Researchers Are Rethinking Communication With Aliens Radio Waves May Not Be Answer, Professor Believes
Saturday, April 18, 1998
By Ian Hoffman
For more than 35 years, scientists have aimed Earth's biggest radio telescopes to the stars, awaiting word from intelligent life.
They've heard billions of signals -- dozens of them tantalizing -- yet all unintelligible and fleeting. So radio proof of extraterrestrial intelligence is nonexistent.
A tempting conclusion: We're alone after all.Astronomer Neb Duric, however, is light years from being convinced. Instead, the University of New Mexico professor muses, Earthlings are merely out of step -- in evolution, technology and culture -- with our potential neighbors in the Milky Way.
"It's very possible there are very many civilizations in the galaxy but very few detectables," Duric told fellow astronomers from UNM and Los Alamos National Laboratory last week in Santa Fe.
"What we don't know is how different civilizations communicate when they've evolved under different conditions. Why should we have the same cultural view of the universe?" he said.
In the mid-1960s, the late Carl Sagan and colleagues figured intelligent extraterrestrials were plentiful everywhere. The Milky Way alone, they thought, must be home to roughly a million civilizations at or above humankind's technology level. This is known as the optimist school in the search for extraterrestrial intelligence, or SETI.
So where are they, pessimists ask. A truly advanced civilization might be expected to colonize the galaxy. But we haven't seen or heard from them.
A branch of this pessimist school -- waning since the Cold War ended -- argued high-tech societies are doomed anyway. Nuclear weapons, the theory went, made self-annihilation inevitable inside of a century.
Still, at least three scientific teams are searching for ETIs. They aim satellite dishes at stars and listen for carrier signals in the fairly quiet microwave band. They tune in to frequencies near the natural emission of radio waves by interstellar hydrogen, at 1,420 MHz -- a frequency any student of the stars would be expected to know.
Duric fits uneasily among the believers. But he is struck by the narrow "window of opportunity" for two civilizations, alien to one another, to possess the same technology, the same desire to communicate and the same understanding.
His idea of a "cognitive mismatch" dawned during a hike with UNM cultural anthropologist Les Field.
Besides teaching, Field is an ethnohistorian for two California Indian tribes who were dismissed as ignorant savages by Spanish conquistadors, despite the tribes' elaborate cultivation of coastal fisheries and wildlife.
Together, the astronomer and anthropologist were chatting skeptically about the premise of the 1997 film "Contact," based on a Sagan novel about finding an ETI. "Why do we assume they're going to use radio waves? Because we would and we know enough to assume they would? That's so unbelievably arrogant," Field said last week. "We're assuming they have the same motivation to communicate, the same desires as us, the same perceptual basis and the same technologies as us."
Earth's history is full of examples of civilizations closing themselves off from the world, Field said.
The Chinese in the 16th century and the Japanese in the 17th century withdrew into isolation, partly to preserve their cultures. Field suspects alien civilizations might do the same.
The structure of the Milky Way itself narrows the odds of contact even more, Duric said.
Voids among the stars are not really empty: A diaphanous curtain of gases scatters light and radio beams coming across the galaxy. These distorted beams wash over Earth like light dancing over the floor of a swimming pool.
This scintillation, Duric said, cuts the range of detectable signals to less than 1,000 light years or roughly 6,000 trillion miles. That's a listening zone smaller than one-fiftieth of the Milky Way edge to edge.
Even assuming the galaxy holds a million advanced civilizations, Duric estimates the radio neighborhood at 30 or so civilizations, very few of which are likely to have the desire and ability to communicate with Earth.
Instead of giving up on listening, Duric said, "we just have to come up with a more clever way to get in touch." SETI scientists should watch for signals among other kinds of radiation, for example.
"We just have to think into the future and leave all possibilities open," Duric said.
A private research team at the SETI Institute in Mountain View, Calif., took up where NASA left off in 1994, when Congress killed its SETI program.
Astronomer Seth Shostak is hardly discouraged by the lack of intelligent signals. The institute's Project Phoenix is looking at microwave transmissions from 1,000 sun-like stars, all too near to Earth for their signals to be disrupted by scintillation.
It's reasonable to think some civilization nearby will reach out for contact, Shostak said.
"Maybe they're hard to find," he said, "but if some are making noise, that's enough. You just hope they've made some signals deliberately simple so they'd be easy to find ... It's a question of, is the glass half full or half empty?"
Even as the Chinese and Japanese cut off contact, Shostak pointed out, "the Spanish were building boats and going all over the place. They were joined by the English and French." Using telescopes in West Virginia, Puerto Rico and Australia, Project Phoenix has scanned 350 stars. Its scientists may one day broaden their search to sweeping large expanses of the heavens.
"In the end, what counts is doing the experiment," Shostak said. "We're looking for a needle in the haystack, but we've only looked at a teaspoon of hay so far."