In another sense, the quantum uncertainty that the uncertainty principle refers to is due to the observer effect.

To measure a physical quantity of system, you have to add a measurement device into the original system, forming a bigger system. In other words, the disturbance is so huge that you do not call it “disturbance” anymore. Instead, you are actually changing the system.

Since the system has been replaced by a new one, the statistical patterns of the potential measurement results change.

— Me@2013-03-11 3:40 PM

2013.03.22 Friday (c) All rights reserved by ACHK