There has always been a keen interest in alien life in the universe. I remember space-oriented comic books, and characters like Buck Rogers and early television’s Captain Video. Today, of course, the possibility of instant communication around the globe via the Internet, coupled with the complexity of miniaturized handheld electronic devices that do astounding things, unintentionally lead people like me to believe that communication with alien life is nearly at hand.
Certainly classic films like 2001, Close Encounters, and the Star Trek TV series not only enhance this belief with their incredible computerized images, but also suggest the very real possibility that our species is not alone in the universe. A few days ago, I watched Avatar in 3-D and was fascinated by the feeling I was somehow present inside the movie, just like the holodeck on the starship Enterprise.
Some time ago, I reviewed Life in the Universe: the Abundance of Extraterrestrial Civilizations by James N. Pierce. Some of what follows is taken directly from that review. Because of the book’s title, I expected its contents to list a variety of newly confirmed proofs for the existence of alien beings, even though I subconsciously know there are no proofs at this time.
Yet, if life is to be found on distant planets, then the critical environmental attributes needed to sustain it as we know it on Earth must be present in those remote places.
What are those characteristics? By interrelating the dating of rocks and fossils, science is able to date somewhat accurately the origin of human life on our planet. This is an important step in pinpointing when the first primitive beings adaptively evolved into a thinking being—man.
Knowing this fact can help science estimate how long it would take intelligent life to develop on other planets. Obviously, only a technical civilization would be advanced enough to engineer extraterrestrial contact. Life in the Universe introduces the Drake Equation, a formula which has been accepted by science as a means of estimating civilizations within our own galaxy. Here is the equation:
N = N. • fs • Np • Fe • Fl • Fi • Fc • L divided by t
Wait, don’t go away. At first sight, this equation looks mean—frightening. But its terms, once explained, any person could understand. With simple math and a calculator, even I could pick a possible value for each term. Now it is your turn to pick a value from those estimated by science.
N = number of technical civilizations possibly existing in our Milky Way Galaxy (what we are seeking)
N. = number of stars in the Milky Way = 200 – 400 billion (pick a value)
fs = fraction of stars sufficiently Sun-like to support a civilization = 0.11 – 0.25 (pick a value)
Np = average number of planets per Sun-like star = 1 – 20 (pick a value)
Fe = fraction of Earth-like planets capable of supporting life = 0.033 – 0.11 (pick a value)
Fl = fraction of Earth-like planets on which life might develop = 0 – 1 (pick a value)
Fi = fraction of life-bearing planets that evolve intelligent beings = 0 – 1 (pick a value)
Fc = the number of life-bearing planets where intelligent beings develop a technical civilization = 0.01 – 0.05 (pick a value)
L = the average lifetime of a technical civilization = 500 years – 100,000 years (pick a value)
t = Average time from the formation of the Milky Way before a technical civilization arose (3 billion years, science’s best estimate)
To prove to myself that solving the formula was not difficult, I simply selected a middle value for each of the above terms except for L. Why? L is the average lifetime of a technical civilization. For that term I picked 5000 years because it seemed like a more realistic time span due to present global climate changes, the movement of the earth’s axis, and our race's propensity for nuclear warfare. Science continually warns us about irreversible catastrophic damage to our planet, and I believe those warnings are real. Here is my equation filled in: