A First loophole-free Bell test?

[atyy]

Superdeterminism would be of this type. Similarly a rejection of Reichenbach's principle of common cause: Once it is rejected, there would be no longer any justification to ask for realistic explanation of observed correlations. The tobacco lobby would be happy, no need to explain correlations of smoking and cancer, astrologers too, because the discussion about astrology would be reduced to statistical facts about correlations - are correlations between positions of planet with various things in our lifes significant or not, and the major point that there is no causal explanation for such influences would disappear.

Why would superdeterminism lead to giving up science? Couldn't one be a Bohmian and a superdeterminist? The Bohmian theory would be an effective theory, and the superdeterminist theory would be the true unknowable theory.

Also, couldn't one still make operational predictions if one gives up Reichenbach's principle? In quantum mechanics, we would still be able to say that a preparation and measurement yields certain correlations. So we would still be able to say that a preparation involving smoking, and a measurement involving cancer would still give the correlations.

 

[gill1109]

Why would superdeterminism lead to giving up science? Couldn't one be a Bohmian and a superdeterminist? The Bohmian theory would be an effective theory, and the superdeterminist theory would be the true unknowable theory.

Also, couldn't one still make operational predictions if one gives up Reichenbach's principle? In quantum mechanics, we would still be able to say that a preparation and measurement yields certain correlations. So we would still be able to say that a preparation involving smoking, and a measurement involving cancer would still give the correlations.

The problem with superdeterminism is that it isn't a theory. It doesn't make predictions. It doesn't explain how those correlations come about. It says they come about because the stuff in Alice's lab knows what is going on in Bob's lab, since everything was predetermined at the time of the big bang. You might like to call this theology. I don't call it physics.

Gerard 't Hooft believes that nature is completely deterministic at the Planck scale. He points out that we do not do experiments at the Planck scale. But he does not explain how determinism at this scale allows coordination between Bob's photo-detector and Alice's random number generator ... a subtle coordination which does not allow Alice to communicate with Bob instantaneously over vast distances but does keep their measurement outcomes and measurement settings mysteriously and delicately constrained, without their having any idea that this is going on.

 

[atyy]

The problem with superdeterminism is that it isn't a theory. It doesn't make predictions. It doesn't explain how those correlations come about. It says they come about because the stuff in Alice's lab knows what is going on in Bob's lab, since everything was predetermined at the time of the big bang. You might like to call this theology. I don't call it physics.

Yes, but is there any problem with believing in it and doing physics?

 

[gill1109]

Yes, but is there any problem with believing in it and doing physics?

I have no problem with what anyone else wants to believe. As long as weird beliefs don't get in the way of doing physics.

Did any good physics come out of superdeterminism?

 

[stevendaryl]

Why would superdeterminism lead to giving up science?

I wouldn't go so far as to say that it's impossible to do science in a superdeterministic universe, but it's a lot harder. We learn about the laws of physics by tweaking conditions and seeing how our observations are changed. To reason about such tweaking, we typically assume that our tweaks are independent variables. To give an example, if you're trying to figure out whether Skittles cause cancer in rats, you give Skittles to some rats and not to others, and compare their cancer rates. If (through some unknown mechanism), you're more likely to give Skittles to cancer-prone rats than non-cancer-prone rats, then such a test wouldn't say anything about whether Skittles cause cancer.

A superdeterministic explanation of EPR results might go like this: The electron/positron pair have predetermined, fixed spins. Depending on those spins, Alice and Bob are more likely to choose one setting over another. Superdeterminism casts into doubt our notions of what is the "independent variable" in an experiment.

As I said, I don't think superdeterminism necessarily makes science impossible, but it makes it much more difficult to understand what's going on in an experiment.

 

[atyy]

I have no problem with what anyone else wants to believe. As long as weird beliefs don't get in the way of doing physics.

Did any good physics come out of superdeterminism?

I was only arguing that there is no problem with believing in superdeterminism and being simultaneously a Bohmian and a Copenhagenist.

One needs some philosophy to do physics, eg. I am not a brain in a vat. Otherwise, quantum mechanics predicts that it is impossible for the Bell inequalities to be violated at spacelike separation.

 

[atyy]

I wouldn't go so far as to say that it's impossible to do science in a superdeterministic universe, but it's a lot harder. We learn about the laws of physics by tweaking conditions and seeing how our observations are changed. To reason about such tweaking, we typically assume that our tweaks are independent variables. To give an example, if you're trying to figure out whether Skittles cause cancer in rats, you give Skittles to some rats and not to others, and compare their cancer rates. If (through some unknown mechanism), you're more likely to give Skittles to cancer-prone rats than non-cancer-prone rats, then such a test wouldn't say anything about whether Skittles cause cancer.

A superdeterministic explanation of EPR results might go like this: The electron/positron pair have predetermined, fixed spins. Depending on those spins, Alice and Bob are more likely to choose one setting over another. Superdeterminism casts into doubt our notions of what is the "independent variable" in an experiment.

