On a serious note, you don’t need to contrive undetectable things like ‘dark matter’ when you take into account the all-pervasive, massive amount of interstellar plasma and its effects at galactic scales.
On a serious note, you don’t need to contrive undetectable things like ‘dark matter’ when you take into account the all-pervasive, massive amount of interstellar plasma and its effects at galactic scales.