It&#x27;s not theoretically undetectable, just very hard to detect, to the point that we haven&#x27;t yet been able to do it. This article suggests that finally, we may be able to see it other than via gravitational effects.<p>For a long time I also subscribed to the idea that the missing matter was better explained by faulty math, somewhere, but as our observations get better it&#x27;s looking more and more like there&#x27;s really something there, that behaves independently and differently than the matter we know.