Astronomers suggest that many extraterrestrial civilizations have already risen in our galaxy during its history. On the other hand, they also suggest that most have probably already disappeared.
Proposed in 1961 by Dr. Frank Drake, the Drake equation is a formula for estimating the potential number of extraterrestrial civilizations in our galaxy. The equation takes into consideration several factors:the number of stars that form annually in our galaxy, the share of stars with planets or the expected number of planets potentially suitable for life per star. It also takes into account the part of these planets where life actually appears, the part of these planets where intelligent life appears and the part of these planets able and willing to communicate. Finally, the equation considers the average lifespan of a civilization (in years).
However, the problem is that at the time of thinking this equation, none of these factors were actually known with certainty. Thus, taking into account this degree of uncertainty, the Drake equation estimated at between one and one hundred million the number of technological civilizations developed in the Milky Way. In other words, the range was huge.
In a recent paper, physicists at Caltech (California) roughly updated this equation based on modern astronomical data and statistical modeling . "We have learned a lot, especially thanks to the Hubble and Kepler telescopes, about the densities [of gas and stars] in the Milky Way, about the rates of formation of stars and exoplanets or even about the rate occurrence of supernova explosions “, underlines Jonathan H. Jiang, the co-author of the study.
As part of their work, the authors consideredseveral factors likely to influence the development of intelligent life in the galaxy, such as the prevalence of Sun-like stars hosting Earth-like planets, the frequency of deadly and explosive supernovae, the likelihood and time required for intelligent life to evolve if the conditions are right, and the possible tendency of advanced civilizations to self-destruct.
By modeling the evolution of the Milky Way over time and considering all these factors, the researchers found that the probability of life emerging peaked at about 13,000 light-years from the galactic center and eight billion years after the galaxy formed . By comparison, Earth is about 25,000 light-years away from the galactic center and human civilization only appeared on the surface of the planet 13.5 billion years ago approximately after the formation of the Milky Way (although simple life appeared shortly after the formation of the planet).
In other words, we are probably a "frontier civilization" in terms of galactic geography, but also laggards compared to other "conscious inhabitants" of the Milky Way.
The authors also believe that while the galaxy reached its "civilizational peak" more than five billion years ago, most of the civilizations that existed at the time are probably already self-annihilating due to scientific and technological progress causing climate change or wars .
The authors do not, however, exclude the idea that there may still be advanced civilizations in the galaxy today. If so, they point out instead that these are probably young, like ours, due to the fact that intelligent life is likely to develop over long periods of time.
