theological implications of fermi's paradox and the drake equation
5/30/2007 03:04:00 PM
I am an avid science fiction fan. I was talking to some friends the other day around a game of Diplomacy, and the topic of Star Trek came up. It quickly became apparent to many that I was perhaps the biggest Star Trek geek at the table. After leaving, I started to wonder some things about the implications extraterrestrial life on theology. This is by no means scholarly and will probably sounds just as much like science fiction as Star Trek, but these are my musings nevertheless.

When considering Star Trek, Star Wars and other science fiction franchises, we usually get a galaxy teeming with intelligent extraterrestrial life. Encountering a new species make a good story line and opens the door for endless imagination and possibilities for character creation, varying species, and many other things, as such. Science fiction as such has often influenced the minds thinkers and has certainly played a part in attempts to discover alien life in reality. Two things that are very familiar to the search for extraterrestrial intelligence are Fermi's Paradox and the Drake Equation. Any casual science fiction fan has probably at least heard of these things, but I will assume you haven't and explain them according. Fermi's paradox, simply put is the apparent contradiction between the seeming possibilities of thousands of sentient species in the galaxy, yet to date, there has been no conclusive proof that any other intelligent species exist other than our own. With this in mind, there are perhaps two possibilities we can come up with: either they do not exist, or we have not made contact them yet. There have been a number of suggestions that have attempted to reconcile the paradox, but generally speaking, most of these fall under the second of the two possibilities, in that for whatever reason we haven't made contact yet.

On the other hand, there is the possibility that human beings are a unique occurrence in the universe, and against all odds have come into existence. Theologically speaking, human beings are the special and unique creation of God, such that there is nothing else like them in all creation. This would seem to rule out the possibility of other sentient life forms in the universe from a theological standpoint. But we are not speaking theologically, but more (or less!) scientifically, and thus there is a need to substantiate such things.

In 1961, Frank Drake came up with the Drake Equation, a proposed way of estimating the number of sentient species capable of transmitting radio communication into space. The Drake Equation is a type of Fermi equation, which are used in physics and other science to identify key aspects of a given situation in order to predict possible outcomes. Here is a summary of the key aspects of the Drake equation:

N = R * fp * ne * fl * fi * fc * fL

N: the number of communicating intelligent species at this time

R: Number of "suns" that develop in the galaxy per year

fp: the percentage of R with planets

ne: number of planets capable of sustaining life

fl: fraction of ne on which life would evolve

fi: fraction of fl on which intelligent life would evolve

fc: fraction of fi of which the intelligent life would learn to communicate with radios

fL: the number of years such civilizations would exist

Here are my assumptions:

R: 1 -- Scientist estimate that 1 "sun" develops in the galaxy per year.

fp: 75% -- Recent evidence shows that planets are not a rare occurrence as they once thought. There have been a number of exoplanets, planets outside our solar system, discovered in the past 15 or so years.

ne: 50% -- This is a guess. It is suggested that every star has what is called a habitable zone. This region surrounding a star where water can exist on a planet as liquid, thus providing the bedrock for life to form as we know it. The discovery of life around hydrothermal vents at the bottom of the ocean and in near boiling temperatures around geysers suggest that the habitable zone is rather large, rather than narrow as it was once thought to be. About the only kind of starts that would not be habitable are those that produce dangerous radiation. Even if planets formed in the habitable zone with liquid water, life is unlikely to form because of the radioactivity of the nearby star.

fl: 100% -- fraction of ne on which life would evolve -- I tend to think that if life can evolve, it will.

fi: .0000001% -- Now here is the catch: Although life may be abundant, intelligent life perhaps is not. What seems to be true is that higher-order life has a narrower band of existence, such that the ranges required for sustaining intelligent life are narrower than those required to sustain lower-order life such as bacteria. Such things would be temperature variation, the existence of lower-order life for the survival of high order life, and the necessarily resources (tool making materials, etc) needed to sustain life among other requirements.

fc: 50% -- I tend to think that if intelligent life evolves, then it is highly probable that such life will develop the technology to use the eltro-magnetic spectrum to communicate.

fL: 200,000 -- Our civilization has only been using radio communication for about 100 years, and our civilization is estimated to only be about 10,000 years old. Our species is relatively young too: an estimated 200,000 years old. This means humans existed for 190,000 years prior to developing civilization and 199,900 years prior to developing eltro-magnetic communication. Given the resilience of the human race, I'd would at least say humans will exist another 200,000 years a species if they don't destroy themselves or face destruction by some other means.

N: .00375 communicating civilizations

If I go based on my guess, then human beings are the only communicating civilization at this time, and that only happened by a .375% chance. Accordingly the human species is indeed rare.

But here are a few problems:

The equation doesn't take into account the possibility of life in other galaxies. There are an estimated 100,000,000,000 galaxies in the which would drastically increase the probability of intelligent life forming.

The equation does take into account the possibility of an intelligent species who can't communicate via radio. If civilizations are anything like humans, then they have only been able to communicate via radios .05% of their entire existence. We don't know however how long humans will continue to exist with this ability. We don't know if we are at the apex of our technological achievements, or if radio communications is just a baby step in technological development.

The equation doesn't take into account the possibility of all civilizations for all time. Scientists estimate that the universe has existed for some 15,000,000,000 years. Taken that into consideration, we could estimate that life began to evolve around 10 billion years ago. If we consider this, then it is possible that intelligent life has existed for 6 billion years ago, taking into account that is perhaps how long it took life on earth to evolve.

With these considerations, we could modify the Drake Equation with these values:

R: 100,000,000,000 -- 1 new "sun" per day per galaxy

fp: 75% -- unchanged

ne: 50% -- unchanged

fl: 100% -- unchanged

fi: .0000001% -- unchanged

fc: -- remove this from the equation to take into consideration aliens that don't develop radio communication

fL: 6,000,0000,000 for all time; 200,000 for current civilizations;

N: 225,000,000,000 for all time; 7,500,000 for current civilizations;

With these new assumptions, there even with the low probability that life evolves into intelligent species, it is still very likely that there are a number of intelligent species in the known universe.

Now consider Fermi's paradox: In spite of the significantly large number of possible civilization, we have no conclusive evidence that such civilizations exist. While this is merely speculative, I think that we can at least consider the possibility with some degree of certainty that perhaps humanity is a unique occurrence in the universe. Going back to the two original possibilities, either aliens don't exist, or we made contact them yet, I think we can rule out that we haven’t made contact with them yet, and conclude that they don’t exist. This doesn't show the theological implications to be true, but certainly leans towards such a thing.

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