Figure 26-3: Inflation Solves the Flatness Problem This sequence of drawings shows how inflation can produce a locally flat geometry. In each successive frame, the sphere is inflated by a factor of 3 (and the number of grid lines on the sphere is increased by the same factor). Note how the curvature of the surface quickly becomes undetectable on the scale of the illustration. Inflation models expand the universe by about a factor 1050, so nearly any original degree of curvature (indicated by the radius of the sphere on the left), will end up nearly flat after inflation.
(Adapted from A. Guth and P. Steinhardt)