In a talk at the National Science Museum to mark the start of a new exhibition Prof Hawking also says the Large Hadron Collider may prove the existence of multiple universes.
Known as M-theory Hawking says multiple universes would occur naturally.
"These multiple universes can arise naturally from physical law. Each universe has many possible histories and many possible states at later times, that is, at times like the present, long after their creation.
Most of these states will be quite unlike the universe we observe, and quite unsuitable for the existence of any form of life. Only a very few would allow creatures like us to exist."
Ending his talk, he tells his audience: "So remember to look up at the stars and not down at your feet. Try to make sense of what you see and hold on to that child-like wonder about what makes the universe exist."
More top news
More than one million passengers travelled through London Southend in 2017.
Another cold, windy day, sometimes bright, but with a few showers, these locally wintry.
House prices in Cambridge have risen higher than anywhere else in the UK according to figures for November 2017. They went up by 16.4%.