&gt; despite our best efforts it cannot be detected but there&#x27;s vast amounts of it.<p>But we have detected it, to the best of our present capabilities. We&#x27;ve measured how much baryonic matter are in formations, calculated how much mass is needed to keep the structure together and spinning, and come up short. That shortness is dark matter. It&#x27;s sort of evidence by absence. There is something there that has mass but doesn&#x27;t experience EM forces.<p>Either that, our our theory of gravity is wrong on a very fundamental level. On proposed alternative, that describes the motion of some stars without missing any mass is MOND: <a href="https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Modified_Newtonian_dynamics" rel="nofollow">https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Modified_Newtonian_dynamics</a>