AMA | October 2024

4015.311 - 4039.751 Sean Carroll

is a way of characterizing the rate of growth of the scale factor. And the Friedman equation relates that to the curvature of space and to the energy density within space. So the fundamental thing you do as a starting out cosmologist is you learn the Friedman equation and you solve it. So you say, oh, the curvature is such and such, or the density of matter is matter or radiation or dark energy.