And I agree with brother Clark, here:
...the results have nothing definitive to say about QM interpretations.... Except you'll find people who disagree with that. The whole many earth's interpretation was developed to address that issue. Reality is a metaphysical characteristic, not a scientific one.
— T Clark

As to our living in a quantum universe, I buy that. But I accept that most of the effects are too small or too unlikely to matter much. Not impossible, just unlikely.

If you care to lay out your own interpretation, "compelling analogy," I'm a reader! — tim wood

I will lay it out soon, because it's one of the most fascinating things I've ever tried to understand. For now let me just reiterate this:

The point of Bell's Theorem and the experiments that test it is to clarify if it's at all possible if we live in a world that's describable classically. You laid out some of the statistics that go into Bells Theorem, but in your first few posts I think you left out an explanation of why those statistics matter. That's what I'm focusing on here.

They matter because they prove with reasonable certainty that we live in a world that does not match up with classical assumptions.

T Clark said many people disagree with that and he brought up "many earths", which I assume to be many worlds - please correct me if I'm wrong. Many worlds is quantum mechanics. Many worlds is NOT classical. Many worlds also believes in indeterminate answers to measurement questions prior to measurement.

The classical idea is that any measurable property of a particle - momentum or position or spin - has a definite, objectively true answer even when you're not measuring it. If you send off a photon at t=1 and measure it at t=100, in classical mechanics that particle still has a singular, definite and true answer for any question you could ask of it at t=2 - 99. Just because you don't know the answer in classical mechanics doesn't mean there isn't one - there always is.

The inequalities in Bells Theorem are there to help us test if our universe is one where it's in fact true that we might live in a classical universe where those questions have singular, definite answers. Many Worlds does not involve singular definite answers to quantum questions, and the key to why is in the name, "many". Many Worlds takes the idea of superposition super-literally, and in many worlds any answer to a quantum question prior to measurement doesn't have a singular definite answer, it has MANY answers.

I'm going to try to take the time later to go over my analogy about why bells theorem says these questions can't have classical answers. I honestly love this topic so much. But I'll leave you with that for now.

Maybe I'm misreading you, MU. It seems to me you're objecting to the use of the English word "spin" to refer to something meaningful to a technical user as a term of art. If that's the case, why? — tim wood

Yes, you very much were misreading me. I was talking about the deficiencies of the concept which is labeled with the word "spin", as stated in the first sentence of my post: "'Spin' is a highly deficient concept." The choice of word to name the concept is irrelevant. All I can say is try rereading, and stay focused this time. That ought not be difficult because it's not a long post.

This is the second time I've ever tried to describe at length what's so important and fascinating about Bell's Theorem, but my first time was a semi-failure (partly because I was trying to explain it to someone who rejected QM out of the gate, and didn't want to understand the maths and probabilities involved - which makes this scenario fundamentally different out of the gate, you guys seem to like QM and have some understanding of the probabilities involved), so this time I'm going to start again without using any of the material I wrote the first time. I'm going to probably be writing some shit you already know, but please bear with me. Also, sorry if this is a lot to read.

I think the best way to contextualize Bell's Theorem is to go back to the beginning, back to when QM was first being introduced to the physics community. I'm going to spin a little narrative that's perhaps not entirely true, but hopefully true enough, to set the stage for why Bell's Theorem was even thought up to begin with.

Before QM, all physical theories were what we now call "classical", including Relativity. I think of "classical" as almost being comparable to basic object-permanence. We all learn at some age that, if we put a book in our backpack and then close our backpack, we can (usually) expect to find it in our backpack later on. When we open up our backpack an hour later, we generally don't assume that the book just appeared there - we have a persistent conception of the world where, even when we weren't looking at the book, it was still in the backpack all the same. Classical Theories are object-permanence at the universal scale - every particle that exists always exists in a specific place at every moment in time, even when we're not looking at it. Our ignorance of where a particle is or how fast it's moving is just a fact about us, not a fact about the particle itself. The particle itself is always existing somewhere, and moving at some specific velocity, at every moment in time, regardless of our ignorance about it.

