# Are quantum properties really indeterminate, or just unknowable?

Early on, it seems like Heisenberg's uncertainty principle was regarded as a principle of ignorance. That is, it says what's possible to measure or to know, rather than what actually is.

However, since its discovery, the uncertainty principle has predominately been interpreted as a principle of indeterminacy. That is, it's not just that we can't perfectly measure an electron's position, rather it's that the electron doesn't have an exact position.

Is the original epistemological interpretation still valid, or are there other reasons to believe that quantum properties are really indeterminate, i.t. not just unknowable?

• Possible duplicates: physics.stackexchange.com/q/24068/2451 , physics.stackexchange.com/q/54184/2451 , physics.stackexchange.com/q/114133/2451 and links therein. – Qmechanic Dec 23 '17 at 17:09
• What's the scientific difference between indeterminate and unknowable? – DanielSank Dec 23 '17 at 17:20
• Violation of the Bell inequality strongly suggests that things are in fact indeterminate. – noah Dec 23 '17 at 17:23
• That is, it's not just that we can't perfectly measure an electron's position, rather it's that the electron doesn't have an exact position. You can measure an electron's position, and it is possible for an electron to have an exact position. The Heisenberg uncertainty principle places a bound on $\Delta x\Delta p$, not on $\Delta x$. – user4552 Dec 23 '17 at 17:53
• The early development of quantum mechanics was quite hand-wavy, in the sense that a consistent, logical, and rigorous framework had yet to be worked out. The idea that the uncertainty principle corresponds to ignorance rather than to indeterminacy is a semi-classical notion which has since been corrected. – J. Murray Dec 23 '17 at 17:58