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Comment by herdcall | Hacker News Reader

Check out "superdeterminism," first proposed by Bell (of Bell's inequality fame) himself and currently being vigorously pursued by Sabina Hossenfelder. There is no "collapse" per se according to this model and everything is really classical with hidden variables, and the entanglement comes because everything shared the same origin (the big bang). A very fascinating and in my opinion the best explanation, though it's extremely controversial and taboo because of its implications on free will (e.g., I see no mention of it at all in this article).

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I have never fully understood that idea, even after reading Hossenfelder's posts about it. The idea that there's a "block universe" and everything is predetermined is comprehensible, sure; but what's the exact mechanism by which Bell's inequality is violated in experiments? Doesn't that require the universe to have been carefully set up to look as if it's acting in a weird non-local way, on an experiment-by-experiment basis? I assume I am just misunderstanding the idea, though. Any suggested reading material much appreciated!

Agreed — superdeterminism is not so much a theory as a theory-for-a-theory at this stage (a vague guess at the form such a theory might take).

It is a sign of the much greater maturity of the physical collapse models that their parameters can be constrained by experiment. The ability to be constrained is a good sign, not a bad one.

I love John Preskill’s standard nod to superdeterminism in his writings: without mentioning it by name he says “I leave it up to the reader to decide how seriously to take this possibility” (get it?)

I think the right way to look at it is that superdeterminism is an umbrella term for a class of theories that have a certain property. Like some interpretations of quantum mechanics are "psi-ontic", meaning the wave function is considered physically real (like many worlds), vs. "psi-epistemic" where the wave function is considered a reflection of our knowledge of reality (Copenhagen).

We had a recent thread about an article from Tim Palmer who has a good take on this:

https://news.ycombinator.com/item?id=33223391

The idea is that the natural laws are fractal, which when mapped out trace many state space configurations. But with a fractal there are always gaps in state space that remain no matter how much you zoom in or out; fractals preserve certain structural invariants at all scales.

So the idea is that counterfactual reasoning sometimes fails in a fractal universe, because statistical independence no longer works as a general rule (your counterfactual could lie in one of those gaps). He first published this idea in 2009 under the name "invariant set postulate":

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

His paper with Hossenfelder is also a good overview:

https://www.frontiersin.org/articles/10.3389/fphy.2020.00139...

Superdeterminism gets an unnecessarily bad rap.

Superdeterminism gets an unnecessarily bad rap.

If determinism is true, don't you mean "necessarily"? :)

> Doesn't that require the universe to have been carefully set up to look as if it's acting in a weird non-local way, on an experiment-by-experiment basis?

Yes. That is a big reason why most physicists do not favor superdeterminism.

I am not so sure. In my understanding of the block universe, causality doesn't really exist, and the universe is simply a consistent solution with boundary conditions both at the beginning and at the end of time (as well as in space).

The game of life is perhaps a nice analogy here. On the 2d grid of the game of life, a glider seems moving in a certain direction when time moves forward. But in the 3d grid, where time is the third dimension, a glider is just a static volume of space.

The reason we experience time is that the evolution of the block universe does depend on the dimension you look at (e.g entropy generally increases in the positive time dimension), and because our consciousness is an emergent property of a self-sustaining structure within the block universe, it's plausible at least that we perceive movement in time different from movement in space. I realize this is very sloppy wording but I'm having trouble finding better words to describe my intuition here.

> In my understanding of the block universe, causality doesn't really exist

That's one way of interpreting it, but superdeterminism does not entail or require this. Superdeterminism can be formulated just fine for a universe that evolves in time from some initial state according to causal processes.

> what's the exact mechanism by which Bell's inequality is violated in experiments?

It’s not violated - it simply doesn’t apply because it’s predetermined that the measurements that are done work well together. The experimenters follow the script.

That a serious scientist can believe this leads me to consider the economic benefits of believing such nonsense, rather than prompting me to examine it further. Just total rubbish

We should be merciful with superdeterminists: they don't have a choice!

> though it's extremely controversial and taboo because of its implications on free will

Uhh, no. Essentially all existing physical theories are devastating for any non-compatabilist account of free will.

I get the impression that physicists who advocate “superdeterminism” are ignorant of the philosophical literature on “determinism” - because from a philosophical viewpoint, there is nothing “super-“ about their position, it is just plain old “determinism”.

Advocates of superdeterminism aren't always in favour of the term. Its most notable advocate, Hossenfelder, disapproves of the term, believing it to be misleading. She suggests the term 'implicate order' (crediting Bohm) be used instead.

Exactly. Even if you dispense with hard determinism and allow randomness in your theory, pure randomness is not really free will.

Free will is also incoherent in any religion or philosophy presupposing a bi-omni deity (which itself is an incoherent notion).

The point, that many ignore, however is that, free will does not matter. It is irrelevant. Regardless of whether one has free will or not, one still has to make choices and support the consequences of said choices. Lack of free will was never the get out of jail free card some fear it to be.

