Hi all, Apologies if my understanding is a bit simplistic but even if my question turns out to be idiotic, I'm sure I'll learn from your replies. Thanks in advance! So the reason dark matter was postulated in the first place is because the observed gravitational effects in the known universe far exceed the observable matter in the universe, right? But we're pretty sure there's a supermassive black hole at the centre of our galaxy and of most other galaxies and that our galaxy probably contains a large amount of smaller black holes, right? So we've never directly observed a black hole. Is it not then possible that this 'extra' matter that we can't see exists in the form of black holes and not dark matter?