As I said, I don't think superdeterminism necessarily makes science impossible, but it makes it much more difficult to understand what's going on in an experiment.

I really don't understand why it would be any harder. Let's suppose our universe is superdeterministic. Experimental evidence shows that we already do science, eg. we developed and tested the Copenhagen interpretation of quantum mechanics. So if the universe is superdeterministic, experimental evidence shows that we have already overcome the hurdles that superdeterminism poses.

 

[stevendaryl]

The problem with superdeterminism is that it isn't a theory. It doesn't make predictions. It doesn't explain how those correlations come about. It says they come about because the stuff in Alice's lab knows what is going on in Bob's lab, since everything was predetermined at the time of the big bang. You might like to call this theology. I don't call it physics.

I don't think that's a fair characterization. One could just as well criticize Newton's laws of motion on those grounds: It doesn't make any predictions to say that acceleration is proportional to the force, if you don't know what forces are at work. That's true. Newton's laws are not a predictive theory in themselves, but become predictive when supplemented by a theory of forces (gravitational, electromagnetic, etc.)

The same thing could be true for a superdeterministic theory. Saying that superdeterminism holds doesn't make any predictions, but if you have a specific theory that allows you to derive the superdeterministic correlations, then that would be predictive.

 

[stevendaryl]

I really don't understand why it would be any harder. Let's suppose our universe is superdeterministic. Experimental evidence shows that we already do science, eg. we developed and tested the Copenhagen interpretation of quantum mechanics. So if the universe is superdeterministic, experimental evidence shows that we have already overcome the hurdles that superdeterminism poses.

I would say that the success of science so far (with the way that we currently do experiments) shows that the laws of physics can be usefully approximated by theories that are not superdeterministic.

 

[atyy]

I would say that the success of science so far (with the way that we currently do experiments) shows that the laws of physics can be usefully approximated by theories that are not superdeterministic.

And if there is another universe in which superdeterminism prevents science, then, well we don't live in it. It's a bit like the anthropic principle.

 

[stevendaryl]

And if there is another universe in which superdeterminism prevents science, then, well we don't live in it. It's a bit like the anthropic principle.

Well, if a superdeterministic theory can be usefully approximated by a non-superdeterministic theory, then we can certainly make scientific progress within that approximate theory in the usual way. The point is that if we want to go beyond that approximate theory to understand how the superdeterminism comes into play, it might require a drastically different way of doing science.

So it's not so much that superdeterminism would prevent us from doing science, but that the current way of doing science isn't likely to tell us much about superdeterministic theories.

On the other hand, superdeterminism only makes interpreting experiments more difficult, where the typical experiment involves intentional setting up certain conditions to see what the consequences are. But not all science involves that type of experiment. For example, astronomy is (almost?) exclusively passive observation. We don't get to put stars or planets into particular configurations to see how they evolve, we have to find instances where they are already in those configurations. I don't think that superdeterminism would have much change in the way such passive-observation science is done.

(My apologies if the word "passive" to describe astronomy is offensive. That wasn't my intention. I'm not sure whether there is a standard term for those sorts of fields where experiments are possible, such as physics, chemistry, biology, and the sorts of fields where experiments are not practical, such as astrophysics.)

 

[Ilja]

Yes, but is there any problem with believing in it and doing physics?

There is none, except that if superdeterminism "would be taken seriously", which was a condition I have made. Knowing human condition, and in particular the human ability to live with a lot of self-contradictions in what one believes, I would not think that there will be any problem in believing superdeterminism together with astrology, intelligent design and the catholic dogma and nonetheless doing physics.

There is, by the way, nothing wrong with this. It helps us to survive: Imagine we would follow what we believe consistently - in this case, we often would have to do quite stupid things, like, in the mentioned examples, to reject science. We usually don't do such stupid things, because the arguments for not doing such nonsense are strong and powerful enough. The result are contradictions in what we believe.

An excuse will be found, that's easy. Say, we reject Reichenbach's principle, because it would, together with the violation of Bell's inequality, require a hidden preferred frame, which is anathema. Do we, that's why, reject Reichenbach's principle consistently? This would mean, we could start to smoke without being afraid of cancer, because this is only a correlation, thus, does not require a causal, realistic explanation. This would be stupid, common sense is enough to tell us about this. So we continue to care about Reichenbach's principle in everyday life. Why don't we care in the case of the violation of Bell's inequality? That's quantum strangeness. Quote Feynman, nobody can understand this. Case closed.

 

[atyy]

There is none, except that if superdeterminism "would be taken seriously", which was a condition I have made. Knowing human condition, and in particular the human ability to live with a lot of self-contradictions in what one believes, I would not think that there will be any problem in believing superdeterminism together with astrology, intelligent design and the catholic dogma and nonetheless doing physics.

I did mean superdeterminism taken seriously. Does it lead to any actual contradiction? In other words, can you already rule out superdeterminism on experimental evidence?

