We Don't Know What Dark Matter Is

It's not just a little bit of stuff out there, it's a lawt right? It's like 80 % of the matter in the universe. So when you look at a galaxy, you're seeing only the bright bits. You're not seeing most of the galaxy. Most of it is actually dark matter. We just don't know what it is yet.We shouldn't know it's there, and we know it has substance to it, right? Because itead of it, like its presence, is affecting things in very large ways.