The survival of the human race depends on its ability to find new homes elsewhere in the universe because there’s an increasing risk that a disaster will destroy the Earth, world-renowned scientist Stephen Hawking said Tuesday. The British astrophysicist told a news conference in Hong Kong that humans could have a permanent base on the moon in 20 years and a colony on Mars in the next 40 years. “We won’t find anywhere as nice as Earth unless we go to another star system,” added Hawking, who arrived to a rock star’s welcome Monday. Tickets for his lecture planned for Wednesday were sold out. “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.”