Posted on 01/07/2002 8:54:10 AM PST by RightWhale
http://www.spacedaily.com/news/life-02a.html
A Universe Of Life: Maybe Not
by Karl Hill
Las Cruces - Jan 7, 2002
This vast universe surely holds plenty of worlds where life can flourish, right? Don't bet on it, says New Mexico State University physicist Slava Solomatov.
The more scientists learn about the conditions that make life possible on Earth, the more they realize how complex those factors are -- and how a relatively small change in one condition or another could have rendered the planet uninhabitable, Solomatov said.
"It's a very finely tuned system," he said. "Some of the factors are well known, but we still don't know what all the factors are."
Solomatov has a key part in a NASA-funded astrobiology research project aimed at better understanding the origin of life on Earth and the conditions in which life might be found elsewhere in the universe. The five-year, $4.9 million grant supports the work of a dozen researchers, headed by a team at the University of Washington.
The scientists come from a variety of fields, because life requires much more than water and the right mix of elements to survive and evolve into higher forms.
Solomatov's part of the project focuses on the role of plate tectonics -- the geologic process that results in the shifting of Earth's continental and oceanic plates. Only in recent years have scientists recognized the importance of plate tectonics in maintaining Earth's long-term temperature stability, through global recirculation of carbon dioxide from the planet's interior into the atmosphere, he said.
"Because carbon dioxide is a greenhouse gas, it helps to keep our planet warm," he said. "Of course, too much of it is not good, but without this cycle over the centuries the temperature would drop and you might have the 'Snowball Earth' scenario."
Plate tectonics also provides diverse geological environments, like mountains, which promote biodiversity, Solomatov said.
No other planets are known to have plate tectonics, although some may have had the feature earlier in their evolution, he said.
Whether plate tectonics might be essential to the development of higher forms of life is unknown, but Solomatov's theoretical modeling of the complex processes aims to shed light on a number of key questions, including: What planetary conditions allow for the formation of plate tectonics? Are oceans necessary for plate tectonics? When and how did plate tectonics begin on Earth?
The question of life on other planets, or even the habitability of other planets, has long captured our imagination, but we tend to be biased in our assumptions, Solomatov said.
"We think this is normal and there should be planets all around the universe like Earth," he said. "The more I work in this area, the more I realize the chances really are very slim."
It's not enough for a planet to be the right size, to have water, and to be located the right distance from a star of the right size. Without the giant planet Jupiter as a neighbor, and without our moon, Earth might not be the living planet that it is, Solomatov said.
Jupiter has protected Earth from too many cataclysmic asteroid collisions, he explained -- but on the other hand, a neighbor much larger that Jupiter would not allow formation of an Earth-like planet in the first place. Similarly, our moon is just the right size to help stabilize Earth's spin axis and, as a consequence, the Earth's climate. With a bigger moon or no moon at all, a planet similar to Earth in other respects might not sustain life.
The list of critical factors grows longer as scientists learn more.
"At the moment there are two camps of believers," Solomatov said. "One believes in the 'Rare Earth' hypothesis and the other thinks life is smart and can adapt to extreme conditions."
The "Rare Earth" hypothesis, which takes its name from a book by University of Washington scientists Peter Ward and Don Brownlee, holds that microbial life might be common in planetary systems, but advanced life is rare.
If pushed into one camp or the other, Solomatov would choose the "Rare Earth" believers.
"We don't have enough data yet but all the evidence we have now points out that the Earth is a very special place," he said. "Maybe we should take better care of our planet."
Humankind is currently balanced at that point in it's history. Stay tuned.
Achieving satori doesn't actually change the world.
To sort of quote a favorite story character:
If the world stopped every time one of us had a bad day, we would all be floating in space.
Life developing on a planet with different characteristics will adapt to that planets conditions.
Mr. Whale, Does satori lead to nirvana?
Next Q. Is nirvana just nothingness rather than eternity?
That sounds like something that Rod Serling might've said at the end of a Twilight Zone episode. Good question, too.
Looks like more evidence for the "anthropic principle."
The spaceships are in great condition and ready to go, we just don't have the Americium to fuel them. ;)
Ten to the twentieth is a mighty big number.
I would agree. The question for me has never been "does life exist elsewhere". The question for me has always been "what is the probability that we would cross paths with life that existed elsewhere in the universe”.
The universe is basically empty. The entire universe is virtually devoid of any matter. Look to any point in the sky and then extend that line to the end of the universe. The odds are enormous that you will never encounter an object in that path even though there are billions of stars. This is because the universe is spread over time and space.
The odds are staggering against ever encountering another life that is within one or two billion years of our own? We may not even be able to recognize life if it were too many billions of years ahead or behind us.
In my mind the universe may be teeming with life but the odds that we would ever cross paths is indeed remote in the extreme.
I'm amazed at all the rare-earthers that have sprung up. The last time I argued this on FR I was shouted down.
My guess is that the radio civilization will last a couple hundred years, being replaced by who knows what -- entangled quantum particles, perhaps? So the window for crossing paths via SETI is brief indeed. I suspect that live, biological humans will never travel to the stars, although our descendents might.
On the other hand, several civilization fronts could have passed through our solar system already. Come and gone. How would we know?
All it will take is one more...
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