SETI

Search For Extraterrestrial Intelligence

The possibility of life existing on other planets has intrigued the minds of many individuals for many years now. At first, thoughts on aliens were expressed through the medium of books and magazines. The literary style known as science fiction embodied the thoughts and hopes that lay within the creative geniuses of many a writer. The actual potential for contacting, or at least receiving signals from, an alien civilization was not taken seriously until the extraordinary forethought of Dr. Frank Drake was applied to the issue. We can see his marvelous insight through his now famous formula, regarding the potential number of communicating alien civilizations.

N = The number of communicating civilizations

R = The rate that suitable stars are formed. (These stars must have a long enough life span to permit the development of intelligent life forms. Furthermore, need an adequate habitable zone, i.e. a surrounding zone whose temperature would allow water to exist.)

L = The average lifetime of communicating civilizations.

Although this equation is imperfect, being that it has too many unknowns, it still provides a hefty framework from which we can analyze the possibilities of communicating with extraterrestrial life.

We do know that many stars are formed every year, in fact, there are around 400 billion stars in our galaxy alone, and there are billions of other galaxies besides ours. Furthermore, astronomers have begun discovering planets beyond our solar system. Although these discoveries are limited to less than 100 planets, it does show that other stars besides are sun have planets orbiting them. The current theory on planet formation rests on the existence of planetary disks, regions of dust and gas around stars. The matter in these disks eventually coalesces into planets and moons. The Hubble Space Telescope has recently photographed images of these planetary disks.

Besides this, the other variables are unknowns. We are not sure how frequently earth-like planets tend to creep up, indeed, of the planets that we have already observed, most tend to be gas giants similar to Jupiter. Our tendency to find gas giants and not earth-like planets is due to the observation method that we are using. Since planets are extremely dark compared to nearby stars, we observe them indirectly by measuring their gravitational pull on close-by objects. The present conception of the origin of life sees it as a natural development in the evolution of an earth-like planet. Carbon, Oxygen and Water are the prerequisites for the existence of life, as we know it. However, other forms of life may exist, for instance silicon-based life may also be present on other planets. Dr. Thomas Gold, of Cornell University, is a leading proponent of the silicon-based life hypothesis. An article about this issue can be found at:

The possibility of intelligent life developing is almost completely uncertain, moreover, our conception of what constitutes intelligence varies greatly. For the case of communicating civilizations, scientific intelligence would suffice to make contact possible. Again, the instance of technology developing is unknown. Finally, and most telling for humankind, the average lifetime of a technological civilization is clouded in incertitude.

I’ve included some interesting links for your surfing enjoyment: