A really interesting talk by Lawrence Krauss about how it might be possible for our Universe to have come into existence from nothing.
It's long, but it's very entertaining and informative (if you're into this kind of thing).
http://thesciencenetwork.org/programs/the-science-reader/a-universe-from-nothing-why-there-is-something-rather-than-nothing
I watched this before, it's excellent, he explains things very well.