Eli5 Why can’t we “know” the speed and position of an electron simultaneously? Why can we only measure one of these properties at a time?

Question

This always confuses me and I’m not sure how it works. Please explain…

In: 252

Answer 1

Imagine a marble rolling across a table and a blind person wants to know where it is and where it’s going. The blind person has a stick that he can poke the marble with, and feel when it touches. The problem is, if he pokes the marble with the stick, that has the effect of changing the motion of the marble. At the quantum level, “measuring” means interacting with something, like poking the marble with a stick. The simple act of measurement changes the thing you are interacting with, like poking the marble with a stick.