How to Estimate the Number of Aliens in the Milky Way

Understanding the Drake equation

The Drake equation summarizes the factors which are thought to affect the likelihood that humans will be able to detect radio-communication from intelligent extraterrestrial life (Burchell, 2006). The argument was first proposed in 1961 by American astronomer Frank Drake, for the purpose of stimulating scientific dialogue at the meeting of the Search for Extra-Terrestrial Intelligence (SETI) community:

As I planned the meeting, I realized a few day[s] ahead of time we needed an agenda. And so I wrote down all the things you needed to know to predict how hard it’s going to be to detect extraterrestrial life. And looking at them it became pretty evident that if you multiplied all these together, you got a number, N, which is the number of detectable civilizations in our galaxy. This was aimed at the radio search, and not to search for primordial or primitive life forms. — Frank Drake

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Read the full essay in Cantor’s Paradise on Medium