Then, Bohr, Planck, Heisenberg, Schrodinger and friends introduced QM to the world. They said that there are some properties of particles that, prior to measurement, we can't actually tell a Classical story about. If we shoot a particle at t=0, through a double slit for example, and measure where that particle landed at t=100, we might be tempted to ask the question "ok, so where was that particle at t=50?" If the world worked classically, then there would be an objectively true answer to that question - even if we as human beings couldn't find an answer. If we can't find an answer, that's just our own ignorance, but there still *is* an answer. QM said, actually, there *is not* an answer. Or at least, not a *singular, definite answer* -- that's the phrasing I like to use. Prior to measurement, some of these properties of things like Photons and Electrons do not in fact have singular definite answers - not even to God. If God himself were to peer into the universe and look at that particle at t=50, he wouldn't have a singular definite answer to the question "where was that particle?" (Please note that I'm using God as a narrative tool, I'm not a theist. "God" is just a stand in for the idea of some external entity who could, in principle, know the world as it really is - could answer any question about any system without disturbing that system).

Shortly after, Einstein and friends produced the EPR paper. In short, they fundamentally disagreed that the QM vision of the world was true. They said, no, if we don't know where a particle is, or its velocity, or any other measurable property of that particle, that's just a matter of personal ignorance. Quantum indeterminacy is not a real feature of reality, it's just a measure of the things we don't know. And they came up with a theoretical class of experiment to demonstrate why. They said (again, I'm using some artistic license here, this isn't exactly how it happened) -- imagine we have a pair of particles that we've arranged to have a correlated state in some measurable property. Now, we have one particle flying east and one flying west, we haven't measured this property yet so according to QM this property doesn't have a singular definite answer yet. After, say, a second we measure the particle flying west -- if their properties are correlated, as by the experimental design, then that means at the moment we measure the West particle, the East particle must also suddenly and immediately have an answer as to what it will be measured as as well, despite being 2 light-seconds away. This thought experiment, as far as I know, is the first time the idea of "entanglement", as we now call it, was discussed at length. Einstein referred to the idea that measuring one particle could affect its entangled paired particle immediately as "spooky action at a distance". The idea of instantaneous causality across space went against every intuition about physics Einstein had - it went directly against intuitive notions of Causality and his own Relativity. After all, if cause-and-effect can happen immediately across distances, that creates a real problem for the idea of Relativity of Simultaneity (please ask if you want more detail on this and why it was such a problem).

So, what we have here is 2 competing ideas: 1. the classical take of Einstein via the EPR paper, that us not knowing what a property would be measured as is just a statement about our own ignorance, not a statement about reality, and 2. the QM take, that these properties are not just something WE are ignorant about - God himself wouldn't have an answer. There objectively is not an answer to these quantum questions prior to measurement. And the tricky part here is, how could you possibly tell? How could we tell what type of universe we live in? A classical one or a QM one? What experiment could tell us the difference between "I don't know this property of this particle" and "this property of this particle genuinely does not have a singular definite value"? On the surface, those two ideas - personal ignorance vs ontoloical lack of an answer in reality - seem experimentally indistinguishable.

THIS is where Bell's Theorem steps in. Bell ingeniously figured out a way to definitely tell us if we live in a world where a lack of an answer to quantum questions was because of personal ignorance, or if in fact QM was right and ontologically the answer to this quantum questions *cannot* in fact have a singular definite answer prior to measurement. This, to me, is why Bell's Theorem is so wonderfully beautiful, and so centrally important - it took us 40-odd years to finally find a way to settle the disagreement betweein Einstein and QM. Thank you, John Bell.

When the EPR paper came out, I'm not quite sure personally how they imagined setting up an entangled pair of particles, but by the time John Bell was approaching the question, I believe physicists had a good idea about this concept of "spin" - that you could create a pair of entangled particles where, due to the perservation of the quantum equivalent of "angular momentum", you could guarantee that one particle had the opposite spin of the other particle. I actually don't believe they had experimentally confirmed this could be done at this point, I think it was still theory when Bell came up with the idea, but nonetheless this is where we can start untangling the disagreement between Einstein and QM. What Bell discovered was, Quantum Mechanics predicts certain correlations of spins at varying degrees of measurement, and the exact correlations it predicts are *incompatible* with Einstein's view of the world. If you read the wiki page on Bell's Theorem, you'll see it referred to as "local hidden variables" - local hidden variables, Bell figured out, could not (at least not without some weird loopholes) explain the statistical results that QM predicts. So let's go into why and what that means.

First, let's just talk about what you alread know: in a Bell Test, they create a pair of particles that have entangled spin. One of them goes left, one of them goes right. If you measure their spin along the same axis, if they're properly entangled then one spin will be up and one will always be down. If you measure them at a different angle, however, the statistics start to differ a little bit.

