The Drake Equasion

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The Search for Extra-terrestrial Intelligence (SETI)
An Introductory Resource Guide, by Andrew Fraknoi

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SETI Institute - Home

The Drake Equation - Wikipedia

The Drake Equasion
50 Years of Giving Direction to the Scientific Search for Life Beyond Earth

Drake's explanation of the equation's significance and its parameters.

A detailed analysis of the parameters and what current estimates of them mean for our chances of finding intelligent life.

The Fermi Paradox
The Fermi Paradox basically asks the question: "if there are so many extraterrestrial civilizations out there, why haven't we had contact." It is the apparent contradiction between the idea intelligent extraterrestrial life is common and has had adequate time to make contact, and the fact no contact has occurred. Here is a link to explanations of the Fermi Paradox

The Drake Equation

N = R^{\ast} \cdot f_p \cdot n_e \cdot f_{\ell} \cdot f_i \cdot f_c \cdot L \!

where:

N = the number of civilizations in our galaxy with which communication might be possible;

and

R* = the average rate of star formation per year in our galaxy
fp = the fraction of those stars that have planets
ne = the average number of planets that can potentially support life per star that has planets
f = the fraction of the above that actually go on to develop life at some point
fi = the fraction of the above that actually go on to develop intelligent life
fc = the fraction of civilizations that develop a technology that releases detectable signs of their existence into space
L = the length of time for which such civilizations release detectable signals into space.

Calculators

A calculator that allows you to put in your estimations of the parameters.

A calculator that allows you to put in your estimations of the parameters, but also gives Drake's estimates, as well as range of scientifically valid estimates and explanations.

Another calculator, but one that also calculates the number of habitable planets in the galaxy, the number of planets in the galaxy with life, and the number of planets in the galaxy with intelligent life.

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