Do we live in a multiverse?

One of the most outlandish ideas in modern physics is the multiverse - the idea that there exist multiple universes. Given that scientists tend to be fairly conservative and that this idea seems like a such a reach, it is natural to wonder why this idea is seriously discussed in leading scientific circles. In this video, Fermilab’s Dr. Don Lincoln explains how the existence of a multiverse is a possible answer to the question of why the universe seems so well tuned for human life.

Related video:
http://www.youtube.com/watch?v=lxWLfEPl8kM