Sept. 7, 2010 -- "One can't prove that God doesn't exist," professor Stephen Hawking told ABC News. "But science makes God unnecessary.
"The laws of physics can explain the universe without the need for a creator," he added.
This week the world's most famous scientist releases his latest work, "The Grand Design," co-authored with the American physicist and best-selling writer Leonard Mlodinow. The book has already stirred one of our deepest debates: Did God create the universe?
According to Hawking, something can indeed be created from nothing. He believes our universe was created from nothing. Hawking writes in his latest book: "It is not necessary to invoke God to light the blue touch paper and set the universe going."
Hawking, arguably the greatest scientific mind of our time, said he believes the laws of physics and not the hand of a god explain why we are here. He said that physics can explain why the Big Bang happened. He writes: "Because there is a law such as gravity, the universe can and will create itself from nothing."
Hawking and other scientists have, in the past, suggested God is used merely to explain away gaps in human knowledge.
Asked by ABC News why so many people need a god he replied: "People want to think there is something they can relate to and which can make them feel they are not isolated but are part of a larger whole. They seek it as the authority for an ethical system and a lifestyle they can aspire to but not necessarily achieve."
Hawking hasn't always thought this way. Back in 1988 in his multi-million selling book, "A Brief History of Time," Hawking wrote: "If we discover a complete theory, it would be the ultimate triumph of human reason: for then we should know the mind of God."
He is not claiming to have discovered that "complete theory." But subsequent research and observations -- including that of a planet orbiting a star other than our sun in 1992 -- have led Hawking to believe that in the creation of our universe God is "unnecessary."
Hawking said something called M-Theory might eventually tie it all together and explain what our universe is made of and exactly how it came into being. All he can say for now is that there was no need for a god to make it happen.
"If we finally find the Theory of Everything and why we are here, it will be the result of the joint work of many people over many years," Hawking told ABC News.
It could take centuries before humanity even comes close, and it could take centuries for practical physicists to prove or disprove Hawking's latest controversial pronouncement.
Is he the greatest mind of our time?
"I certainly wouldn't claim to be the greatest mind of our time," he told us. "It is only after the passage of time that we will see who were the outstanding figures."