The Standard Dust Models (Λ=0)
	• Have a Newtonian Analog: – Replace x by comoving value r using the scale factor R, x = Rr, and express density in terms of its value at the present epoch ρ = ρ0R-3, then: – Which matches eq. 7.1 for dust and lambda=0. Multiplying by the derivative of R and integrating gives us essentially eq. 7.2