An interesting application of the anthropic principle to inflationary cosmology. I'm impressed with the successful "predictions" of the cosmological constant. Note that the "multiverse" involved here is not the "many worlds" of the Everett interpretation of quantum mechanics nor a space of theories like the string theory landscape. It's just a universe with different regions---"bubbles"---expanding differently.

It would nice to explain why the cosmological constant is what it is. Yet, no one tries to explain why the earth's orbital radius is what is beyond saying that it needs to be roughly what it is to support life. Where does this analogy break down? We have observed many other, apparently lifeless solar systems; it is possible but improbable that we might someday find indirect evidence for a bubble beyond our own in the cosmic microwave background.