Do we really need dark matter?

Abstract
Stars that between them contain a very small proportion of the mass in a typical stellar population, generate the bulk of the population’s luminosity. Consequently the overall mass:light ratio Y of the population depends on exactly how much of the population’s mass is in luminous stars, and we should not be surprised if stellar populations that formed in different physical conditions were characterized by very different values of Y. Actually, the well-observed regions of galaxies show minimal variation of Y.It is argued that even the most extended H i rotation curves could be understood in terms of constant Y if estimates of the brightness of the night sky were subject to systematic errors in the region of 4-8% .