Creation of Spiral Galaxies
  The spiral galaxies, including our galaxy, are created by the gravito-radiative forces generated by colliding black holes at the center of quasars. The gravito-radiative force is predicted by Einstein's general relativity. A quasar is assumed to have a circular disk of highly compressed neutrons (ylem) orbiting around black holes. The collision of two black holes at the center generates the gravito-radiative force, exerted on the ylem disk, producing a pair of bars with 180 degree rotational symmetry. This pair of bars develop into a pair of spiral arms, keeping the 180 degree rotational symmetry. Therefore, the number of spiral arms must be even. Our Milky Way galaxy has two pairs of arms, and has the 180 degree rotational symmetry, indicating that we have had two galactic nuclear explosions. The theory proposed by Gamow and others on the making of chemical elements fits into this theory. Thus, the age of the Milky Way must be equal to or greater than the age of the earth, 4.5 billion yr. The spirality of the Milky Way galaxy is examined under this assumption, and it is found that our galaxy was once about 10 times larger than it is now, and has been shrinking during the last half of its life. 
Masataka Mizushima