A gaussian wave package is moving in x-direction without disturbance.
During the movement, it is corroding increasingly (dispersion).
If you turn on "fourier-analysis", you will recognize, that the wave spectrum
of a gaussian distribution is again a gaussian distribution that is widening
with the sharpness of the wave. As the wave package is corroding, the wave
spectrum gets narrower.
If you choose a higher speed, i.e. a smaller wave length (for example wellenlänge
= 5), the particle corrodes more slowly. If it had the speed of light,
no dispersion could be observed.
Vice-versa, particles with a large wave length (for example: wellenlänge
= 20), corrode very quickly.