Sołtan calculated the mass density of accreted material as it is directly related to the energy density of quasar light. He derived a value of approximately 10 solar masses per cubic Gigaparsec. This mass would be discretely distributed (since quasars are single point sources); given an average mass of approximately ten million solar masses, it would be statistically likely for a "dead quasar" to be within a few megaparsecs of Earth.