How long it will take to find out if we are alone in the universe is unknown to anyone. One thing is clear - the hope of finding their own kind is unlikely to ever leave a person. Are there other civilizations in the Universe? If so, are there many of them? These questions have always fascinated humanity. Now there is finally hope of definitely answering them. Recent studies have led scientists to conclude that there are habitable planets outside of our solar system. Over the past five years, more than thirty stars similar to the Sun have been discovered, with planets approximately equal in mass to Jupiter. And although so far not a single Earth-like star has been discovered in the retinues of such stars, astronomers are quite sure that the number of its "twins" is also large. The origin and development of life is impossible without planets. Their presence in distant luminaries seems to convincingly support the point of view that life fills the Universe. This opinion is also based on advances in understanding how all life on Earth arose and at what speed it developed. The oldest confirmation of the existence of life on our planet (and possibly in the Universe)? fossil bacteria. Their discovery in an Australian rock, which is 3.5 billion years old, was announced in 1993 by William Schopf of the University of California, Los Angeles. The bacteria were quite developed organisms - a fact that testifies to a long evolution. The Earth itself is only 4.6 billion years old. It turns out that life on it appeared very quickly by geological standards. The conclusion suggests itself that for nature this step turned out to be relatively simple. Nobel laureate biochemist Christian de Duve made a bold thought:"Life is almost bound to arise … as soon as physical conditions become similar to those that existed on our planet about four billion years ago." In other words, there is reason to believe that our Galaxy is "teeming" with living beings. Does it follow from this that the number of technological civilizations is also great? According to some scientists, as soon as primitive life emerges, natural selection will inevitably force it to improve, moving towards knowledge and technology. Nuclear physicist Enrico Fermi doubted the correctness of this opinion. In 1950, he formulated a reasonable question: if extraterrestrial civilizations? something quite ordinary, then where are they, should not their very presence be obvious? This logical structure has come to be known as the Fermi Paradox. The problem of detecting civilizations has two aspects:are the current search tools capable of picking up radio signals sent from the depths of space, and is there sufficient evidence that aliens have ever visited Earth.
WHAT IS SPACE SAFE ABOUT?
In 1960, American researchers at the National Radio Astronomy Observatory in Green Bank, West Virginia, received signals from two nearby stars. Since then, many complex experiments and studies have been carried out, but no manifestations of extraterrestrial intelligence have been recorded. There is no dispute, the purposeful probing of the Universe has just begun and the lack of success cannot serve as a basis for the final verdict: there are no extraterrestrial civilizations. The Fermi paradox becomes clearer when we try to comprehend the likely number of galactic civilizations, both existing and existing. One of the leading experts in the field, Paul Horowitz of Harvard University, has suggested that within 1000 light years of the Sun, in space containing about a million stars like it,there is at least one radio transmitting civilization. If so, then our entire Galaxy is "inhabited" by about a thousand civilizations. The figure is impressive. Suppose the duration of the existence of such civilizations was not very long. Then it turns out that a huge number of them originated and disappeared during the lifetime of our Galaxy. It is believed that the average number of existing civilizations at each moment of time is equal to the product of the rate of their formation by their average life span. The rate of formation can be roughly determined by dividing the total number of all civilizations that have ever existed by the age of our Galaxy (approximately 12 billion years). Let's say civilizations are formed at a constant rate and live on average for a thousand years. In this case, the existence of a thousand civilizations at the moment means the presence of about 12 billion technically advanced civilizations. Incredibly many! And that's why the Fermi Paradox becomes obvious. Is it possible that billions of civilizations (or at least one of them!) Left no evidence of their existence?
SHOULD I WAIT FOR SPACE COLONISTS?