Here's where I introduce the "analogy" I've been touting prior. Local Hidden Variables and entanglement. I'm absolutely certain I'm oversimplifying this but I think the simplification I'm going to present is useful at the very least, so here it goes: Local Hidden Variables theories are basically Classical theories, which is to say they match this idea of Object Permanence I talked about - regardless of our own ignorance, every property of a particle has a singular definite value at all moments in time. Now the idea that two particles could have some correlated value isn't itself incompatible with Classical theories, so here's the first layer of the analogy: A person called FJ (me) is offering a service online. You send me 2 addresses and a dollar, and I'll send an envolope with a piece of paper in it to each address. The service is very simple: to one address I'll send an envelope with a red piece of paper inside, and to the other addrss I'll send an envelope with a green piece of paper inside. This is "classical entanglement", aka the Local Hidden Variables view of entanglement. You purchase my services and send me your address and T.Clark's address, and when you get your envelope you open it and you see a Green piece of paper. You have *immediately and instantaneously* learned information about the envelope heading to T.Clark's house. You know for a fact that the paper going to him is Red, regardless of the fact that it hasn't been measured yet. This isn't magic and it's not quantum, this is the classical view of entanglement.

So, the analogy is a "particle" is an envelope, and a "measurement" is opening the envelope here, and in a classical system, there's nothing weird or strange about the idea that the contents of one envelope could be perfectly correlated with the contents of another envelope, right? I hope that all makes sense. We consider it classical because, even if you opened the envelope, say, 24 hours after I mailed it off, you could reasonably ask the question "what color was the paper in this envlope 12 hours after it was sent?" and, common sense says, it was green when you opened it and so it was green 12 hours before you opened it as well. And 23 hours before you opened it. And 1 hour before you opened it. When you opened this envelope, you weren't generating some new fact about the color of the paper, you were discovering a fact that was true the whole time - that's what makes it classical. Complete object permanence. Objective facts regardless of your ignorance.

I send you an email a few days later letting you know I'm offering a more advanced service. I'm offering to send the 2 envelopes with a paper inside, same as before, but this time I'm going to write a number on each one. On the first paper I write a number from 0 - 359 - let's call this number X. On the second paper, I'm going to write whatever this formula outputs: (X + 180) MOD 360. So, whatever the first number is, the second number is 180 degrees rotated from the first number. If the first number is 1, the second number is 181. If the first number is 90, the second number is 270. If the first number is 320, the second number is (320 + 180) mod 360 which is 140. Now this service I'm offering is *almost* directly comparable to the experiment in a Bell test. The only thing you have left to do to make it actually comparable to a Bell test is devise a *measurement scheme* that makes it similar to a Bell test, which is actually remarkably easy.

Like before, you ask me to send one envelope to your house and one to T.Clark's house. You've agreed with T.Clark for the first round to measure every number received according to this scheme: If the number is between 0 and 180 (including 0, not including 180), you record an UP on your spreadsheet, and if it's from 180 - 360 (including 180, not including 360 aka 0) you'll record a DOWN on your spreadsheet.

So, you run the test 1000 times, say, and after you compare your spreadsheet with T.Clark's spreadsheet, you're completely unsurprised to discover that every time you've recorded UP, he's recorded DOWN, and vice versa. Again, this is just basic, classical entanglement. These envelopes are classical envelopes, filled with classical paper, written on with classical pen. You might measure a particle as UP after you receive it, but the number was already written in pen long before you received it. Nothing weird here.

But meanwhile you and T.Clark have also set up some entangled quantum photons to arrive at your houses, and you're measuring their spins, and you've noticed with the entangled particles that when you run the test above, measuring their spin at the same angle, you get the same results as the envelope experiment - every result you see as UP, T.Clark sees as DOWN, and vice versa. So in this case, our classical experiment is looking a lot like our quantum experiment.

So, you and T.Clark start changing the experiment up, and you start doing a proper Bell test. Some of the time, you measure a particle at, say, 0° and he measures it at 20°. Some of the time, you measure a particle at 20° and he measures it at 40°. And some of the time, you measure a particle at 0° and he measures it at 40°. {0° above means UP if it's [0-180) and DOWN if it's [180-360), 40° means UP if it's [40-220)}. You both record your ups and downs now, and you discover the following set of facts:

When you're measuring 0° and he's doing 20°, you BOTH record UP 5.8% of the time (as in, 5.8% of the time yours and his both register UP for the same run).

