aquabug918 Messages 17 Reaction score 0 Thread starter Nov 14, 2006 #1 is it proportional to a^3 or 1 / a^3 . thanks!
Garth Science Advisor Gold Member Messages 3,580 Reaction score 107 Nov 14, 2006 #2 [tex]\rho_{matter} \propto a^{-3}[/tex] As the universe expands its matter density decreases. Garth