For the precocious hunter of off-Earth life, the Drake equation is the ever-ready, go-to toolkit for estimating just how (not) lonely humans are in the Milky Way galaxy. The equation was developed by astronomer Frank Drake in 1961 in a slight hurry so that attendees of an upcoming conference would have something to confer about, and it breaks down the daunting question “Are we alone?” into more manageable, bite-size chunks.
The equation starts with some straightforward concepts, such as the rate of star formation and the fraction of stars hosting planets. But it quickly moves into tricky terrain, asking for numbers like what fraction of those planets that could host life actually end up evolving intelligent species and what fraction of those planets blast out friendly signals into the cosmos, inviting us Earthlings to a nice little chat.
The end result is supposed to be a single value (or, at worst, a range of values) that predicts the total number of intelligent and conversation-ready species in the galaxy. And if that seems a little unsettlingly bold, then at the very least, the Drake Equation serves as a philosophical device for instigating conversation. It also frames a proper scientific discussion about the ultimate question of finding and talking to alien species in the galaxy.
Except that it fails on both counts.