Most scientists proceed from the fact that there is no definitive evidence of visits to our planet by representatives of other civilizations. And no matter what people think about UFOs, we can state that the Earth has not yet been captured by aliens. There are four ways to reconcile the fact that there are no traces of extraterrestrial intelligence with the widespread belief that highly developed civilizations are supposedly common in the Universe. First, it is possible that interstellar travel is not feasible for their representatives. If so, then aliens will never get to Earth. Secondly, it is possible that extraterrestrial civilizations are actively exploring the Galaxy, but so far they have simply not reached us. Third, perhaps they deliberately abandoned interstellar travel. And, finally, fourthly, being active in the vicinity of the Earth, they so far refrain from contacts with us. The first explanation doesn't stand up to scrutiny. None of the known laws of physics contradict the possibility of interstellar travel. Now, at the dawn of the space age, do engineers know that you can achieve a speed of 10? 20% light, and reach the nearest stars in decades. For the same reason, the second explanation also appears dubious. Any civilization with rocket technology is capable of colonizing our Galaxy in a very short space-time period. Let us imagine how the development of the nearest planetary systems would go. Having settled on one planet, the colonists would move further and further. The number of colonies would grow exponentially. Suppose the distance between colonies is ten light years, the speed of the ships? ten percent of the speed of lightand the period between the founding of the colony and the departure of new settlers from it is four hundred years. In this case, the wave of colonization should propagate at a speed of 0.02 light years per year (such a unit for measuring speed will not seem unusual if you remember that a light year is a measure of distance, the path that light travels in a year? Ed.). The radius of our Galaxy? one hundred thousand light years. Its full colonization would take no more than five million years. This is only 0.05% of the age of the Galaxy. Compared to many astronomical and biological processes? a short period of time. The most uncertain factor? the time required to set up the colony, that is, until the next "jump". A reasonable upper limit could be around five thousand years? so many,how much it took humanity on the way from the first cities to space rockets. If we stop at this figure, then the complete development of the Galaxy would take fifty million years and the most technically advanced civilization, capable and willing to occupy our Galaxy, would do it. In principle, this could have happened billions of years ago, when the Earth, inhabited only by microorganisms, was defenseless against invasion from outside. But no facts (neither physical, nor chemical, nor biological) confirm that the invasion of the Earth ever took place. Any attempt to resolve the Fermi Paradox must be based on the possibility of different behaviors of other civilizations. Suppose they are capable of destroying themselves, abandoning the idea of colonizing the Galaxy, observing strict prohibitions on contacts with primitive life forms. Many people, including scientists, who are convinced of the existence of aliens, are trying to refute the Fermi Paradox by appealing to the above considerations. However, are they facing a fundamental problem? the proposed explanations are plausible only if the number of extraterrestrial civilizations is small. If there are millions or billions of technological civilizations in the Galaxy, it is unlikely that all of them will end in self-destruction, doom themselves to a settled lifestyle, or adopt the same rules for less developed forms of life. It is enough for the envoys of one civilization to start carrying out a program to conquer the Galaxy. The only such civilization that we know anything about? our. She has not yet destroyed herself, is prone to expansion, not particularly scrupulous in terms of contacts with other living beings.convinced of the existence of aliens, they try to refute the Fermi Paradox, appealing to the above considerations. However, are they facing a fundamental problem? the proposed explanations are plausible only if the number of extraterrestrial civilizations is small. If there are millions or billions of technological civilizations in the Galaxy, it is unlikely that they will all end in self-destruction, doom themselves to a settled lifestyle, or adopt the same rules for less developed forms of life. It is enough for the envoys of one civilization to start carrying out a program to conquer the Galaxy. The only such civilization that we know anything about? our. She has not yet destroyed herself, is prone to expansion, not particularly scrupulous in terms of contacts with other living beings.convinced of the existence of aliens, they try to refute the Fermi Paradox, appealing to the above considerations. However, are they facing a fundamental problem? the proposed explanations are plausible only if the number of extraterrestrial civilizations is small. If there are millions or billions of technological civilizations in the Galaxy, it is unlikely that they will all end in self-destruction, doom themselves to a settled lifestyle, or adopt the same rules for less developed forms of life. It is enough for the envoys of one civilization to start carrying out a program to conquer the Galaxy. The only such civilization that we know anything about? our. She has not yet destroyed herself, is prone to expansion, not particularly scrupulous in terms of contacts with other living beings.appealing to the above considerations. However, are they facing a fundamental problem? the proposed explanations are plausible only if the number of extraterrestrial civilizations is small. If there are millions or billions of technological civilizations in the Galaxy, it is unlikely that they will