Superdeterminism and the Mermin Device

[atyy]

So where exactly is fine tuning in the Bohmian theory?

The fine tuning is in the quantum equilibrium assumption. But maybe Valentini's version is able to overcome it the fine tuning, at the cost and benefit of predicting violations of present quantum theory without fine tuning. There's a discussion by Wood and Spekkens on p21 of https://arxiv.org/abs/1208.4119.

 

[Nullstein]

So where exactly is fine tuning in the Bohmian theory?

See atyy's post (although I don't agree that Valentini's version fixes this).

I can't find this claim in the paper. Where exactly does the paper say that?

He shows that his superdeterministic model requires only 1/15 bit of shared information to reproduce QM, while a non-local model requires 1 bit.

 

[Fra]

The system is made of particles that evolve just fine according to Hamiltons equations of motion. There is no fundamental need for a quantity like temperature. It's invented by humans to quantify an aggregate property of the system.

The new states and concept arr evolved IN HUMANS as it increases our fitness and responsiveness and learning. Even a human has to act under information processing constraints. The model of simulating hamilton dynamics from initial values as we know is not viable due to deterministic chaos. This is a key insight i think to understand how relations evolve and persist. Non commutative logic to me is a form fo datacompression that nature likely evolved because its the only way to achieve stability. This in itself has imo nothing todo with humans. The IGUS or agents are themsleves just subsytems of matter.

/Fredrik

 

[Demystifier]

See atyy's post (although I don't agree that Valentini's version fixes this).

OK, so why do you not agree that Valentini's version fixes this?

 

[physika]

So, how do we explain violations of Bell's inequality without nonlocal interactions, violations of Statistical Indendence, or "shut up and calculate" (meaning "the formalism of QM works, so it's already 'explained'")? Our principle explanation of Bell state entanglement doesn't entail an ontology at all, so there is no basis for nonlocality or violations of Statistical Independence. And, it is the same (relativity) principle that explains time dilation and length contraction without an ontological counterpart and without saying, "the Lorentz transformations work, so it's already 'explained'". So, we do have an explanation of Bell state entanglement (and therefore of the Tsirelson bound).

A explanation for the "Tsirelson Bound" ??


"An explanation is a set of statements, a set of facts, which states the causes, context, and consequences of those facts. It may establish rules or laws"
.

 

[RUTA]

A explanation for the "Tsirelson Bound" ??


"An explanation is a set of statements, a set of facts, which states the causes, context, and consequences of those facts. It may establish rules or laws"
.

Yes, here is the explanatory sequence:

1. No preferred reference frame + h --> average-only projection for qubits
2. Average-only projection for qubits --> average-only conservation per the Bell states
3. Average-only conservation per the Bell states --> Tsirelson bound

In short, the Tsirelson bound obtains due to "conservation per no preferred reference frame".

 

[PeterDonis]

Thread closed for moderation.

 

[PeterDonis]

Moderator's note: Two off topic subthreads have now been split into their own separate threads:

https://www.physicsforums.com/threads/derivation-of-statistical-mechanics.1013629/

https://www.physicsforums.com/threads/interpretations-of-the-no-communication-theorem.1013630/

This thread is now reopened, with a reminder to please keep it focused on discussion of the article about superdeterminism referenced in the OP.

 

[maxulu]

The modern entanglement swapping examples have entangled particles which never exist in a common backward light cone - so they cannot have had an opportunity for a local interaction or synchronization. The A and B particles are fully correlated like any EPR pair, even though far apart and having never interacted*. That is quantum nonlocality, plain and simple. There are no "local" explanations for entanglement swapping of this type (that I have seen), of course excepting interpretations that claim to be fully local and forward in time causal (which I would probably dispute). Some MWI proponents makes this claim, although not all.*Being from independent photon sources, and suitably distant to each other.

Hi ! I hope these questions haven't been asked a lot. I checked another thread, but couldn't find exactly this. what you said here was basically what I interpreted yours and many other replies in it: that particle A and B have non-local transfer. What about, say, a computer program of a universe like ours: it would seem like there's no local transfer in it, but there is (electrons from the program). Would such hidden variables be necessarily detectable in experiments in our universe (Bell, von Neumann Existence Theorem) if these hidden local variables existed like a program (or superdeterminism) as well? If so, does superdeterminism presuppose no contact info-transfer?

