The debate on weather the Multiverse really exist or not is a hot topic since many years. The proponents of parallel universes strike back with multiverse. Read the links for a fascinating overview of these reveling concepts which challenge our perceptions.
Finally a man (Theoretical Physicist) who is a rebel in his own field always challenging his fellow men about current concepts or theories. He even disputed Stephen Hawking about black holes and eventually made him concede with his black hole physics. He is the man behind the development of parallel universe concept again challenging with the concept of a Level 1 multiverse.
We may never be able to grasp that reality. The universe and its ingredients may be impossible to describe unambiguously - Leonard Susskind