19106

If large black holes are at the heart of most galaxies and they are dark by definition and we have no way to tell what their size is, couldn’t they be hiding enough mass to make up the missing mass in the universe?

Georges Kaufman
Tampa, Fla.

A central black hole would not cause the visible outskirts of a galaxy to spin at roughly the same rate as the interior, as astronomers have observed. Not only is a vast amount of unseen material needed to account for this spin–much more than the visible mass of the galaxy, let alone a central black hole–but the material must be distributed in a huge halo around the galaxy .–R. Cowen