No, there are dozens of distinct verifications; its presence is established essentially beyond the shadow of a doubt. It is anything but an assumption. See for

No, there are dozens of distinct verifications; its presence is established essentially beyond the shadow of a doubt. It is anything but an assumption. See for instance https://en.wikipedia.org/wiki/Dark_matter#Observational_evidence https://en.wikipedia.org/wiki/Dark_matter#Observational_evid... Also https://www.reddit.com/r/space/comments/a8vgm9/how_many_of_you_think_that_dark_matter_is_just_a/ https://www.reddit.com/r/space/comments/a8vgm9/how_many_of_y... has a good summary.