Another question: if the info transfer is non-local, does that mean information can travel outside space (and thus outside time)? What I mean is, that it basically comes out of nowhere: there doesn't need to be any CoA - Contact of Action, it simply "knows"?

Finally, is the entanglement state change between particle A and B instantaneous? How does this relate to causality if there is no time difference? Is it perhaps like a Halting Problem? (this last question is a bit vague and strange so feel free to say Yes/No/Idk, I really can't explain it better, more like an idea)

 

[kclubb]

I am a novice here. But I have been studying about SD for about 8 months now. Going back to the basic issue Einstein had with non-locality…. No one seems to be addressing a point in this discussion - assume that causality cannot travel faster than the speed of light (we have never observed violation of speed of light, and without particles we have no causality).

We see measurements that SEEM to violate locality, BUT we do have a way out by SD (John Bell himself said so). We do believe in symmetry laws, conservation of energy, momentum, etc. We CAN predict in a real sense where planets, baseballs, etc will be in the future. I think, prior to QM we would all agree that if all factors were considered in initial conditions and all particles (heat=photons, etc) could be taken into account we could predict a small system in its entirety. I have never seen an argument where someone says “conservation of energy is only approximate”, because they would need to demonstrate this experimentally.

So given that conservation laws are all assumed to be exact (pre QM), what happened to the argument that all events are pre-determined? Not predictable as that is impossible, but pre-determined given the belief that we have discovered all the laws of motion and with the assumption that particles are real (again particles became non-real after QM, only when the wave function was available did we consider that ball are not real.)

So here is my question: If the Universe is not pre-determined, where did the differences in energy, momentum, etc go? A non-pre-determined Universe needs to violate conservation laws somewhere. Either we have not discovered all the laws, or there is a leak in Energy somewhere we have not discovered yet. Do we not believe our own laws of Physics?

If we

1. Assume conservation laws hold everywhere for all time and are exact
2. Assume speed of light is universal.
3. Assume causality depends on particles

then the Universe MUST be pre-determined, there is no way around it that we have actuality observed. NONE. SD, it seems to me does not need to prove itself, it seems to me that SD must be disproven, as it is an obvious result of the above assumptions. Which of the 3 assumptions would we abandon?

Now enter QM. We see entanglement experiments confirm QM predictions, but we also believe in the above 3 assumptions, then why do we need to introduce non-local interpretations at all - SD is the way the Universe works based on the 3 assumptions, what is the problem? Based on what I have read, the only argument seems to be the disbelief that we are not free to do Science. That is the only argument I have heard - that we FEEL that we are free to make decisions on our own and this somehow invalidates all our scientific evidence for SD.

But this was a problem early on - yes we SEE that our laws work, we understand we cannot take into account all factors when trying to predict an outcome - but the ASSUMPTION underneath was that there are laws that govern the Universe and therefore, unless someone can demonstrate how these laws are violated the Universe is pre-determined down to the last photon.

There are those who think we live in a simulation - pre-determined again. No evidence for that really, BUT the world view helps explain why we THINK we have free will. An AI living in a simulation may go through its life believing it had free will without ever realizing otherwise. If we ditch the FEELING that we are making free decisions, then SD is absolutely the simplest way to explain the seemingly non-local results of QM. Not “many worlds” which has no observational evidence. I do not see an alternative to SD that is consistent with all our laws and measurements, and the AI worldview easily explains at least ONE way we can be fooled into believing we have free will. But in any case, FEELINGS have been the bane of science forever.

Non-local QM theories are not necessary, as far as I can tell, if SD is considered an option. If AIs and simulations had been around BEFORE QM was discovered I do not think that non-local theories would ever have been seriously considered.

 

[RUTA]

I am a novice here. But I have been studying about SD for about 8 months now. Going back to the basic issue Einstein had with non-locality…. No one seems to be addressing a point in this discussion - assume that causality cannot travel faster than the speed of light (we have never observed violation of speed of light, and without particles we have no causality).

We see measurements that SEEM to violate locality, BUT we do have a way out by SD (John Bell himself said so). We do believe in symmetry laws, conservation of energy, momentum, etc. We CAN predict in a real sense where planets, baseballs, etc will be in the future. I think, prior to QM we would all agree that if all factors were considered in initial conditions and all particles (heat=photons, etc) could be taken into account we could predict a small system in its entirety. I have never seen an argument where someone says “conservation of energy is only approximate”, because they would need to demonstrate this experimentally.

So given that conservation laws are all assumed to be exact (pre QM), what happened to the argument that all events are pre-determined? Not predictable as that is impossible, but pre-determined given the belief that we have discovered all the laws of motion and with the assumption that particles are real (again particles became non-real after QM, only when the wave function was available did we consider that ball are not real.)

So here is my question: If the Universe is not pre-determined, where did the differences in energy, momentum, etc go? A non-pre-determined Universe needs to violate conservation laws somewhere. Either we have not discovered all the laws, or there is a leak in Energy somewhere we have not discovered yet. Do we not believe our own laws of Physics?

If we

1. Assume conservation laws hold everywhere for all time and are exact
2. Assume speed of light is universal.
3. Assume causality depends on particles

then the Universe MUST be pre-determined, there is no way around it that we have actuality observed. NONE. SD, it seems to me does not need to prove itself, it seems to me that SD must be disproven, as it is an obvious result of the above assumptions. Which of the 3 assumptions would we abandon?

Now enter QM. We see entanglement experiments confirm QM predictions, but we also believe in the above 3 assumptions, then why do we need to introduce non-local interpretations at all - SD is the way the Universe works based on the 3 assumptions, what is the problem? Based on what I have read, the only argument seems to be the disbelief that we are not free to do Science. That is the only argument I have heard - that we FEEL that we are free to make decisions on our own and this somehow invalidates all our scientific evidence for SD.

But this was a problem early on - yes we SEE that our laws work, we understand we cannot take into account all factors when trying to predict an outcome - but the ASSUMPTION underneath was that there are laws that govern the Universe and therefore, unless someone can demonstrate how these laws are violated the Universe is pre-determined down to the last photon.

There are those who think we live in a simulation - pre-determined again. No evidence for that really, BUT the world view helps explain why we THINK we have free will. An AI living in a simulation may go through its life believing it had free will without ever realizing otherwise. If we ditch the FEELING that we are making free decisions, then SD is absolutely the simplest way to explain the seemingly non-local results of QM. Not “many worlds” which has no observational evidence. I do not see an alternative to SD that is consistent with all our laws and measurements, and the AI worldview easily explains at least ONE way we can be fooled into believing we have free will. But in any case, FEELINGS have been the bane of science forever.

Non-local QM theories are not necessary, as far as I can tell, if SD is considered an option. If AIs and simulations had been around BEFORE QM was discovered I do not think that non-local theories would ever have been seriously considered.

As I showed in this Insight, the indeterminism we have in QM is unavoidable according to the relativity principle. And, yes, that means conservation of spin angular momentum is not exact when Alice and Bob are making different measurements. Conservation holds only on average (Bob saying Alice must average her results and Alice saying the same about Bob) when they make different measurements.

 

[PeterDonis]

without particles we have no causality

This is not correct; field theories that do not contain any particles still have causality.

 

[PeterDonis]

A non-pre-determined Universe needs to violate conservation laws somewhere.

No, it doesn't. Events that are not pre-determined can still happen in a way that obeys conservation laws.

 

[PeterDonis]

that means conservation of spin angular momentum is not exact when Alice and Bob are making different measurements. Conservation holds only on average

I don't think this claim can be asserted as fact at our current level of knowledge. When we make measurements on quantum systems, we bring into play huge sinks of energy and momentum (measuring devices and environments). But we don't measure the change in energy and momentum of the sinks. We only look at the measured systems. But if a measurement takes place, the measured systems are not closed systems and we should not in general expect them to obey conservation laws in isolation; they can exchange energy and momentum with measuring devices and environments. To know that conservation laws were violated we would have to include the changes in energy and momentum of the measuring devices and environments. But we don't. So I don't see that we have any basis to assert what you assert in the above quote. All we can say is that we have no way of testing conservation laws for such cases at our current level of technology.

 

[DrChinese]

If we

1. Assume conservation laws hold everywhere for all time and are exact
2. Assume speed of light is universal.
3. Assume causality depends on particles

then the Universe MUST be pre-determined...

You are completely ignoring Bell's Theorem. I realize that Bell himself has mentioned Superdeterminism (SD) as an "out" for his own theorem (as you point out). However, SD requires substantially more assumptions than the 3 you have above. In other words: unless you have substantially more (and progressively more outrageous) assumptions than those 3, then at least one of those 3 must not hold true.

And I get tired of saying this, but: There is no candidate SD theory in existence. By this I mean: one which explains why any choice of measurement basis leads to a violation of a Bell Inequality, in any of the following scenarios:

a. Measurement basis does not vary between pairs. This is the most common Bell test, and violates a Bell inequality.

b. Measure basis does vary:
i. By random selection, such as by computers or by radioactive samples. This too has been done, and violates a Bell inequality.
ii. By human choice (such as the Big Bell test, and violates a Bell inequality).

If there were such a theory, it could easily be falsified by suitable variations on the above. Further, there is no particular rational to invoke SD as an explanation for observed results in the area of entanglement, but no where else in all of science. You may as well claim that the "true" value of c is 2% higher than the observed value... due to Superdeterminism.

 

[kclubb]

As I showed in this Insight, the indeterminism we have in QM is unavoidable according to the relativity principle. And, yes, that means conservation of spin angular momentum is not exact when Alice and Bob are making different measurements. Conservation holds only on average (Bob saying Alice must average her results and Alice saying the same about Bob) when they make different measurements.

Wikipedia claims that John Bell made this statement in the 1980s (I have not tracked down this)
There is a way to escape the inference of superluminal speeds and spooky action at a distance. But it involves absolute determinism in the universe, the complete absence of free will. So your explanation goes beyond what John Bell claimed in that interview - that SD does not eliminate the need for non-locality?

 

[kclubb]

This is not correct; field theories that do not contain any particles still have causality.

Interesting. What would be an example? My understanding is that all forces have corresponding particles - the Standard Model.

 

[kclubb]

No, it doesn't. Events that are not pre-determined can still happen in a way that obeys conservation laws.

We have to usually apply multiple laws simultaneously in classical Physics to arrive at a unique trajectory (energy + momentum etc). Are you speaking of not being able to measure two properties at the same time exactly, satisfying one law but not knowing the exact value for another property? In this case we just cannot measure EXACTLY the values of both momentum and energy, say, at the same time and therefore cannot say one way or the other in order to to apply the laws at the same time. But just because we cannot measure the two properties at the same time does not mean that the event happened in a non-deterministic way.

In any case, when you say “Events that are not pre-determined” you are already biasing your argument, because the argument is about whether the Universe is pre-determined, and you are already claiming that it is not in your answer. What you need to show is an example where a conservation law was VIOLATED when the observation is made.

 

[kclubb]

You are completely ignoring Bell's Theorem. I realize that Bell himself has mentioned Superdeterminism (SD) as an "out" for his own theorem (as you point out). However, SD requires substantially more assumptions than the 3 you have above. In other words: unless you have substantially more (and progressively more outrageous) assumptions than those 3, then at least one of those 3 must not hold true.

And I get tired of saying this, but: There is no candidate SD theory in existence. By this I mean: one which explains why any choice of measurement basis leads to a violation of a Bell Inequality, in any of the following scenarios:

a. Measurement basis does not vary between pairs. This is the most common Bell test, and violates a Bell inequality.

b. Measure basis does vary:
i. By random selection, such as by computers or by radioactive samples. This too has been done, and violates a Bell inequality.
ii. By human choice (such as the Big Bell test, and violates a Bell inequality).

If there were such a theory, it could easily be falsified by suitable variations on the above. Further, there is no particular rational to invoke SD as an explanation for observed results in the area of entanglement, but no where else in all of science. You may as well claim that the "true" value of c is 2% higher than the observed value... due to Superdeterminism.

