Stephen Hawking said on Tuesday that in order to ensure the survival of the human race we'll need to find new homes elsewhere in the universe because there's an increasing risk that a disaster will destroy Earth.
Humans could have a permanent base on the moon in 20 years and a colony on Mars in the next 40 years, the British scientist told a news conference.
"We won't find anywhere as nice as Earth unless we go to another star system," added Hawking, who came to Hong Kong to a rock star's welcome Monday. Tickets for his lecture Wednesday were sold out.
Hawking said that if humans can avoid killing themselves in the next 100 years, they should have space settlements that can continue without support from Earth.
"It is important for the human race to spread out into space for the survival of the species," Hawking said. "Life on Earth is at the ever-increasing risk of being wiped out by a disaster, such as sudden global warming, nuclear war, a genetically engineered virus or other dangers we have not yet thought of."