The Drake Equation (developed in the 1960’s by SETI’s Frank Drake) was a theory that claimed to be able to approximate the number of radio transmitting civilizations in our galaxy simply by producing a product between a number 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.
Using these numbers- as highly speculative as they are- Drake was able to divine that there are some 10,000 tech savvy civilizations out there in the nothing just waiting for us to pick up what they are laying down…
But so far, after fifty years of looking... not a peep…
While some theorized that perhaps the silent treatment we were receiving from the cosmos had more to do with our presumption that all civilizations would do things the same way we did- ie using radio signals- others feel that the issue isn’t a technological one… it’s a mathematical one.
In a recent article, astrophysicist David Spiegel at Princeton University and physicist Edwin Turner at the University of Tokyo are claiming that life like that found on Earth could be very common throughout the cosmos or it could be very rare indeed… even exceptional… and to assume one conclusion or another with certainty would be inaccurate. Using a statistical method called the Bayesian reasoning, Spiegel and Turner deemed one of the factors necessary to complete the Drake Equation is impossible to absolutely determine (thus invalidating any results spewed out by the Drake Equation).
"Although life began on this planet fairly soon after the Earth became habitable, this fact is consistent with … life being arbitrarily rare in the Universe," the authors state. In the paper, they prove this statement mathematically.
Their result doesn't mean we're alone — only that there's no reason to think otherwise. "[A] Bayesian enthusiast of extraterrestrial life should be significantly encouraged by the rapid appearance of life on the early Earth but cannot be highly confident on that basis," the authors concluded, noting that a second data point where life had independently spawned would serve as a far better proof for the inevitability of life spawning throughout the universe.