Pretty much all massive objects except black holes emit light/radiation, and black holes, afaik, are detectable. Thus there's something else that we give a plac

Pretty much all massive objects except black holes emit light/radiation, and black holes, afaik, are detectable. Thus there's something else that we give a placeholder name "dark matter". It's possible it's not a matter of any kind at all, but just some very smooth but irregular field that interacts with the space-time curvature (gravity).