Cellular automata, downward causation, and libertarian determinism

[Giulio Prisco]

Cellular automata, downward causation, and libertarian determinism
(2). Some more thoughts, and a Sudoku-like game based on cellular
automata.
https://www.turingchurch.com/p/cellular-automata-downward-causation-644

[John Clark]

 Jason Resch  wrote:

> If reality consists of a sufficiently large multiverse, then we can expect a vast plenitude of parallel universe states which are almost the same, but different only by the position of a single particle, for example.

I agree. Maybe somebody will come up with a better idea tomorrow but as of today I think Hugh Everett's "Many Worlds" is the least bad quantum interpretation; if it is not at the foundation of reality then something even weirder is. 

> Such parallel universes contain identical copies of brain states of all the conscious observers

According to Everett a universe splits if there is a change, if everything is identical then there is no split. So in one universe an electron in your lab goes to the left and your instruments register that it went to the left, and the other universe the electron goes to the right and your instruments register that it went to the right, but you would have no way of knowing which universe you are now in until you look at your instruments. 

But how would Many Worlds explain bizarre things like  quantum erasure and the delayed choice experiment?  In Many Worlds a split happens when there is a difference; and normally the universes will never coalesce again because thanks to the butterfly effect even a tiny difference will exponentially growing magnitude so its astronomically unlikely they will ever become identical again, but if the difference between 2 worlds is very small, like the only difference between two universe is  that in the two slit experiment in your lab an electron went through the left slit rather than the right, and if you don't wait so long that other effects might change then, then a very skilled experimenter can coax those worlds to become identical again and coalesce back into just one world; but when contemplating the history of that electron you will find evidence that it went through the left slit but equally strong evidence that it went through the right slit, and that is what some call "quantum indeterminism".  

The big advantage Many Worlds has over the Copenhagen interpretation is that Copenhagen claims there are two separate laws of physics, one for things that have been observed and another for things that have not been observed, but Many Worlds says there is only one set of physical laws, and it has no need to explain exactly what an "observer" is or how consciousness works because those things have nothing to do with it. So according to Occam's Razor it is superior.

> But once the measurement is made, the observer's mind state changes in a way that partitions the set of similar but not quite identical universe she is a part of. The observer is said to have "collapsed the wave function" but really, she has only adjusted her knowledge

Exactly, until you look at your instrument you don't know which universe you're in. As for downward causality, the trouble with it is that even if the laws of physics are completely deterministic, causality could still be asymmetrical. For example the laws for John Conway's "Game Of Life" are very simple and completely deterministic so if you are given a pattern you can always predict how it will evolve, but you can't determine what pattern produced it. You can predict the future but you can't know the past. 

John K Clark 

[Lawrence Crowell]

These things are beyond our ability to observe and measure. Speculations about the multiverse suffer from the problem that we will never observe another cosmos.

LC

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[Stuart LaForge]

But we don't have to observe other cosmoses to infer their existence, just like we didn't need to observe atoms to infer their existence. Admittedly it was still really cool when scanning tunneling microscopy allowed us to observe them for the first time, however, we were still very confident in their existence before we actually saw them since Einstein's work on Brownian motion. I think we are seeing a lot of similar inferential evidence of a multiverse. Quantum computing, the Elitzer-Vaidman  Bomb Test, and now this crazy paper from Nature:

https://www.nature.com/articles/s41586-025-09595-7

If I understand it correctly, it seems to be saying that you don't need a quantum theory of gravity for macroscopic objects to become entangled with one another, you just need matter fields from QFT, and classical space time and gravity. This means that the entire universes full of matter can become entangled with one another in gigantic cat states and that would be how the multiverse branches.

Stuart LaForge

[John Clark]

On Tue, Oct 28, 2025 at 6:01 PM Lawrence Crowell <goldenfield...@gmail.com> wrote:

 

 > Speculations about the multiverse suffer from the problem that we will never observe another cosmos.

Many theories make predictions that cannot be checked but I think a theory should be judged on the predictions that can be checked not on the predictions that cannot be. And we CAN check the 2 slit experiment and Many Worlds is the best way I have of making sense of the strange results of that experiment. Professor David Deutsch goes as far as saying that talking about many worlds as just an interpretation of Quantum Mechanics "is like talking about dinosaurs as an interpretation of the fossil record ". And some say the Many World's idea is not falsifiable so it's not science, but that's not true; right now experiments are underway to see if they can detect the objective collapse of the quantum wave function, if they are successful then Many Worlds is wrong.

John K Clark

 

[Lawrence Crowell]

There is this common belief that quantum computing involves computing with other universes. There is no necessity to model it that way. This also fuses the many world interpretation of QM with multiverse hypothesis. This fusion is evident with quantum cosmology, of which we know little, but with our q-computers there is nothing of that sort.

The paper referenced here is making the rounds. Now, it is important to remember Feynman showed that on first order quantization on the "tree level" Feynman diagrams that quantum gravity is identical to classical gravity, but with a WKB type phase. This is why weak gravity is quantized in a nice linear manner. The adage we know nothing about quantum gravity is wrong. We do know about weak, low energy and linearized quantum gravity. I have done a fair amount of work on how signatures of quantum gravity should exist in LIGO data. So this paper is telling us that quantum phase present in classical spacetime can be transferred to construct entanglements.

LC

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[Lawrence Crowell]

Many Worlds Interpretation is an auxiliary postulate or physical axiom that really is unneeded. It is there to give a heuristic about decoherence and the odd behavior of wave functions in measurement.

LC

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[Stuart LaForge]

On Thu, Oct 30, 2025 at 6:07 AM Lawrence Crowell <goldenfield...@gmail.com> wrote:

On Thu, Oct 30, 2025, 5:15 AM John Clark <johnk...@gmail.com> wrote:

On Tue, Oct 28, 2025 at 6:01 PM Lawrence Crowell <goldenfield...@gmail.com> wrote:

 

 > Speculations about the multiverse suffer from the problem that we will never observe another cosmos.

Many theories make predictions that cannot be checked but I think a theory should be judged on the predictions that can be checked not on the predictions that cannot be. And we CAN check the 2 slit experiment and Many Worlds is the best way I have of making sense of the strange results of that experiment. Professor David Deutsch goes as far as saying that talking about many worlds as just an interpretation of Quantum Mechanics "is like talking about dinosaurs as an interpretation of the fossil record ". And some say the Many World's idea is not falsifiable so it's not science, but that's not true; right now experiments are underway to see if they can detect the objective collapse of the quantum wave function, if they are successful then Many Worlds is wrong.

John K Clark

 

Many Worlds Interpretation is an auxiliary postulate or physical axiom that really is unneeded. It is there to give a heuristic about decoherence and the odd behavior of wave functions in measurement.

LC

If MWI is an axiom, then it is axiomatized at the level of Schrodinger's Equation. Schrodinger's equation gives the probability amplitudes, really just relative statistical frequencies, of every possible universe. Done. Where's the additional axiom? It is wave function collapse, whether objective or psychogenic, that is the additional axiom and it comes along and breaks Schrodinger's equation by changing the unitary evolution of the system every time a measurement is made. By what physical mechanism are the interference terms traced out of existence by wave function collapse? In MWI, there is no collapse and the quantum information simply decoheres through correlations with measuring devices and the observers that notice them, while Yggdrasil itself remains in a pure state.

Stuart LaForge

 

 

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