In the first model of inflation discovered by Alan Guth, there was not a consistent way to end the inflationary period and yield the homogeneous & isotropic universe we see today — the “graceful exit” problem. This was solved by Andrei Linde (and, independently, Andreas Albrecht and Paul Steinhardt) by introducing “slow roll” or “new” inflation. Instead of sitting in the false vacuum as Guth proposed, the universe would slowly roll down the potential energy hill; the nearly constant value of the scalar field would then drive inflationary expansion. In the steeper section of the hill, the scalar field rolls faster compared to the expansion of the universe, inflation ends and reheating can occur. In this video demonstration you can look at how the scalar field would evolve in Andrei Linde’s updated inflationary model.

Click the demonstration to start.