Man has always sought to find someone in the Universe who could share his existential loneliness. Despite the fact that modern telescopes are able to look into even the most distant corners of the Universe, we have not found any hints of even the simplest life. Does this mean that we are truly alone in the universe? And if so, how can awareness of this fact affect science and society as a whole?
Unique Earth hypothesis
The universe is incredibly huge. Thus, our home galaxy, the Milky Way, includes more than 100 billion stars, while the visible Universe contains more than a trillion galaxies of various sizes and shapes. Even if we consider that habitable worlds can be incredibly rare, the number of exoplanets that we have already discovered in the Universe indicates that there may be even more planets orbiting distant star systems than the stars themselves. So where is everyone? For the first time this question was asked by the famous Italian physicist of the 20th century, Enrico Fermi, who was one of the first in the history of science to question the possibility of human detection of any alien civilizations.
Could life be something truly unique in the universe? The international SETI project, aimed at finding and studying traces of alien life in the Universe, has shown that despite the huge number of exoplanets discovered by man, none of the civilizations hypothetically existing on them is in no hurry to get acquainted with earthlings. There may be a great many reasons for this: some of the researchers believe that our Universe was created according to the principle of a grandiose matrix, someone seriously believes that we live in a kind of space “zoo” and highly developed alien civilizations simply do not want to contact us, and someone enthusiastically says that the Earth is a unique place that could embody an extremely low, almost tending to absolute zero, probability of the origin of life in general.
The SETI (Search for Extraterrestrial Intelligence) project aims to search and study potential habitable exoplanets.
Evolution may answer the question of the origin of life on exoplanets
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In order to answer the question about the existence of life on a particular planet, we can involve in our search the concept of evolution. Having studied 4.5 billion years of Earth's history, you can come to the rather interesting conclusion that evolution has the property of repetition. According to newsweek, evolutionary processes occurring inside living organisms often repeat themselves due to the fact that different species, independently of each other, come to similar results. A prime example of this behavior is the extinct Australian marsupial thylacin, which had a pouch similar to a kangaroo's pocket, while possessing all the characteristics of a typical wolf. It is noteworthy that the entire evolutionary history of Australia, which has been in long-term isolation from the rest of the world since the death of the dinosaurs, is parallel to other continents.
We see a similar convergence if we consider the individual organs of living beings. So, eyes were able to develop not only in vertebrates, but also in octopuses, arthropods, jellyfish and worms, which may indicate that nature always strives to use similar solutions to complex problems. Surprisingly, many critical events in our evolutionary history are unique and perhaps incredible. One of them can rightfully be considered the bony skeleton of vertebrates, which allows large animals to move on land. Complex eukaryotic cells, from which all animals and plants, containing nuclei and mitochondria are built, have evolved only once. Photosynthesis, which increased the energy available to life and produced oxygen, is a one-time evolutionary process that makes it a truly unique phenomenon not only on Earth,but also in the universe.
In order for the emergence of man and his intellect to occur, nature had to comply with countless conditions.
Moreover, the occurrence of all of the above events depended on each other. Humans could not evolve until the fish developed bones that allowed them to crawl out onto land. Bones could not develop until complex animals appeared. Complex animals, in turn, needed complex cells, and complex cells needed oxygen produced by photosynthesis. Thus, it turns out that in nature nothing happens without the evolution of life, which manifests itself in stages and step by step, covering billions of years in its development. Such a long and complex development of natural “technologies” once again proves their extreme improbability, which eventually led to the emergence of human intelligence.
Many indirect factors can indicate that the Earth is unique in the universe.
Such accidents may look like if life on our planet would constantly draw out a lottery ticket that would allow the life that originated on it to constantly evolve. On other worlds, such critical adaptations may have started too late for intelligence to emerge before their nearby stars went supernova. Or they did not appear at all.
If we consider that the origin of human intelligence depends on a chain of very unlikely events, which manifested itself in the form of complex cells, photosynthesis, sexual separation, animals, people and their ability to understand the world, then the chances of intelligent life in the Universe become catastrophically low, which can to confirm the theory of supporters about the "unique Earth".
Will our lives change if scientists one day prove a theory about the uniqueness of the Earth?
Despite the fact that our planet may turn out to be the only “living world” in the Universe, it is the “Great Silence” of our neighbors that can give humanity the opportunity to realize its uniqueness, thereby changing the existing socio-political system and making it more scientific, aimed at comprehending oneself and the world around us. It sounds, of course, like one of the utopias, but what if this is the essence of human life, which was wonderfully illustrated by A. Tarkovsky's “Solaris”: we must explore, comprehend and transform the surrounding Universe, transform the lifeless space into a world similar to Earth …
Daria Eletskaya