Yes, I’m taking “a totally different direction”.

Going back to your concerns about subjectivity (#147), what you call the “subjective trap”:

What one can infer about the world depends on the model one is using. The equations that represent the laws of nature represent relationships; they can’t be used to represent subjectivity: subjectivity seems like an aberration.

But the symbols used in computer algorithms, like IF, AND, OR, IS TRUE and THEN, are a natural fit if one wants to represent subjectivity, and one could still retain relationships (i.e. laws of nature). These symbols can be used to represent perception of situations a subject faces, and the response to situations.

This subjectivity would have to be an inherent part of the system as a whole, it would be a system of subjects. Inherent subjectivity (and agency) would seemingly make the world more like the world of the quantum mechanics models. But, this view would conflict with some people’s deeply held beliefs about the nature of the world. However, subjectivity can’t exist if the world is fully describable by the type of equations that represent the laws of nature.

One can’t ever “escape the “subjective trap””, because living things are subjective. The problem is the model. Equations can’t ever model a world of subjects and agents; I think one needs to model the world using the type of symbols used in computer algorithms, while still retaining laws of nature.

Re “Does a tree falling in the forest make a sound?”: Of course, it doesn’t make a sound. Physical sound waves don’t have a sound. Sound is the conscious experience of sound waves: the experience of sound requires consciousness, as well as functioning sound detectors (ears). But there is no mathematical relationship connecting physical sound waves with experienced sound, just like there is no mathematical relationship connecting light wavelength with experienced colour. Consciousness/ subjectivity/ experience is a different type of thing, and one needs to use different types of symbols in an attempt to represent it.

]]>Yes, I agree with you … “illusion” was a poor word choice! Maybe fabrication? In any word, you are certainly correct that our model maps successfully enough to the world in the sense that it allows us to navigate the world at our level of interaction/abstraction … which pretty much was the goal of evolution, right? In saying that … it seems obvious that whatever our model of cognition (C) might be it is at least strictly contained (like a proper subset) in the model running the universe (U) (if we presume that the universe is running *like* a computational model, that is). And maybe we could say that evolution/life was/is *aiming for* achieving a model (class) of computation that is at least equal to the class of computation running in/on the universe.

Could evolution evolve a model in our cognition so that the class of the universe would be strictly contained within the class of the model of our cognition? Since the model of our cognition must *run on or in* the model of the universe … then I think complexity theory tells us, no. At best then, evolution could equal the class of computation running the universe. However, the “model” of our cognition, while it could be of an equal “class” as the model running the universe, it may be much weaker in practical performance. For example, both the Fugaku supercomputer and the Digi-Comp II have the same “class” of computation … but classical computation is realized in them in very different models of classical computation with very different practical results 🙂 We have no reason not to expect that for the “quantum” class of computation that there will also be different models of quantum computation that are extremely different in practical performance.

So I’m contending that we need to work out which part of a model is what people are doing, and which part of a model is what the “external” world is doing.

I would like to hear more about this idea. I don’t understand.

Probably a totally different direction … But this reminded me of a thought that I once had … When thinking early on about computers I had the eerie feeling that the computers required me to observe their output in order for what they were doing to be considered “computing”. After all … it’s nothing but voltages, currents, EMFs, and semiconductor devices, right?! So, if the transistor doesn’t *really know* that it is representing a value from the set {0,1} … then who does know this?? or where is it known??

This is of course the “Does a tree falling in the forest make a sound?” philosophical paradox/problem. The resolution requires us to agree on a definition. And as Godel was quick to correctly observe, it was Turing who gave us the definition of “what does it mean to say something is computing.” That way we can say that if a “computer” multiplied 18*343=6174 then it wouldn’t matter whether that was done with a Commodore F4146R, the Fugaku supercomputer, the Digi-Comp II, GPT-3, the IBM Eagle r1 quantum processor, or a human being with paper and pencil … in all cases it’s “a computer computing”. Of course, the class of computation and the models of those classes realized physically can vary *enormously* in their practical performance 😉

Again, you are probably going in an entirely different direction! Which I would enjoy hearing about. Thank you for your interesting comments.

]]>“Of course you do – “P1: B0=B1”

This is the third time I have to explain this elementary logical deduction. You want locality, so you want the state of B NOT to change when A is measured. If the state of B does not change it has to be the same, so B0=B1, therefore B0=B1 FOLLOWS from the locality assumption. I don’t assume B0=B1 from the start. If B0 does not equal B1 it means the B changed as a result of the distant measurement at A, so a non-local physical effect occurred. What could be simpler than that?

Can you please explain me how it is possible for B not to change, while B0 is different than B1?

GHZ is another experiment. You need to understand EPR first in order to properly interpret GHZ.

