B Some questions about "superdeterminism" and Bell's Theorem

[jeremyfiennes]

I'm not sure whether this is the correct place to ask a simple question: are hidden variable theories inherently deterministic. I.e. given a unique initial state for a particle (position and momentum), do they predict a unique future state?

 

[Lord Jestocost]

I'm not sure whether this is the correct place to ask a simple question: are hidden variable theories inherently deterministic. I.e. given a unique initial state for a particle (position and momentum), do they predict a unique future state?

To answer the question, I quote Ethan Siegel (https://www.forbes.com/sites/starts...es-of-einsteins-scientific-life/#27dfd8888db4):

"... Einstein rejected the indeterminate, quantum nature of the Universe. This one is still controversial, likely primarily due to Einstein's stubbornness on the subject. In classical physics, like Newtonian gravity, Maxwell's electromagnetism and even General Relativity, the theories really are deterministic. If you tell me the initial positions and momenta of all the particles in the Universe, I can -- with enough computational power -- tell you how every one of them will evolve, move, and where they will be located at any point in time. But in quantum mechanics, there are not only quantities that can't be known in advance, there is a fundamental indeterminism inherent to the theory. ... But rather than accept these self-evident facts and try and reinterpret how we fundamentally view the quanta making up our Universe, Einstein insisted on viewing them in a deterministic sense, claiming that there must be hidden variables afoot. It's arguable that the reason physicists still bicker over preferred "interpretations" of quantum mechanics is rooted in Einstein's ill-motivated thinking, rather than simply changing our preconceptions of what a quantum of energy actually is. ..."

 

[jeremyfiennes]

Ok, thanks. I am aware that QM admits neither hidden variable theories nor predictive determinism. My question is: are all hidden variable theories by nature deterministic. Or are there some that do allow indeterminacy.

 

[PeterDonis]

are all hidden variable theories by nature deterministic.

In principle, it seems like you could certainly construct a hidden variable theory that was not deterministic. But since the usual reason for constructing them is to investigate the possibility of finding a deterministic theory that underlies QM (in order to interpret the indeterminism in QM as just due to our lack of knowledge of the full state in the underlying theory), I'm not sure what the point would be of constructing a hidden variable theory that wasn't deterministic.

 

[jeremyfiennes]

As I suspected. Thanks for confirming it.

 

[Demystifier]

I'm not sure what the point would be of constructing a hidden variable theory that wasn't deterministic.

Ontology. Even if physical theories are just a thinking tool and not a description of true reality, physicists like to think in terms of concepts which they imagine they are there even if they don't measure them. In that sense ontological models may be better thinking tools than non-ontological ones.

 

[Demystifier]

I'm not sure whether this is the correct place to ask a simple question: are hidden variable theories inherently deterministic. I.e. given a unique initial state for a particle (position and momentum), do they predict a unique future state?

The main reason for introducing hidden variables is not determinism but ontology. See also my post above.

 

[Zafa Pi]

To answer the question, I quote Ethan Siegel (https://www.forbes.com/sites/starts...es-of-einsteins-scientific-life/#27dfd8888db4):

"... Einstein rejected the indeterminate, quantum nature of the Universe. This one is still controversial, likely primarily due to Einstein's stubbornness on the subject. In classical physics, like Newtonian gravity, Maxwell's electromagnetism and even General Relativity, the theories really are deterministic. If you tell me the initial positions and momenta of all the particles in the Universe, I can -- with enough computational power -- tell you how every one of them will evolve, move, and where they will be located at any point in time. But in quantum mechanics, there are not only quantities that can't be known in advance, there is a fundamental indeterminism inherent to the theory. ... But rather than accept these self-evident facts and try and reinterpret how we fundamentally view the quanta making up our Universe, Einstein insisted on viewing them in a deterministic sense, claiming that there must be hidden variables afoot. It's arguable that the reason physicists still bicker over preferred "interpretations" of quantum mechanics is rooted in Einstein's ill-motivated thinking, rather than simply changing our preconceptions of what a quantum of energy actually is. ..."

I have several issues with this quote from Siegel you give.
1) Einstein's attachment to to local hidden variable was not ill-motivated. There was a couple of centuries of determinism and when he spoke of them in 1935 many agreed with him. It wasn't until 30 years later when Bell showed they were incompatible with QM and another 15 years until the definitive experiments.
2) His concern was not the indeterminate nature of QM (in spite of his statement of God's distaste of dice). It was that he claimed that QM was incomplete. At the time nothing was self-evident about QM nor would I say it is self-evident today. The double slit and Bell's Inequality are constantly brought out to show the unintuitive nature of QM, the opposite of self-evident. And then there is Feynman's famous statement that no one understands QM.
3) That people squabbling over which interpretations are preferable can be blamed on Einstein is nuts.
4) The sentence in bold above (paraphrased from Laplace) is "not even wrong".

