The Drake Equation is a mathematical equation that estimates the number of extraterrestrial civilizations that we could detect at present or in the near future. It was conceived in 1960 by Frank Drake from the University of California at Santa Cruz.
Drake’s purpose was to quantify the number by determining the number of stars that have planets, which of these might be occupied, then the fraction of those inhabited by creatures, and out of these, the fraction of the planets with creatures who may become intelligent.
But Drake’s calculations were mere guesses. For example, the number of extraterrestrial civilizations that we can detect today is extremely sensitive to the fraction that could self-destruct with their own technologies through a nuclear war, for instance. But it is impossible to know all these for sure.
However, many researchers have tried to come up with a figure, their estimates ranging from several civilizations throughout the world to tens of thousands of alien civilizations.
Astrobiologists argue that if life has grown so rapidly on our planet, it would be possible that the optimal conditions for the maintenance of life can also be found on others as well.
But David Spiegel at Princeton University and Edwin Turner at the University of Tokyo say that this theory is wrong. They used a different type of thinking, called Bayesian reasoning, to prove that life on Earth is consistent with the idea that life can rarely occur elsewhere in the Universe.
At first glance, this seems rather counterintuitive trial. But if Bayesian reasoning tells us something, is that we can deceive ourselves thinking that things are much more likely than they really are.
Spiegel and Turner emphasized that our thinking about the origin of life is strongly influenced by the fact that we are here to observe it. They also emphasized the idea that it took 3.5 billion years for intelligent life to evolve on Earth. Thus, the only way that such a large development was possible in a short period of time is the rapid emergence of life. And this rapid emergence of life is an independent factor for the likelihood of life in general.
” In other words, if evolution requires 3.5 Gyr for life to evolve from the simplest forms to sentient, questioning beings, then we had to find ourselves on a planet on which life arose relatively early, regardless of the value of [the probability of life developing in a unit time],”said Spiegel and Turner.
However, the two scientists say that their theory could prove wrong if we manage to discover in the future that life independently arose several times on Earth.