On November 1st, 1961, a number of prominent scientists converged on the National Radio Astronomy Observatory in Green Bank, West Virginia, for a three-day conference. A year earlier, this facility had been the site of the first modern SETI experiment (Project Ozma), where famed astronomers Frank Drake and Carl Sagan used the Green Bank telescope (aka. “Big Ear”) to monitor two nearby Sun-like stars – Epsilon Eridani and Tau Ceti.

While unsuccessful, Ozma became a focal point for scientists who were interested in this burgeoning field known as the Search for Extraterrestrial Intelligence (SETI). As a result, Drake and Sagan were motivated to hold the very first SETI conference, wherein the subject of looking for possible extraterrestrial radio signals would be discussed. In preparation for the meeting, Drake prepared the following heuristic equation:

N = R x fp x ne x fl x fi x fc x L

This would come to be known as the “Drake Equation,” which is considered by many to be one of the most renowned equations in the history of science. On the sixtieth anniversary of its creation, John Gertz – famed film director, amateur astronomer, a board-member with BreakThrough Listen, and the three-term former chairman of the board for the SETI Institute – argues in a recent paper that a factor by factor reconsideration is in order.

Frank Drake writing his famous equation on a white board. Credit: SETI.org

In this paper, which was recently accepted for publication by the Journal of the British Interplanetary Society (JBIS), Gertz makes the case for a revised equation and a lot more searching! To break it down, the Drake Equation consists of the following parameters:

N is the number of civilizations in our galaxy we could communicate withR is the average rate of star formation in our galaxyfp is the fraction of stars with planetary systemsne is the number of planets that can support lifefl is the number of those planets that will develop lifefi is the number of those planets that will develop intelligent lifefc is the number of civilizations that might develop transmission technologiesL is the amount of time that these civilizations would have to transmit their signals into space.

Rather than being an actual means for quantifying the number of intelligent species in our galaxy, the purpose of the equation was meant to frame the discussion on SETI. In addition to encapsulating the challenges facing scientists, it was intended to stimulate scientific dialogue among those attending the meeting.
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