Richard Dawkins (http://en.wikipedia.org/wiki/Richard_Dawkins), has given a few excellent talks on atheism and our universe, at TED conferences. Richard Dawkin’s genius and work in his field cannot be described in a few words, thus the link to the article at Wiki, of him.
Also he is the author of “The God Delusion”, a best seller discussing the non-existence of a God, a supernatural creator, and also religion and morality. It is no argument that many amongst us, specially in Sri Lanka, have a “sitting on the fence” attitude when it comes to discussing God, or personal Gods. If you are one of them, please read this.