So we do need to find a valid theory that works. Sean Carrol advocates for the “many worlds” interpretation. Speculating that every time a “measurement” is made a new Universe comes into existence. Is this one of the “acceptable” and not “outrageous” assumptions that work for you? Because there is a real need to deal with non-locality. I am not studied on all the “outrageous” assumptions you speak of, but a new Universe being created every time there is a measurement seems outrageous to me, compared to a an deterministic Universe we have give up free will for. How would we ever test many worlds? I am not refuting you statements, but there are Physicists who believe SD is viable, including Bell himself. I hope to find the time to read through the original works that Bell started with, when I retire and I have the time perhaps. But I have to believe that, since there are legitimate scientists who believe SD is a possible reality, that it is a least POSSIBLE a theory can be developed. It just seems odd that most of the arguments I have read by Physicists against SD are emotional opinionated arguments dealing with free will, and “many worlds” is considered over SD as a better alternative, but Bell recognizing SD as a possible loophole to his theorem. Did he just not think it through before he made that statement? Is there something in the points that you make above the John Bell was not aware of? Specifically something that has been discovered after Bell that invalidates his claim?

 

[PeterDonis]

all forces have corresponding particles - the Standard Model.

The Standard Model is a quantum field theory. Certain quantum field states are described as "particles", but there are many quantum field states that cannot be described that way. The fundamental entities are fields.

 

[PeterDonis]

What you need to show is an example where a conservation law was VIOLATED when the observation is made.

No, you need to show that a conservation law must be violated if the universe is not fully 100% deterministic because you are the one who is making that claim. I am simply pointing out that you have not shown that. You have simply assumed it, and you can't just assume it. You have to show it.

The rest of your post is irrelevant to mine because I did not say any of the things you are talking about.

 

[PeterDonis]

Speculating that every time a “measurement” is made a new Universe comes into existence.

This is not what the MWI says. The "universe" in the MWI is the universal wave function, and there is always just one universal wave function. The wave function doesn't "split" when a measurement is made; that would violate unitary evolution, and the MWI says that the wave function always evolves in time by unitary evolution.

 

[PeterDonis]

a deterministic Universe we have give up free will for

You are aware that the MWI is 100% deterministic, correct?

 

[Lord Jestocost]

I am not refuting you statements, but there are Physicists who believe SD is viable, including Bell himself.

At the last resort, “questions of faith” are irrelevant for doing physics. All one needs to carry out physics are observations that can be used to construct and test models – on the basis of the observed phenomena.

 

[RUTA]

I don't think this claim can be asserted as fact at our current level of knowledge. When we make measurements on quantum systems, we bring into play huge sinks of energy and momentum (measuring devices and environments). But we don't measure the change in energy and momentum of the sinks. We only look at the measured systems. But if a measurement takes place, the measured systems are not closed systems and we should not in general expect them to obey conservation laws in isolation; they can exchange energy and momentum with measuring devices and environments. To know that conservation laws were violated we would have to include the changes in energy and momentum of the measuring devices and environments. But we don't. So I don't see that we have any basis to assert what you assert in the above quote. All we can say is that we have no way of testing conservation laws for such cases at our current level of technology.

My claim is a mathematical fact that follows from the Bell state formalism alone. It has nothing to do with experimental uncertainty.

 

[PeterDonis]

My claim is a mathematical fact that follows from the Bell state formalism alone.

As I said, this can't be correct because during the measurement process angular momentum is exchanged between the measured particles, which the formalism you refer to describes, and the measuring devices and environment, which the formalism does not describe. So the formalism is incomplete and cannot support any claims about conservation laws.

It has nothing to do with experimental uncertainty.

My point has nothing to do with experimental uncertainty. It has to do with the fact that during measurement, the measured particles are open systems, not closed systems.

 

[RUTA]

As I said, this can't be correct because during the measurement process angular momentum is exchanged between the measured particles, which the formalism you refer to describes, and the measuring devices and environment, which the formalism does not describe. So the formalism is incomplete and cannot support any claims about conservation laws.My point has nothing to do with experimental uncertainty. It has to do with the fact that during measurement, the measured particles are open systems, not closed systems.

