  Open Inflation has recently been suggested as a possible way out of the age
crisis caused by observations of a large rate of expansion of the universe, in
conflict with the existence of very old globular clusters. It proposes that our
local patch of the universe originated in a quantum tunneling event, with the
formation of a single bubble within which our universe inflated to almost
flatness. I review the different models proposed together with their
predictions for the amplitude of temperature anisotropies in the cosmic
microwave background.

Astrophysics