If you bring in to the discussion sociology and psychology, free will makes even less sense.

> it's extremely controversial and taboo because of its implications on free will (e.g., I see no mention of it at all in this article).

"True" free will is ruled out by all existing physical theories, so that's not why it's controversial. The bigger problem with superdeterminism is that it wants to explain physics without assuming statistical independence, even for far away events.

Even without superdeterminism free will is a concept that only makes any sense in specific contexts. To say otherwise is to introduce God of the Gaps style woo.

Free will is about choosing what binds us, as we can't choose being free of matter without becoming inmaterial.

The notion that a probabilistic world enables free will in a way that a deterministic one doesn't still confuses me. A coin I flip isn't exercising free will.

Could free will be explained as super-physical phenomena that "haunts" the physical world, w/ choice manifest as which of the branching many worlds' paths consciousness "chooses" to experience?

E.g., I am in some universe taking every possible action right now, but I'm only experiencing the actions which I "chose" to take.

What is the point of such a theory besides trying to relieve us from the uncomfortable idea of many worlds? It is no better at explaining our perceived world than the simpler theory that consciousness exists across all these states and we aren't following some particular path through them. All states of conscious existence are being perceived and the perception of it being a coherent path through time is just an illusion created by memory and the similarity of adjacent states.

Furthermore it still removes any actual willed choice of path within the context of our existence. I am not some meta-entity seeing all possible paths and choosing one for some unknown reason. That would be an existential alien "haunting" me and not "free will".

I am trying the reconcile the feeling of free-will we experience with its evident absence, per the theory.

(Of course, you could also just say the feeling is an illusion.)

I don't know if you can ever answer it one way or the other, because while consciousness certainly exists (again a fact I believe just because I feel it), it can't in any way influence the universe, at least per current theories of physics.

On the other hand, if you're right that many-worlds is real and our consciousness persists in all of them, then we will, individually, come to realize that is the case, as find ourselves still alive, forever, ever more improbably (since, I think, the odds of dying would never be 1, so you'll always be alive in some lucky world).

Consciousness does influence the universe by being part of it. That's why we have the illusion of choice within the context of each moment rather than some meta-alien's perspective. But no it can't defeat determinism if that's what you meant.

I believe someone called that idea "quantum immortality" and I find it conceptually interesting if not somewhat terrifying. However it does seem like the inevitable conclusion of these ideas.

> Consciousness does influence the universe...

I'm not sure I'm following the argument. Let me phrase it this way: can you devise an experiment which will determine if a given entity is conscious?

> I believe someone called that idea "quantum immortality"

(Thanks for the term; I'd heared the idea expressed before, but not that phrase.)

Skimming the wikipedia page, I didn't find any of the counter-arguments to be particularly compelling.

So, while I'm not sure how deeply I believe it (simply because it feels very unintuitive -- and I'm definitely not about to try to kill myself to test it!†), I agree with you: it really does seem like the inevitable conclusion of these ideas; I also agree it's somewhat terrifying!

Especially when you consider that as time goes on, probably in the majority of the universes where you are alive, you are just barely alive, in great pain. The only consolation is that, perhaps, you'll still have enough awareness to think to yourself, "incredible that I haven't died yet -- I guess many-worlds really is true!"

(† Even if you are knock-down 100% convinced in quantum immortality, you probably still don't want to engage in wildly risky behavior or try to kill yourself -- because you will be killing yourself in a large number of universes, and causing a lot of pain to your loved ones in those universes. A similar argument could be applied to engaging in any sneaky behavior which would cause significant pain if discovered.)

> can you devise an experiment which will determine if a given entity is conscious?

No, without being able to define what consciousness is we can't make an experiment to test for it. The simplest explanation in my view is that qualia are a base "element" of the universe and information systems and our consciousness is a loosely drawn subset of qualia associated with our brain/body's information system. To be clear this is not dualism, the qualia are not some magical thing riding on top of physics and cannot change the path of particles from their physically determined routes.

Regarding quantum immortality I don't know if it necessarily demands a universe in which some form of every person lives forever by some unexpected chance of quantum improbability. At least in terms of a continuity of normal life it may be that the probability of a person living longer than a human body physically can is zero. However some have argued there is a non-zero chance that random quantum fluctuations could lead to brief instances of a person arising from "nothingness" anywhere and anytime in the universe, and some of those persons could by pure luck happen to match the mind of a person elsewhere. However this does start getting into the realm of silliness and quantum randomness and infinite universes allowing for literally every possible combination of particles.

Well, I'm not sure how you square that definition(ish) of consciousness w/ the claim that consciousness can influence the universe. Because, how?

Yeah, intuitively somehow it seems absurd to think that "everything possible is happening", somewhere, in some dimension. It almost feels like a modern version of Zenos paradox. Like, in the limit, there are no universes in which you're alive...

