In truth I know very little about the subject, so this is somewhat an ignorant speculation, and I invite other insight, and comments. However I have recently been doing some self motivated research. To me the hidden variables theory makes the most sense, yet it seems most people are more inclined to believe Indeterminism reigns supreme at the quantum level. It seems outlandish to me that so many would presume there is no causal factors explaining some uninterpretable phenomenon regarding quantum particles, and that they would rather explain it away by saying particles act on chance to some degree. I've done a little bit of reading on Schrödinger's cat, Bell's theorem, and the de Broglie-Bohm theory. Can anyone lead me to good evidence that quantum mechanics is, or is not, determinate?

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Thanks, but I'm beyond broke.
Where does this video originate? I think this is J. Z. Knight stuff.
I was right, this guy is a hack, his name is Fred Alan Wolf. He believes that all matter is directly affected by our minds, and that all minds combined create God. Read this interview with him. In the video the part in the double slit experiment where observing the particle from one slit changes the outcome of the pattern, isn't recorded in any scientific journal as far as I can find. Do you seriously believe that observing matter changes its properties? Everything preceding that part seems to be legit. However knowing what we do know about the double slit experiment (subtracting Dr. Wolfs bit), the only problem to arise is why a single fired particle seems to hit a random position within the wave pattern. So until new data can be found we're left to guess based off of that. One theory states that as a particle goes through one slit, part of its electro-magnetic field goes through the other causing the interference pattern, and the improbability is due to hidden variables, which in the history of science is not at all uncommon.
The idea of hidden variables in QM has been around for a long time - since the beginning of the theory, essentially. But it's been found that quantum theory as we know it is not compatible with these so called hidden variables. I recommend reading about the EPR paradox to familiarize yourself a bit with this. There's a lot that extends from the EPR paradox, but I'll save that for another time if you're still interested.

If we were to assume that hidden variables were indeed responsible for what is going on in QM, then we would need to first have experimental results that depend on these hidden variables. None have been found, that anyone knows of. In other words, there would need to be observables that indicate there are these hidden variables controlling outcomes that we do not understand. Were this the case, it is extremely unlikely that every experiment done to date would be verifying the predictions of quantum theory as we know it, without any consideration for or dependence on these hidden variables. This suggests that even if such hidden variables existed, they have no physical significance. It's possible one day that an experiment will show the theory to be lacking, and it's possible it may even be due to hidden variables. But as it stands, there's no reason to believe they exist. I won't get into it here, but it's been shown that no theory of defined hidden variables can lead to all of the results of QM as they are today. This is what extends from the EPR paradox, with a few other things thrown in for good measure.
From a purely theoretical point of view, quantum mechanics is inherently probabilistic. There are numerous phenomena which arise from this quantum 'randomness', from radioactivity to the Casimir effect.

EDIT: First post ^_^
Theoretical, being a key word.
It bums me out to see a self-labeled atheist make the same mistake of misunderstanding scientific terminology that Creationists and I.D. advocates use every minute they get a chance. That is, unless I'm making the mistake of misunderstanding what point you're trying to make... which I am taking to be that you find it unlikely that physical reality is truly probabilistic because quantum mechanics is merely "theoretical". Anyway, if that's the main gist if what you're saying, that's wrong. To begin, "theoretical" doesn't simply mean it's just an idea someone has about reality. Theoretical, in the scientific sense, means that it is tested, reviewed, tested some more, observed, over and over again, found to be experimentally sound, and found to accurately describe every observable characteristic...

The probabilistic nature of quantum mechanics is a very highly tested and experimentally verified facet of nature that is, of course, a strange and unpredictable aspect of reality. It's not merely "theoretical" but also experimentally, physically verified. Superficially, it may appear that this interpretation of the physical behavior on a quantum level is just due to our inability to probe deeper the workings of nature to a satisfactory degree. The fact is that the Uncertainty Principle leads to the concept being discussed here - that indeterminism is inherent to the quantum mechanical world and the structure of matter. David Bohm (a physicist) likes to say that the uncertainty principle should actually be called the principle of limited determinism in the structure of matter. Not as catchy, though, but pretty accurate. This concept seems bizarre because it goes against what we're used to seeing every day in our lives on the macroscopic scale of everything around us. This leads to our understandings of nature being based on observations around us that, under little scrutiny, are based on assumptions that seemed safe to make at one point (and at certain scales) but aren't totally accurate. The idea of all matter (particles) being able to be described with perfectly defined values of characteristics such as momentum or position, for instance, is something that seems so naturally plain and commonplace. It's not until studying the smaller scales that it becomes apparent that this just isn't how matter really behaves. Quantum mechanics has shown us that there simply exist no particles which have definitely defined momentum and position at the same time.

