Scientists sparred at a conference in California over whether humans should actively attempt to contact intelligent life on other planets – and, if so, what we should say.
Researchers at the SETI Institute have been listening with radio telescopes for signals from outer space for more than three decades, but so far have found no evidence of extraterrestrial life.
They took part in a conference this week in San Jose, California, organized by the American Association for the Advancement of Science.
SETI director Seth Shostak argued that earthlings must do more than listen for other life forms.
“Some of us at the institute are interested in 'active SETI,’ not just listening but broadcasting something to some nearby stars, because maybe there is some chance that if you wake somebody up you'll get a response,” Shostak said.
Shostak and other “active SETI” advocates want to send repeated signals from the world’s largest radio transmitter in Puerto Rico toward hundreds of stars within about 82 light-years of Earth.
However, he admits that some scientists -- including physicist Stephen Hawking -- oppose “active SETI” as potentially dangerous.
David Brin, the scientist and science fiction writer, argued during the conference against active attempts to contact alien life forms.
"Historians will tell you that first contact between industrial civilizations and indigenous people does not go well," he told the BBC.
Brin accused Shostak and others of "railroading the public” toward sending messages into space without addressing the potential cultural impact.
The likelihood of contact is extremely low, he said, but he argued that the risks are extremely high.
“The arrogance of shouting into the cosmos without any proper risk assessment defies belief,” Brin said. “It is a course that would put our grandchildren at risk.”
Shostak understands the concerns, even if he does not share them.
“It is like shouting in the jungle,” Shostak said later in a BBC interview. “You don't know what is out there -- you better not do it. If you incite the aliens to obliterate the planet, you wouldn't want that on your tombstone, right?"
However, he can’t imagine what incentive extraterrestrials would have to destroy Earth and its inhabitants – who he said have made less-focused attempts to send messages into space and “leaked” television, radar, and radio signals for more than 70 years.
"Any society that could come here and ruin our whole day by incinerating the planet already knows we are here,” Shostak said.