The search for habitable exoplanets is becoming increasingly difficult as scientists expand the very concept of "the possibility of life" in distant worlds and put forward new evaluation criteria. Recently, Professor Toby Tyrrell from the University of Southampton (UK) conducted a large-scale simulation of how life on our Earth could develop if its history had developed somewhat differently. The conclusions are frankly depressing, but at the same time encouraging.
It is known that the Earth has experienced climatic catastrophes, asteroid collisions, mass extinctions and other cataclysms that could completely destroy life on the planet. It is also known that evolution is slow, it took about 3 billion years for the transformation of unicellular microorganisms into Homo sapiens. What is the probability that during such a period no event of a planetary scale interrupted fragile life, and the Earth is still not only inhabited, but has also raised an intelligent civilization?
Professor Tyrrel with the help of a supercomputer generated 100, 000 random worlds with initial conditions close to those on Earth. For each of the worlds, 100 simulations of their existence were carried out over 3 billion years with a random set of incidents. It turned out that only 9% or 8170 worlds turned out to be fit for life in principle, for 8000 of them it developed to reasonable in less than 50 cases, and for 4500 in less than 10 cases. And only one single planet managed to keep life in all 100 models.
The professor's conclusion is disappointing: we only exist because the Earth is an incredibly lucky planet, and not at all the best world to live in. And it is not a fact that luck will last for a long time, from the point of view of mathematical randomness. But there is also a positive moment in the news - if a certain civilization ended up on the young Earth and carried out similar calculations, it simply would not settle here. We can follow the same principle when examining exoplanets for colonization suitability.