We can learn something about how important black holes are to the evolution of galaxies and to star formation by considering the life cycle of the Smith Hydrogen Cloud. . Left to their own devices, atoms that have reached a stable state with an even temperature distribution have no net gravitational effect upon one another, and thus we see that the Smith Cloud, which has the potential to form a million suns, has just drifted aimlessly through space for millions of years. Atoms are useless for forming stars and galaxies, and what is required for star formation and for the formation of galaxies is the Black hole. It is the Black hole that will attract the free energy that is required to generate the gravitational field that will allow lazy atoms to coalesce into stars.
In the image above we can see the Smith Hydrogen cloud approaching our galaxy and being pushed into a circular course by the lines of magnetic force of our rotating galaxy. My hypothesis is that the Smith cloud will become enlongated, and then as it enters the densest part of the gravitational field, where free energy can be found, star formation will begin to fire up, first in the leading edges of the cloud, as, after millions of years of aimless drifting, those hydrogen atoms finally had an encounter with a black hole and with the gravitational field effects generated around a black hole, which is what obviously must produce galaxies. We know that atoms of hydrogen are useless for producing stars, much less galaxies. I would then presume that the Smith Hydrogen cloud will form one more of those spiral bands rotating around our galaxy, as circled in the image above, since it would appear that this was not the first passing cloud of hydrogen that fell under the spell of the black hole rotating at the center of our galaxy, and no doubt at the center of every other galaxy in the universe.