The universe is 13.8 billion years old and 91 billion light-years across in its observable part. It is big and although that age places it more on the “young” side than the “adult” side, it remains a staggering amount of time. So when we ask ourselves whether there is life in other star systems and other galaxies, perhaps we are asking from the wrong angle. A new series of calculations cannot confirm if extraterrestrial civilizations exist today, but even with very pessimistic parameters, it almost certainly guarantees they existed in the past.
Until a few years ago, finding an exoplanet was reason enough to celebrate. Since the Kepler mission began its work, they are now discovered by the hundreds each time. The size of the “samples” is becoming larger and larger, but it is still not enough to prove beyond all doubt whether extraterrestrial life exists or not The odds are definitely on our side, however, the Fermi paradox keeps coming and hits us in the head: If there are so many aliens, where are they?
Thanks to a new study published by Adam Frank of the University of Rochester and Woodruff Sullivan of the University of Washington, perhaps the solution lies in asking the question differently. It is possible that the human civilization is the only one right now, but with the 13.8 billion years of age the universe has, it is very likely that intelligent species existed before. Perhaps several of our readers might think at this point “that's what the Drake Equation is for”, but the truth is that the Drake Equation does not aim to establish “hard numbers” on the number of civilizations, but to open the debate and expand the scientific analysis, not to mention the fact that four of its seven elements are still unknown.
The work of these two astronomers modifies in some way the profile of the Drake equation, and eliminates one of the unknown elements (“L”, that is, the time interval a civilization needs to send detectable signals into space) Instead of calculating how many civilizations exist out there, what they propose is to calculate the probability that the human species has been (and is) the only one to appear. Adding all the new data on exoplanets (including their formation), orbital positions, and habitable zones, the only way for the human species to meet that condition would require a probability lower than 1 in 10,000 trillion (our trillions, “10 billion trillion” American as Frank himself says, or 1 in 10^22) In summary: There were aliens, we just haven't met them yet.
