Now, the physicist Werner Heisenberg theorized that the velocity and position of an electron cannot be calculated simultaneously, meaning that you might know the velocity or speed of an electron as it's traveling, but you won't know its position, and conversely, you might know where it's located, but you wouldn't know how fast it's moving.

Now, related to an electron behaving both as a wave and a particle is a reason for this issue. We're going to say here that the velocity or speed of an electron is related to its wave nature. Remember, light energy can move in the form of a wave, and we're going to say that the position of an electron is related to its particle nature.

Again, some say that light energy can be seen as just a cluster of particles known as photons. Now this relationship we call it complementarity, where electrons can be seen as either particles or waves, but not both simultaneously. And that's the reason why you can't know both the velocity and position of an electron at the same exact time.