" When we make a measurement on a system, we disturb it, typically by forcing it to interact with a measuring instrument. So Rule 1 does not apply to measurements. This is true not only of measurements, but of any interaction between the system and outside forces. So is there anything special about measurements? Measurements are special because they are where probabilities enter quantum theory. "

― Lee Smolin , Einstein's Unfinished Revolution: The Search for What Lies Beyond the Quantum