Famed physicist Stephen Hawking set off chatter in late April when he posited the existence of intelligent aliens on his new TV series, "Into the Universe with Stephen Hawking" -- adding that it would be best for human beings to avoid contact with them.
Hawking speculated that such aliens would likely be nomads, living in ships after sucking their own planet dry of resources, and hopping from one interstellar refueling station to the next.
"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 Native Americans," he said.
Hawking has made such statements for years - in a 1996 essay, for example, he said humans should be "wary of answering" aliens until our species has become more sophisticated.
Though most of the show focused on what alien life -- even primitive alien life -- might look like, it was the comment on alien invasion that captured public attention.
The Journal of Cosmology compiled responses from a dozen scientists and has published them online. Some criticized Hawking's use of human behavior to predict what aliens would do, but others said that human behavior was a reasonable yardstick. Few, however, questioned the premise of Hawking's statements -- that alien life forms probably exist and we are likely someday to encounter them.
The commentaries can be read at journalofcosmology.com/Aliens100.html . Here's some of what the scientists had to say:
Blair Csuti, a biologist at Oregon State University, defended Hawking's trepidation, arguing that the principles of evolution would have shaped those beings just as they did life on Earth, selecting for self-preserving behavior. "Aliens visiting newly discovered planets, like Earth, would place their own interests above those of unsophisticated indigenous residents."
Robert Ehrlich, a physicist at George Mason University agreed, further imagining that the aliens would be "adaptable robots whose mental processes reflect those of their senders."
Others, like Chandra Wickramasinghe of Cardiff University in the United Kingdom and B.G. Sidharth at the B.M. Birla Science Centre in India, took a more low-tech view of alien invasions. They argued that the threat would come not from green people with fancy stun guns, but from pathogenic microbes that could infect life on Earth.
"When Columbus was followed by the Spanish conquistadors, it was not advanced weaponry which destroyed the native civilizations, but disease," Sidharth wrote.
Randy D. Allen, a biologist at Oklahoma State University, argued that a smart-enough species could develop a quantum computer and eventually transfer their consciousnesses into it.
""Perhaps ... they can "see" or "feel" the entire universe. Maybe they've gained the ability to manipulate elementary particles and can control its evolution and its fate. They would have become, by any human definition, gods."
GianCarlo Ghirardi, a physicist at Italy's University of Trieste, asked why intelligent aliens should have negative intentions toward earthlings. "If Hawking's aliens are anything like humans, then I am optimistic ... that their scientific development should be accompanied also by an ethical development, and (they) might value life," he wrote.
Stephen Freeland, an astrobiologist at the University of Hawaii, didn't focus on the likely intentions of invading aliens. Instead, he blasted Hawking for speaking out of turn. He noted that the Astrobiology Science Conference ran the same week as Hawking's TV program. "I doubt that any of (the astrobiologists) will be opining about the origin and early evolution of the universe as if professor Hawking's field of science did not exist," he said.
The most whimsical reaction was also the shortest -- a limerick, courtesy of biologist John Menninger of the University of Iowa:
"Aliens, as perceived by Hawking
"Could soon visit Earth for some gawking.
"They might do good, but Oy!,
"They might wish to destroy!
"We'll more likely be bored by their talking."
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