Intelligent Life, ETIs, Aliens, and UFOs Part 1
About the prospect of intelligent life, ETIs, aliens, and UFOs, history of arguments, possibility of life in this or other solar system.
Is there intelligent life on other planets?
For a generation of Americans raised on TV shows like "Twilight Zone" and "Star Trek," the question hardly needs asking. Yet for all its current popularity, the concept of extraterrestrial intelligence (ETI) has been a long time coming. The Greeks proposed it 1st, hundreds of years before Christ, using exactly the same argument we use today--statistical probability.
ETI is only one possible type of extraterrestrial life. Life, in some form, may be scattered across space like weeds. Already, the precursors of life--organic molecules--have been detected in meteorites and interstellar dust. Planets with vegetation or animal organisms may be routine cosmic events.
For the general public, interest centers on ETI--particularly upon 3 questions: Where is it? What does it look like? Why doesn't it contact us?
First of all, you can forget about intelligent life on planets like Mars and Venus. Data from Mariner 9, which took 7,200 pictures of Mars in 1971, show a cold, barren surface swept by violent dust storms and blemished with enormous volcanic piles. No sign of artificial activity, such as road construction or farming, was evident. The so-called "canals" of Mars don't exist, except as natural features. Moreover, the only water on Mars is a small amount of ice in the polar cap and possibly a layer of permafrost beneath the surface. If ETI exists on the red planet, it lives in caves and taps a concealed water supply, or doesn't require water to survive. Scientists aren't betting on either possibility.
As for Venus, it's literally hot as hell. Data from 2 Soviet spacecraft that landed on Venus in the early 1970s reveal a searing 900 deg.F. as the average surface temperature. Just as bad, the Venusian atmosphere is dense and heavy--so dense that almost no sunlight reaches the surface, and so heavy that a human being would be crushed like a beer can under a truck (if he wasn't fried 1st by the heat). In a nightmarish world like this, no scientist seriously expects ETI to exist. As astronomer Carl Sagan speculates, any organism able to survive on Venus would need leathery skin, stubby wings, and a passion for the color red (virtually the only part of the visible light spectrum perceptible on Venus).
The 6 other planets in our solar system (besides earth) also contain environments that appear inhospitable to ETI, although discovery of lower biological forms cannot be ruled out. Jupiter, Saturn, and possibly some of their moons are regarded as possible sites for micro-organisms or other forms of primitive life.
No one, of course, knows the conditions necessary for the evolution of intelligence. While it's easy to postulate weird creatures that could adapt to habitats like Venus or Jupiter, this doesn't tell us which environments are suitable for ETI and which aren't. To search for ETI, we need to make assumptions about how common it is and how long it typically survives.
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