all end in self-destruction, doom themselves to a settled lifestyle, or adopt the same rules for less developed forms of life. It is enough for the envoys of one civilization to start carrying out a program to conquer the Galaxy. The only such civilization that we know anything about? our. She has not yet destroyed herself, is prone to expansion, not particularly scrupulous in terms of contacts with other living beings.appealing to the above considerations. However, are they facing a fundamental problem? the proposed explanations are plausible only if the number of extraterrestrial civilizations is small. If there are millions or billions of technological civilizations in the Galaxy, it is unlikely that they will all end in self-destruction, doom themselves to a settled lifestyle, or adopt the same rules for less developed forms of life. It is enough for the envoys of one civilization to start carrying out a program to conquer the Galaxy. The only such civilization that we know anything about? our. She has not yet destroyed herself, is prone to expansion, not particularly scrupulous in terms of contacts with other living beings. If there are millions or billions of technological civilizations in the Galaxy, it is unlikely that they will all end in self-destruction, doom themselves to a settled lifestyle, or adopt the same rules for less developed forms of life. It is enough for the envoys of one civilization to start carrying out a program to conquer the Galaxy. The only such civilization that we know anything about? our. She has not yet destroyed herself, is prone to expansion, not particularly scrupulous in terms of contacts with other living beings. If there are millions or billions of technological civilizations in the Galaxy, it is unlikely that they will all end in self-destruction, doom themselves to a settled lifestyle, or adopt the same rules for less developed forms of life. It is enough for the envoys of one civilization to start carrying out a program to conquer the Galaxy. The only such civilization that we know anything about? our. She has not yet destroyed herself, is prone to expansion, not particularly scrupulous in terms of contacts with other living beings. The only such civilization that we know anything about? our. She has not yet destroyed herself, is prone to expansion, is not particularly scrupulous in terms of contacts with other living beings. The only such civilization that we know anything about? our. She has not yet destroyed herself, is prone to expansion, not particularly scrupulous in terms of contacts with other living beings.
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WILL THE PARADOX BE SOLVED?
Regardless of how peaceful, sedentary, or uncommunicative most extraterrestrial civilizations are, they have motives for interstellar migration. At least one: stars don't last forever. Hundreds of millions of suns, after hydrogen disappeared from them, turned into red giants and white dwarfs. Imagine that intelligent life existed around these stars. What happened to her? Have all civilizations resigned themselves to their inevitable death? Obviously, technological civilizations are quite rare in the universe. One of the possible reasons for this? chemical composition of the Galaxy. Is life on Earth and beyond dependent on elements heavier than hydrogen and helium? mainly from carbon, nitrogen and oxygen. Arising as a result of a nuclear reaction in stars, they gradually accumulate in the space environment, where new stars and planets are born. Once the concentration of these elements was lower (or even too low), which made it impossible for the birth of living organisms. Unlike other stars in our part of the Galaxy, the Sun turned out to be much richer in these elements than would have been expected given its age. It is possible that the solar system received an unexpected advantage in terms of the origin and development of life. But this argument is not as compelling as it seems at first. Scientists do not know the threshold mass of heavy elements required for life. If even a tenth of what is on the Sun is enough (which looks plausible), then life could arise around much older stars. Take, for example, the Sun-like star 47 Ursa Major? one of those around which planets close in mass to Jupiter were discovered. There are just as many heavy elements in its composition,like the sun, but its age? seven billion years. Life that could arise in its planetary system would be 2.4 billion years ahead of ours. Millions of such old "chemically rich" stars fill our Galaxy, as if crowding around its center. It turns out that the chemical evolution of the Galaxy almost certainly does not explain the Fermi Paradox. A more acceptable explanation is suggested by the history of life on Earth. Life has existed on our planet almost since its inception. However, multicellular organisms appeared here only about 700 million years ago, and before that (over three billion years!), The Earth was inhabited only by unicellular organisms. This time interval means how unlikely the evolution of anything more complex than a single cell is. Therefore, the transition to multicellular forms could occur only on a small part of the existing millions of planets,assimilated by unicellular organisms. It can be argued that the long history of bacteria alone was a prelude to the emergence of animals on Earth. It seems that it took so long (and will be needed on uninhabited planets) for the bacteria to produce enough oxygen as a result of photosynthesis for the emergence of more complex life forms. But even if multicellular organisms live on all planets where there is life, it does not at all follow that they will initiate the emergence of intelligent beings, especially technological civilizations. A graphic illustration of the role of chance? the fate of the dinosaurs. They prevailed on our planet for 140 million years, but they would hardly ever create a technological civilization. If they did not disappear for a random reason, life on Earth could evolve