Hello everyone, Heisenberg's Uncertainty Principle states that the less uncertainty there is of a particles position, the more uncertainty there has to be of its momentum. Since mass is a constant in this case, we can refer to the uncertainty of the velocity instead. I was reading a physics book, The Feynman Lectures on Physics, and it mentioned, "if we try to pin down a particle by forcing it to be at a particular place, it ends up by having a high speed." My question is, what does high speed of a particle have to do with the uncertainty of its velocity? Is it that it is more difficult to precisely measure the velocity of a particle at high speeds?