A relativistic examination of gravity in the galaxy may indicate that the invention of dark matter may not be necessary to solve the not-enough-matter problem. "The motions of stars in galaxies is realized in general relativity's equations without the need to invoke massive halos of exotic 'dark matter' that nobody can explain by current physics."
Update: mjt has doubts about the paper referenced here and notes that there's other evidence for dark matter that is not questioned by the above study.