When you're measuring 20° and he's doing 40°, you BOTH record UP 5.8% of the time.

When you're measuring 0° and he's doing 40°, you BOTH record UP 20.7% of the time.

Now, you decide to run the same sort of tests using FJ's mailing service just to see what the results are, to compare your quantum measurements to a classical system. Here's what you get.

When you're measuring 0° and he's doing 20°, you BOTH record UP 5.55...% of the time.

When you're measuring 20° and he's doing 40°, you BOTH record UP 5.55...% of the time.

When you're measuring 0° and he's doing 40°, you BOTH record UP 11.111...% of the time.

You notice this, tim, and you have a little intuition: you think that in my classical mailing service, it's actually impossible for my classical mailing service to produce the 5.8, 5.8, 20.7% statistics from the quantum tests. You think that it might be the case that the 0-20 and 20-40 statistics might have to add up to the 0-40 statistics, but maybe you can't quite explain why yet. You intuitively think there's no way for me to recreate that distrubituion. So, you tell T.Clark and he disagrees (I'm sure you wouldn't actually disagree, mr Clark, it's just a story). So you make a bet - you tell T.Clark that HE can call up and tell me (FJ, the mailing man) exactly what numbers to put in the envelopes, BUT you, tim, YOU get to decide how they're going to be measured (0 and 0, 0 and 20, 20 and 40 or 0 and 40), and you decide that 12 hours after the envelope is sent off, so T.Clark and FJ have no way of knowing which angles you're going to measure them at. So the bet is this: under those conditions, can T.Clark and FJ create a scheme that will make it so that at 0 and 0, all the result are opposite, at 0 and 20 they're both up 5.8% of the time, and 20 and 40 they're both up 5.8% of the time, and at 0 and 40 they're both up 20.7% of the time?

So, at this stage, what do you think? Can FJ and T.Clark devise any system of sending these letters to you in the conditions given? Is there any strategy at all they could take to produce these distributions reliably?

Bell's Theorem says there isn't. The only out that I know of, the only loop hole, is that if T.Clark and FJ already know ahead of time how you're going to be measuring them, THEN FJ and T.Clark can conspire to rig the results (this is essentially what Superdeterminism means, it means that the mechanism creating the spin values knows ahead of time how they're going to be measured and has conspired to give the results QM predicts). But I've worded it such that that loophole is closed - "BUT you, tim, YOU get to decide how they're going to be measured, and you decide that 12 hours after the envelope is sent off" - so they can't cheat in the superdeterministic way.

If there's no way for FJ's classical mailing system to produce the statistical outputs that QM predicts - that 5.8% and 20.7% numbers - then that means we can possibly prove that we don't live in a classical world.

So what do you think? Can FJ and T.Clark devise such a system, so that the mailing system can output those numbers? Can you devise such a system?

"Spin" is a highly deficient concept.... So the property which is represented by "spin" is not adequately represented in this way, — Metaphysician Undercover

It seems you fail to distinguish between spin and "spin." Forget the ordinary English word "spin". And for clarity's sake just for you in this post let's call the other spxn. Let's suppose what is actually the case, that certain people use the term that we call here spxn to represent a set of ideas that they have collectively, and that they can convey to each other by speaking and writing the word spxn. In as much as I am not one of those people, I will leave to them the choice of their own words for their own use; and I (shall) assume the the word is efficacious when used by them among themselves. So much for the word

As to the ideas represented, it appears they, those people, have a pretty good grasp of what they mean and do not mean, and what they understand and do not understand about them. So much for the people, so much for the ideas. And that leaves you. Please explain what, exactly, you're on about, so that either I may attend and learn, or know that there is nothing there and skip over yours without concern and without wasting time.

They matter because they prove with reasonable certainty that we live in a world that does not match up with classical assumptions.... The point of Bell's Theorem and the experiments that test it is to clarify if it's at all possible if we live in a world that's describable classically. — flannel jesus

There seems a not entirely warranted enthusiasm in your descriptions - which may cause trouble. Let's see if we can ignore it.

