Question

Is a fish swimming in river located at the exact position you observe? Why or Why Not?

Answer 1

A fish swimming in river is a macroscopic object.

According to the Heisenberg's Uncertainty Principle, for objects with a substantial mass (i.e., a macroscopic object) , even a small uncertainty in speed suggests a huge uncertainty in momentum. Heisenberg's Uncertainty Principle at that point requires just a correspondingly little uncertainty in position. Thus for a fish swimming in river we locate it at the exact position we observe it since the uncertainty in position is insignificant.