Asked the meaning of life, the supercomputer in the Hitchhiker's Guide to the Galaxy came up with a very specific answer: 42. Tasked with a different Big Question—how many intelligent alien civilizations exist in our galaxy—real-life scientists have gotten just as specific: 36. That's the estimate from a team of researchers out of the University of Nottingham in England, reports the Guardian. The estimate is based on a big assumption: that life elsewhere in the Milky Way would form in generally the same way as it did on Earth. Starting from that premise, researchers crunched data on existing stars, exoplanets, conditions, etc., and came up with a range of four to 211, with 36 being the most likely number, according to the study in the Astrophysical Journal.
"The classic method for estimating the number of intelligent civilizations relies on making guesses of values relating to life, whereby opinions about such matters vary quite substantially," says co-author Tom Westby. He's referring to the long-standing Drake equation, which results in not-so-helpful estimates ranging from zero to billions, per a news release. "Our new study simplifies these assumptions using new data, giving us a solid estimate of the number of civilizations in our galaxy." Alas, the study figures the nearest one to be 17,000 light-years away, making communication a little difficult. Researchers estimate our own civilization would have to last more than 6,000 years before any two-way communication could take place. A weak point of the study? That original assumption that Earth is a handy model, a skeptical scientist tells Live Science. (Read more discoveries stories.)