”In a spiral galaxy, the ratio of dark-to-light matter is
about a factor of ten. That’s probably a good number
for the ratio of our ignorance-to-knowledge. We’re out
of kindergarten, but only in about third grade.”
Vera Rubin
Modified Newtonian Dynamics (MOND) in the framework of covariant and non covariant field theory, Advances in Classical Field Theory (2011) 1: 166. https://doi.org/10.2174/978160805195311101010166