At the January 16 meeting of the National Academy of Sciences Committee on Astrobiology Science Strategy for the Search for Life in the Universe, held here at the University of California, Irvine, SETI astronomer Jill Tarter explained that the “search for extraterrestrial intelligence” generates an incorrect perception of what scientists in this field are actually doing. Tarter is one of the few researchers to have devoted her career to hunting for signs of sentient beings elsewhere.
A more up-to-date name for the field, Tarter said, would be “the search for technosignatures,” or signs of technology created by intelligent alien civilizations. “We need to be very careful about our language,” Tarter said during a presentation at the committee meeting on Jan. 18. “SETI is not the search for extraterrestrial intelligence. We can’t define intelligence, and we sure as hell don’t know how to detect it remotely. [SETI] … is searching for evidence of someone else’s technology. We use technology as a proxy for intelligence. “[The acronym] ‘SETI’ has been problematic in history, and we should just drop [it] and just continue to talk about a search for technosignatures.”
“We have a pragmatic definition for technology, which is the ability to deliberately modify an environment in ways that can be sensed over interstellar or interplanetary distances, including the unintended consequences of that modification,” Tarter said. “Life does this, but it doesn’t do it deliberately.”
One technosignature that scientists have been actively seeking for decades is communication signals. These could include signals used by members of an alien civilization to communicate with each other or attempts to communicate with other civilizations, reports Space.com. The SETI Institute continues to search for alien communications in radio waves, using the Allen Telescope Array. (Tarter was the inspiration for the main character in Carl Sagan’s novel “Contact,” which was adapted into a movie; in that story, aliens make contact with Earth via radio waves.) But recent SETI efforts have expanded to look for other mediums of alien communication, and SETI scientists have theorized that an interstellar civilization might use laser light to communicate.
Science-fiction writer Arthur C. Clarke wrote that “any sufficiently advanced technology is indistinguishable from magic,” which would mean that alien technology could be as mysterious and unexplainable to humans as technologies that appear in science-fiction TV shows and movies. That opens up a dauntingly large range of possibilities for what technosignatures might look like. What if an alien civilization were communicating via a mechanism that Earth-based scientists haven’t discovered yet? Would humans immediately recognize these “magical” technosignatures, or would we not see them as unnatural?
“The period of time occupied by organic intelligence is just a thin sliver between early life and the long era of the machines,” says Martin Rees is Emeritus Professor of Cosmology and Astrophysics, at the University of Cambridge, the Astronomer Royal, a member of Britain’s House of Lords, and a former President of the Royal Society. “Because such civilizations would develop at different rates, it’s extremely unlikely that we will find intelligent life at the same stage of development as us. More likely, that life will still be either far simpler, or an already fully electronic intelligence.”
“The question of whether advanced civilizations exist elsewhere in the universe has always been vexed with three large uncertainties in the Drake equation,” said University of Rochester astronomer, Adam Frank. “We’ve known for a long time approximately how many stars exist. We didn’t know how many of those stars had planets that could potentially harbor life, how often life might evolve and lead to intelligent beings, and how long any civilizations might last before becoming extinct.”
Estimates from NASA’s Kepler Mission data suggests that out of the estimated 2 x 10^22 stars in the known universe, 20 percent have planets that reside in habitable zones that have temperatures, atmospheres, and other traits that could support life. So that takes care of one uncertainty.
“Aliens could exist in forms we can’t conceive,” says Rees. “They could be staring us in the face and we just don’t recognize them. The problem is that we’re looking for something very much like us, assuming that they at least have something like the same mathematics and technology.”
“I suspect there could be life and intelligence out there in forms we can’t conceive. Just as a chimpanzee can’t understand quantum theory, it could be there as aspects of reality that are beyond the capacity of our brains.”
Tarter said she prefers to focus on an alteration from Arthur C. Clarke’s prediction that “any sufficiently advanced technology is indistinguishable from magic,” to that written by the futurist Karl Schroeder: “Any sufficiently advanced technology is indistinguishable from nature.”
“[The system] will be so efficient that there will be no wastage, and [it] will appear to be natural,” Tarter said. If this prediction is correct, it might also be impossible for humans to identify technosignatures from very advanced civilizations.
“As we begin to look for exoplanets and image them, you might get an unexpected glint, [because] maybe mirrors re cooling their planet, reflecting light away from the planet,” Tarter said.
“In 2004, Craig Venter and Daniel Cohen made a really bold statement: They said the 20th century had been the century of physics, but the 21st century would be the century of biology,” Tarter said. “I think they were right, but I don’t think they were bold enough. Because I think the 21st century is going to be the century of biology on Earth and beyond.”
The Daily Galaxy via University of Cambridge, National Academy of Sciences, and Space.com