SILVER SPRING, Md., April 26 (UPI) -- British theoretical physicist Stephen Hawking surmised extraterrestrial life exists but earthlings would be well-advised not to come into contact with it.
Hawking, in a U.S. cable outlet Discovery Channel documentary that covers many of the physicist's thoughts on the universe, said alien life is likely to exist but for humans to meet it might have negative unintended consequences.
"If aliens ever visit us, I think the outcome would be much as when Christopher Columbus first landed in America, which didn't turn out very well for the (American Indians)," Hawking says in the program.
He also said, "We only have to look at ourselves to see how intelligent life might develop into something we wouldn't want to meet."
Producers said the documentary, "Into the Universe with Stephen Hawking," took several years to create. Hawking's mobility and speech is severely limited by amyotrophic lateral sclerosis, which was diagnosed nearly 50 years ago, but he was said to be closely involved with the script and filming.
The multi-part documentary airs "Aliens" for the first time April 25, along with a second chapter called "Time Travel." There is also an episode scheduled on "The Story of Everything."