The first thing that we observe about organized galaxies is their rounded form, whether it is nearly spherical, or a perfectly flat disc. Assuming that all of these galaxies were once peculiars, the rounding suggests that one or more times in their past, they have imploded and exploded. The implosions would have occurred simply due to the "like-likes-like" force, followed by inevitable explosions after the implosions developed excess hydrostatic pressure in the center. The reason for the spherical form is that explosions accelerate matter outward in a radial pattern. This is true whether all of the matter implodes simultaneously, or one clump at a time — whatever goes in will come out in a form that is centered on the explosion. It might take several cycles to completely change a peculiar shape into a perfect sphere, but this will happen eventually. So we will suspect that organized galaxies are in implosion/explosion cycles.
CLC: implosion/explosion cycle
