The Drake Equation - Russ McGlenn

A recent National Geographic article alluded to a scientific formula that "proves" we will find life in the Galaxy. My ears pricked up at that because normally neither search for extraterrestrial intelligence nor evolution have any mathematical formulas that could be used to prove or falsify a statement.

In September 1959, physicists Giuseppe Cocconi and Philip Morrison published an article in the journal Nature with the provocative title "Searching for Interstellar Communications." Cocconi and Morrison argued that radio telescopes had become sensitive enough to pick up transmissions that might be broadcast into space by civilizations orbiting other stars. Soon thereafter, Radio astronomer Frank Drake hosted a "search for extraterrestrial intelligence" meeting on detecting their radio signals. The meeting was held in 1961. The equation that bears Drake's name arose out of his preparations for the meeting and is touted as proof of the existence of life in the galaxy. SETI is still searching!

What it proves depends on the assumptions and guesses you put into the equation.