The Drake Equation
There is a question that has captured the human mind since ancient times: is there life out there? In fact, as far back as 300 B.C., the Greek philosopher Epicurus wrote that “there are infinite worlds both like and unlike this world of ours” (Arny 543). In about 50 B.C., the Roman scholar Lucretius stated that “it is in the highest degree unlikely that this Earth and sky is the only one to have been created” (Arny 543). Interest in life out there has stretched from these ancient thoughts of the past all the way to present time.
It wasn’t until September 1959 that two physicists, Giuseppe Cocconi and Phillip Morrison, believed that radio telescopes had become sensitive enough to detect galactic civilizations (MacRobert/Schilling). It was only a mere seven months later that radio astronomer Frank Drake began a systematic search for intelligent life. In 1961, Drake developed the “Drake Equation” to express the chances of intelligent life in space (Gribbin 180). The Drake Equation, which is featured as the title of this paper, can be broken down and easily understood in this way (Pree/Axelrod 354):
N the number of civilizations in our galaxy with whom we should be able to communicate with via radio signals
R the rate at which our Galaxy produces stars
fp the fraction of stars with planetary systems
Np the average number of planets per star
fe the fraction of Earthlike (life supporting) planets
fl the fraction of planets in which life actually develops
fi the fraction of planets on which intelligent civilizations arise
fc the fraction of planets upon which technological civilizations arise
L the lifetime of a civilization in years
This equation is, of course, affected by wether or not you are a pessimist or an optimist. To view this scientifically, it seems wise to take a middle of the road approach. However, just for the fun of it (and because it is much more interesting) I will take the Carl Sagan approach and assume that life will form wherever it is able, which is factored as (fp=1). Also, let’s take the Darwinian approach that intelligence will evolve (fi=1), and that such civilizations will develop the technology needed to communicate (fc=1). In this very optimistic view, there would be an estimated 100,000 advanced societies thriving in our galaxy alone, or one radio-emitting civilization per every 4 million stars (MacRobert/Schilling).
If we put these equations in a very pessimistic light, with all factors equaling 0.000001, we find that only 1 out of every million habitable planets actually develops life (Pree/Axelrod 357). However, even with this very pessimistic viewpoint, I still find it astounding, considering how many suns there are out there with planets that fall within the habitable zone (such as our Earth), that these is a substantial chance that life can indeed develop elsewhere in our incredible universe.