We have in fact detected one type of dark matter - neutrinos.  They aren&#x27;t sufficient to account for the mass needed to explain observations, but they are definitely dark matter in that they do not interact electromagnetically with regular matter.<p>The problem with modified gravity, is that it requires a lot more theoretical complexity to explain observations like the Bullet cluster and galaxy rotation, and the large-scale distribution of matter in the observable universe.  Ie. a modified gravity theory that works for one of those observations, fails for others.  Slow, massive dark matter clouds explain all of them quite nicely.