Since the middle of the 20th century, astronomers have been looking for signs of intelligent extraterrestrial civilizations. But the universe is still silent. Let's try to figure out why.
Enrico Fermi is one of the "fathers" of the atomic bomb, radioactive research, and also a Nobel Prize winner. It is difficult to overestimate his contribution to the development of quantum mechanics and theoretical physics. Most often, however, his name is associated with a simple question that was originally a kind of joke among scientists discussing UFOs at Los Alamos in 1950: Where is everyone?
Fermi was not the first person to ask the question of extraterrestrial intelligence. But it is with him that he is most often associated, so in the end it became known as the Fermi paradox. It can be summed up like this: the universe is inconceivably huge, the existence of intelligent alien life is almost undeniable, but the universe is almost 14 billion years old and other creatures have had enough time to reveal themselves to humanity, so where is everyone?
First, think about human space achievements. It is possible that in the coming decades we will already send the first interstellar probes - to the Alpha Centauri system. But not even a century has passed since the flight of the first man into space. What will we be capable of in hundreds, thousands or even millions of years?
Enrico Fermi, after whom the described paradox was named / Smithsonian Institution Archives.
Fermi and his colleagues asked this question 11 years before Yuri Gagarin exclaimed: "Let's go!" In theory, a technologically advanced alien race should have no difficulty colonizing the Galaxy, especially if it had many millions of years for it.
But in order to say with confidence that we are not alone in the universe, scientists need proof. This evidence, to put it mildly, is small, if not to say that it does not exist at all. And the stipulations that the laws of physics do not allow spaceships to move above a certain speed are not suitable for everyone.
Take Proxima Centauri, for example. Even if you go to it at 0.25% of the speed of light, you will be able to get there not earlier than in 16 years. The TRAPPIST-1 system is about 160 years old. For a long time, but this is a drop in the ocean compared to the age of the Universe and the Milky Way.
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Drake's equation
The first thing to consider is the Drake equation. This is a simple mathematical formula originally proposed by astronomer Frank Drake in 1961. In a nutshell: through it we are trying to calculate the number of technologically advanced civilizations and communicating communities in the Galaxy. The Drake equation looks like this:
Drake Equation / PPT-Online.
Many astrophysicists have tried for a long time to calculate each value, but today the equation has no final solution. R can also be the number of stars in the Galaxy - it is believed that there are 100 billion in the Milky Way. Even if we take the minimum, the proportion of stars with planetary systems is about 20%, and each of these stars should have at least one habitable planet. Suppose that only 10% of them were able to develop intelligent life forms capable of communication. So we get rid of considerable probabilities, because we end up with 10% of 10% of 10%.
L is the time during which there is life on the planet that is able to establish a connection. Suppose a certain race existed on our planet as long as we did on ours: it will turn out 10 ^ -8 (one hundred millionth). The result is rather pessimistic: the result is two.
With such a result, given that one of these races is we who carried out the calculations, there is another civilization in the Galaxy. But it should be noted that we are talking about technologically advanced civilizations. Drake's equation does not take into account the pre-tech communities.
Kardashev scale
The Kardashev scale can be safely added to the discussion of the Fermi paradox. This is a method of technological development of civilization, developed by the Soviet astrophysicist Nikolai Kardashev, which classifies civilizations according to the amount of useful energy they can use. The scale divides civilizations as follows:
Type 1. A civilization capable of harnessing all the energy available on its planet.
Type 2. A civilization capable of harnessing all the energy radiated from its star.
Type 3. A civilization capable of harnessing the energy of the entire galaxy.
Astronomer Carl Sagan believed that we are somewhere 70% of the way to a civilization of the first type and we will be able to reach this level in one or two centuries. Modern calculations suggest that we can become a type II civilization within a few thousand years, and that it will take from 100 thousand to a million years to become a type III civilization.
According to some scientists, such as Freeman Dyson, a Type II civilization will be able to build a so-called megastructure (also known as a Dyson sphere) around its star to maximize its energy harvest / pcworld.com
As a civilization of the second or third type, creatures must be able to move around the Galaxy at a speed close to light (or faster if they learn to break the known laws of physics).
Given the age of the universe and the Milky Way, and the example of our own civilization, there seem to be many more questions than answers.
Possible solutions to the Fermi paradox
Solution 1. There is no one else and there has never been
One of the possible answers is: there are no aliens and never have been. Such a scenario can easily be imagined in the universe of Aristotle and Ptolemy - a small cluster of spheres orbiting the Earth. But we do not live in such a universe. After centuries of searching for Earth-like planets over the past two decades, cosmologists have smashed the cosmic piñata. Every year, more and more stars with planetary systems are discovered, approximately every fifth of which has Earth-like planets. The more we learn about the Universe, the more absurd it seems the statement that only one of such planets can exist. Astrophysicists and astrobiologists - like Adam Frank, who searches for and studies biospheres in exoplanets - believe that this is the least likely solution to the Fermi paradox.
Solution 2. Life is, but not reasonable
Some suggest that in the next 10-30 years we will find traces of the simplest forms of life on Mars or one of the satellites of gas giants like Europa or Enceladus. Of course, we are talking about microbes or algae. This decision changes the question of where everything is, to a more complex version of it: what exactly prevents an infinite number of molecules from gathering in the form of intelligent life?
Saturn's moon Europa, under the ice of which scientists hope to find signs of life, albeit not intelligent.
Here you can think about all the factors that contributed to the appearance of man. First - the spark of life, followed by the formation of simple cells, then - complex multicellular organisms, and then - the formation of organs, such as the brain. If a humanoid mind is rare, then one of these steps can be very difficult to overcome. For example, it is known that there are several million species of living organisms on Earth, but only one of them produced civilization (at least as we know it). The relative silence of the Universe presupposes the presence of some kind of "great filter" limiting the development of a larger number of intelligent beings. Some scientists also believe that we did not overcome this "great filter" in the distant past, but that it awaits us in the future. That is, the point is not that intelligent life is rare, but thatthat it appears for several thousand years before disappearing for unknown reasons.
Solution 3. There is a lot of intelligent life, but it is silent
This probability, also known as the "zoo hypothesis", offers some strange explanations. Perhaps humanity is still so primitive that advanced civilizations do not consider us worthy of attention or communication. Or perhaps other civilizations have figured out that self-discovery will lead to destruction by violent intergalactic colonizers. Or the solar system is simply located in a quiet and peaceful corner of the universe - purely by chance. But perhaps one of the most exotic explanations is that our universe is a huge computer simulation.
There are many reasons for the universal silence, and it cannot be said that any of the hypotheses is 100% true. In any case, so far, mankind has not managed to find a single extraterrestrial civilization. Until we have an accurate explanation, the Fermi paradox will keep astrophysicists awake at night, tormenting them with the question of where everything is.
Vladimir Guillen
