In electrical engineering circles, it's common knowledge that any stimulus in the time domain can be decomposed into a Fourier series, or a Fourier transform in the frequency domain. In other words, you can build an arbitrary signal in the time domain using sine/cosine waves whose frequencies and amplitudes are specified by the Fourier transform. In physics, a similar concept arises in quantum mechanics. Objects that live in the space we're familiar with, position space, can be described as waves in momentum space where the wave number, (analogous to frequency), k, of a given wave is described by the momentum, p of an object as: . This is the principle behind De Broglie wave descriptions of electrons for example. An illustration of what the terms local vs. non-local mean in quantum mechanics led to a much better understanding of the uncertainty principal and wave functions for me anyway. Our professor mentioned that in momentum space, a potenti...