Is superdeterminism even falsifiable?

Is Many-Worlds even falsifiable?

David Deutsch seems to think that a general intelligence running on a quantum computer ought to be able to observe itself existing in parallel worlds if many-worlds is true.

I'm skeptical that Deutsch actually meant that, but even smart people have crazy ideas.

He wrote a pretty well known article about it that as far as I can tell wasn’t written off-hand and hasn’t been retracted or disavowed. I’m pretty confident he meant it.

There has to be some misinterpretation going on here (or David Deutsch just hasn't thought this through). You can have a quantum computer in a superposition of states, but that isn't many worlds; to have many worlds, the computer has to interact with the outside world and split the outside world into a corresponding superposition of states. Such interaction with the outside world prevents a quantum computer from functioning - and it's precisely such information leakage to the outside world that is a major difficulty when trying to scale up quantum computers.

Which sadly means nothing, so many details being hidden behind the words "general", "intelligence", "running", "quantum computer", "ought", "oberve" and "existing".

If you could refine what these words all mean, I guess we could understand it as something more than "Deutsch seems to think that yes", which can replace your sentence entirely, "yes" describing it all as precisely.

I am myself, in some ways, a general intelligence running on a quantum computer but I dont feel like I can observe myself existing in a novel special way. Let alone being able to then express it for you in a way that is novel as well.

Most of those words don’t cause definitional problems here any more than they do for all other scientific tests which involve general intelligences (humans) making observations about things that exist. “Quantum computer” is a unique term that doesn’t show up in every description of a scientific experiment, but as far as I know it doesn’t have a particularly ambiguous definition.

And while you are indeed a general intelligence, I don’t think you’re running on a quantum computer.

> observe itself existing in parallel worlds if many-worlds is true

If many-worlds is true, we are already observing ourselves in each of those universes in which we can observe, we just don't communicate with our replicas. And if the AGI can communicate with its other instances, the exponential replicas will quickly overload their channel.

I think the point of the claim is that a general intelligence running on a quantum computer would make different observations if many worlds is true versus if many worlds is false.

Discovery of non-linearity in the evolution operator would falsify MWI. Like e.g. this germanium experiment gave a positive result.

Yes, because it falsifies every interpretation of quantum mechanics not just MWI itself. I think in context here, "is superdeterminism falsifiable" is as silly a question as "is logic falsifiable" or "is causality falsifiable". Specific mmathematical, causal or superdeterministic models are always falsifiable, but the idea that superdeterminism as a whole is not falsifiable should be no more surprising or interesting than the fact that logic is not falsifiable.

If superdeterminism allows specific models. The idea is that the experimenter's behavior is fine tuned so he can't discover superdeterminism, which means falsification would be a paradox by definition.

Given we can enumerate all possible models because we can enumerate all possible Turing machines, we clearly have enough degrees of "freedom" in this universe that that isn't an issue.

> Specific mmathematical, causal or superdeterministic models are always falsifiable

I request further elaboration here, please. Examples would be great.

> than the fact that logic is not falsifiable

What?

There is non-linearity in the evolution operator though - it's called gravity. It's why MWI in its trivial form is falsified - though with a linear theory of everything (potentially string theory) - it might be possible.

Hopefully this is on point https://www.lesswrong.com/posts/DFxoaWGEh9ndwtZhk/decoherenc...

Yes. You could, for example, allow a measured particle to interact with an isolated measuring apparatus of varying size - from a few atoms to a macroscopic object - and see how the size affects the system - so you get evidence of decoherence?

Also, many worlds interpretation as it currently exists is already falsified by its incompatibility with gravitational nonlinearity.

't Hooft's version of superdeterminism, according to his book, can be falsified by demonstrating a large scale quantum computer. I don't know if Hossenfelder's version is something different or how she would account for this.

> Check out "superdeterminism," first proposed by Bell (of Bell's inequality fame) himself

“Proposed” - but as something that avoids the issue but it’s not worthy of much consideration.

  - I was going to ask whether it is still possible to maintain, in the light of experimental experience, the idea of a deterministic universe?

  You know, one of the ways of understanding this business is to say that the world is super-deterministic. That not only is inanimate nature deterministic, but we, the experimenters who imagine we can choose to do one experiment rather than another, are also determined. If so, the difficulty which this experimental result creates disappears.

  - Free will is an illusion - that gets us out of the crisis, does it?

  That's correct. In the analysis it is assumed that free will is genuine, and as a result of that one finds that the intervention of the experimenter at one point has to have consequences at a remote point, in a way that influences restricted by the finite velocity of light would not permit. If the experimenter is not free to make this intervention, if that also is determined in advance, the difficulty disappears.

I'm a fan of hers but I think many of her criticisms of string theory, multiverse stuff, etc, apply equally well to superdeterminisim.

That being said, in her latest book she has a pretty strong argument against free will that does not require superdeterminisim so if that sounds interesting check it out.

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