Money quote:

    Perhaps the best way to explain local 
    realism is that it’s the thing you believe in, 
    if you believe all the physicists babbling 
    about “quantum entanglement” just 
    missed something completely obvious.

In my mind, all the quantum observables are not real properties, therefor it's obvious/trivial that they don't exist until measured. That is, I have no problem accepting they are not "real".

What gets to me is the locality aspect of it.

Of course I'm not a physicist (read: I am layman).

See Noether's theorem.

(Sorry to be nitpicky, but the asterisk is very important haha)

I'm sorry but I don't understand your point, can you explain it further?

Also one weirdness of QM is not only that it is non-local, it is that it is non-local allowing instantaneous remote 'interaction' BUT without allowing to send information instantaneously (not faster than light).

Simply 'flipping around the "argument"' is playing with words and has no usefulness from a scientific point of view; it is definitely not "more intuitive" (as you put it) since it has nothing to do with science.

This is not locality. This is translational invariance.

However, equations have parameters.

The principle of locality is that these parameters come from nearby regions of space. Basically, things are only affected by what's near them.

It's violated by quantum mechanics.

Prof. Aaronson is teaching a grad seminar this Fall at MIT on Computation and Physics. Here's hoping he makes the lecture notes public ;)

EDIT: well that's not a great explanation of why I dislike the many-worlds hypothesis, let me try again. Like some other ideas, including the existence of God, it's not (yet?) falsifiable. Which doesn't make it false, of course. But it's a really extraordinary idea. It's not just many worlds, it's a fuck-ton. And what can we do with all of them? Are they for nothing? Does nothing that happens matter because it happened differently in a separate but equally real "world"?

I guess, I can believe that "god plays dice with the universe", but I can not believe that "god makes infinite copies of the whole universe and tries all possible quantum outcomes".

EDIT: response to parent edit

Almost by definition interpretations are not falsifiable. The many world interpenetration is literally equivalent to the other interpretations, because they all describe how we understand the meaning of the same mathematical model; and it is that model that is making predictions.

In my opinion (as a mathematician, not a physicist), the many worlds interpretation is the more natural way to read quantum theory. That is to say, if I were tasked to design a universe given quantum physics as the specification, my naive implementation would correspond to the many worlds interpretation.

An equally valid interpretation is that we are a computer simulation, and quantum physics describes the rounding behavior of said simulation. As far as I am concerned the only point of having an interpretation is to help build an intuition for the models.

Another way of looking at it is that there's only one "world": the amplitude distribution over quantum configuration space. https://www.quora.com/How-does-observation-collapse-probabil... has a decent explanation/argument.

MWI says that probability is conserved across the multiverse (unitarity of the global wavefunction)! The only reason we can "create universes" is because we're in the low-entropy time near the Big Bang. As we start getting closer to the heat death of the multiverse, then less "universes" are being created, because there's no room for them. In fact, given enough time, eventually some of the "universes" will actually join back together! If the multiverse is finite and closed (we don't know this), then sooner or later (like e^2^120 years later, according to a back-of-envelope calculation I saw) all of the universes will be lucky enough to join back up (Poincare recurrence), and we'll end up where we started.

I like looking at MWI not as the creation of universes, but as the creation of perspectives on one universe. In any case, it obeys conservation laws.

Or zero. (But it's definitely not one.) Personally I find the zero-worlds view to be the most intuitively satisfying:

http://www.flownet.com/ron/QM.pdf (Or the movie version: https://www.youtube.com/watch?v=dEaecUuEqfc)

David Mermin's Ithaca interpretation is essentially the same thing:

http://arxiv.org/abs/quant-ph/9609013

The slogan is that "we are correlations without correlata".

If the latter, then I would ask, "Do you believe the ocean is deep, even though you can only see the surface?"

I don't really understand the ocean metaphor, since humans have seen below the surface, quite a distance with remote-controlled submersibles.

Because of the expansion of the universe, it is theoretically possible for me to get in a space ship and travel away from you at such a high speed that we would never be able to meet again, even if at some point we both decided to head back toward each other as fast as possible, and even if we were both immortal. Our light cones would no longer intersect.

Probably you would assume that I continue to exist, despite that for all intents and purposes I cannot affect your life in anyway and therefore "don't" exist.

Similarly if I crossed the event horizon of a black hole.

I believe that a qubit is in superposition (i.e. exists in multiple miniature "universes"), because that theory produces results that are consistent with experiment. When the qubit's universes de-cohere with mine, such that for all intents and purposes I can now only ever observe the qubit in one particular state, why should I assume that the other universes have ceased to exist? Decoherence is a continuous process, just like traveling outside of a light cone, so why treat them any differently. It's rather arbitrary to say that increased distance in space preserves existence, while increased distance in phase space does not.

