In other words, they have both wavelike properties and solid properties. And that means, because elementary particles are no longer solid spheres, there is no way to know its position and at the same time, its velocity with complete certainty. So the formula or the equation for this uncertainty principle is the following plaques constant a very, very small number divided by two is always less than our change in x or the uncertainty of our position. Change in position times mass times change in velocity. Now remember, mass times velocity is momentum. So this guy is change in momentum.