 

[Lord Jestocost]

I have several issues with this quote from Siegel you give.
1) Einstein's attachment to to local hidden variable was not ill-motivated. There was a couple of centuries of determinism and when he spoke of them in 1935 many agreed with him. It wasn't until 30 years later when Bell showed they were incompatible with QM and another 15 years until the definitive experiments.
2) His concern was not the indeterminate nature of QM (in spite of his statement of God's distaste of dice). It was that he claimed that QM was incomplete. At the time nothing was self-evident about QM nor would I say it is self-evident today. The double slit and Bell's Inequality are constantly brought out to show the unintuitive nature of QM, the opposite of self-evident. And then there is Feynman's famous statement that no one understands QM.
3) That people squabbling over which interpretations are preferable can be blamed on Einstein is nuts.
4) The sentence in bold above (paraphrased from Laplace) is "not even wrong".

With all due respect, I don’t get the point. At the same time, other physicist were already looking much further ahead in their thinking than Einstein. Maybe, you should read Heisenberg’s memories of his talks with Einstein (in “Der Teil und das Ganze” by Werner Heisenberg).

 

[stevendaryl]

It's arguable that the reason physicists still bicker over preferred "interpretations" of quantum mechanics is rooted in Einstein's ill-motivated thinking, rather than simply changing our preconceptions of what a quantum of energy actually is. ..."

Einstein may have been motivated by the desire for a deterministic theory, but I think that the interpretation of quantum mechanics has more daunting problems than lack of determinism.

 

[Lord Jestocost]

Einstein may have been motivated by the desire for a deterministic theory, but I think that the interpretation of quantum mechanics has more daunting problems than lack of determinism.

I agree!

“Our result suggests that giving up the concept of locality is not sufficient to be consistent with quantum experiments, unless certain intuitive features of realism are abandoned.“ (S. Gröblacher et al., “An experimental test of non-local realism,” Nature (London), 446, 871 (2007))

 

[1977ub]

To me, some form of superdeterminism is the most logical. If one believes in cause-and-effect, then there are no "dice of god", no random number generators to inject randomness into the universe. I like this anonymous guy's thinking about determinism & superdeterminism. A determinist doesn't believe in some random free will to whimsically move the apparatus measuring angles either. These are events in the warp and woof of the universe.

Just search on the net for
"Von Neumann's Postulate and Bell’s Freedom"

 

[Zafa Pi]

With all due respect, I don’t get the point. At the same time, other physicist were already looking much further ahead in their thinking than Einstein. Maybe, you should read Heisenberg’s memories of his talks with Einstein (in “Der Teil und das Ganze” by Werner Heisenberg).

Do you have a link to an English translation of Heisenberg's memories not behind a paywall? I would be curious to read his recollections from decades earlier. You are most likely aware that Bohr disputed Heisenberg's account of conversations.

Many luminaries today not only consider Einstein's perspectives on QM were mistaken, but those of Bohr, Schrodinger, von Neumann, Planck, Rosen, Podolsky, et. al. as well. And there is much disagreement still, as this very forum reveals. That's why I like it.
It's a shame the brilliant Heisenberg didn't come up with Bell's argument in 1935 so we could have heard Einstein's reaction.

 

[Lord Jestocost]

Do you have a link to an English translation of Heisenberg's memories not behind a paywall?

No.

Many luminaries today not only consider Einstein's perspectives on QM were mistaken, but those of Bohr, Schrodinger, von Neumann, Planck, Rosen, Podolsky, et. al. as well. And there is much disagreement still, as this very forum reveals. That's why I like it.

Maybe, the paper "A Snapshot of Foundational Attitudes Toward Quantum Mechanics" by Maximilian Schlosshauer, Johannes Kofler, Anton Zeilinger might be of interest: https://arxiv.org/abs/1301.1069

 

[Zafa Pi]

Ontology. Even if physical theories are just a thinking tool and not a description of true reality, physicists like to think in terms of concepts which they imagine they are there even if they don't measure them. In that sense ontological models may be better thinking tools than non-ontological ones.

How philosophical, how Platonic! OK, hidden variables are a fluffy/dubious ontological thinking tool in the service of Einstein's "elements of reality". But your "true reality" is an even more gossamer ontological thinking tool in the service of allowing you to call out fluffy ontological thinking tools of others. :-)

 

[Blue Scallop]

Ok, thanks. I am aware that QM admits neither hidden variable theories nor predictive determinism. My question is: are all hidden variable theories by nature deterministic. Or are there some that do allow indeterminacy.

https://en.wikipedia.org/wiki/Hidden_variable_theory

"Although determinism was initially a major motivation for physicists looking for hidden variable theories, non-deterministic theories trying to explain what the supposed reality underlying the quantum mechanics formalism looks like are also considered hidden variable theories; for example Edward Nelson's stochastic mechanics."

So non-deterministic hidden variables are valid and not cooked up only as figment of imagination or thinking tools... but maybe it is valid to argue why call it hidden variables if it is non-deterministic.. so if you read some papers that give solid arguments for either.. do drop us a line.. thanks..