We address some issues of topological defect inflation. (1) We clarify the causal structure of an inflating magnetic monopole. The spacetime diagram shows explicitly that this model is free from the ``graceful exit'' problem, while the monopole itself undergoes ``eternal inflation''. (2) We extend the study of inflating topological defects to Brans-Dicke gravity. Contrary to the case of Einstein gravity, any inflating monopole eventually shrinks and takes a stable configuration. (3) We reanalyze chaotic inflation with a non-minimally coupled massive scalar field. We find a new solution of domain wall inflation, which relaxes constraints on the coupling constant for successful inflation.
Categories: gr-qc astro-ph hep-ph