We study a class of “landscape” models in which all vacua have positive energy density, so that inflation never ends and bubbles of different vacua are endlessly “recycled.” In such models, each geodesic observer passes through an infinite sequence of bubbles, visiting all possible kinds of vacua. The bubble abundance $p_j$ can then be defined as the frequency at which bubbles of type $j$ are visited along the worldline of an observer. We compare this definition with the recently proposed general prescription for $p_j$ and show that they give identical results.

• Received 16 May 2006

DOI:https://doi.org/10.1103/PhysRevD.74.043520