Here's an interesting view I've encountered somewhere: yes, complex (not to mention intelligent) life might be very rare, but simple life might be extremely com

Here's an interesting view I've encountered somewhere: yes, complex (not to mention intelligent) life might be very rare, but simple life might be extremely common (either easily arising from primordial soups, and/or trivially spread by panspermia). Imagine - millions of Earth-like planets in the Milky Way alone, all covered (or: infested) by unicellular goo. (Before eventual colonization, this would warrant a really thorough "gamma soak" as in Alastair Reynolds' "Revelation space" SF series.)