Many Worlds takes the idea of superposition super-literally, and in many worlds any answer to a quantum question prior to measurement doesn't have a singular definite answer, it has MANY answers. — flannel jesus

Which is not the claim that answers impossible in one world are possible in others, or is it? In some worlds do I murder my own parents before I am born? My understanding of many-worlds is that whole entire complete universes flash into and out of existence at every juncture of every instant of the existence of every thing, and that seems unlikely.

So at heart it seems, reading yours, it becomes a matter of interpretation. And we have to take care not to suppose we know because we don't know, which lots of people seem to do. Experimentally we know that single particles have spin values, that measured at the settings a or b or c degrees are just a+ or a-, or b+ or b-, or c+ or c-: in all, in one actual of eight possible configurations. Bell's theorem and experiments seem to show that with entangled particles, the measurements on entangled particles do not always comport with the measurements on single particles. That is, measurements on single particles allow for a classical interpretation, and on entangled particles, not.

So far just between us, the only assumption is that the particle is in one actual configuration (of eight). Beneath this is the assumption that the configuration is persistent. Actual, persistent. One or both of these have to give. We know at least potentially actual because at measurement it is actual (that, or we know nothing). But actuality is a supposition until measurement. The evidence for persistence, on the other hand, is the absolute consistency of results at, e.g., zero and 180 degrees - and persistence implies actuality.

Two fundamental assumptions, actuality, persistence. Can't do with 'em, can't do without 'em. Aristotle, I believe in Nicomachean Ethics, referring to the law of the excluded middle (either-or), observed that sometimes either-or yields to neither-nor. That is, neither actuality-persistence, nor not actuality-persistence.

It seems it must be either classical all the way down, or it isn't, And apparently it is not. It follows that (it seems reasonable to say) something happens that is not accounted in either QM or classical models. And it seems to me difficult to avoid this conclusion, that something happens. Doesn't mean we will find out what - our fingers may be too big and the details too tiny.

That something happens, it seems to me, is an absolute presupposition of classical thinking. The two alternatives being that nothing happens, or the neither-nor of something-nothing happening. That nothing happens seems untenable. That something-nothing happens, however that might work, would seem to imply a something, in turn a classical explanation.

So I conclude that QM, in sum, is a model that highlights deficiencies in classical physics but that does not replace classical physics, or, rather instead, becomes it. That is, that QM perfected will be seen to be a classical theory that is an advance on and refinement of current classical theory, in a way as relativity refines and advances on Newtonian physics.

Many Worlds takes the idea of superposition super-literally, and in many worlds any answer to a quantum question prior to measurement doesn't have a singular definite answer, it has MANY answers.
— flannel jesus
Which is not the claim that answers impossible in one world are possible in others, or is it? In some worlds do I murder my own parents before I am born? My understanding of many-worlds is that whole entire complete universes flash into and out of existence at every juncture of every instant of the existence of every thing, and that seems unlikely. — tim wood

The many worlds thing was an aside, and not at all necessary or required to understand everything I'm saying about bells theorem. The stuff I'm saying about bells theorem is entirely agnostic about which interpretation of quantum mechanics is correct.

So I conclude that QM, in sum, is a model that highlights deficiencies in classical physics but that does not replace classical physics, or, rather instead, becomes it. That is, that QM perfected will be seen to be a classical theory that is an advance on and refinement of current classical theory, in a way as relativity refines and advances on Newtonian physics. — tim wood

I suppose you're free to conclude that but that's certainly not my understanding, or I dare say the understanding of physicists who study qm. My entire post was getting at the point that QM is entirely at odds with some classical assumptions, and bells theorem and the experiments that test it go on to show that the classical assumptions cannot hold, they don't match experimental results.

I suppose you're free to conclude that but that's certainly not my understanding, or I dare say the understanding of physicists who study qm. — flannel jesus

What, then, do you or they say? That nothing happens? That something happens? Or neither? QM cannot be indeterminacy all the way down, because then where would persistence and consistency and actuality come from? You might argue that at our end, from probability, but at the tiny end? No room for QM woo. I've made my case, such as it is; you make yours or drive me off mine!

That is, measurements on single particles allow for a classical interpretation, and on entangled particles, not. — tim wood

Sorry for multiple responses, maybe I should post these together. In any case, this bit is probably not generally agreeable either. There are other single-particle experiments which are hard to explain with classical mechanics and start making more sense when modelled with quantum mechanics. The double slit experiment is one. The Mach zender interferometer experiment is another.

I really don't know why you're talking about nothing happening Vs something happening. There's nothing in my understanding of any of this that leads me to think that's a debate physicists are now or have ever had.