Look at a Bell spin triplet state in the symmetry plane. When Alice and Bob both measure in the same direction, they both get the same outcome, +1 or -1. That is due to conservation of spin angular momentum. Now suppose Bob measures at an angle $\theta$ with respect to Alice and they do many trials of the experiment. When Alice partitions the data according to her +1 or -1 results, she expects Bob to measure $+\cos{\theta}$ or $-\cos{\theta}$, respectively, because she knows he would have also measured +1 or -1 if he had measured in her direction. Therefore, she knows his true, underlying value of spin angular momentum is +1 or -1 along her measurement direction, so he should be measuring the projection of that true, underlying value along his measurement direction at $\theta$ to conserve spin angular momentum. Of course, Bob can partition the data according to his $\pm 1$ equivalence relation and say it is Alice who should be measuring $\pm \cos{\theta}$ in order to conserve spin angular momentum. It is impossible to conserve spin angular momentum exactly according to either Alice or Bob because they both always measure $\pm 1$ (in accord with the relativity principle), never a fraction. However, their results do average $\pm \cos{\theta}$ under these data partitions. It has nothing to do with momentum transfer with the measurement device. All of this follows strictly from the Bell spin state formalism.

 

[PeterDonis]

It is impossible to conserve spin angular momentum exactly according to either Alice or Bob because they both always measure $\pm 1$ (in accord with the relativity principle), never a fraction. However, their results do average $\pm \cos{\theta}$ under these data partitions. It has nothing to do with momentum transfer with the measurement device.

Sorry, these statements are simply false as a matter of what actually happens in an experiment. Measurement involves interaction between the measured system and the measuring device. That interaction can exchange conserved quantities. So it is simply physically invalid to only look at the measured systems when evaluating conservation laws.

 

[RUTA]

Sorry, these statements are simply false as a matter of what actually happens in an experiment. Measurement involves interaction between the measured system and the measuring device. That interaction can exchange conserved quantities. So it is simply physically invalid to only look at the measured systems when evaluating conservation laws.

The Bell spin states obtain due to conservation of spin angular momentum without regard to any loss to the environment. Therefore, the theoretical results I shared are independent of experimental uncertainties, which is what you're trying to invoke.

 

[PeterDonis]

The Bell spin states obtain due to conservation of spin angular momentum without regard to any loss to the environment.

How do you know? You're not measuring the exchange of angular momentum with the environment. That doesn't mean you can assume it doesn't happen. It means you don't know.

the theoretical results I shared are independent of experimental uncertainties, which is what you're trying to invoke.

I don't know where you're getting this from. There can't be any experimental uncertainty in something that's not being measured. The fact that measurement involves interaction between the measured system and the measuring device is basic QM. But it does not imply that all aspects of that interaction are captured in the measurement result. In fact they practically never are.

 

[vanhees71]

Sorry, these statements are simply false as a matter of what actually happens in an experiment. Measurement involves interaction between the measured system and the measuring device. That interaction can exchange conserved quantities. So it is simply physically invalid to only look at the measured systems when evaluating conservation laws.

I don't know, how often we have discussed these wrong statements in the forum. Should this really be part of the Insights?

 

[PeterDonis]

Should this really be part of the Insights?

I don't know. The point I have made is not one I have seen addressed in the literature. But that doesn't make it wrong.

 

[Lord Jestocost]

How do you know? You're not measuring the exchange of angular momentum with the environment. That doesn't mean you can assume it doesn't happen. It means you don't know.

If a particle's spin is "measured" along a certain axis, it will "exhibit" spin that corresponds to a vector parallel to the axis of measurement. The question is: Does a quantum spin "exhibition" actually impart quantum spin to the surroundings?

 

[PeterDonis]

The question is: Does a quantum spin "exhibition" actually impart quantum spin to the surroundings?

"Impart quantum spin" is too narrow; it should be "exchange angular momentum". Quantum spin can be inter-converted with other forms of angular momentum.

I would be interested in seeing any references in the literature to analyses of measurement interactions that address this question.

 

[vanhees71]

I don't know. The point I have made is not one I have seen addressed in the literature. But that doesn't make it wrong.

I didn't mean that you are wrong but the statements by @RUTA . We had extended discussions about this repeatedly!