The Big Bang was strange -- and we still don't understand it, said Professor Stephen Hawking in his latest speech.
But whatever happened in the first seconds of creation, it didn't take God's help.
Our universe did not require the intervention of any divine being, he said.
"What was God doing before He made the world?" Hawking asked in his new address, delivered at the California Institute of Technology.
"Was He preparing Hell for people who asked such questions?"
At the speech, attended by a full house and another 1,000 people crammed on a lawn outside watching giant TV screens, the hugely respected scientist and author said that humanity should not seek to fill areas of its current ignorance with fantastical stories.
"There are two attitudes one can take," Hawking said.
"One is to that God chose how the universe began for reasons we could not understand. This was the view of Pope John Paul. At a conference on cosmology in the Vatican, the Pope told the delegates that it was OK to study the universe after it began, but they should not inquire into the beginning itself, because that was the moment of creation, and the work of God.
"I was glad he didn't realize I had presented a paper at the conference suggesting how the universe began. I didn't fancy the thought of being handed over to the Inquisition, like Galileo."
Hawking went on to discuss current theories for the creation and expansion of the universe, and outlined the areas he believes are most exciting for future study.
British theoretical physicist Stephen Hawking, Cambridge in January 1993. Photo: David Montgomery/Getty Images
Cast member actress Jane Fonda (who portrays a Musicologist with ALS) talks with Physicist Stephen Hawking backstage after a preview performance of '33 Variations' Los Angeles, California in February 2011. Photo: Ryan Miller/Getty Images
Cellist Yo-Yo Ma and Physicist Stephen Hawking attend the 2010 World Science Festival Opening Night Gala at Alice Tully Hall, Lincoln Centre in New York on 02 June 2010. Photo: Wireimage
U.S. President Barack Obama presents the Medal of Freedom to physicist Stephen Hawking during a ceremony in the East Room of the White House in 2009. Obama presented the medal, the highest civilian honor. Photo: Chip Somodevilla/Getty Images
Dr. Stephen Hawking, professor of mathematics at the University of Cambridge, and his daughter Lucy Hawking at George Washington University's Morton Auditorium in Washington, DC in 2008. Dr. Hawking gave a speech entitled 'Why we should go into space'. Photo: George Washington University/Getty Images
South Africa former President Nelson Mandela meets with British scientist Professor Stephen Hawking in Johannesburg in 2008. Photo: AFP/Getty Images
Physicist Stephen Hawking experiences a zero-weight moment during a flight on a Zero Gravity jet above Orlando, Florida in 2007. Photo: PA
Queen Elizabeth ll meets professor Stephen Hawking during a reception at Buckingham Palace to mark the importance of British Science in 2006. Photo: Anwar Hussein Collection/Getty Images
Professor Stephen Hawking and his second wife Elaine Mason arrive at the European Premiere of 'Lemony Snicket's A Series Of Unfortunate Events' at the Empire Leicester Square, London in 2004. Photo: Dave Hogan/Getty Images
Physicist Stephen Hawking smiles during a symposium in honor of his 60th birthday at the University of Cambridge on 11 January 2002. Hawking is the Lucasian Professor of Mathematics, a post once held by Sir Isaac Newton. Photo: Sion Touhig/Getty Images
Professor Stephen Hawking,the leading theoretical physicists, attended by his wife Elaine before delivering a lecture on 'Science in the Future' to a packed auditorium on on 14 January 2001 in Bombay. Photo: AFP/Getty Images
US President Bill Clinton and Professor Stephen Hawking watch a scene from 'Star Trek the Next Generation', during a 'Millennium Evening' at the White House in 1998. Theoretical physicist Hawking talked about the future of science during the live telecast with the Clintons. Photo: AFP/Getty Images
Theoretical physicist Stephen Hawking (second left) makes a guest appearance on Star Trek; The Next Generation in 1993. The episode features a scene in which the character Data participates in a poker game with a group of brilliant scientific figures consisting of Hawking, Einstein, and Newton. Photo: Julie Markes/AP
Microsoft President Bill Gates meets Professor Stephen Hawking on a visit to Cambridge University in 1997. Photo: AFP/Getty Images
British physicist Professor Stephen Hawking with his first wife Jane Hawking in 1990. Photo: David Montgomery/Getty Images
Famed jazz singer Ella Fitzgerald (back right) applauds renowned theoretical physicist Stephen Hawking, as he given an honorary degree, Doctor of Science, at the 339th Harvard University commencemen in 1990. Photo: Charles Krupa/AP
British theoretical physicist Stephen Hawking with student Chris Hull in Cambridge, January 1985. Photo: David Montgomery/Getty Images
He finished with a plea to continue exploring the universe, and to keep searching for answers.
"We must continue to go into space for the future of humanity," he said - adding that humanity would not survive another 1,000 years if it did not.
After being diagnosed with a rare form of motor neurone disease in 1964 at the age of 22, Stephen Hawking was given just a few years to live.
Nearly half a century later, he celebrated his 70th birthday as one of the most brilliant and celebrated scientists of the modern age.
Despite his illness leaving him almost completely paralysed and unable to speak, Prof Hawking's countless scientific papers, best-selling books and numerous awards have earned him comparisons with Albert Einstein and Sir Isaac Newton.