You can **never simultaneously know** the exact speed and exact position of an object. The [[uncertainty]] principle exists because everything in the universe behaves like **both a particle and a wave at the same time. ** In quantum mechanics, the exact speed and exact position of an object **have no meaning.** An objects wavelength is related to it's momentum = mass x velocity. Atoms and electrons have wavelengths big enough to measure in physics experiments. > A fast moving object has lots of momentum which **corresponds to a short wavelength.** A heavy object also has a lot of momentum even if it's not moving very fast. We do not notice the wave nature of everyday objects because they have incredibly short wavelengths. For example, a tossed baseball has a wavelength of a billionth of a trillionth of a trillionth of a meter. We can know a particles position very well, but it does not have a wavelength, so we don't know it's momentum. If we add many waves, they add / cancel out, and they create a wave packet with a clear wavelength in one small region = A quantum object with both wave and particle nature. To accomplish, this we lose certainty of both position and momentum. Both position and momentum are uncertain and their **uncertainties are connected. ** - If you want to reduce the position uncertainty, Add more waves to make a smaller wave packet which means a bigger momentum uncertainty. - If you want to know the momentum better, you need a bigger wave packet, which means a bigger position uncertainty The uncertainty principle is the inevitable result of combining particle and wave nature. > It is not just a **practical limit on measurement**, it's a **limit on what properties an object can have** built into the fundamental structure of the universe itself.