Scientists engaged in the search for extraterrestrial intelligence (SETI) work under the assumption that there is, in fact, intelligent life out there to be found. A new analysis may crush their optimism.


To calculate the likelihood that they'll make radio contact with extraterrestrials, SETI scientists use what's known as the Drake Equation. Formulated in the 1960s by Frank Drake of the SETI Institute in California, it approximates the number of radio-transmitting civilizations in our galaxy at any one time by multiplying a string of factors: the number of stars, the fraction that have planets, the fraction of those that are habitable, the probability of life arising on such planets, its likelihood of becoming intelligent and so on. [10 Alien Encounters Debunked]


The values of almost all these factors are highly speculative. Nonetheless, Drake and others have plugged in their best guesses, and estimate that there are about 10,000 tech-savvy civilizations in the galaxy currently sending signals our way — a number that has led some scientists to predict that we'lldetect alien signals within two decades.

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