Does the Universe Contain Enough Mass To Reach Critical Density?
A fundamental problem is that telescopic observations show that the Universe contains only 1/100 the luminous (i.e., stars and galaxies) mass that it needs to reach critical density. Astrophysicists hold that dark matter must account for the rest. Observational evidence showing that dark matter affects the rotation rate of galaxies, and behavior of clusters of galaxies, boosts estimates of the amount of matter in the Universe to 10% of the value needed to reach critical density. To date the remaining 90% of the required mass to reach critical density is missing and unaccounted for.
