Abandon Earth or Face Extinction, Stephen Hawking Warns -- Again

Stephen Hawking speaks via satellite during a Science Channel presentation in Pasadena, Calif. (AFP)

It's time to abandon Earth, warned the world's most famous theoretical physicist.

In an interview with website Big Think, Stephen Hawking warned that the long-term future of the planet is in outer space.

"It will be difficult enough to avoid disaster on planet Earth in the next hundred years, let alone the next thousand, or million. The human race shouldn't have all its eggs in one basket, or on one planet," he said.

"I see great dangers for the human race," Hawking said. "There have been a number of times in the past when its survival has been a question of touch and go. The Cuban missile crisis in 1963 was one of these. The frequency of such occasions is likely to increase in the future."

"But I'm an optimist. If we can avoid disaster for the next two centuries, our species should be safe, as we spread into space," he said.

That said, getting to another planet will prove a challenge, not to mention colonizing it for humanity. University of Michigan astrophysicist Katherine Freese told Big Think that "the nearest star [to Earth] is Proxima Centauri which is 4.2 light years away. That means that, if you were traveling at the speed of light the whole time, it would take 4.2 years to get there" -- or about 50,000 years using current rocket science.

Still, we need to act and act fast, Hawking stated. "It will be difficult enough to avoid disaster in the next hundred years, let alone the next thousand or million. Our only chance of long-term survival is not to remain inward looking on planet Earth but to spread out into space. We have made remarkable progress in the last hundred years. But if we want to continue beyond the next hundred years, our future is in space."

This is not the first time Hawking has warned of impending planetary doom. In 2006, the physicist warned that Earth was at an ever increasing risk of being wiped out. And lately, Hawking has become quite outspoken.

In April, he warned of the dangers of communicating with aliens, telling the Discovery Channel that extra-terrestrials are almost certain to exist -- and humanity should avoid contact with them at all cost.

“To my mathematical brain, the numbers alone make thinking about aliens perfectly rational,” he said. “The real challenge is to work out what aliens might actually be like.”

The answer, he suggests, is that most of alien life will be the equivalent of microbes or simple animals -- the sort of life that has dominated Earth for most of its history -- and they could pose a serious threat to us.

In May Hawking said he believed humans could travel millions of years into the future and repopulate their devastated planet. If spaceships are built that can fly faster than the speed of light, a day on board would be equivalent to a year on Earth. That's because -- according to Einstein -- as objects accelerate through space, time slows down around them.

“Time travel was once considered scientific heresy, and I used to avoid talking about it for fear of being labelled a crank," he said in Stephen Hawking's Universe.

"These days I’m not so cautious.”