Soved ! Thank you ! <| sep |> Are you buying a prebuilt ? <| sep |> it also doesn ' t show up in your daily goal tally so it might be easy to miss , depending on where you are looking <| sep |> Update that archive , a mod rekt the idiot poster and it is freaking glorious . <| sep |> Fast food or custodian <| sep |> i think it ' s Tyggbar <| sep |> There are three main observations that suggest our model of gravitational forces on large scales is missing something 1 Galaxies have faster rotation at large radii than we would expect given the measurable galaxy mass 2 Galaxies within clusters are traveling faster than we would expect given the measurable cluster mass 3 Gravitational lensing effects are stronger than we would expect for galaxy clusters etc . Two main ideas are proposed to address this problem 1 There is extra material that we cannot see 2 Our model of gravity is just wrong on large scalesNumber 2 , mostly called MOND Modified Newtonian Dynamics has some specific instances where it works well , but it ' s a bit adhoc and can ' t provide a good general solutionexplanation . Number 1 is split into two campsA The missing material is ordinary , dark stuff that is just not visible . B The missing material is a new type of matter , not detectable by EM radiation . ' A ' has been shown in research to be highly unlikely , given what we know , and it would take some bizarre distributions of black holes , dark material etc to explain our observations . ' B ' has been very successful at reproducing observations in everything from galactic rotations to the very formation and evolution of galaxies . See the cosmological simulations called Illustris . The best theory so far is that whatever DM is , it doesn ' t interact much or at all with light or regular material and interacts only weakly with itself . However , detecting DM and identifying exactly what it is is still an open question and an active field of research .