Isn't a core idea of SR "relativity of simultaneity", i.e. simultaneity of events is entirely dependent on the reference frame of the observer?

By my understanding, in PWT the pilot wave controls the velocity of the particle. And that velocity depends not only on the position of the particle, but also the positions of all the particles it is entangled with; and that information is all available instantaneously to the pilot wave which controls the velocity of the particle. I don't see how that can be reconciled with SR.

Is there a way to block somebody in this forum?

I tried to help you. You think you know alot more than you actually do know.

You're mixing up "medium" with the QM wavefunction. That's a linguistic mistake, which is understandable because the word "wave" is in there.

You also confuse the physical property of "energy", which can really only be defined in mathematical terms in specific contexts with what you say is its linguistic definition, "the ability to do work".

But even linguistically, that is still not quite right. Here is the first sentence from the Wikipedia article on "energy":

"In physics, energy is the quantitative property that must be transferred to an object in order to perform work on, or to heat, the object."

So if you get to a state like "heat death", energy can no longer be transferred. "the quantitative property that must be transferred in order to perform work" is still there, but no such transfer is possible and there is no longer any "ability to do work".

idk, by my understanding decoherence would render interaction between specific separate branches highly improbable. But because there are SO MANY separate branches, it would happen regularly. Sorta like what happens with quantum tunneling.

Please excuse my ignorance. I have done searches for "transtemporal symmetry" and didn't find anything, other than items written by you, in this thread.

In a Bell Inequality experiment, when one of the detectors (Alice's?) is "randomly" altered, after entangled "particles" have left the source, is the reading ultimately registered at the altered detector changed, or does it stay the same as if it hadn't been altered at all, because of this transtemporal symmetry? Or is it that the other detector (Bob's?) somehow recognizes that Alice's detector has been altered and for this reason registers a reading in correlation with Alice's reading.

I recognize that this question is in some fashion a reiteration of my previous question, but I didn't quite grasp your answer. Sorry.

I'm just giving a classical-world example of how a "branch" consisting of an event which did not occur in my "branch" (me blowing out the candle) could conceivably have a causal effect on the "branch" I inhabit going forward (me being more careful with candles).

We think about possible worlds that did not occur all the time, and those possible worlds which did not occur have causal effects. That is one way that we learn from mistakes. If there were no possible worlds to compare our actual world to, there would be no incentive to ever change behavior, for instance. It probably wouldn't occur to us to change behavior.

Are you saying that by randomly changing the detector settings of one detector the other detector's multi-electron wave function is likewise changed through transtemporal symmetry?

"This confirms what I said earlier about the non-independence of detectors in Aspect-type experiments. The detector wave functions are related and constrained by a transtemporal symmetry extending through all space-time. So, entanglement does not involve action at a distance, but transtemporal symmetry."

... and if the settings on one of the detectors is changed randomly, before a particle has reached it, but not soon enough for any subluminal signal to have reached the other detector...what? The "randomness" used to change the setting on the detector wasn't really "random", but part of the "transtemporal symmetry"?

For Everett "real" meant "something that could affect the results of an experiment"; and, Everett was pretty clear that these different branches do interact.

"In MWI, the branches can interact. But the likelihood of this interaction is negligible. (By the way, this is another really weird feature of MWI...)"

I'm not sure how weird it is. As an analogy in the classical world suppose that I forget to blow out a candle before I go to sleep and the house burns down. I'll experience regret because there is some world out there where I did not forget to blow out the candle and the house did not burn down.

That alternative world will have a causal effect on my world in which the house DID burn down. I will be more careful in the future and make sure to blow out candles before I go to sleep (or not light them in the first place!). If no alternative world in which the house did not burn down existed, it would never occur to me to be more careful in the future.

I'm not sure how to put that analogy in direct terms of the wave function, but it allows me to see the possibility of different branches interacting. A possibility which didn't actually occur in my current branch could have a causal effect going forward.

I think it's important too to differentiate between Everett's Interpretation and MWI, as first put forth by DeWitt. Everett's definition of "real" was anything that could affect the results of a future experiment. Everett was also pretty adamant that separate branches could affect one another; the separate branches, according to Everett's (relative State Formulation) https://plato.stanford.edu/entries/qm-everett/interpretation, can and do interact.

I'm not sure why, in MWI, the separate branches are said to not be able to interact with one another. Especially if, as you say, it is all one thing in Hilbert space.

I meant boundless.

I meant to tag you too in my question but couldn't find a way to do it. I'm still learning the idiosyncrasies of the site.

So, if the universal wave function is real, and continues evolving unitarily, probabilities would need to be somehow preserved. They would be reflected in the wave function itself. At least that's how I understand it.

How does MWI handle probabilities in its branching of worlds? For instance if there are two possibilities (+ or -) and each has a probability of 50%, it makes sense to say that two separate branches result.

But what if the probability of + is 51% and the probability of - is 49%? In order to preserve probabilities we would need 100 worlds! (51 +, and 49 -).

It seems rather contrived to me that the number of branches would depend on probabilities like that. Or are some worlds considered to be more "probable" than others? (Which I understand to be a question that might not make sense, because all worlds are considered to be equally "real")

https://en.m.wikipedia.org/wiki/Bell_test_experiments
These experiments, with the underlying theory, show that "local realism" is not possible. "Local" means that information can't travel faster than the speed of light. If it does, then causality is violated and effects can precede causes. "Realism" means that entities have properties whether or not they're being observed.

These experiments show that either "locality" (causation) or "realism", or both, are untenable.

What if one finds something "supernatural" and then manages to find ways to predict its actions? Wouldn't it then become "natural" or "physical"?

So I'm wondering what "supernatural" means. It seems to be anything that isn't yet a part of physics.

I had in mind the Bell Inequality theorems and experiments which imply that a "realist" "causal" world cannot be supported. By "realist" I mean the belief that things have properties with definite values even when they're not being observed. By "causal" I mean that when you look at an interaction and say "A caused B", that A always preceded B.

So Wigner's friend measured a definite value while Wigner measured a value in superposition? I am trying to decide if it is worthwhile to read this paper.