Gregory's Server@ZachWeinersmith Being flat is unstable-- an accelerated expansion will expand more when it is bigger and a closed universe will collapse faster the more it has collapsed, so if the expansion is too gradual, the universe will run away from flatness too fast
@wild mind checking my work :D?
@kdund @ZachWeinersmith you're basically describing the flatness problem: general relativity predicts that different sources of energy form a delicate balance, described by the Friedmann equation. As the universe expands, the density of matter and radiation decrease, and curvature (being a source of energy in GR) should dominate over time. This is not what is observed. Inflation solves this by having the inflaton field provide the difference.