[baytrailcat]

>I'm ok with FTL information transfer

Which will lead to the conclusion that Special Relativity (which was extensively validated) is either wrong or incomplete.

I have seen a revival of Pilot-wave theory here on HN, but the real conclusion (a real particle pushed around by the enigmatic pilot wave or quantum potential or whatever) is as bizarre or as satisfying as saying particle is in a superposition. Also, I haven't seen anyone satisfyingly explain, in a classical-deterministic sense, the Delayed Choice Quantum Eraser Experiment (also, see the the Wheeler Thought Experiment)

[goatlover]

There is the silicone oil droplet phenomena which is a classical version of the pilot wave, and it does reproduce some quantum behavior, including the double slit. That a pilot wave has been discovered (granted at macro scale) does make one reconsider.

https://youtu.be/WIyTZDHuarQ

[krastanov]

It does not, really. The macroscopic realisation is not particularly surprising (although it is quite awesome and original). If you put a ball floating on top of a wave you will observe the predictions from a mathematical model of that system, which is exactly what the pilot wave theory is, and there is nothing surprising here. Moreover, the macroscopic model simulates something which by definition is an unobservable construction in the quantum model. It does not simulate any inherently quantum behavior (classical waves is a thing we already knew exists).

[lisivka]

Nobody tells that walkers are simulate all quantum behavior and doing that correctly. However, they helps to understand some of quantum puzzles. For example, droplets have spin. Can you predict behavior of the classical droplet spin in compare to the puzzling quantum spin?

[krastanov]

But you can do the same with classical setups that mimic some effects from the typical quantum mechanical formulations. Those classical experiments are indeed amusing and interesting, but they do not illuminate the "quantum puzzles", no matter whether they are modeled after pilot wave theory or after quantum mechanics. And very importantly, those amusing demonstrations do not scale! Sure, you can mimic with classical contraptions the pilot wave (or the wave function) of a single particle, but the nice intuitive demonstrations fail when you try to scale it up to more particles (or anything that would be exhibiting the interesting, nontrivial quantum behavior).

[lisivka]

So, your prediction for walker droplet spin is that walkers, in kind of Stern and Gerlach experiment, will behave like classical magnets, not like quantum particles, right?

[krastanov]

No, they would behave like a ball floating on top of a wave and given that there are waves involved there will also be interference patterns. There is nothing quantum here. Sure, in one particular way it looks like a quantum particle (to the extent of a cargo cult), but in all the important ways it does not (entanglement, computational power, generalisation to multiple particles).

[kkylin]

As far as I know there is no analog of entanglement in these experiments. If someone has heard or read something in that regard, I'd be interested in a reference!

[lisivka]

Nobody even tried to entangle two walkers. AFAIK, uncharged non-magnetic particle without any inclusions (e.g. bubbles) has spin and phase of vibration only. How to entangle them?

Moreover, spin is 3d, walker is 2d, phase is 1d, while our Universe is 3d. It's like studying of 2d/1d projection of 3d world.

[naasking]

> Which will lead to the conclusion that Special Relativity (which was extensively validated) is either wrong or incomplete.

Not necessarily. The simplest relativistic pilot wave theory requires only a preferred foliation of spacetime.

This is seemingly unappealing to most physicists, but recent work has shown that the wave function itself contains just such a structure, so the needed foliation is present in every interpretation of QM.

[lisivka]

Did you saw double slit experiment reproduction in 2D macro?: https://www.youtube.com/watch?v=nsaUX48t0w8

Observer breaks interference pattern.