According to renowned astrophysicist Stephen Hawking, aliens are not to be trifled with. In his new Discovery Network TV series, Mr. Hawking says it’s likely aliens exist, given the vastness of the universe, and that we don’t want them down here on Earth, since they’re likely to view our precious blue marble of a planet as a tasty, exploitable resource.
OK, so we shouldn’t be down on the beach waving “hello” to those incoming galleons, metaphorically speaking. Should we be peering through the trees – make that spying on the heavens – in an effort to spot aliens in secret, before they spot us?
In the past, we earthlings have launched spacecraft with drawings of humans and directions to our planet. We have beamed radio waves towards the heavens as a sort of electromagnetic greeting. This sort of active Search for Extra Terrestrial Intelligence (SETI) is just the sort of thing Hawking believes we should not do.
Other ways to comb the cosmos
But there are other ways. A recent interesting paper from a scientist at the Fermi National Accelerator Laboratory suggested an alternative to conventional SETI called “interstellar archeology.”
In essence, this involves passively scanning the cosmos for the equivalent of earth’s Egyptian pyramids, or the Great Wall of China – obvious signs of intelligent life that can be seen from space.
“Uncovering such an artifact does not require the intentional transmission of a signal on the part of the original civilization,” writes Fermi scientist Richard Carrigan.
Carrigan’s paper, “Starry Messages: Searching for Signatures of Interstellar Archaeology,” was first posted on the blog of the Project on Government Secrecy of the Federation of American Scientists.
Truth be told, this study is pretty involved. There are equations. Built structures visible from space are really just the starting point – it also covers possible atmospheric changes as signatures of civilization, as well as galactic-scale engineering.
An example of the latter, says the study, might be a Dyson sphere – a hypothetical megastructure, first dreamed up by physicist Freeman Dyson, in which a star is completely surrounded by orbiting solar power satellites as a means of capturing a high percentage of its energy output.
Passive SETI research could also involve just listening for “we are here” alien radio transmissions that are similar to the sort of thing we earthlings have broadcast into the unknown.
But aliens looking for other worlds might not necessarily be friendly, writes Carrigan in an echo of Hawking’s warning.
“A message from an extrasolar civilization could have an agenda behind it,” the Fermi scientist writes. “This agenda might not necessarily be positive. Indeed, it might be malevolent.”