My source is the high school chemistry textbook: General Chemistry, 2nd Edition, by Donald A. McQuarrie and Peter A. Rock, published 1987 (This is not for a high school homework assignment.) According to Heisenberg's Uncertainty Principle, the product of the uncertainty in the momentum measurement Δp and the uncertainty in the position measurement Δq of a particle is greater than or equal to Planck's constant h divided by 4[itex]\pi[/itex]: Δp Δq ≥ h / (4[itex]\pi[/itex]) This is not due to poor measurement or poor experimental technique, as is sometimes supposed: that bouncing waves or particles affects the location of the particle being measured, like in a billiard collision. (The measurement waves or particles are presumed to be of comparable size to the particle being measured.) Heisenberg's Uncertainty Principle is usually limited to only small particles. Does this mean that particles do not have a physical location unless and until we observe them? (I do not want to make a broad question, but rather a narrow question.) Does Heisenberg's Uncertainty Principle necessarily pit Classical physics (and Logic and common sense and billiards) against the Copenhagen School? Has Heisenberg's Uncertainty Principle agreed with the majority of experimental laboratory results?