everything wrote:it's so darn confusing.
It is. All physics and science is. "Black matter" was originally just something Einstein invented out of the blue to make his equation work. And the most important equation of quantum mechanics is based on an imaginary number. Neither quantum mechanics or energy engineering would be possible without those "imaginary numbers". And no one knows what those imaginary numbers really are.
You can only say that an equation adds up, or that something "works" or "doesn’t work". So most knowledge, regardless it's about stars or the Universe, or about really small things we can't see, is not direct, but indirect. Much of it is assumptions that make sense in its own system of thought, or in practical application, until someone comes up with a better explanation.