Possibilities, hundreds of thousands of possibilities! To read and enjoy Life in the Universe: the Abundance of Extraterrestrial Civilizations, one must be prepared to deal in the realm of probability and possibility to an enormous degree. So often the media almost reports as fact, the alleged encounter someone had with an alien-appearing object either in space or on the ground. Movie makers with their bag of computerized tricks have produced films which are extremely convincing. These herald as truth the idea that distant space travel is somehow possible — alien beings exist not only in our own galaxy but in uncountable others — some have visited our earth.
Life in the Universe attempts to show in a logical and realistic fashion what conditions must be necessary for life — as we know it — to exist elsewhere in our galaxy. After a brief explanation of the scientific method, probability and possibility, Pierce’s book describes science’s present understanding of atoms and molecules, and the basic interaction of their chemistry to produce life. If life is to be found on distant planets, then the critical environmental attributes needed to sustain life must be present in those remote places.
Pierce then reviews what those characteristics are, here on our home planet. He describes how interrelating the dating of rocks and fossils has helped science date the origin of life on planet earth. This is necessary to pinpoint rather accurately how long it took the first primitive living creatures to adaptively evolve into thinking man. Knowing this can help science estimate how long it would take intelligent life to develop on other planets once they estimate when those planets came into existence. Obviously, only a technical civilization would be advanced enough to engineer extra terrestrial contact.
Near the middle of Life in the Universe: the Abundance of Extraterrestrial Civilizations, Pierce introduces the Drake Equation, a formula which has been accepted by science as a means of estimating civilizations within our own galaxy. The equation at first looks mean and frightening, but Pierce provides an explanation for each term that any layman could understand, along with an equally simple rationale for the possible value of each term.
N = N. • fs • Np • Fe • Fl • Fi • Fc • L ÷ t
N = number of technical civilizations possibly existing in our Milky WayGalaxy (what we are seeking).
N. = number of stars in the Milky Way = 200 – 400 billion
fs = fraction of stars sufficiently Sun-like to support a civilization = .11 – .25
Np = average number of planets per Sun-like star = 1 – 20
Fe = fraction of Earth-like planets capable of supporting life = .033 – .11
Fl = fraction of Earth-like planets on which life might develop = 0 – 1
Fi = fraction of life-bearing planets that evolve intelligent beings = 0 – 1
Fc = the number of life-bearing planets where intelligent beings develop a technical civilization = .01 – .05
L = the average lifetime of a technical civilization = 500 years – 100,000 years
t = Average time from the formation of the Milky Way before a technical civilization arose (3 billion years)
To prove to myself that solving the formula was not hard, this reviewer selected a middle value for each of the above terms except for L (the average lifetime of a technical civilization). For that term I picked 3000 years because it seemed like a more realistic time span due to present global climate changes 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: