For this week’s episode, I addressed one of the most important and well-known theories in the Search for Extraterrestrial Intelligence (SETI). It’s known as the Drake Equation, a thought experiment proposed by famed astronomer and SETI researcher Dr. Frank Drake. Drake presented this equation during the first SETI meeting in 1961, held at the Green Bank Observatory in West Virginia and attended by some of the most influential scientists of the day (including Carl Sagan). As Drake later said about his famous equation:

“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.”

The equation basically states that the number of intelligent species we can communicate within our galaxy (N) can be determined by multiplying the average rate of star formation in our galaxy (R*) by the number of stars that have planetary systems (f_p), the number of planets that are habitable (n_e), the fraction of habitable planets where life will emerge (f_l), the fraction of those where intelligent life will emerge (f_i), the fraction of those that will develop transmission technologies that are detectable from space (f_c), and the average longevity of civilizations (L).

To this day, the equation remains foundational to SETI and is comparable only to the Fermi Paradox and the Kardashev Scale. Dr. Frank Drake passed away on September 2nd, 2022, at the age of 92. He is one of many luminaries to pass on in recent years, like Stephen Hawking (2018) and Freeman Dyson (2020), and he will be missed!

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