I have read this question:
where Puk says in a comment:
I see. I would call both "random", with the degree of "randomness" defined by ψ. But yes, just a matter of semantics.
where Arnold Neumaier says:
On the other hand, it is clear from the laws of physics such a computing device can never be built, and the required knowledge can never be collected since an infinite amount of storage is already needed for representing a single transcendental number numerically. Therefore, in fact, one has to be content with approximations, resulting in a probabilistic prediction only. Thus, in practice, physics is probabilistic.
So based on these, the probabilistic nature of QM is basically just the same as randomness, we can never build a computer that could incorporate all the needed information, and we need to use approximations.
where CR Drost says:
In a very superficial sense of the term, one which has to do with excluding the possibility of determinism and therefore asking, "is there a way to understand the system as having an initial state which forced it to come to this conclusion," the answer is a qualified "no" he qualification here is the word "global": using some thought experiments (my favorite is a game called Betrayal) one can prove that there are quantum effects which cannot be understood in terms of classical local information In a deeper sense randomness is our way of reasoning about information that we do not know
But this one says more. This says that randomness means there is no way for the system to have a initial state which (because of causality) forces the system to evolve to a certain state. And that basically the world is quantum mechanical and there are quantum effects which cannot be understood in classical sense. This would mean that QM is not just simply random, but there are quantum effects that we do not understand and cannot even explain classically, it is not just simply random, but the underlying nature of the universe is probabilistic, and that is what we can model with mathematics.
But my question is about randomness meaning unpredictable, that is in some ways excluding causality. I do believe that QM probability does include causality, that is, it is predictable (to some extent).
- Is the probabilistic nature of QM simply just randomness (does it exclude causality)?