Life Beyond Earth?
Ok, so this isn’t exactly about the show, but its kind of topical, and I thought it was an interesting article.
U. Washington scientists question existence of life beyond Earth
Updated 12:00 PM ET January 28, 2000
By Scott Waletzko
The Daily
U. Washington(U-WIRE) SEATTLE — Are we alone in the universe?
This fundamental question has intrigued humankind since ancient times. Devout believers profess the existence of alien beings at Roswell, N.M., while some religious groups decry the possibility of extraterrestrial life as heresy.
Hollywood has portrayed aliens as menacing in Independence Day, comical in Galaxy Quest and benevolent in The Day the Earth Stood Still. Trekkies study Klingon language and culture, while Star Wars fans envision a universe teeming with Muppet-esque creatures. One possibility, however, is lost in all this science fiction.
Maybe we are alone.
A new book from two UW scientists challenges the idea, set forth by the late astronomer Carl Sagan, that the universe potentially hosts millions of advanced alien civilizations.
In Rare Earth, paleontologist Peter Ward and astronomer Donald Brownlee describe the unlikely conditions under which microbial and, later, advanced life evolved on Earth. The remarkable combination of just the right conditions was so rare, they write, that is probably has not happened anywhere else in the cosmos.
“We are the product of a great number of lucky events,” said Brownlee, who also serves as principal investigator on the Stardust project, which launched a probe last year to collect and retrieve comet material.
His partner, Peter Ward, is traveling and could not be reached for comment.
Rare Earth marks the first book collaboration between Brownlee and Ward, who has investigated mass extinctions on Earth through examination of the fossil record.
The scientists identified several advantages that make advanced life possible on our planet. Earth lies at the right distance – not too close like the inferno Venus, and not too far like frozen Mars – allowing for liquid water.
No other planet has plate tectonics, which slowly shifts continents over millions of years, builds land masses and acts as an atmospheric thermostat. Without this, the planet might be completely covered by the oceans, making “Earth” a huge misnomer.
The Earth-to-moon size ratio is quite smaller than most planets to their natural satellites, keeping the planet’s spin axis constant, stabilizing the climate and ensuring smooth seasonal transitions.
The position of Jupiter, the largest planet in the solar system, deflects many oncoming obstacles, like comets and asteroids, with its gravitational pull. In July 1994, Comet Shoemaker-Levy 9 came too close to the gas giant. The gravitational force broke the comet into several pieces that smashed into Jupiter, raising concerns about a similar perilous event occurring on Earth.
At the heart of Ward and Brownlee’s book is the Rare Earth theory. The theory can be summarized in two parts: First, microbial life is likely common. As Brownlee succinctly stated, “When conditions are right, it forms.”
Microscopic life exists in some of our planet’s most extreme conditions – near volcanic vents under the oceans, frozen in methane ice below the Gulf of Mexico and thriving in dry, Antarctic valleys – facing conditions that exist in other parts of the solar system.
Second, evolution to complex organisms barely happened here, even with all the favorable conditions. The odds of this process occurring elsewhere are very slim. Even if the ingredients were out there, higher evolution takes time – cosmicly speaking.
“If you landed on Earth at any given time in history, you’d likely be talking to bacteria,” said Brownlee. In other words, if life evolves at this rate throughout the universe, do not expect to be beamed aboard a starship anytime soon.
Ward and Brownlee have also identified “dead zones” in the universe where, they say, life cannot form. These include small galaxies, where stars are too metal-poor, hindering planet formation, and the center of galaxies, where energetic processes impede complex life.
Has life existed, or could it presently exist, somewhere in our solar system?
Brownlee acknowledges the possibility. “Mars might have microbial life,” he said, “but it’d be hiding under the surface where it’s protected.”
He cited Ganymede and Europa, both moons belonging to Jupiter, as candidates.
Europa is slightly smaller than Earth’s moon and has an ice-covered surface which, according to some NASA scientists, “suggests the possibility of a subsurface organic-rich ocean, sustained by the gravitational heating of the interior.”
Ganymede, the largest moon in the solar system, shows signs of frozen water and geologic activity.
When asked about the Search for Extraterrestrial Intelligence (SETI) program, Brownlee supported the effort, saying, “It’s an exciting thing, and you never know.”
The search has yielded no conclusive results so far.
“If you have no data, you have no data,” he said. “It doesn’t rule it out.”
Prospective alien abductees, take hope.
So, are we alone? Nobody knows for sure, but Rare Earth provides another theory for a profound mystery. Until the answer comes, keep watching the stars.
