There are two problems that have to be taken into account when studying the spiral density wave theory. How does a galaxy get started, and how does it become stable?

The correct answer is: True

Explanation:

The density wave theory is preferred to explain how these structures are formed. According to her, the spiral arms are denser areas in the disk of a spiral galaxy produced by waves of density, which move at a different speed than those of the stars. The gravitational attraction of the material present in a spiral arm causes that when approaching it the stars accelerate, and that when leaving they are stopped, causing the material to accumulate in those areas. In addition, being denser areas, hydrogen is compressed and star formation occurs there.

The origin of density waves is unknown, but it is believed that it may be related to gravitational interactions, since many galaxies of this type have close companion galaxies; The presence of a central bar can also be the cause of its appearance.

it doesn't. it was imagined up in the middle ages.