SETI researcher proposes we look for signs of past alien life on Earth or in our solar system.
Any intelligent extraterrestrial life that exists probably won't announce itself by blowing up the White House, or win over the hearts of children as a lovable alien with a glowing finger. Many scientists simply hope to find evidence of them by scanning the skies for a radio signal from a distant star's alien civilization. But such efforts may also risk overlooking clues of past alien activity right here on Earth.
If aliens did leave their mark on Earth by some wild chance, we could search for the possible "footprints" of alien technology or even analyze the DNA of terrestrial organisms for signs of intelligent messages or tinkering. Such a CSI-style forensics search could complement, rather than replace, the Search for Extra-Terrestrial Intelligence (SETI) astronomers who continue to look skyward, said Paul Davies, a physicist and cosmologist at Arizona State University in Tempe, Ariz.
"My proposals aim to spread the burden from a small band of heroic radio astronomers to the entire scientific community," Davies said. "Projects like genomic SETI are an attempt to complement radio SETI, not undermine it."
Davies wants scientists to broaden their thinking about how aliens could have left behind their mark. Having worked with SETI for three decades, he has written about his ideas in a book, "The Eerie Silence" (Houghton Mifflin Harcourt, 2010) and articles such as one that appeared in the online August edition of the journal Acta Astronautica.
But Davies does not think such intelligent alien life must necessarily exist. And his many years of supporting SETI have not stopped him from describing the needle-in-a-haystack search as "a search without any clue as to whether there is a needle there at all, or how large the haystack may be."
There's also a chance that past visits to Earth by intelligent aliens left signs much closer to home. But probability and the length of the universe's age suggest that any such alien visit would have taken place before humans ever emerged on Earth, Davies said.
That means any traces of an alien visitation would have had to survive for hundreds of millions or billions of years for humans to still find them today.
"If there is another form of life on Earth, we could find it within 20 years, if we take the trouble to look," Davies told Astrobiology Magazine. "Of course, it may not be there, but searching our own planet is far easier than searching another one."