Doesn't decoherence just mean entanglement with other particles increases as the particle interacts with its environment? I never understood it to mean that the "total entanglement" (loosely speaking) will decrease somehow. Rather, I thought it means that mutual entanglement between N particles starts involving N + 1 particles, N + 2, etc. until it grows large and N just becomes insignificant.
I believe the idea is that lots of 'random' entanglement effectively concentrates the probability distribution, which is what destroys super-positions. Effectively saying things are due to the central limit theorem.
Saying 'everything is entangled' might not be that meaningful if the entanglement is random. If you want to get to super-determinism then it takes some very weird 'knowledge' in the entanglement. Rather than the entaglement being random.
What I have had physics PHD friends explain to me is that the 'wave' evolves completely deterministically. The way they see it, measurement is just 'getting entangled with the wider world, thus concentrating the wave function'.
Almost everything we interact with has this concentrated wave function. And when you see something without this concentration the process of how it 'decoheres' is chaotic. It just turns out that the chance of concentrating in a spot is proportional to the wave self-conjugation.
I could imagine the idea 'almost everything is engangled' meaning the chaotic nature of this concentration process is essentially perfectly random. Since you'd be interacting with trillions of other waves.
Do I understand correctly that you're claiming it's "at least exponentially unlikely" (so to speak) for a fully-deterministic-since-the-Big-Bang model to result in a superdeterministic world? Or to rephrase, something along the lines of: "a vanishingly small set of evolution trajectories from a fully-deterministic-since-the-Big-Bang would result in a superdeterministic world that would explain ours"?
No, I wasn't talking about superdeterminism at all.
My point is that the evolution of the waveform is deterministic. Waveform collapse is where lots of theories introduce indeterminism. I propose a theory in which waveform collapse is technically deterministic.
My proposition is that the process is deterministic but chaotic. With the simultaneous state of all other particles determining how this collapse happens. Making it deterministic, but truly impossible to predict without a picture perfect representation of the outcome.
If I have entangled particles A and B, and then B interacts with and becomes entangled with particle C, can that interaction not qualify as an "observation" that collapses the wave function of A + B and de-entangles them?
Not as I understand it. I think of it as: A and B were correlated, and now you caused B and C to become correlated. That cannot possibly imply that A and C's correlation dropped to zero.
Or if you prefer to think of balls; if A hits B, and then B hits C, then C's future trajectory is still (forever) affected by what A was doing, as is the trajectory of anything else it hits.
That is classical systems and "classical" probability. In quantum systems particle functions collapses all the time making parts of it go to zero. At least as we understand quantum mechanics today, the math we have doesn't explain experimental results without those collapses.
From what I've read on Wikipedia [1], my guess would be that the answer is probably: "Since it's impossible to falsify, we should only be satisfied with it if science can eliminate literally all other possible falsifiable explanations." In which case, I guess if your goal is solely to "push the boundaries of science", then this is fair enough. But in that case, it seems to me the amount of effort and resources we could ostensibly pour into eliminating falsifiable explanations might well be unlimited, which raises the question of: at precisely what point do you cut your losses and realize you need to move on (to philosophy? idk), so to speak. Science is supposed to be a means to an end, after all, and I thought that end was "understanding the universe"—not "exploring the space of all falsifiable predictions just for the sake of it".
But I'm curious to hear physicists' takes on this! e.g., the implausibility claim in the Wikipedia article would seem like a compelling rebuttal, except that I don't see why I should believe superdeterminism to be an implausible explanation at all. If anything, it sounds like the most plausible explanation we have—either that, or the Big Bang somehow doesn't imply superdeterminism (how is that even possible?), or the Big Bang theory is bogus to begin with.
