(ORDO NEWS) — The chances of an intelligent life on Earth’s double turned out to be about 3: 2, according to a new study in the journal Proceeding of the National Academy of Sciences. But primitive organisms on planets similar to ours can be found much more often. The author came to this conclusion by constructing a probabilistic model that takes into account the evolution of earthly life.
The question of how widespread life is in the Universe is one of the fundamental for modern science. Today, scientists have no direct evidence of the existence of even primitive organisms beyond the Earth, and the remote detection of chemical biomarkers (e.g. methane or carbon dioxide) outside the solar system does not yet allow us to clearly say that they are associated with the presence of life. However, today astronomers continue to develop projects to search for extraterrestrial civilizations and send signals to space, and the development of probabilistic models can help them choose the most successful candidates for their research.
David Kipping of Columbia University proposed using Bayesian analysis to determine the likelihood of intelligent life on Earth if we were to go back in time to its inception. In his work, the researcher took into account three main factors: the time of the appearance of the first living organisms, the time of the appearance of intelligent life, and the size of the habitability window of our planet.
Life on Earth by cosmic standards was born quite early. Carbon of organic origin, found in miniature crystals, indicates that primitive microbes on the planet could exist already 400 million years after its formation. But intelligent life appeared much later, along with the emergence of human civilization several million years ago (Kipping notes that the starting point can be both the appearance of hominids and the separation of Homo sapiens, since this does not create a significant error on the scale of the study). Since this event occurred in a rather late period of the Earth’s habitability time window, the size of which the researcher estimated at 5.3 billion years, Kipping concludes that the process of the emergence of intelligent life was neither easy nor guaranteed.
Numerous simulation runs showed that the chances of life appearing on Earth’s double are equal to at least 9: 1, which, according to the astronomer, suggests that the existence of primitive organisms outside the solar system should not be too rare. However, the situation with intelligent life turned out to be somewhat different: the probability that during processes similar to those that took place on our planet, civilization appears on its twin, capable of developing to our level, was only 3: 2. According to Kipping, if we lose the history of the Earth again, then intelligent life is unlikely to arise on it.
Nevertheless, Kipping notes that his work cannot be regarded as proof that life is widespread in space, since our knowledge of it is limited only by knowledge of one single world – the Earth. The model he proposed provides only statistical estimates of the processes taking place on our planet, and not an unambiguous forecast.
Today, astronomers are considering different methods of detecting life outside the solar system. So, recently, scientists proposed to search for extraterrestrial civilizations not only by radio signals, but also by space debris surrounding their planets.
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