The Origin of Galactic Rotation

The early universe consisted of many systems of already formed pre-galactic arms, the arms in orbit about each other. As the orbits of the arms decayed due to gravitational attraction, the fore sections of the arms tangentially collided and stuck together forming spiral galaxies. The orbital motion of the pregalactic arms became transformed into rotational motion of the newly formed spiral galaxies. As the rotational motion of the newly formed spiral galaxies slowed down, the spiral arms collapsed into the body of the galaxy forming elliptical galaxies rotating slower than spiral galaxies.