Q&A: Black Holes

Q:
Is it possible for a black hole to "eat" an entire galaxy? If so, what about the 1% mass rule? It would seem at some point the universe would be nothing but black holes, thereby after succumbing to evaporation

A:
We cannot think of a scenario where a black hole would eat an entire galaxy. The gravitational reach of supermassive black holes contained in the middle of galaxies is large, but not nearly large enough for this task. Also, gravity by itself isn't enough. For example, if the Sun suddenly turned into a black hole of the same mass, we'd continue to orbit it without being pulled in. Of course, this wouldn't be good for life on Earth!