I have already debunked Mermin’s take on locality in #154. You agreed with me:

“That quote from the QBists about timelike vs spacelike correlations is indeed nonsense”

Yet, you failed to replace that nonsense with something better. Why is that? By no means, find a proper local explanation for EPR by Mermin or Werner, or any other physicist you admire and we’ll see how coherent it is. I predict you will come empty-handed.

]]>“Are you serious?”

Of course I’m serious.

“I don’t make such an assumption either.”

Of course you do – “P1: B0=B1” – and for pity’s sake please just watch that Mermin lecture video about GHZ or something. This is all quite *elementary*.

“Your argument isn’t a “rock solid logical deduction”, it’s a non sequitur.”

Really? Are you saying that from:

B1=B0 and B1=spin DOWN it does not follow that B0 must also be spin DOWN? Are you serious? Where is the non-sequitur?

“Copenhagen interpretations simply don’t need to and don’t assume that definite values found / measured must have been there all along;”

I don’t make such an assumption either. The only assumption is locality, that the measurement at A does not disturb B. The necessity of the preexisting definite values is the conclusion of the argument. As long as you don’t deny any of the premises (and you didn’t) you have to accept the conclusion.

The argument works perfectly regardless of your assumptions about the state of B. You can assume there is no B at all, or that it is undefined, or that it is a pink 6-dimensional rabbit, whatever. The problem is that locality requires that the A measurement does not disturb this state. But then QM tells us what the state of B is after the A measurement. It’s a spin eigenstate (spin-DOWN in our case). So, locality + QM forces us to accept that the pre-mesurement state has to be spin-DOWN as well. The superposition simply describes our incomplete knowledge about the system. Such a view is not naive, it’s the only logically consistent view that is also local.

]]>That quote from the QBists about timelike vs spacelike correlations is indeed nonsense but it doesn’t detract from the fact that, as is well known, neither QBism nor any other [neo-]Copenhagen interpretation is “nonlocal”. See those papers by Werner I linked to in the Quanta Magazine comment, or Landsman’s book or Rovelli’s take on this issue or Griffiths’ or Gell-Mann’s or Mermin’s in that video I linked or the other comments of mine in that Quanta article or…

Your argument isn’t a “rock solid logical deduction”, it’s a *non sequitur*. It fails to take into account that [neo-]Copenhagen interpretations simply don’t need to and don’t assume that definite values *found / measured* must have been there all along; that they are/were “possessed values”. They just don’t subscribe to that naive, classically motivated metaphysical prejudice (“Realism_2 (=C)” as Werner puts it).

Thanks for a very interesting discussion!

„Does the EPR argument then suggest that we should discard the “no-superdeterminism” assumption in the “local friendliness” theorem?”

I think that a true theory must pass all arguments. The EPR argument proves that there are only two options:

1. Non-locality

2. Deterministic hidden variables.

If we take into account the implications of Bell’s theorem we remain with:

1. Non-locality

2. Superdeterminism

I cannot say that one must accept superdeterminism, since the non-local option is still available, but, given the importance of relativity for both QM and GR I think superdeterminism is the most reasonable option.

„Superdeterminism (determinism with pre-existing correlations between the systems being measured and the measurement settings and/or observers) I concede undercuts subjective interpretations!”

I am not sure what the subjectivity of those „ subjective interpretations” is supposed to achieve. The assumption of objectivity does not enter anywhere in the EPR argument, as presented in post #148, so its denial cannot possibly avoid the conclusion of the argument, which is that only deterministic hidden variable theories can be local. Of course you could have subjective non-local theories or subjective hidden variable theories, but what’s the point?

„If you are not advocating for superdeterminism, then … where do the measurement settings come from?”

I do consider that superdeterminism is indeed the most reasonable option.

„It is fascinating that we have actually been able to conceive of an experimental protocol that forces us into these two “radical” positions, either

(A) Superdeterminism, or

(B) Subjectivism„

Again, I don’t see where „subjectivism” appeared as an option. It’s not, it is just a different property a theory could have, a property unrelated to the issue of locality. The two options are 1. Non-locality and 2. Superdeterminism.

What does IOCH mean?

„I guess what bugs me about Superdeterminism is … It feels like it actually violates the “extraordinary claims require extraordinary evidence” rule.”

Well, it does not. Unfortunately many scientists associate superdeterminism with some finely tuned initial state, at the Big-Bang. Scott is one of them. I have no idea where this originates, since no superdeterminist proposal (’t Hooft Cellular Automaton Interpretation, or Stochastic Electrodinamics) postulates such a thing.

In the context of Bell’s theorem superdeterminism implies that the states of the particle source and detectors are not independent. They are correlated in some way. This is all.

The fact that some distant physical systems are correlated is not something extraordinary.

