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I'm not an expert, but I think the "orthodox" understanding is that quantum mechanics is fundamentally rooted in probabilities at the lowest level. The position you're taking, that quantum uncertainty isn't inherent in the system, but just related to us not knowing enough about it, is considered a "hidden variables" hypothesis.

And I think those have been ruled out by Bell's Theorem, or at least implies other very counterintuitive things have to be true instead.

>> And I think those have been ruled out by Bell's Theorem, or at least implies other very counterintuitive things have to be true instead.

Non locality seems less weird to me than any of the other interpretations of quantum mechanics. But I feel like I'm in a small minority with this. Besides, what we think about it isn't really relevant.

> Heisenberg uncertainty principle is more a statement about the limits of knowledge than about "God throwing dice".

This isn't what physicists believe though, Heisenberg uncertainty principle is about a wave not having both a well defined position and velocity. They either drift apart (undefined velocity) or they are spread apart (undefined position). Then the wave collapse keeps the wave together over time by randomly removing parts of it, we have no theory where that isn't random even "many world" means you randomly select one of the branches to follow.

We do know for sure that particles are waves that spread out and exist in all of those parts, it isn't just that it represent a point particle with unknown location. And we know for sure that those waves under certain circumstances withdraw from parts and just keep other parts, ie wave collapses. Both of those are easily observed in experiments and not up for debate.

In many worlds selection isn't random, but bayesian - really deterministic that can be subjectively interpreted as random.

Not sure I agree fully in the case of Uncertainty. To the best of our knowledge, an undetermined quantum property is actually undefined. Whether we go with the simple Many Worlds or the Copenhagen wave function collapse or even Pilot Wave theory, when the value becomes defined it is randomly selected (or our World is a random selection of all of them) according to the wave function.

I believe what you're saying is that there is indeed a superdeterministic hidden variable that would allow us to know before the value is defined what it will be. For simplicity let's assume the Many Worlds interpretation... this variable would tell us which world we're in.

The issue with this explanation is that we're not in that World yet, because our current World is only the result of past quantum events. When this next undefined value becomes defined, our single world splits into Many more Worlds, each of which has ours as a parent, so how could one of those be more or less intrinsically ours? Each is equally our World, and if we back up a single "step", our World contains all of the supposed hidden variables that say which child World is which. So I find that Many Worlds seems to invalidate superdeterministic hidden variables.

With other, single-World interpretations, the hidden variables make more sense. What you say would be true. But single-World interpretations are already more complicated than Many Worlds, with or without hidden variables and superdeterminism.

I don't think you're right about the many worlds interpretation here.

In the most popular "simple" many worlds interpretation, the whole universe is a QM system described by the universal wavefunction. The "worlds" are just "branches" of the wavefunction that are not entangled with one another.

The Schrodinger equation (and the more advanced QFT versions) are fully deterministic differential equations: the state of the universe at time T is fully determined by the state of the universe at time T-x, for any x. This remains true even if x is negative: there is no "arrow of time" in QM, there is no distinction between the past and the future in any QM equations.

The only "non-determinism" in Many Worlds is thus of the knowledge kind: you don't know which "world" you happen to be in, so you don't know which result you'll notice. But this is like being spun around a coin: you don't know which face you'll end up looking at, but you know both faces actually exist. All the possible outcomes of any QM event are realized in "some world", there is 0 uncertainty.

Hm, that could be correct actually. Perhaps Many Worlds is the most deterministic interpretation and I've got it backward - this clearly is not my day job :)

If QM is correct and there is no "deeper" hidden variable theory that explains the movement of all particles, then you're wrong.

Heisenberg uncertainty as it exists in QM today is not a statement about your knowledge, it is a statement about the possible interactions between particles. It tells you that if a particle collides with another at a specific point in space, then their trajectories after that collision can't depend on the momentum of either particle, for example, because that would violate the inequality.

This indeed does not necessarily imply randomness per se. But it is much more than a statement about precision of measurements at a human scale: it is a statement about the possible interactions at even the lowest scales.

