Dark matter forms a diffuse spherical halo, whereas ordinary matter can collapse into a disk, such as the familiar disk of stars of the Milky Way plane.
Does "diffuse spherical halo" mean that our galaxy or galaxy cluster is sitting with a dark matter shell and that there isn't a whole lot of dark matter here? A halo does have a big hole in the center after all, at least in 20th and 21st century depictions.
That shell would seem to be what the words suggest, but it would also seem to be absurd. Since there is 5x as much dark matter as light, wouldn't the structures inside this shell be torn apart by the gravitational effects of the shell?
