We don’t know where the medium black holes are
You probably knew how ridiculously large some black holes are, like those that lurk at the centers of galaxies. You may have known that some black holes are quite small, on the scale of some stars. But there’s a significant “mass gap” in black holes, which leaves astronomers and astrophysicists struggling to find so-called intermediate-mass black holes. Some possible intermediate mass black holes have been spotted—they are expected to exist, because supermassive black holes must grow out of something—but they remain something of an open question.
