Famed physicist Stephen Hawking set off chatter in the scientific community 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. Earth, he said, shouldn't do anything to encourage their visit.
"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 very 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.
You can read the commentaries at journalofcosmology.com/Aliens100.html. Here's some 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 tasers, but 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.
"No more inefficient metabolism requiring huge energy input, no chemically derived bodies to wear out, no reproduction, no death, no taxes. Just supermassively parallel collective consciousness with unlimited capabilities," he wrote. "Perhaps, through super symmetry or entanglement, 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 the University of Trieste in Italy, questioned why intelligent aliens should have any negative intentions toward earthlings at all. "If Hawking's aliens are anything like humans, then I am optimistic, in a certain sense, 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 spend his time wondering whether invading aliens would be antagonistic or not. Instead, he blasted Hawking for speaking out of turn.
"Scientific knowledge is quite different from the authoritatively-voiced opinions of a famous scientist," he wrote, adding that the annual 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."