality. if I am the first with this this then i claim it. adrians universal causality
 
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  • #172
lugita15 said:
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.)

if you could match experimental settings, which you cant, then you wouldn't have correlations, youu would have the exact same result.
 
  • #173
lugita15 said:
OK, let me give you an example of why you need special initial conditions.

In a deterministic theory, in order to predict the current behavior of any object, you need to know the initial conditions of the object, as well as the deterministic laws of the universe. In Newtonian mechanics, for example, you need to know the positions and velocities of all the particles at time t=0, and then F=ma will tell you the behavior of the particles at all later times.

Now let's consider what a local deterministic explanation of entanglement would look like. Let particles A and B be an entangled pair of photons, which are separated by a great distance and then sent through polarization detectors. We also have particles C and D: C tells the experimenter what angle he should set the polarizer that measures A, and D tells the experimenter how to set the polarizer that measures B. You can think of C and D as neurons in the brains of the experimenters if you like.

Now we find experimentally that the behavior of particle A through its measurement device is strongly correlated with the angle at which B's measurement device is set. And that angle is determined by particle D. So we have a correlation between the behavior of particles A and D.

But particles A and D are separated by such a large distance, so they cannot communicate with each other to coordinate their behavior (unless you have a nonlocal theory like Bohmian mechanics which allow undetectable faster-than-light signalling between particles). So a local determinist has to conclude that A and D are correlated not based on a current relationship between the present states of A and D, which would be impossible, but based on a past relationship of the initial states of A and D.

This is what we mean by special initial conditions: A and D seemingly have nothing to do with each other. After all, it is A and B that were in the entangled state, and yet somehow we have to conclude that the initial conditions of A and D had to be specially set so that a correlation between A and D would be observed in the future. And instead of just D, we can have a large number of particles D1, D2, D3,... which together determine the measurement setting, so the initial state of particle A had to have been set based on the initial states of all these particles. And in the real world, almost all particles in the universe are interacting in some way with almost all other particles, so really the setting of measurement device depends on almost everything in the universe, from which we conclude that the initial conditions of the whole universe were specially set so that the right kind of correlation would be displayed billions of years later between particle A and the measuring device.

This is why superdeterminism is called "conspiratorial". That doesn't mean it's wrong, it just has some issues which make it rather difficult to construct a viable superdeterministic theory, but let me repeat that some potential first steps toward such a theory have already been taken by a few people.

also with d could have this instantaneous effect on a as i could decide to shoot my self in the head or not depending on the angle, wouldn't this be faster than light info tranfer, violating relativity?

this further seems proof that d and are within the lightcone of the distant past, in which case, the info about what d will do to affect a is predetermined. and nonlocal interactions can only occur within a lightcone or you violate relativity.
 
  • #174
also, has it been proven in a lab that time moves forward and isn't frozen or moving backwards? it seems like that is something our intuition has guided us to regard as truth. is there not enough intuition in the world to regard determinism as truth?
 
  • #175
DrChinese said:
Free will is not a necessary component of QM. So I certainly am not rejecting superdeterminism because of that. I reject superdeterminism as an explanation for Bell test results, and I do so for the reasons already stated.

Please bear in mind that there are no candidate superdeterministic theories to reject at this point, so it is a moot point in many ways. The reason I mention the amount of local information to be stored in every particle is because a candidate theory will end up postulating this (in some form or fashion) as a way to explain Bell test results. It is not necessary to assume free choice for measurement settings in any stage of the argument, but you must explain how (i.e. the exact mechanism, since we have no other reason to suspect it exists) the choice is propagated in a superdeterministic candidate.

Not so easy, I assure you. Which is again, the answer to your original question.



then why even call it superdeterminism. there is no conpiracy! its simply causality governed by relativity. call it universal causality. yes it is that easy.
 
<h2>1. Why is superdeterminism not the universally accepted explanation of nonlocality?</h2><p>Superdeterminism is not the universally accepted explanation of nonlocality because it goes against the widely accepted principle of free will. Superdeterminism suggests that all events, including human decisions, are predetermined and therefore there is no true randomness or free will in the universe. This goes against our understanding of human agency and the ability to make choices.</p><h2>2. What evidence supports the rejection of superdeterminism as an explanation for nonlocality?</h2><p>One of the main pieces of evidence against superdeterminism is the violation of Bell's inequality, which suggests that there is a limit to how much information can be hidden from an observer. If superdeterminism were true, this limit would not exist and the observed correlations in nonlocal systems would not be possible.</p><h2>3. Are there alternative explanations for nonlocality other than superdeterminism?</h2><p>Yes, there are alternative explanations for nonlocality that do not rely on the concept of superdeterminism. Some theories suggest that there are hidden variables or hidden information that can explain the observed correlations in nonlocal systems without resorting to predetermined events.</p><h2>4. What implications would accepting superdeterminism have on our understanding of the universe?</h2><p>If superdeterminism were to be accepted as the explanation for nonlocality, it would have significant implications on our understanding of the universe. It would mean that all events, including our thoughts and actions, are predetermined and there is no true randomness or free will. This would challenge our understanding of causality and the role of human agency in shaping our reality.</p><h2>5. Is there ongoing research and debate surrounding the concept of superdeterminism and its relation to nonlocality?</h2><p>Yes, there is ongoing research and debate surrounding the concept of superdeterminism and its relation to nonlocality. Scientists continue to explore alternative explanations for nonlocality and gather evidence to support or refute the concept of superdeterminism. This is an active area of study in the field of quantum mechanics and there is no consensus yet on the ultimate explanation for nonlocality.</p>

1. Why is superdeterminism not the universally accepted explanation of nonlocality?

Superdeterminism is not the universally accepted explanation of nonlocality because it goes against the widely accepted principle of free will. Superdeterminism suggests that all events, including human decisions, are predetermined and therefore there is no true randomness or free will in the universe. This goes against our understanding of human agency and the ability to make choices.

2. What evidence supports the rejection of superdeterminism as an explanation for nonlocality?

One of the main pieces of evidence against superdeterminism is the violation of Bell's inequality, which suggests that there is a limit to how much information can be hidden from an observer. If superdeterminism were true, this limit would not exist and the observed correlations in nonlocal systems would not be possible.

3. Are there alternative explanations for nonlocality other than superdeterminism?

Yes, there are alternative explanations for nonlocality that do not rely on the concept of superdeterminism. Some theories suggest that there are hidden variables or hidden information that can explain the observed correlations in nonlocal systems without resorting to predetermined events.

4. What implications would accepting superdeterminism have on our understanding of the universe?

If superdeterminism were to be accepted as the explanation for nonlocality, it would have significant implications on our understanding of the universe. It would mean that all events, including our thoughts and actions, are predetermined and there is no true randomness or free will. This would challenge our understanding of causality and the role of human agency in shaping our reality.

5. Is there ongoing research and debate surrounding the concept of superdeterminism and its relation to nonlocality?

Yes, there is ongoing research and debate surrounding the concept of superdeterminism and its relation to nonlocality. Scientists continue to explore alternative explanations for nonlocality and gather evidence to support or refute the concept of superdeterminism. This is an active area of study in the field of quantum mechanics and there is no consensus yet on the ultimate explanation for nonlocality.

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