중앙데일리

[The Fountain] Lifetime of a Civilization

Mar 09,2001
Based on the belief that intelligent life can develop elsewhere in the universe as it has developed through natural laws on earth, the U.S. National Aeronautics and Space Administration launched the Search for Extraterrestrial Intelligence in 1992. In this program, radio telescopes worldwide search for signals which may come from other civilizations.

How many civilizations in our galaxy may have reached the level to communicate between stars? British astronomer Frank Drake devised a formula to calculate the number. The Drake Equation identifies seven factors thought to play a role in the development of technological civilizations. It is relatively simple to estimate six of the seven factors. Let us calculate the number of civilizations in our Milky Way galaxy capable of communications. We can estimate the number of suitable stars in our galaxy at 400 billion. There is 10 percent chance that those stars have planets, normally 10 each. Among those planetary systems, one out 10 would be earth-like, suitable for living organisms. There is 10 percent chance that life develops in those "earths," and 1 percent of those creatures may have developed into intelligent beings. Among those intelligent beings, there is 10 percent chance that they will develop technology to communicate with other planets. In the calculations so far, 4 million planets may have intelligent beings that can communicate with us. And yet most of them must have perished already, because 10 billion years have passed since the birth of our galaxy.

Let us think of the seventh ? and final ? factor, the lifetime of communicating civilizations. If we estimate that lifetime as 10 million years on average, there may be 4,000 civilizations which are capable of emitting detectable signs of their existence into space (4 million x 10 million / 10 billion). If the lifetime is 10,000 years, then the answer is reduced to four.

We can only estimate the seventh factor by determining how long we will survive. Technology has always been driven by weapons, especially weapons of mass destruction, but morality has not increased along with technical sophistication. That is why the 20th century can be referred as the century of science and the most violent century in the history of humans at the same time.

The Bush administration announced its plan to develop a National Missile Defense system despite international fears that it will encourage a new arms race.

Currently, there are 26,000 nuclear warheads on earth, many times larger than the number required to destroy human life on earth. If NMD is implemented, then we will have more of those weapons. If an extraterrestrial civilization were to use the Drake Equation with respect to earth, what number would the seventh factor be?


by Cho Hyun-wook




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