When it comes to dark matter, the mysterious substance that makes up the vast majority of the mass in the Universe, there’s a whole lot we don’t understand or know about it. You might think that there are so many unknowns that are so huge that — quite reasonably — perhaps it doesn’t exist at all, and there’s some other explanation for the behavior of masses on galactic scales and up?
And yet, you can’t make that leap unless you’ve honestly (and scientifically) considered the full suite of evidence and facts that speak to the question of dark matter’s existence.
What about galaxy collisions? Cluster collisions? The fluctuations in the CMB? Large-scale clustering? Baryon acoustic oscillations? And so much more?