Elementary quantum theory teaches there exists a symmetry between position space and momentum space - you are free to switch by Fourier transform between position eigenvectors or momentum eigenvectors to express the wave function of a particle.
In articles on decoherence I have read, but don't understand, that this symmetry is broken by environmental interaction and position becomes the preferred basis (or the preferred observable is the position of the system).
Have I understood this correctly? If so is there a simple way to understand the origin of this asymmetry between position and momentum (or an SE post where this has already been discussed at a simple level)?