> Also, it's not like the 𝛬CDM crowd says they are certain of the nature of DM.
They seem pretty certain given how easily the epicycles keep getting adopted to keep DM alive, and how readily they dismiss MOND.
> and they don't really offer a physical/geometric justification for why it should exist or why it should take the value that it apparently has.
There are papers that do this actually, such as superfluid DM. Regardless, the lack of justification for an empirical law does not refute the existence of the effect it describes. Unfortunately, DM proponents seem adamant in not trying to explain this effect in terms of DM.
They seem pretty certain given how easily the epicycles keep getting adopted to keep DM alive, and how readily they dismiss MOND.
> and they don't really offer a physical/geometric justification for why it should exist or why it should take the value that it apparently has.
There are papers that do this actually, such as superfluid DM. Regardless, the lack of justification for an empirical law does not refute the existence of the effect it describes. Unfortunately, DM proponents seem adamant in not trying to explain this effect in terms of DM.