50 years of astrophysical research that make extraterrestrial life more and more likely.
In 1960, Frank Drake had his chance. He had at his disposal the National Radio Astronomy Observatory and a question: «Would there be signs of extraterrestrial life?». First with the Ozma Project and, later, with the well-known SETI, this radio astronomer dedicated a good part of his life (and his ingenuity) to the search for life up there.
However, he was primarily a scientist. That is why in 1961, at the first SETI scientific congress, he systematized the reflections that he had been developing with the idea of stimulating debate among specialists. Thus was born the Drake Equation, the best tool we have to estimate the number of extraterrestrial civilizations that may be in the Universe.
Drake focused on the specific factors that would allow the development of civilizations and time has shown that this was a winning approach. However, there is no shortage of specialists who believe that the formula has errors. The last one, who I come to through Alex Riveiro, is Robert Zubrin, one of the greatest defenders of the colonization of Mars.
Zubrin’s critique
That is precisely where the main criticisms of Drake are concentrated: in the resilience of life (and civilization) on the one hand and on its ability to spread to nearby planetary systems. They are two small corrections that, although they do not seem like it, radically change the calculation.
First of all, we have to take into account that ‘civilization’ for Drake is “a species that has radio telescopes.” That is we did not have a “Drakian” civilization on Earth until the 1930s. Therefore, along with the number of planets capable of developing a biosphere, the fundamental piece of information in the equation is the time it takes for these civilizations to be born (and die).
By convention, we take as a reference about 50,000 years half-life. The problem is, Drake didn’t take into account that planets can develop various civilizations over time. Zubrin gives as an example the extinction of the dinosaurs and how, just five million years after that brutal cataclysm, the biosphere had already fully recovered.
In addition, Zubrin highlights one of his favorite topics: space colonization. And, it must be recognized, in this he is right. Our own experience makes it reasonable to think that ‘Drakian’ civilizations tend to expand to nearby planets and planetary systems.
Every thing we discover makes it more probable
With all this in mind, Zubrin posits that between 3% and 4% of the stars in our galaxy they could be within the sphere of influence of some civilization. In a galaxy of 400,000 million stars, it is a lot of stars. Much more than Drake thought. But also very distributed.
As Riveiro reflects, Zubrin’s annotations they are not a substantive critique of the Drake Equation. Rather, they are the direct consequence of everything we have learned since the 1960s. Be that as it may, what is clear is that all the discoveries we have made since 1961 seem to point to the same place: extraterrestrial life it has to be more common than we had suspected.
