How does the electron travel? I've heard that it just exists at a certain point, it fluctuates in and out of existence. Electron cloud densities are maps of where the e- has a high probability of 'existing'. How can we relate this to Heisenberg's uncertainty principle when we can't calculate the speed of the e- when we know it's position. How can we calculate it's speed when it merely just 'exists' at a point?