The quantum uncertainty that the uncertainty principle refers to is not due to the observer effect in the sense that the uncertainty is not due to the disturbances caused by any measurements on a system. The uncertainty principle is about the intrinsic statistical properties of the system.

For one single measurement, or even one single system, you cannot talk about the quantum uncertainty. The uncertainty principle is about the statistical patterns of a lot of identical measurements on a lot of systems which are all identical to the single system you are observing.

— Me@2013-03-11 3:40 PM

2013.03.14 Thursday (c) All rights reserved by ACHK