The uncertainty principle is just a really misunderstood concept because it was first discovered in the context of quantum physics (Heisenberg 1927) and only later (Gabor 1946) the underlying mathematical principle that causes it was discovered.

It has nothing to do with measurement, knowledge, randomness or even our physical reality at all. It is a much more fundamental mathematical phenomenon [0] that always occurs when you switch representation between time and frequency domains and it tells you how you can arrange information in such mixed representations.

[0]: https://en.wikipedia.org/wiki/Uncertainty_principle#Signal_p...

"Random" is a property of your mind, not of the world.

Limited information about the initial state is one source of randomness but not necessarily the only one. Whether there is true randomness in the universe is at very least an open question.

Can you clarify what "true randomness" means out side of the context of human agency and perception?

Can you also give an example where "true randomness" would differ from the randomness I describe on the actions a human would take? That is to say, if a my internal model of the world tells me a coin landing on heads is 50/50 how does "true randomness" or not of the resulting coin toss impact how I should gamble on coin tosses?

imho the idea of "randomness" separate from our own internal state of belief is a nonsensical concept, but would appreciate examples to the contrary.

You can not predict the future state from the current state, not even in principle.

Measure the spin of an electron along two different axis, to the best of our knowledge - or maybe just my - the result of the second measurement is not predictable by anything. Of course only until it turns out that hidden variables is the correct interpretation and that the hidden variables can be measured, then this also becomes the other kind of randomness.

In basic interpretations of quantum events, quantum properties are not defined until measured. It's not just that we can't see the other side of the card; the card is blank until we flip it.

> Can you clarify what "true randomness" means out side of the context of human agency and perception?

Depending on your Interpretation of QM, randomness is a fundamental aspect of reality. How does a quantum superposition of two states resolve? The canonical view is wavefunction collapse, which is ultimately random, and attempts to find some pattern underneath it all generally fail. Look at the Bell Inequalities, which demonstrate that any theory which attempts to reproduce the successful predictions has to either be non-local, or non-realistic, and must be incompatible with local hidden variables.

Now does that mean nature is random? I don't know, no one does, because we're sure that QM isn't a complete theory. It is a really good theory though, in some domains such as QED it's been tested to more than 11 decimal places and found to hold. The difficulty of making a new theory that matches that precision and represents a paradigm shift can't be overstated. The result is that a lot of time is spent on those aforementioned Interpretations, you've probably heard of some, such as "The Many Worlds Interpretation" aka parallel universes. After all if everything happens, and we just happen to only perceive a part of it, then there is no randomness... no hidden variable. When a quantum state collapses, part of it doesn't just vanish, it's just out of our site.

The problem with that is... there's no evidence to support it, probably no way to even test it. Anyway, the bottom line is that maybe there is real randomness, and maybe there isn't, we just don't know.

Do you count wave particle duality as randomness?

Certainly the dual slit experiment makes hidden variables very hard to preserve.

Additionally several tests have shown that hidden variables don't work to explain quantum mechanics, there aren't possible coins the allow the kind of probabilities we see.

> Can you also give an example where "true randomness" would differ from the randomness I describe on the actions a human would take? That is to say, if a my internal model of the world tells me a coin landing on heads is 50/50 how does "true randomness" or not of the resulting coin toss impact how I should gamble on coin tosses?

It's pretty simple. If the world is fundamentally deterministic, then you should only gamble with someone who you believe doesn't possess knowledge you don't. If an advanced alien or an angel offers to call a coin toss, you shouldn't take their bet, since they might know how to determine the result of the coin toss based on the weather and the color of the coin tosser's pants.

On the other hand, if the universe is fundamentally random at every turn, then you can safely take the bet: nothing they know could give them more information than you have about the result of the coin toss.

This is very similar to the difference between pseudo-random number generators (PRNGs) and sources of true randomness in a computer. There is no test you could do on the outputs of an RNG to determine if it is a (good, cryptographic-grade) PRNG or if it is a "true" RNG. However, if you're gambling based on the results of a PRNG, you should try to find out if the one you're gambling against doesn't happen to know the seed (in which case they can predict with 100% certainty what the next number will be).