Honest question.  If the concept of dark matter flows from our current understanding of gravity, and gravity is so admittedly poorly understood, how confident are we that dark matter is &quot;a thing&quot;?  I know an intuitive sensibility is not the best foundation for an understanding of The Universe, but every time I read about dark matter, I get a very &quot;Aether&quot;-ish vibe.  I just imagine comments section in the 2070 version of HN getting a good natured laugh about dark matter.