in a completely different way. It can be argued that the long history of bacteria alone was a prelude to the emergence of animals on Earth. It seems that it took so long (and will be needed on uninhabited planets) for the bacteria to produce enough oxygen as a result of photosynthesis for the emergence of more complex life forms. But even if multicellular organisms live on all planets where there is life, it does not at all follow that they will initiate the emergence of intelligent beings, especially technological civilizations. A graphic illustration of the role of chance? the fate of the dinosaurs. They prevailed on our planet for 140 million years, but they would hardly ever create a technological civilization. If they did not disappear for a random reason, life on Earth could evolve in a completely different way. It can be argued that the long history of bacteria alone was a prelude to the emergence of animals on Earth. It seems that it took so long (and will be needed on uninhabited planets) for the bacteria to produce enough oxygen as a result of photosynthesis for the emergence of more complex life forms. But even if multicellular organisms live on all planets where there is life, it does not at all follow that they will initiate the emergence of intelligent beings, especially technological civilizations. A graphic illustration of the role of chance? the fate of the dinosaurs. They prevailed on our planet for 140 million years, but they would hardly ever create a technological civilization. If they did not disappear for a random reason, life on Earth could evolve in a completely different way.that the long history of bacteria alone was the prelude to the emergence of animals on Earth. It seems that it took so long (and will be needed on uninhabited planets) for the bacteria to produce enough oxygen as a result of photosynthesis for the emergence of more complex life forms. But even if multicellular organisms live on all planets where there is life, it does not at all follow that they will initiate the emergence of intelligent beings, especially technological civilizations. A graphic illustration of the role of chance? the fate of the dinosaurs. They prevailed on our planet for 140 million years, but they would hardly ever create a technological civilization. If they did not disappear for a random reason, life on Earth could evolve in a completely different way.that the long history of bacteria alone was the prelude to the emergence of animals on Earth. It seems that it took so long (and will be needed on uninhabited planets) for the bacteria to produce enough oxygen as a result of photosynthesis for the emergence of more complex life forms. But even if multicellular organisms live on all planets where there is life, it does not at all follow that they will initiate the emergence of intelligent beings, especially technological civilizations. A graphic illustration of the role of chance? the fate of the dinosaurs. They prevailed on our planet for 140 million years, but they would hardly ever create a technological civilization. If they did not disappear for a random reason, life on Earth could evolve in a completely different way. It took so long (and will be needed on uninhabited planets) for the bacteria to produce enough oxygen as a result of photosynthesis for the emergence of more complex life forms. But even if multicellular organisms live on all planets where there is life, it does not at all follow that they will initiate the emergence of intelligent beings, especially technological civilizations. A graphic illustration of the role of chance? the fate of the dinosaurs. They prevailed on our planet for 140 million years, but they would hardly ever create a technological civilization. If they did not disappear for a random reason, life on Earth could evolve in a completely different way. It took so long (and will be needed on uninhabited planets) for the bacteria to produce enough oxygen as a result of photosynthesis for the emergence of more complex life forms. But even if multicellular organisms live on all planets where there is life, it does not at all follow that they will initiate the emergence of intelligent beings, especially technological civilizations. A graphic illustration of the role of chance? the fate of the dinosaurs. They prevailed on our planet for 140 million years, but they would hardly ever create a technological civilization. If they did not disappear for a random reason, life on Earth could evolve in a completely different way.it does not at all follow that they will initiate the emergence of intelligent beings, especially technological civilizations. A graphic illustration of the role of chance? the fate of the dinosaurs. They prevailed on our planet for 140 million years, but they would hardly ever create a technological civilization. If they did not disappear for a random reason, life on Earth could evolve in a completely different way.it does not at all follow that they will initiate the emergence of intelligent beings, especially technological civilizations. A graphic illustration of the role of chance? the fate of the dinosaurs. They prevailed on our planet for 140 million years, but they would hardly ever create a technological civilization. If they did not disappear for a random reason, life on Earth could evolve in a completely different way.
LONG TO SEARCH FOR EXTRATERRESTRIAL CIVILIZATIONS?
Until we receive their signals, or, most likely, we can clearly limit the number of those that eluded our attention. A detailed study of Mars in order to establish whether life has ever existed on it, and if not, then why, seems promising. We need to accelerate the development of radio telescopes that can distinguish Earth-sized planets around nearby stars, and detect signs of life using spectral analysis of their atmospheres. It is necessary to create technologies for sampling in interstellar space. Only systematic, consistent research will help us understand what our place in the universe is.
ALEXANDER SVETLOV