Why can’t we find an alien civilization? Scientists speculate that they may have been extinct

This paper takes part in the series essay competition of “great science” of Recordunkown.

Millions of years ago, after billions of evolution and evolution of life on earth, intelligent life human was finally born. And the earth has also upgraded from the original life planet to a civilized planet. After a long period of development, human civilization finally entered the era of science and technology hundreds of years ago, opening a new era of human civilization.

With the help of human science and technology, we finally walked out of the earth half a century ago. When we walked out of the earth, we realized that there was such a vast starry sky outside the earth, in which the earth was not even a grain of dust. At the same time, people will think of the same question, that is, does alien civilization exist?


Before seeing the vastness, many people may doubt the existence of alien civilization. However, when human beings really see the vast universe, this doubt has disappeared. More and more people believe that alien civilization exists, so human beings launched the SETI project. However, after decades of exploration and efforts, human beings have not found any trace of the existence of extraterrestrial civilization.

So some people have doubts about the existence of alien civilization. Does alien civilization exist? Scientists believe that the vastness of the universe is beyond our imagination. The range of the universe we can observe now is 92 billion light-years, and this range may only be the tip of the iceberg of the whole universe. Even if the Milky way is about 20% Yao years in diameter, there are hundreds of billions of galaxies, let alone the whole universe, which is a number we can’t imagine.

In such a vast universe, if there is only one intelligent civilization for human beings, it seems to be contrary to common sense from any angle. But why can’t human beings find alien civilization? Some scientists have put forward a bold conjecture: alien civilization may have been extinct. Why do scientists think so? This should be analyzed from two aspects: civilization itself and the cosmic environment.

From the perspective of civilization itself, when a living planet is born with intelligent life, it means that the resource consumption of the planet is increasing. Let’s take human beings as an example. Before the birth of human beings, those resources on the earth were basically in a sealed state, but after the birth of human beings, they began to use these resources. Especially when human beings enter the era of science and technology, the demand for resources is growing, and the earth’s resources are limited, we are bound to face the situation of resource depletion in the future.


If before the earth’s resources are exhausted, we have not entered a first-class civilization and cannot exploit and utilize the resources of space, then we have to wait for the end of mankind. It is possible for human civilization to be like this, and it is also possible for other intelligent civilizations in the universe to be like this. And don’t forget, the earth is a planet rich in resources. It’s hard to say whether other intelligent civilization planets have such rich resources as the earth.

If the resources of extraterrestrial civilization are very scarce, it is difficult to support a civilization to eventually go to the interstellar and make use of space resources. Before becoming an interstellar civilization, once the planet’s resources are used up, the only thing waiting for this civilization is extinction. This is where resources lead to the end of a civilization.

Another internal problem that will lead to the end of civilization is war. As we all know, the history of human civilization is also a history of war. From ancient times to the present, there have been many wars of different sizes in human civilization. Even in the modern era of peace, the internal wars of human civilization have never stopped, big wars have never stopped, and small wars have never stopped.


Before human beings enter the era of science and technology, no large-scale war will cause much damage to the earth itself. However, with the rapid development of science and technology, the mode of war is also changing. Powerful weapons are constantly emerging. Take the nuclear bomb, the ultimate weapon of mankind, as an example. Once there is a global nuclear war, the ecological environment of the earth will be completely destroyed, and human civilization may end.

It is possible for human civilization to end due to war. Similarly, there is a great possibility of alien civilization. As long as it is an intelligent civilization, internal contradictions are inevitable, and war is inevitable. The stronger the civilization is, the stronger the destructive power will be once internal war breaks out, which may eventually lead to the end of the whole civilization.

Even after going out of the interstellar world and becoming an interstellar civilization, due to the existence of the dark forest law of the universe, interstellar wars may break out among civilizations, and the end of interstellar wars may be the fate of civilization. Therefore, scientists believe that there may have been a lot of alien civilizations in the universe long ago, but due to various reasons of civilization itself, they finally became extinct.

This is the disastrous result of civilization itself. In addition to this, disasters from the universe may also make civilization extinct. There are many disasters that can threaten the life of the planet, and the more common one is asteroid impact. 65 million years ago, an asteroid hit the earth, leading to the extinction of dinosaurs. A civilization needs good scientific and technological strength to intercept asteroids. At least human science and technology can not intercept asteroids.


If an asteroid as big as 65 million years ago hits the earth again, then human beings will have no way to intercept it and can only wait for the end of fate. The asteroid impact is only one of the most powerful disasters in the universe, and then it is the expansion of red giant stars after the end of stellar life.

When a star changes to a red giant, the living planet in its habitable zone will inevitably be engulfed by it. Even before it is engulfed, the temperature on the surface of the living planet rises sharply, and the life on the surface of the planet will be extinct. At this time, if you want to escape extinction, you have to become an interstellar civilization to have the ability to immigrate exoplanets. Otherwise, you have to wait for the end of civilization.

As a matter of fact, these two cosmic disasters are not the most despairing of civilizations. What really makes a civilization feel scared and despairing is actually gamma ray bursts. Gamma ray bursts, also known as gamma ray bursts, are the phenomenon that the intensity of gamma rays from a certain direction in the sky suddenly increases in a short time, and then decreases rapidly, lasting from 0.1 to 1000 seconds.


Gamma ray bursts (GRBs) are the most violent explosions in the universe. Theoretically, GRBs are produced by the collapse and explosion of giant stars when they run out of fuel or the merger of two neighboring compact stars (black holes or neutron stars). Gamma ray bursts can be as short as one thousandth of a second, or as long as several hours, releasing huge amounts of energy in a short period of time. If compared with the sun, the energy it releases in a few minutes is equivalent to the sum of trillions of years of sunlight, and the single photon energy it emits is usually hundreds of thousands of times of the typical sunlight

Gamma ray bursts can be called the terminator of life, and its energy can radiate thousands of light-years around. Even stronger gamma ray bursts can affect living planets within 5000 light-years. As long as the life in this range will be terminated by it, there is no possibility of survival, this is its hegemony.

Just imagine, if several intelligent life planets happen to be within the influence range of an impending gamma ray storm, will these alien civilizations feel despair and fear? I believe that in the face of such a disaster, few civilizations can escape, unless this civilization has the ability to fly faster than light and can escape ahead of time. If we don’t have the ability to fly faster than light, we can’t do anything even if we have observed the gamma ray bursts hundreds or thousands of years earlier. In the end, it is hard to escape the fate of extinction.

From the above analysis, we can see that it is very difficult for an intelligent civilization to survive in the universe for a long time. Whether it is the cause of civilization itself or all kinds of disasters from the universe, it is possible for this civilization to end at any time. It is possible that many powerful civilizations have been born in the vast universe. They have developed for hundreds of millions of years and have become very powerful, but they are finally extinct for various reasons.


After reading these, I believe many people are also worried: how many years can human beings develop? In fact, no one can answer this question. Naturally, we hope that human beings can be as eternal as the universe. However, in the process of actual development, it seems very difficult for us to see. Taking the degree of damage to the earth’s ecological environment, it is possible that in a few hundred years, human beings will not have to choose to immigrate. At that time, did humans have the technology of alien migration? If not, we will be able to understand it.

Guys, what do you think of this? Welcome to leave a message below to discuss and express your opinions.

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