You should give the book "We Have No Idea"[0] a try. It's the author of PhD Comics. It's first chapter explains pretty well why we know dark matter exists. [0]

You should give the book "We Have No Idea"[0] a try. It's the author of PhD Comics. It's first chapter explains pretty well why we know dark matter exists. [0] https://www.amazon.com/gp/aw/d/0735211515/ https://www.amazon.com/gp/aw/d/0735211515/