The Meaning of Life
The possibility of life beyond Earth - particularly intelligent life - permeates popular culture. For the fearful, there are evil extraterrestrials intent on dominating and killing humans ("War of the Worlds," "Alien," "Independence Day"). For people inspired by hope and awe, there are wise, benevolent aliens ("Contact," "E.T., the Extra-Terrestrial" and "Close Encounters of the Third Kind").
Turning to non-intelligent life, scientists by and large believe that if life is discovered on the planets and moons of our solar system, it will be microbial - perhaps bacteria on Mars or microscopic creatures swimming in a sea beneath the ice on Jupiter's moon Europa.
Even if the public seems less than awestruck by the prospect that alien life is a bunch of microscopic bugs, astrobiologists say unequivocal discovery of microbial life beyond Earth will change human society in profound ways, some unfathomable today.
"It would sink in slowly over decades and then would become part of the new way in which we look at the universe," says John Billingham, who ran NASA's Search for Extraterrestrial Intelligence (SETI) program until Congress killed it in 1993.
"In some sense, that had the effect of displacing humans from the center of the biological universe," says planetary scientist Bruce Jakosky, director of the Center for Astrobiology at the University of Colorado at Boulder. "It would be truly profound to find evidence for life elsewhere if it had an independent origin from life on Earth. It says life very likely is the natural consequence of chemical reactions that occur in a planetary environment, and that life is probably widespread through the universe - at least microbial life. This would be the final nail in the coffin" that life exists only on Earth.
Jakosky believes scientists should pay greater attention to discussing the social implications of discovering extraterrestrial life - even though many researchers shy away from the subject because they don't consider it "hard" science.
"Your first thought is: [Discovering extraterrestrial] microbial life - there wouldn't be much impact compared to intelligent life," says historian-astronomer Steven J. Dick of the U.S. Naval Observatory. Yet Dick notes the worldwide hubbub in 1996 when researchers from NASA's Johnson Space Center claimed they had found evidence of fossilized microbes in ALH84001, a meteorite from Mars.
"If you had fossilized life that existed on Mars at one time, the implication would be life must be abundant in the universe," says Dick. "And people make the jump to, 'There must be intelligent life.'"
"We're interested in the search for extrasolar planets because it tells us … is our solar system unique or common?" says Jakosky, a member of the NASA Astrobiology Institute. "We are interested in the possibility of life on Mars because it provides context for understanding the value of life on Earth.
"By learning about the world around us, we are learning about ourselves. We are an exploring society. In the end, that is the most significant aspect: that we are searching."
Social scientist Kathleen Connell, an official at the Research Institute for Advanced Computer Science in California, adds: "The very act of looking for microbial life is a cultural manifestation of our own intelligent life form. Some suspect that we as a species are evolving from our home planet Earth, via the international space program. As the space program has reached out to the solar system and beyond, we have evidence of the impact of this evolution from the home planet on contemporary culture."
For example, she notes how the Apollo astronauts' stunning photograph of Earth floating in space spurred the fledgling environmental movement.
"Perhaps following the path of life is a bold challenge for all of humanity to pursue with renewed vigor, just as the Kennedy generation pursued the challenge of going to the moon," Connell says.
She also believes the discovery of extraterrestrial life may have direct economic benefits by providing Earth with new materials and energy sources.
Many people feel "incredible wonder about the natural world," says University of Colorado journalism professor Tom Yulsman. "I cannot help but think that the sense of wonder will only deepen if they discover any kind of life elsewhere."
Dick notes that if we found microbial extraterrestrial organisms, "we would learn a lot more about biology in general, universal biology, about how life works in different ways, maybe not DNA-based or even carbon-based."
But for the public, that soon "would stop being exploration and start being biology, and that becomes uninteresting unless it's a cure for cancer," says Jakosky, offering a perspective learned from essays written by students who took his course on extraterrestrial life.
When asked the significance of finding life beyond Earth, "the most common answer was that finding microbes might be interesting, but finding intelligence would be profound," he says. "Some people felt it would save the world"; others believed aliens "would destroy the Earth, either by intent or by accident. Those views are in such contrast with each other that it struck me it says more about the individual - are you an optimist or a pessimist - than about extraterrestrials."
Jakosky says another common student view about extraterrestrial intelligence is, "We've already discovered it, they are visiting the Earth and the government is hiding it in an area outside Roswell, New Mexico, or in Area 51 in Nevada."
Citing European domination of New World peoples, Dick notes that during Earth's history, "almost any physical culture contact has been bad, at least at the outset. But that's probably not what's going to happen with [intelligent] extraterrestrial life.… It's much more likely that you're going to have radio contact" because of the vastness of space.
He compares that with "the transmission of Greek knowledge to Europe in the 12th and 13th centuries, by way of the Arabs. The result was the Renaissance."
Take religious belief. If extraterrestrial life is found and "if humanity is not the center of attention of a deity, what does that do to various theologies and religions?" Dick asks. "If it is Christianity, for example, [what does it mean for] the doctrines of redemption and incarnation? Would Christ have to die on other worlds for their sins the way he did here? … For Eastern religions, where you don't have the idea of salvation or a single deity, it would be quite different."
Billingham believes finding a long-lived extraterrestrial society could give humanity hope.
"For example, there are doomsayers who say, with some reason, that we might not last more than 100 years. But if you found a civilization that was 10 million years beyond us, it would tell us instantly that it can be done. That's pretty profound. It might turn a few of the pessimists into optimists."
Research is ongoing to find both microbial and intelligent life. The search for microbial life is a central goal of the Mars and Europa exploration programs of NASA and the European Space Agency. A number of organizations, the SETI Institute principal among them, are engaged in projects designed to detect electromagnetic signals sent by intelligent life forms from other worlds.