Wow. I am not saying this to be rude, but you really don't know what you are talking about. You really do have as much of an understanding of dark matter as you do about invisible unicorns. But that doesn't mean the rest of us do. Don't conflate your misunderstanding of the concepts with a problem of the science.You have mentioned other observations that point to the fact that there is something we do not understand. I am not saying that 'something' isn't causing what we see, I am saying it is not 'dark matter'. Dark matter is an undefined identity, it just sounds scientific but has as much base as my invisible unicorn theory. Why couldn't invisible unicorns be causing these effects? Nothing in science actually disallows the existance of invisible unicorns, what makes invisible unicorns less viable then dark matter.