The idea is that the classical model makes predictions. Bell experiments reveal a circumstance where classical predictions are made and fail. Why do they fail? For some reason or for no reason? What do you say?

Are those the two options? Well they clearly fail for a reason, I think. And the reason is, the world is not classical. That's why our experimental results show correlations that are predicted by qm, and not explainable by classical means

Are you asking me why they're not explainable by classical means?

The question may be, if QM is actually classical. I think it must be. In the sense that classical means that at bottom determinate. And if not, if at bottom all is simply indeterminate, then we all may as well default back to appropriate classical theories as those that are maximally efficiently predictive, in a way - not the same way - that Newtonian physics is still perfectly good for how large parts of the world works. That is, is your car which you left in the garage last night still there this morning? QM at the moment says maybe, classical theory says yes. Will QM always say maybe? Only if QM remains incomplete. When, if ever, QM is complete, what will it say? And if your car is not there, for QM reasons, will QM say that something happened, or that nothing happened? After all, your car is gone, can you accept "nothing happened" as a complete account of its disappearance?

by determinate do you mean deterministic? Or do you mean something else, like "what's actually happening under the hood still involves objective facts"?

QM will always be indeterminate in the sense I've said above - that even God himself doesn't have a singular answer to a question like "where was this particle at t=50" - that's the nature of qm. That doesn't mean there aren't objectively true facts, however, even at t=50. It just means those objectively true facts aren't the type of facts we're used to asking about, they aren't the type of answers we're used to receiving. You have to bend your mind to accept different kinds of answers than that.

QM will always be indeterminate — flannel jesus

And do you not see that it, QM itself, cannot be? Whether you or I can get there isn't my point. There is number that QM can in principle if not in practice generate that just is the probability that your car itself will quantum tunnel from your garage to your ex's garage, instantaneously. Extremely unlikely, although quantum tunneling is observed in the lab. So your car disappears; do you accept and are you satisfied that it disappeared for no reason? That is the price of indeterminacy. And either it is that way or it is not that way. If you hold for indeterminacy, then how, exactly, does anything happen? Not to be confused with the proposition that you and I don't know and are essentially ignorant.

Let's stick with the basic question here. Your car disappears, Reason (whether or not you may ever know it)? No reason?

No, this whole line of questioning doesn't even make sense to me. I don't understand why you're even asking it. Quantum indeterminacy doesn't mean everything happens for no reason, and I've never claimed it does. Your questions along this line seem nonsensical to me.

I'm also still concerned that you're treating the words indeterminate and indeterministic as interchangable.

Many worlds doesn't disagree with it at all. — flannel jesus

I didn't say that the two approaches disagreed, I said that one of the reasons many worlds is appealing is that some people see it as addressing the claim that quantum phenomena are "ontologically indeterminant."

Try reading. Quantum tunneling is a real thing that happens. The most simple question I can think of is, does it happen for some reason, or not? If you cannot address this, then you cannot address anything. If quantum tunneling, i.e., quantum effects, happens for no reason, then what is quantum mechanics about? You might reply that QM isn't about reasons, but is instead about measuring phenomena. In that case QM is not about reasons and is silent about them, which is to say the question of reasons is still open, but that QM has nothing to say about them and they must be sought elsewhere.

Or QM tunneling is for some reason, and QM is about that reason. If QM cannot give an account of that reason, then QM, not being able to give an account of something that it should be able to give an account of, is incomplete. I think that's where we all are, the theories are all incomplete.

Classical theories, at the moment, cannot be complete because they (apparently) cannot account for the Bell results. QM is incomplete because it offers no account for the Bell results. One cannot, the other does not. It's a fair question to ask if QM will, at least in principle, ever be complete. If yes, then it will become itself a classical theory, a modification of current theory. If not, if in principle incomplete, then another theory waits in the wings.

Either you fall somewhere in this, if so where and maybe why? Or if not, then where? The fundamental question is that things that happen, happen for a reason or they do not. Corollary is the question if the reason is in principle knowable, or in principle unknowable (and if unknowable, then how do you know?).

Questions like these propaedeutic to our discussion.

They matter because they prove with reasonable certainty that we live in a world that does not match up with classical assumptions.

