“SO, WHERE ARE THEY?”
The above question is known as “The Fermi Paradox.” It refers to the fact that in a universe of hundreds of billions of galaxies, each containing hundreds of billions of stars and therefore, hundreds of billions of planets, how come there’s no evidence for extraterrestrial life?
So, where are they?
Why aren’t they here now? Why haven’t they been here already for millions or even billions of years. Why hasn’t anyone been here before? If they are here now (or have been in the past) why aren’t we stumbling over their artifacts? Are they really that clever? Or are we not looking in the right places or for the right things?
A conference of Sci-Fi writers a few years ago came up with some possible explanations:
1. We are the first on the scene or at least we are so early that there is nobody around to visit us or to try to communicate with us.
2. Technological societies have a negligible life span. There have been a lot of other races but they have all died off.
3. Interstellar travel is impossible.
4. Interstellar travel is possible but is not very economic. We have not been visited because the cost is much higher than any potential return.
5. Interstellar communication is impractical. (We know enough now to rule out the impossibility - barring, of course, a rather startling level of cosmic perversity.) In the absence of knowledge about where anybody is, the problem of establishing interstellar communication, even for a mature technology, may simply be too formidable.
6. Communicating with immature races is simply not very interesting for mature races. The grownups will talk to us when we have something interesting to say.
7. We may simply be well out of the center of action. Stars (and planets?) are sparser in our neck of the woods than they are in the central regions of the galaxy. In short, we are hicks.
8. Reason X - a favorite of mine. The motives of mature societies are not comprehensible to us. We are in the position of children trying to speculate about the motives of adults of another culture.
Whatever the reason, it’s not stopping us from searching for life-any life-close to home.
It’s becoming more and more apparent that life can and will exist wherever it’s even remotely possible. Over the last decade, we’ve found life existing in places thought to be completely inhospitable to living organisms; bacteria found two miles beneath the surface of the earth, microbes found in the permafrost of Antarctica. And now life has been discovered in what was once thought to be the most unlikely place on the planet; a place so barren that NASA uses it as a model for the Martian environment. Chile’s Atacama desert gets rain maybe once a decade. In 2003, scientists reported that the driest Atacama soils were sterile. But now:
“We found life, we can culture it, and we can extract and look at its DNA,” said Raina Maier, a professor of soil, water and environmental science at the University of Arizona in Tucson.
The work from her team contradicts last year’s widely reported study that asserted the “Mars-like soils” of the Atacama’s core were the equivalent of the “dry limit of microbial life.”
Maier said, “We are saying, ‘What is the dry limit of life?’ We haven’t reached it yet.”
It’s possible that the microbes in Atacama’s soil actually hibernate between rainfalls and reanimate when the rainfall reaches the layer of soil where the dormant microbes reside (about 3 feet).
The study holds some rather exciting prospects for future rovers on Mars. The Viking landers of the 1970’s barely scraped the surface soil in their analysis looking for the chemical reactions of life. The next generation of rovers may have to dig several meters beneath the surface of the red planet so that a thorough analysis can be done.