# The probability that we are alone in the universe has never been lower

According to two American researchers, the probability that humans are the only intelligent species in the universe is incredibly low. About a one in ten billion trillion chance.

Are we alone in the universe ? If for some the answer is obvious, others need to quantify, to encrypt, to calculate the probabilities. The answer is in no way anecdotal, since the simple fact of measuring one’s own place in the cosmos has the gift of putting ideas back in place. Imagine then that we tell you, certify that we are not alone in this immensity. In a recent study published in the journal Astrobiologytwo American researchers bring today a mathematical proof, therefore radical, that we have, or that we had, neighbors in the universe.

This statement we owe to Adam Frankfrom the Department of Physics and Astronomy at the University of Rochester, and to Woodruff Sullivan, from the Department of Astronomy and Astrobiology at the University of Washington. The two researchers have recently looked into THE famous question, and they have thus undertaken to bring the famous Drake equation (an equation for quantifying the number of extraterrestrial civilizations living in the universe) up to date, by drawing on the latest data captured by NASA satellites. And according to their calculations, the probability that we are the only intelligent species in the cosmos is only one in ten billion trillion, or the number 1, followed by 24 zeros.

The two researchers summed up their theory in the following equation: A = Nast x fbt.

A = Nast * ƒbt. “A” here is the probability that an intelligent species, including Earthlings, has appeared in the universe. « Nast » is the number of planets located in the habitable zone of their star. “ƒbt” is the probability that an intelligence evolved enough to have developed advanced technologies can do so in said habitable zone.

Unlike Drake’s equation, this new equation does not focus on the number of extraterrestrial civilizations likely to exist, but rather the number of extraterrestrial civilizations likely to have existed. The nuance is important. For the authors of the study, an intelligent species of extraterrestrials has certainly appeared in the history of the Milky Way if the probability of the appearance of another species on a habitable planet is greater than one in sixty billion“.

In an observable universe which today has several hundreds of billions of galaxies, each containing hundreds of billions of stars, it is difficult to imagine being alone in the immensity of the cosmos. So when math gets involved…

Source: Astrobiology