The recommendation above of the Feynman Lectures is sound advice. Read those. Something else I think is important to read on the topic is about the continuity of motion, which sheds more light on the idea of the uncertainty principle and how it really relates to the quantum mechanical world.
Actually, "theoretical" in physics and a scientific theory are different - in physics, theoretical research is all mathematical and not experimental, so something could be "theoretical" in physics, and might seem to fit nicely in a theory, but not actually be experimentally sound. String theory is considered theoretical physics, and cannot be experimentally tested right now at all. Theoretical physics is it's own field that is separate from experimental physics, and doesn't have to be shown to be experimentally sound to be considered part of theoretical physics, but DOES have to be shown has experimentally sound to be considered a theory.

But, I do agree that there have been many experiments that exhibit the probabilistic nature of quantum mechanics.
That's a well thought-out point, Danielle. But it's incorrect to say that theoretical physics research is all mathematical and not at all experimental in nature. It's necessary for theoretical physics to always retain physical meaning, as theoretical physics still bases itself in physical reality making it necessary to be confirmed by observation and experiment. It is not mathematical physics, nor pure mathematics, which do not always have the requirement of meaningful physical interpretation. Were we talking about pure mathematics or mathematical physics, however, then what you said would be accurate. Even when theorists are knee-deep in math and theory, their work has to ultimately be physically interpreted, and tested. Often times it is the experiment which paves the way for the requirement of stronger theory, and other times it is the theory which makes predictions that experiment must verify. Theoretical physics is not as separate from experimental physics as many tend to think, actually. Both go hand in hand, and often times overlap.

What I was referring to in my post was Ninja's remark on "theoretical being the key word". It seemed to me he was insisting that quantum mechanical theory is "only a theory"... though I see that's probably not the case now that you pointed out what he probably meant. But it's still incorrect to say that quantum mechanics is only mathematically or "theoretically" probabilistic, and not physically probabilistic. It is, in fact, completely probabilistic physically. So "theoretical" is not 'the keyword', there.

And don't get me started on string theory... !
I think what she meant is that cutting edge theoretical physics is all mathematical. While we will surely find ways to test such concepts (LHC!), until we do it is all math based. Eventually, theoreticals move into experimental stages and sort of become mundane and boring (yeah right).

Or maybe this is all just the theoretical beer talking.
Oh, I don't know what she meant exactly. You may be right. But I'd also disagree with that if she meant it's all purely mathematical. Sure, string theory is pretty cutting edge, and it relies more on math than physics, but it's also eh... very troubling, partially for this very reason.

To say theoretical physics is all mathematical is just like saying physics in general is all mathematical. Sure, it is a rigorously mathematical science, but the mathematics of theoretical physics is in need of physical interpretation so that it is not strictly mathematics. Theoretical physics doesn't END with the equations. Mathematics is simply the tool of physics, and the language of the models. But without being able to attach physical meaning or interpretation to the math (even before any experiment is proposed or done), it belongs in the realm of something else, less physical. That's why a field such as mathematical physics exists, for a more purely mathematical approach to physics, where it is more in line with the work mathematicians do rather than the work physicists do.

I suppose my underlying point is that the mathematics of theoretical physics has physical meaning, and is interpreted by the theorists to explain our world as we see it. This can even be independent of experiment, and often times it is, until the experiment becomes sophisticated enough to verify it or debunk it. So when the "theoretical" aspect of quantum mechanics is indicating that matter behaves probabilistically/indeterminately on the microscopic scale, it's not simply a limiting factor of the mathematical framework, but a consequence of the physical reality that the mathematics aims to explain. I hope this makes sense.
It might when I'm sober tomorrow. ;)


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