Open Inflation

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.