 

[Ilja]

Why would superdeterminism lead to giving up science? Couldn't one be a Bohmian and a superdeterminist? The Bohmian theory would be an effective theory, and the superdeterminist theory would be the true unknowable theory.

Also, couldn't one still make operational predictions if one gives up Reichenbach's principle? In quantum mechanics, we would still be able to say that a preparation and measurement yields certain correlations. So we would still be able to say that a preparation involving smoking, and a measurement involving cancer would still give the correlations.

First, the usual studies do not use smoking as a preparation. It is purely observation of correlations between people smoking, for some periods, and lung cancer. Then, with superdeterminism a preparation would not give you anything. Because your act of preparing the experiment is superdetermined.

 

[stevendaryl]

An excuse will be found, that's easy. Say, we reject Reichenbach's principle, because it would, together with the violation of Bell's inequality, require a hidden preferred frame, which is anathema. Do we, that's why, reject Reichenbach's principle consistently? This would mean, we could start to smoke without being afraid of cancer, because this is only a correlation, thus, does not require a causal, realistic explanation.

Well, such philosophical principles (including Occam's razor and Popper's falsifiability) can be understood as "more of a guideline than a rule". Given two theories, you prefer the one that satisfies some cherished principle, unless it contradicts some other cherished principle. "Cigarettes are harmless" isn't considered, by people other than tobacco executives, to be a cherished scientific principle.

 

[stevendaryl]

First, the usual studies do not use smoking as a preparation. It is purely observation of correlations between people smoking, for some periods, and lung cancer. Then, with superdeterminism a preparation would not give you anything. Because your act of preparing the experiment is superdetermined.

As I said in another post, superdeterminism might call into question the notion of a "controlled experiment", but certain kinds of science can be done in spite of the lack of controlled experiments. We can figure out the evolution of stars, for example, even though we don't have any way of preparing a star with a particular mass and angular momentum.

 

[stevendaryl]

I did mean superdeterminism taken seriously. Does it lead to any actual contradiction? In other words, can you already rule out superdeterminism on experimental evidence?

I don't think that there is any way to rule out superdeterminism on the basis of experimental evidence. To rule out superdeterminism, you would need to show that things could have happened differently than they actually happened. But since we only get one "run" of the universe, I don't see how you could possibly show that.

 

[Ilja]

I did mean superdeterminism taken seriously. Does it lead to any actual contradiction? In other words, can you already rule out superdeterminism on experimental evidence?

No, superdeterminism simply does not allow to make any reasonable predictions, thus, is unfalsifiable.

My point was that this, taken alone, is not yet sufficient to reject a metaphysical principle. Because this is a quite typical situation for principles. For example, if one takes into account the possibility of yet undetected forms of energy, energy conservation would be empty too, as well as its rejection. So, I propose to reject superdeterminism not because it is unfalsifiable (even if it is) but because, if taken seriously, it would make experimental science a meaningless exercise.

 

[atyy]

First, the usual studies do not use smoking as a preparation. It is purely observation of correlations between people smoking, for some periods, and lung cancer. Then, with superdeterminism a preparation would not give you anything. Because your act of preparing the experiment is superdetermined.

I didn't mean to believe in superdeterminism and give up Reichenbach's principle together. Let's just give up Reichenbach's principle, and accept quantum mechanics and be agnostic about hidden variables. Then let's consider smoking to be the preparation - in the usual studies, this would be a mixed state of the different smokers with their different life histories and smoking habits. Then we could compare this with another preparation of non-smokers - that would be a different mixed state. So comparing the two mixed states, we would be able to show that cancer was more common in one preparation than another.

 

[atyy]

No, superdeterminism simply does not allow to make any reasonable predictions, thus, is unfalsifiable.

My point was that this, taken alone, is not yet sufficient to reject a metaphysical principle. Because this is a quite typical situation for principles. For example, if one takes into account the possibility of yet undetected forms of energy, energy conservation would be empty too, as well as its rejection. So, I propose to reject superdeterminism not because it is unfalsifiable (even if it is) but because, if taken seriously, it would make experimental science a meaningless exercise.

But if superdeterminism cannot be ruled out, then it is consistent with all available data.

Also, available data shows that science is possible.

So by logic, superdeterminism is consistent with the possibility of science.

 

[Heinera]

Another point is what would be the consequence of rejection: It could be that, once it is rejected, one would have to give up doing science, because, if the rejection would be taken seriously, no experiment could tell us anything nontrivial. Superdeterminism would be of this type.

With superdeterminism, would you actually have the luxury of choosing to give up doing science?

 

[Dale]

Closed pending moderation

Edit: the thread will remain closed. Everyone has had a chance to pontificate on their pet philosophy of the day.

 

[ZapperZ]

The Hansen et al. paper has now been published in Nature in this week's (Oct. 21, 2015) issue. As a reminder, the preprint can still be found on ArXiv, with the link listed in the first post of this thread.

Zz.