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The Answer:

17 – This means that seventeen civilizations are currently listening for extraterrestrial life within our own Milky Way galaxy right now!  They are waiting to hear from us.

Don’t believe me?  Why not find out for yourself?

It’s quite easy when using the famous Drake Equation.  Created by Dr. Frank Drake in 1960 as more of an outline of the potential variables involved in arriving at a number, the equation gets kicked around a lot for fun and amusement.  It’s also a wonderful conversation topic in social gatherings.

What does the Drake Equation attempt to answer?

The equation attempts to answer the following question:

“How many communicating civilizations exist in the Milky Way today?”

What does the equation look like?

Nova has kindly created the following Flash application to allow you to view and play with the equation.  Because the Flash app does such a great job at explaining the variables, there’s no point wasting time describing them here.  It should be noted, however, that the variables are in order from left to right in order of certainty.  Those on the left are generally accepted to be more certain than those on the right, which amount to blind guesses.

Also note that all values are multipliers, therefore they must all be non-zero in order to arrive at a non-zero result.

Discussion of my chosen values

Here is what I chose for each variable and why…

• R = 5;  I’ll assume that astrophysicists know what they are doing and accept the default number of 5 new suitable stars forming every year.
• fp = 20%;  I’m choosing a number lower than average because I want to be conservative here.  I think that only 20% of new suitable stars will form planets.
• ne = 0.1%;  I’m setting this VERY low because I think it is very low.  Of the planets formed by a suitable star, I’m saying that only 1 out of a 100 of them are suitable for life.
• fl = 20%;  I think that life is much more common than we think.  All it takes is a suitable chemical soup and some physics in the form of lightning.  Bam, you’ve got amino acids forming proteins.
• fi = 5%;  I think that only 5% of life forming on planets will emerge as intelligent.  I may be totally wrong on this, as intelligence may be the most default life strategy given enough time.
• fc = 50%;  It seems to me that intelligent life has a very good shot at developing interstellar communications.  Discovery of ectromagnetism is a sure thing, so I think 50% is still conservative.
• L = 40,000;  This is a complete guess, but it doesn’t seem unreasonable to expect an intelligent civilization to exist for a good 40,000 years before wiping itself out.

Play with the equation yourself