Study: we do not see extraterrestrial life, since our origin was too early

Another possible solution to the Fermi paradox

On Geektimes articles were repeatedly published in which a solution to the so-called Fermi paradox was proposed. The paradox itself is formulated as follows: “If life is a common phenomenon in the Universe, therefore, in its observable part there should be a large number of developed civilizations that a person could already notice. But for dozens of years of observing space, this has not happened. ” That is why Fermi and asked: "Well, where are they in this case?".

There are many prospective answers to this question; you can read about some of them here , here and here . Now a group of scientists from Harvard gives another possible answer . Experts have suggested that the civilizations that we might have noticed were simply not born yet. In their opinion, there is a high probability that our own civilization is the most developed in the observable part of the Universe. “If you want to know when life began to emerge in the universe, the answer is“ now, ”says Avi Loeb, a team leader at the Harvard-Smithsonian Center for Astrophysics. The authors of the paper, published in the Journal of Cosmology and Astroparticle Physics, believe that in the future life will emerge on other planets more often than it does now or what happened in the past.

It is likely that even now life exists on a large number of other planets in a number of star systems. But humanity is one of the first intelligent forms of life. And the signals of the “ancient civilization” you can not only hear, but also see. Just turn on your TV or computer. That's because this ancient civilization is ourselves.
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In their work, scientists consider only carbon-based life, without paying attention to its other possible forms. In order for a carbon-based life to originate, three basic conditions are necessary: ​​organic compounds, liquid water and an energy source. The source of all this is the star. It supplies the elements necessary for the existence of life, heats the water to a liquid state in the "habitable zone" and is a source of energy. Stars play an important role in the understanding of the problem of the origin of life by scientists.

According to the Loeb team, favorable conditions for the emergence of life could have arisen already 30-40 million years after the Big Bang. Then the first stars of the universe exploded, planting the surrounding areas of space with heavy elements. Life will die down, according to the same scientists after 100 trillion years, when the last survivors of the Universe are red dwarfs. An analysis by scientists from Harvard showed that the most favorable conditions for the existence of intelligent life will arise in a few billion years. In the past and present, these conditions are not favorable enough, and our civilization is an exception to the rules.

Because of the low rate of hydrogen combustion, a type of star like red dwarfs has a very long life expectancy - from tens of billions to tens of trillions of years (a red dwarf with a mass of 0.1 solar masses will burn 10 trillion years). Our Sun is a yellow dwarf, stars of this type are much less common red dwarfs. The life of yellow dwarfs is about 10 billion years.

The fact that yellow dwarfs can support life on the planets of their system can be considered proven only because the Sun supports life on Earth. According to the authors of the study, the probability of intelligent life for the nearest stars in our time is 0.1%. In the future, intelligent life, according to scientists from Harvard, may appear on planets orbiting red dwarfs. There are at least 100 billion planets in our galaxy. According to some reports, most of the stars around which exoplanets rotate are red dwarfs.

“Many other stars whose lifetimes are longer than the life of the Sun can give rise to life in the future. The probability of life in the future on the planets of other star systems is a thousand times higher than the probability of life in the past, for all the past 13 billion years of the evolution of the Universe, ”says Alan Duffy, an astronomer from Australia.

Other experts disagree with this point of view. Life on planets orbiting dwarf stars may not arise due to adverse conditions. The yellow dwarf appears to provide optimal conditions for the emergence of carbon-based life, but there are not many such stars, as mentioned above. There are much more red dwarfs, but the conditions for the emergence of life within such star systems are minimal — conditions are too unfavorable. There are many scientific papers explaining this point of view.

A planet that rotates around a red dwarf may be in a zone where conditions ensure the appearance of water in the form of liquid rather than ice. But other conditions may not be suitable for the existence of life or complex organic molecules. It's all about the hard radiation of a star that reaches the surface of such a planet, which is much closer to its star than the Earth - to the Sun.

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Charley Lineweaver, an astrobiologist at the Australian National University, supports the view that red dwarfs are unsuitable for sustaining life on their planets. He agrees with the methodology used by English scientists to analyze the probability of the existence of other civilizations in the Universe. But he does not agree with the conclusion, which refers to the equally probable occurrence of intelligent life on the planets of red dwarfs and on the planets of yellow dwarfs. In his opinion, life cannot appear on red dwarfs and, moreover, cannot develop at all.

Lineweaver does not believe that humanity is one of the first civilizations in the observable part of the universe. On the contrary, he argues that we are one of the last intelligent forms of life. All the others have already appeared, developed to the highest point and died for one reason or another. He draws his own conclusion on the basis of the fact that the Earth appeared rather late by cosmic standards.

Whatever it was, scientists still have not come to a common opinion about why a person cannot detect traces of the existence of other intelligent life forms and why our Solar System allowed life and mind to originate on Earth. Whatever point of view is true, obtaining irrefutable evidence in favor of any of the versions will have a tremendous impact on people's worldviews (in any case, the thinking part of humanity) and on the future of our entire civilization as a whole.