
Originally Posted by
TheObserver
To determine the momentum of a particle requires a measurement of position at two points. On way to intuitively think about the problem is to note that the measurement of a particle requires us to bounce light off of it to see it, or at least something to that effect. But when we hit the particle with a photon of light, this inherently changes the momentum of the particle. There is no way to make measurements without altering the state of the particle. The more accurately we want to know the particles position, the shorter wavelength and in turn higher energy of light we must use. As a result, very accurate measurements require very energetic light, the higher the energy the bigger the effect on the momentum.
Heisenburgs uncertainty principle goes even deeper than that though, and an understanding of the phenomena requires a bit of knowledge about Fourier transformations and conjugate variables.