The question that elicited the response about extraterrestrials was submitted by a Twitter user named @CazCarpSnail. The question asked, “What do you think the impact will be on humankind if Kepler 22-b [Earth-like planet found by Nasa's Kepler Space Telescope] does indeed support life?” Hawking responded:
Hawking made similar comments in a 2010 Discovery channel special titled “Into The Universe With Stephen Hawking.” In the special, he cautioned against attempting contact with extraterrestrials, suggesting that they would likely be hostile. But despite his grim warnings, in April 2011, Hawking participated in a ceremony where a winner was named in a writing contest called “Dear Aliens,” which asked students to answer the following questions: What would you say to extraterrestrials if earthlings are contacted from outer space? If you had to speak for humanity, what would you say? The contest was launched by Hawking’s daughter Lucy Hawking, and the winning answer was beamed into space during the ceremony.
The discovery of intelligent life elsewhere in the Universe would be the biggest scientific discovery ever. But it would be very risky to attempt to communicate with an alien civilization. If aliens decided to visit us then the outcome might be similar to when Europeans arrived in the Americas. That did not turn out well for the Native Americans.
On Today, Hawking also commented on space colonization, stating his opinion that humans need to colonize Mars and other bodies in the solar system to prevent extinction. Just yesterday, former Apollo astronaut Buzz Aldrin wrote about the same topic on the Huffington Post website. He stated, “[T]o make a real difference — from an exploration, science, national security and international leadership perspective — our Nation needs to commit to seeking a permanent presence on Mars.”
When the first Mars colonies arrive on the red planet, they better hope that Martian theoretical physicists haven’t been offering similar cynical views about extraterrestrials . . .