T Clark said many people disagree with that and he brought up "many earths", which I assume to be many worlds - please correct me if I'm wrong. Many worlds is quantum mechanics. Many worlds is NOT classical. Many worlds also believes in indeterminate answers to measurement questions prior to measurement. — flannel jesus

You keep misstating my position. It's frustrating. I never wrote and I don't believe that the subatomic world is describable in terms of classical physics. I said I don't see that quantum mechanics rules out realism. Quantum mechanical phenomena behave differently than classical phenomena, but that doesn't mean they're not real.

The inequalities in Bells Theorem are there to help us test if our universe is one where it's in fact true that we might live in a classical universe where those questions have singular, definite answers. — flannel jesus

In my understanding, this is not true. It is your interpretation, not mine and probably not Bell's. The inequalities are not "there to help us," they describe phenomena at very small scales.

to explain it to someone who rejected QM out of the gate, and didn't want to understand the maths and probabilities involved — flannel jesus

Are you talking about me again? If so, stop misrepresenting what I wrote.

I don't know why you keep saying this "no reason" stuff. I've never indicated that things happen for no reason

no, not about you, I was referring to something that happened on another forum possibly around a year ago.

my mistake. Your post said some disagree, and then you brought up many worlds in a way that sounded like you think many worlds is an example of disagreement.

↪T Clark my mistake. Your post said some disagree, and then you brought up many worlds in a way that sounded like you think many worlds is an example of disagreement. — flannel jesus

The inequalities in Bells Theorem are there to help us test if our universe is one where it's in fact true that we might live in a classical universe where those questions have singular, definite answers.
— flannel jesus

In my understanding, this is not true. It is your interpretation, not mine and probably not Bell's. The inequalities are not "there to help us," they describe phenomena at very small scales. — T Clark

The Wikipedia page on bells theorem states explicitly - Bell's theorem is a term encompassing a number of closely related results in physics, all of which determine that quantum mechanics is incompatible with local hidden-variable theories. The quote of mine is just rewording that, where I replace "local hidden variable theories" with the phrase "classical universe where those questions have singular, definite answers." Those phrases may not be perfectly interchangeable, but they are close to interchangeable. Despite your misgivings, I have read enough about bells theorem to be relatively confident that what I said is at least loosely close to the way it was intended by bell and understood by modern physicists.

in addition to the above quote from Wikipedia, please see this quote from the Stanford article on bells theorem

https://plato.stanford.edu/entries/bell-theorem/

Finally, in 2015, experiments were performed that demonstrated violation of Bell inequalities with these loopholes blocked. This has consequences for our physical worldview; the conditions that entail Bell inequalities are, arguably, an integral part of the physical worldview that was accepted prior to the advent of quantum mechanics. If one accepts the lessons of the experimental results, then some one or other of these conditions must be rejected.

If one accepts the experimental results, then some of the conditions that were integral to the physical world view accepted prior to quantum mechanics must be rejected. The physical world view prior to quantum mechanics was what I've been referring to as "classical". I do believe Stanford is saying, in different wording, the same thing I'm saying : the experimental results we get from the tests of bells theorem tell us that we, in fact, do not live in a classical world.

I'm not pulling this interpretation of bells theorem out of my ass. It is possible, however, that I'm terrible at explaining myself or defending myself

Sorry to bombard, but here's another quote from the same Stanford article:

7. Significance for Quantum Information Theory
The set-up envisaged in the proof of Bell’s theorem highlights a striking prediction of quantum theory, namely, long-distance entanglement, and experimental tests of the Bell inequalities provide convincing evidence that it is a feature of reality. Moreover, Bell’s theorem reveals that the entanglement-based correlations predicted by quantum mechanics are strikingly different from the sort of locally explicable correlations familiar in a classical context.

"Bell’s theorem reveals that the entanglement-based correlations predicted by quantum mechanics are strikingly different from the sort of locally explicable correlations familiar in a classical context." This sounds a lot like what I've been saying.

The quote of mine is just rewording that, where I replace "local hidden variable theories" with the phrase "classical universe where those questions have singular, definite answers." Those phrases may not be perfectly interchangeable, but they are close to interchangeable. — flannel jesus

I don't see how the two phrases are interchangeable at all.

I don't see how the two phrases are interchangeable at all. — T Clark

Does the second quote from stanford lend any clarity in that direction for you at all?

Bell’s theorem reveals that the entanglement-based correlations predicted by quantum mechanics are strikingly different from the sort of locally explicable correlations familiar in a classical context.