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To be precise, Bell's inequality rules out a local hidden variable theory. Pilot wave theories/Bohmian mechanics is an attempt to describe a nonlocal hidden variable theory of quantum mechanics.
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To be even more precise, it rules out hidden variable theories that satisfy Bell locality, i.e. the assumptions that the theorem makes.

Superdeterminism and retrocausality both allow for local hidden variables - it’s just that they don’t satisfy Bell’s assumptions.

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They're also generally regarded as weirder than the problem they are trying to solve.
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Intuitive notions of “weird” aren’t necessarily a good guide here. We already know time doesn’t behave the way we intuitively imagine, because of relativity: there can’t be universal agreement on what is past, present, or future. Once you’ve accepted that, retrocausality seems much less strange.

Similarly, superdeterminism is simply the application of the determinism that was believed to apply to physics before QM, to QM itself. In a way, one might have expected it to be the default interpretation.

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No? Superdeterminism says that there’s no way to pick your experimental choices in a way that reveals things because any possible random number sources you could use have contrived correlations that prevent that? Why would one ever consider that as “the default”?
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The strong belief before QM was discovered was that the universe was deterministic - that given sufficient knowledge of a physical system's present state, you could accurately predict its specific future states (not just possible future states.)

Laplace expressed this in "A Philosophical Essay on Probabilities" in 1814: "We ought then to regard the present state of the universe as the effect of its anterior state and as the cause of that which is to follow. [...] For [an intelligence that has sufficient information] nothing would be uncertain, and the future, as the past, would be present to its eyes."

Superdeterminism essentially extends this idea of deterministic physical evolution to quantum mechanics. It could be considered an appropriate default simply because it was previously considered to be, not only the default, but the strongly believed truth.

> Superdeterminism says that there’s no way to pick your experimental choices in a way that reveals things because any possible random number sources you could use have contrived correlations that prevent that

You're arguing against a consequence of superdeterminism, not its motivation. Its motivation is as I've described.

The word "contrived" is doing some heavy lifting in your statement. Nothing needs to be contrived in superdeterminism, even if it seems that way to an observer within the universe.

The explanatory problem you've alluded to only arises because we're trying to understand the universe from within the universe. The universe is under no obligation to make itself sensible to us.

Essentially, you're saying little more than that you don't like the idea of superdeterminism.

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Can you explain how determinism applied to quantum mechanics results in superdeterminism? I feel like you've just skipped over an important step here. Determinism isn't a controversial idea, and indeed in QM the wavefunction is fully deterministic anyway, it's only interpretations which require a collapse where non-determinism appears. I can understand roughly why the many worlds in MWI are a consequence of assuming the wavefunction is reality and that there is never a collapse, I do not understand how you get to the consequences of superdeterminism from applying determinism to quantum mechanics.

(And yeah, preference for any of these interpretations will essentially boil down to what idea you like the most, or more likely what idea you dislike the least. With QM you pick your reasonable base assumptions and then take the uncomfortable conclusions that result)

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I've got a feeling that our intuitive ick around spooky action at a distance is due to out intuitive view on locality and the nature of space, maybe time too, being wrong. IOW remote is really not remote.

Perhaps we've got it backwards and quantum entanglement is what defines "locality" rather than mysteriously existing in the face of it.

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Ironically everyone assumed non spooky action at a distance for most of human history, until relativity.
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it doesn't if you assume superdeterminism
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I don't understand the superdeterminism idea. Wasn’t that already the classical/Newtonian view - that everything was predetermined, a universe of billiard balls following their destiny exactly?
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Newtonian is just plain determinism. One thing causes another, but does not imply things are fixed in any particular way.

Superdeterminism implies that things are fixed in advance in such a way that the things we "choose" to measure always looks as if there are no local hidden variables (e.g. Bell's inequality) even though there are.

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No, they are completely different. Determinism is the idea that if you have a perfect snapshot of the universe at one time, you could run that snapshot forwards or backwards using the laws of physics and have a complete history of the entire universe. It's a valid scientist idea, but Bell's Inequality experiments pretty much prove it false by showing that either realism or locality is false, and you kind of need both to have determinism.

Meanwhile, superdeterminism is the idea that you can still have realism and locality by claiming that Bell's Inequality experiments are invalid because the universe could somehow "know" you are performing a Bell's Inequality experiment and rig it to get the "wrong" answer. Superdeterminism is equivalent to saying that we can't prove smoking causes lung cancer, because the universe might rig any science experiments to make it look like smoking causes cancer. Anytime you ask why the universe would do that or how you can prove anything in such a universe, they shrug their shoulders. It's a completely BS idea that got traction because specific people pushed it and others don't understand quantum physics enough to know how unserious of an idea it is.

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You can imagine the general idea by imagining the state space of a bunch of billiard balls: their position and velocity in a 6D space.

This is a metaphor and not the state or experiment that superdeterminism seeks to answer. I am also speaking well outside the areas of physics I was trained in. So huge grain of salt.

In classical determinism, the trajectories of all billard balls can be derived precisely from their initial conditions. Due to sensitivity to initial conditions and our ability to know them precisely, we can see chaotic mixing behavior where the trajectory of even two billiard balls that start at nearly the same place become more and more uncorrelated as time goes on as they bounce around and into each other. One expects that many accessible observables and functions loose detectable correlations as this billiard ball universe goes on and the billiard balls go on to roughly fill the full 6D state space up to conservation of momentum.

Now imagine the weirder scenario, that there exists some function and statistical comparison you can make between state variables from sets of billiard balls. Although these state variables themselves seem uncorrelated after enough time has passed, there are these properties that always hold with perfect correlation even after infinite chaotic time bouncing around. The points in state space that the balls cover is restricted to some manifold where these statistical properties are true when checked. The system cannot evolve in a way where those correlations of bulk quantities would disappear.

In this toy metaphor it’s not so horrifically odd. Superdetermism gets more flak because: (i) the state space and property in question is so much weirder and more complicated than the kinematic example, the correlations are between objects that measure and the objects being measured! (ii) if these properties are always true under any check we can make there is no way to falsify. Then it doesn’t matter if the behavior is from some unimaginable underlying universal state space geometry or local quantum effects. This same argument could also be applied more generally and inappropriately to reduce any experiment to “that’s just the way the structure of the universe is”.

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It's quite deeply weird. It's basically looking at the seemingly impossible correlations that occur in quantum mechanics and saying that they happen because the decision about what to measure is correlated with the state of the system somehow (Bell's inequality assumes that these are independent). This is very strange in a universe where we apparently could base that decision on many different seemingly unrelated processes. (including processes that have been causally seperated for near the lifetime of the universe, e.g. by choosing the measurements based on noise in the CMB).
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If you saw that in section 15, the very next paragraph covers Bell.
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