The movement of galaxies is not arbitrary. It was established a relation between the mass of the central supermassive black hole and the activity of the core of the galaxy.
The matter represents one of the two edges of the potential well. It is the maximum point of the length of x (position B). At its opposite there is the singularity which represents the other end of the potential well, and which is the maximum point of the length of -x (position A). These two positions represent the pure correlated mass.