Open universes, inflation, and the anthropic principle

Abstract

Models of open inflation with a variable density parameter $\Omega$ provide the most natural way to reconcile an open universe with inflation. The use of anthropic principle is essential to derive observational predictions of such models. I discuss how this principle can be used in a quantitative way to determine the most probable value of $\Omega$. I also comment on recent work by Hawking and Turok on quantum creation of open universes from nothing.

Comments: Final version. Some typos corrected, a reference added