Is E.T. dead? Scientists listen for a pulse
A conference at nonprofit SETI Institute maps new strategies
MOUNTAIN VIEW » If we finally hear from aliens, it may be a death rattle.
Civilizations are ephemeral things— and messages take so long to travel across our vast galaxy that E.T. probably perished long before we ever receive them, according to a newly published update of astronomy’s famed Drake Equation, which estimates the probability of intelligent life in our galaxy.
But that doesn’t mean we can’t learn from what’s been said, according to scientists at a conference this week at the nonprofit SETI Institute, which oversees a network of computers and telescopes scanning the skies.
And there’s the chance that civilizations still alive are sending signals yet to arrive, they added. They might not look or think like us; they might be machines, with empires farmore durable than our own. Maybe we’re just not listening hard enough. Maybe they’re saying things we can’t understand. Maybe they packed up and moved, so we’re looking in the wrong places. Maybe they don’t live on planets but fly through space.
Or perhaps they simply unplugged “and walked away from high technology,” said astronomer and astrophysicist Frank Drake, who inaugurated the
modern search for extraterrestrial intelligence nearly 60 years ago.
It’s a poignant effort to answer a question posed by physicist Enrico Fermi in 1950: If the universe is so vast and so old, so rich with stars and planets, where is everybody?
This week’s conference aims to map out SETI’s new strategies for finding E.T.— dead or alive.
Analysis of the data from the NASA Kepler mission shows that about 10 to 20 percent of Sun-like stars in the Milky Way harbor Earth-size planets in Earthlike orbits — billions of potential Earths.
“New tools are available that can enable this approach and help us decipher the evolutionary and probabilistic nature of advanced alien life,” said organizer and SETI Institute Director Nathalie Cabrol. “We can build a new roadmap that is multidisciplinary, that opens the toolbox.”
This approach will vastly expand search methods and data analysis, she said. Advanced intelligent life beyond Earth is likely plentiful, she asserts, but we have not yet opened ourselves up to all its diversity.
The conference comes on the heels of a new study, published Feb. 27 in arXiv, by Claudio Grimaldi, a scientist at Switzerland’s École Polytechnique Fédérale de Lausanne, along with Drake and UC-Berkeley astronomers Geoff Marcy and Nathaniel Tellis.
Expanding on the equation used to consider the search for intelligent life, they constructed a model of our galaxy containing tech- savvy civilizations that format a specified rate, emit electromagnetic waves for a specified time, then die within 100,000 years.
The Milky Way is 100,000 light years wide. And electromagnetic radiation travels the speed of light. So if a civilization on the other edge of galaxy lived fewer than 100,000 years, only a part of the galaxy would be filled with its messages — and the odds of these ‘ghost signals’ reaching Earth are bleak, according to the research. If we hear it, it’s likely old news.
“The signals will be from the civilization as it was,” said Drake. “It is not a remote possibility — it is a high probability — that signals we receive will be from a civilization that no longer exists.”
There’s the chance that it’s still alive “but no longer be transmitting,” he added. “Or it may have changed in a very big way, such as migrating from the planet to escape its expanding star.”
Should we send a eu- logy? We, too, may be gone by the time it lands. Or it may get lost in space; we’ve been sending steady signals for 80 years but have filled only about 0.001 percent of the volume of our galaxy, according to the new research.
This is disappointing news for those looking forward to a chat, admitted astronomer Seth Shostak, director of the SETI Institute’s Center for Research.
“It’s not a conversation,” he said. “If they’re 100 light years away and ask, ‘ Want to join our book club?’, we aren’t going to respond, ‘ What’s the selection this month?’ “
Even if they’re dead, that doesn’t mean they don’t have something to say, he said.
“To me, it is like finding a bottle on a beach with a note in it,” said Shostak. “It may be that whoever put the note in is long gone. But at least you know there’s somebody on the other side of the world.”
But reports of their death may have been greatly exaggerated, said Andrew Frakno, a retired professor of astronomy at Foothill College in Los Altos Hills.
“Until we know more about our longevity, it is pure guesswork,” he said. “Every year we don’t destroy ourselves, we add one more year to what we know civilizations can do.”
And there’s no way to confirm whether they’re dead or alive.
“Unless they are giving off their death scream, unless they’re saying, ‘ Oh my God, this is our last message!’, we don’t know,” said Fraknoi.
Civilizations might be made not of decaying mortals but portable long-lived machines, said Shostak.
“The idea that they’re soft and squishy and sitting on some planet somewhere is very parochial,” he said. “A bunch of little gray guys with big eyeballs and no hair? No.
“They don’t have to be on planets. They’ll just rust there,” he added. “They’ll be out in space.”
Their signals may already have landed, but we missed them, scientists said. It’s a cosmic twist on that existential question: What if a tree falls in the forest, but it doesn’t sound like a tree?
There’s comfort in this: Any signals suggest a deeply human-like motive, said Drake. They wanted to talk. And perhaps, against all odds, that altruistic trait helped them stay alive.
“Why did they spend the resources sending signals from which they’ll never get any benefit?” he asked. “Only an altruistic civilization sends signals for the benefit of others.”