Choose two stars in a binary system. Their position and momentum are correlated, since they orbit around the common center of mass, in the same plane, and their orbits are ellipses. The explanation for this correlation has nothing to do with some special conditions at the Big Bang. It’s a consequence of how gravity acts (the inverse square law). No initial condition would generate square orbits.

In the general case of a system of N interacing objects, the state of the system would be a solution to the corresponding N-body problem. None of the N objects would have a state independent of the rest, since the solution to the N-body problem depends on all N objects.

What about a Bell test? The source and detectors are made out of atoms, so electrons and nuclei. They are charged particles, so they all interact electromagnetically. The outcome of a Bell test must be a solution of the corresponding N body EM problem. So, the state of the source (which in turn determines the hidden variable) is not independent on the states of the detectors. So, Bell’s independence assumption fails. All particles in the experiment interact, so you need to consider all of them.

Since any experiment involves electrons and nuclei, and they all interact electromagnetically, at any distance, we have a proper justification for the claim that superdeterminism (pre-existing correlations) are to be expected in the general case. There is nothing extraordinary about that.

There is a regime where independence is true, to a very good approximation, the Newtonian/macroscopic regime. When you are interested in macroscopic properties, the microscopic correlations between electrons and nuclei are hidden in the statistical noise. Large objects consisting of same number of positive and negative charges approximate very well non-interacting objects, at least when they are far away. This is why we can assume independence in medical tests. And this is why superdeterminism does not conflict with the scientific method. You should expect correlations at the fundamental level (where they indeed manifest as the so-called quantum contextuality), but you should not expect them at the so-called classical level.

]]>„The QBists have themselves pointed out why QBism – and QM more generally – isn’t and doesn’t need to be “nonlocal”.”

Sure they did, it’s just that they are wrong. Let’s see how Qbists argue that their interpretation is local. I quote the paper you linked:

„An Introduction to Qbism with an Application to the Locality of Quantum Mechanics”, page 4:

„Quantum correlations, by their very nature, refer only to time-like separated events: the acquisition of experiences by any single agent. Quantum mechanics, in the QBist interpretation, cannot assign correlations, spooky or otherwise, to space-like separated events, since they cannot be experienced by any single agent. Quantum mechanics is thus explicitly local in the QBist interpretation. And that’s all there is to it.”

But of course, the space-like events can be experienced by the agent at the moment this agent looks on the experimental records received from the A and B labs. Sure, he does not experience them in real time, but then what? Whould a Qbist deny the correctness of experimental data collected by two distant computers located at A and B? If so, Qbists would be unable to do any science.

The time when the agent looks on the experimental records is completely irrelevant. What he needs to do is explain those experimental records acquired at the time they were acquired. And, as proven by my version of the EPR argument presented in my comment #148, such an explanation involves either non-locality, or the existence of deterministic hidden variables.

Or take a classical measurement of the speed of some object. The Qbist would record the initial position, X0, at time T0 and the final position, X1, at time T1. The velocity of that object would be given by the formula (X1-X0)/(T1-T0). Say the result is >10^10c. What would our Qbist say? That the speed is still <c because he cannot experience space-like separated events?

„The idea that non-disturbance implies predetermination is simply wrong.”

On the contrary, it’s a rock-solid logical deduction. Let B0 be the state of B before the A measurement and let B1 be the state of B after the A measurement. If the A measurement does not disturb B we have:

P1: B0=B1.

But we know from the A measurement that:

P2: B1=spin DOWN on Z.

From P1 and P2 it necessarily follows that B0=spin DOWN on Z. The measurement result was predetermined.

I see that you linked a very long article dealing with the EPR argument. If you think you can find a rebuttal of my argument in there, please be more specific. I don’t see anything about ping-pong in there either.

]]>As it happened to be I was reading the histories [0] only a week or so ago and came across an answer to whether Einstein refuted von Neumann’s proof on page 68. Abner Shimony relates a story told to him by Peter Bergmann about one time Bergmann asked Einstein for his opinion on the proof. Apparently Einstein was quite familiar with it and fetched von Neumann’s book, pointed to one of the assumptions, and said there was absolutely no reason to believe that the assumption should hold in general for all alternative theories. However Einstein never published this criticism, with the authors suggesting that because von Neumann was very careful in his wording of the proof not to claim too excessively, Einstein didn’t see the need to publish a criticism of something von Neumann never specifically claimed (although even to this day there’s still arguments in the literature to what exactly von Neumann said and meant[1]; I suppose it’s just another one of many things that we unfortunately never got clarification from von Neumann from because he died so early). On Bohr, I am sure he would have known of the proof but if I remember correctly reading somewhere else he did not use it specifically in his arguments (although others in the Copenhagen school did).

[0]: https://link.springer.com/chapter/10.1007/978-3-662-05032-3_6

[1]: https://arxiv.org/abs/2105.13996