Briefly, there's no way to explain the statistical correlations between spin polarization states: if we measure the polarization of a photon in a basis that's only, say, 5 degrees offset from its known polarization, the statistical breakdown between the two resulting polarization states is something like 9:1; what if it's only a few arc-seconds off? Then the universe must divide more and more finely.

You quickly realize the universe must be infinitely-divisible (because quantum collapse occurs so often, and each collapse anywhere in the universe must divide the universe, it can't even be discretized at, say, some Planck-like scale).

That said, it does neatly solve local realism. But you have to believe in an immortal soul or something non-material -- I believe that has to be the 'weighting factor'. (Again, that was the uncomfortable conclusion of my paper, wish I could conjure more of it.)

I use it to mean that there are no outside forces describing the state of the universe beyond what's materially measurable/describable; in other words, probably we have no transmaterial soul.

That's a strong assumption for anyone who's religious, but it's sort of gospel for atheists. That said, it's the many-worlds hypothesis doesn't square with a totally-naive interpretation of Bell's Inequality and materialism/atheism.

So... are you saying that we have to admit there's a God/transmaterial soul / some other magical thing because we don't understand the implication of Bell's inequality? If so, that's a big jump, but I can't say it's wrong. Just that I don't take that leap along with you.

You know, there are more things in heaven and earth, Horatio, than etc etc. For both of us.

I'm probably not using the same definition. I'm just of the view that what we think of as material often gets reduced to atoms or particles representing the four forces for which no other 'outside' component can be entertained to exist. To me, this is a over simplification that erases all the other seemingly non-material components of our material world (thoughts, feelings, experiences, math itself, and etc). It's easy to assume it to be true, but every time I bump into this argument I always point out that the number 1 isn't of any singular substance but the number itself exists everywhere there is any form of divisibility or unitary attribute in use.

I'm not suggesting that it actually works this way, I'm just giveng my drunken monkey interpretation of how particles could exhibit this behaviour without many worlds ;-)

That said, you're articulating a version of what's called a 'hidden variable' view of QM, which is actually explicitly what Bell's inequality is meant to disprove. I'm going to write a long post at root to try to explain this more, because I think it's really important to talk in particulars when discussing QM... hopefully it helps.

I wasn't really suggesting that the system was deterministic. The coin is neither heads nor tails until someone looks at it. I was suggesting that it is the same coin in 2 different places (from the vantage point of the people observing it). However, you can't know a priori that it is the same coin. You have to observe it in both places and communicate your discovery. Since you are trapped in your torus, it will take time communicate it.

But it's not like the coin is sending messages to itself to say, "if someone looks at the other side, make sure it is tails". It just is. Similarly, it is not in a determined state at the point of entaglement. It is only determined when one party looks at it. But then that decides what the other party will see.

I honestly don't see how you would create a test for this because you would not be able to determine if 2 particles were entanlged (the same coin in my silly example) without observing them.

Anyway, I appreciate your patience. I am keenly aware that "crazy theories from people who have no idea what they are talking about" are not particularly helpful. But if you write a blog post on the topic, that's the kind of area I'd like to see explained better ;-)

If the two parties are separated by a significant distance, that implies that one viewer (Alice?) determines what the other viewer (Bob) sees the moment she looks at the coin. But of course, our notion of who 'looks' first is a function of relativity; there are reference frames where Bob looks first.

The fact that they always correspond suggest that either A) the result was predetermined (hidden variable, i.e. local reality) or B) the two particles 'communicate' faster than light. (Note that, because the 'communication' can't actually convey information, it doesn't technically violate relativity, just, you know, that last shred of common sense you hoped applied to physics.

I'd write more -- didn't get to that meta-post, because I recently turned on the 'no procrastinate' flag on HN... and though it's made me way more productive I'm not sure if it's made me happier. C'est la whatever.

Either that or you're talking of a hidden variable theory, which is exactly what Bell's theorem disallows.

"distance is relative and depends on the reference frame." does not imply " There will always been some reference frame where their is no distance between points.". It just means that distances may be different.

Special relativity is a linear transformation, so a nonzero distance cannot become zero.

Relativity doesn't help locality violation, far from it. Relativity has issues (EPR) with locality violation.

Also, distance isn't really what locality is about; it's really about the causal sequence of events. If two events are close enough in time and far enough in space that light couldn't get from one to the other (in jargon: they're separated by a spacelike interval), then there'll be some reference frames where one happened before the other, and some where they happened in the opposite order. So if one of the events caused the other, there are reference frames where the cause came after the event.

So nonlocality violations imply that effects can come before causes in at least some reference frames. That's why people don't like it.