This paper takes part in the series essay competition of “great science” of Recordunkown.
Is there an alien civilization in the universe? In fact, such a question has already been answered at the moment when human beings walk out of the earth. Everyone who has seen the vast universe and the number of galaxies is too large to count will not doubt the existence of alien civilization.
Standing on the scale of the universe, the probability of the non existence of alien civilization is basically zero, and the existence of human itself is the best evidence of the existence of alien civilization. Since there is an alien civilization, why has human beings searched for it for more than half a century and still haven’t found anything? In fact, the main reason is that our scientific and technological strength is limited and the scope of exploration is very limited.
In the vast universe, the basic unit of distance is light years, while the distance between stars is more than a few light years. The solar system is the star system where human beings live. In the solar system, there is only human intelligence civilization. Therefore, we can only search for alien civilization in other galaxies.
However, the nearest star system to the earth is 4.2 light-years away from us, and it will take at least hundreds of thousands of years for human spacecraft to reach 4.2 light-years away. The speed limit makes it impossible for us to go out of the solar system and explore other galaxies, so it is difficult to find the trace of alien civilization.
Although we have no contact with any alien civilization and almost know nothing about the cosmic civilization, this is not to stop human curiosity and thinking about the cosmic civilization. We often guess what the intelligent life of extraterrestrial will look like, and what the development mode of extraterrestrial civilization is different from that of human civilization.
Although we haven’t been in contact with alien civilization, according to the increasing understanding of cosmic matter by scientists. Scientists believe that the basic elements of the universe all originated from the singularity explosion 13.7 billion years ago, so the matter and various physical laws possessed by the solar system and the earth are basically applicable everywhere in the universe.
That is to say, no matter how many intelligent civilizations there are in the universe, all kinds of physical laws and cosmic laws that these civilizations need to follow after they enter the era of science and technology are basically the same. Although there may be differences in the direction of scientific and technological development, the general exploration direction and goal are the same.
The rules of the universe determine that different civilizations are basically in the same direction of scientific exploration. The difference is that due to the different birth time and development speed of civilization, the strength of civilization will have different levels. So how is the strength level of cosmic civilization divided? In 1964, Soviet astronomer Nikolay Kardashev divided the possible civilizations in the universe into four levels.
The first level civilization is planetary civilization, which means it can completely control the whole planet, change the climate and environment of the planet at will, and use all the energy and resources of the whole planet. According to this standard, the current civilization strength of mankind is not even level one civilization, but only level 0.7 at most.
In fact, human control of the earth is far from enough. Our exploration of the ocean is only 10%, and there is little use of marine resources, and our control of the earth’s interior is basically not enough. At present, human control of the earth is basically limited to the surface land and 10% of the ocean, and there are many unknown exploration areas, which need our continuous efforts in the future.
Secondary civilization is the civilization of the stellar system, which means that it can completely control the whole parent galaxy and use all the energy and resources of the whole galaxy. An important symbol of the second level civilization is the Dyson sphere. I believe many friends have heard of the Dyson sphere. It is an energy collection device around the star proposed by the famous scientist Freeman Dyson.
The development of any civilization is inseparable from energy, and the higher the level of civilization, the greater the demand for energy. After upgrading from the first level civilization to the second level civilization, the traditional planetary resources may not be able to meet our development. At this time, we need a more powerful and inexhaustible energy. In the vast universe, the star is undoubtedly a very powerful, almost unlimited nuclear fusion energy.
Therefore, Dyson thinks that the most important energy source of secondary civilization may be the stars in the parent galaxy. To make full use of the energy of absorbing stars, we need to build a giant man-made building Dyson sphere that can surround the stars. Of course, it is not easy to build such a Dyson sphere. In addition to solving the relevant technical conditions, it also needs huge construction resources.
Let’s take the solar system as an example. If human beings want to build a Dyson sphere after entering the second level civilization, they need to pay the price of each planet and asteroid. At that time, all the planets in the solar system will disappear except the earth and the sun. Only by concentrating the planetary resources of the whole solar system can we build a Dyson sphere around the sun.
The third level civilization is the river civilization, which means that we can use all the energy and resources of the big galaxy. For human beings, when we can use all the energy of the galaxy, we will be upgraded to the third level civilization. The most powerful energy source in the galaxy is not the star, but the supermassive black hole in the center. In fact, for the third-class civilization, the stellar energy source may not be able to meet the needs of the development of civilization. At this time, we need to seek more powerful energy, and the black hole is undoubtedly a good choice.
The fourth level civilization may be the legendary cosmic civilization, which has been able to use the most mysterious and powerful dark matter and dark energy in the universe. We all know that dark matter and dark energy are the core of the universe, and they are the real masters of everything in the universe.
Now that we have understood scientists’ criteria for the classification of different levels of intelligent civilization in the universe, how many levels of civilization will human beings become in the future? Many people may say that as long as human beings develop, they will eventually become the most powerful four level civilization and the overlord of the universe. Will that be achieved?
From the perspective of human beings, everyone hopes that human beings can become the most advanced four level civilization in the universe. However, from the perspective of rational thinking, the possibility of achieving this goal is very small. One reason for this is that human beings may not be able to continue in the future.
We all know that there is no eternity in this universe, whether it is matter or life. Stars have their own lifespan, and life has its own lifespan. Then human civilization naturally can not violate the laws of the universe, probably there is a cycle of civilization. When human civilization develops to a certain stage, it is possible for some reason to usher in the end of civilization, and then after a long period of time, there will be new intelligent life and new civilization on the earth.
Modern scientists have been speculating that the earth may have gone through several other prehistoric civilizations before human beings appeared. If there is a time cycle for the continuation of civilization, it may be difficult to reach the highest level of cosmic civilization. Because it takes a long time for civilization to upgrade.
Maybe it is for this reason that the universe appears very quiet and we can’t really get in touch with advanced civilization. For the vast universe, if civilizations want to communicate with each other, they can only master the technology of superluminal flight. To master the preliminary technology of superluminal flight, at least a third level civilization is required.
However, most of the civilizations in the universe may not be able to upgrade to the third level, and then they will be extinct. Those three-level civilizations may be too far away from the earth, and they can’t rely on primary superluminal technology to come to the solar system. Only by upgrading to the ultimate four level civilization, may they have the ability to go through wormholes, break space at will, and quickly travel around the universe.