If an almost point-like source emits an electron the Uncertainty Relation UR says that it will be in superposition of a great spread of momenta [0,p] where p>h/dx where dx is the measure of the source.
But as the particle moves the wavefunction spreads (spherical wave). So after time t, the region where the electron is localized is much greater. Applying UR again it follows that the spread of p has diminished. Is this true and if How is it possible (the electron has not interacted with anything so change in its state is not to be expected)?
