The universe is vast. In ancient times, people knew little about the universe, so there were many myths and legends. In modern times, with the invention of the astronomical telescope, people began to have a new understanding of the universe. It turns out that the stars in the sky are stars, and the earth is only one of them. At this time, people have a question: is there life in the universe? Is there the same intelligent civilization as human beings?
How big is the universe? At present, it is impossible to know the observable range of human beings. Since modern times, with the start of human satellites, the pace of exploring the universe has begun, and the search for extraterrestrial life is one of the important missions of exploring the universe. Fifty years ago, mankind launched Voyager 1 and Voyager 2, which carried all kinds of information of human civilization and sailed out of the solar system. It is estimated that they have now reached the edge of the solar system or may have gone out of the solar system.
In addition to launching detectors, human beings also receive cosmic radio signals to search for alien civilizations. But after so many years, human beings have not found aliens, even extraterrestrial life. Is there really no life in the universe? Or are we looking for a limited range, and alien life or aliens may be on more distant planets.
Maybe many astronomers will ask, how many stars or planets are there in the universe? This scientist can’t estimate it, but we can narrow down the scope. We can roughly estimate how many stars and planets there will be in the Milky way by focusing on the Milky way, so as to roughly infer how many living planets and even civilized planets there will be.
The diameter of the Milky way is 100000 light-years, in which there are about 150 billion stars. Each star may be surrounded by many planets, and the number of planets is even more. The sun is one of the stars. There are eight planets around the sun, and the earth is one of them.
If a star is surrounded by six planets on average, there will be more than one trillion planets in the solar system, among which there will be living and civilized planets. So far, NASA has found hundreds of earth like planets very similar to the earth within a radius of 1000 light-years from the earth, and many of them are located in the habitable zone of the star. In fact, less than 1% of the total number of planets in the galaxy can be found. Most of the planets can not be found with our current observation equipment.
Let’s take 1% of the planets within 1000 light-years as an example, so there will be no less than 1 billion earth like planets in the Milky way. If only 1% of them have life, there will be nearly 10 million living planets. Even if the number can’t reach this level, if it is further reduced by 1%, there will still be 100000 earth like living planets.
How many civilized planets will there be among these 100000 living planets? Although there is life on the planet, it is not easy to evolve intelligent life and develop it to the stage of civilization, but the possibility is still very big. It is only a few million years since human beings were born on the earth. It is estimated that the age of these living planets in the galaxy is much older than that of the earth, so it is very likely that these old living planets will be born into civilization. The number of civilized planets in the galaxy will not be less than 1000.
In fact, the above is only the most conservative figure based on the current observable range of human beings. It is estimated that the number of real life planets and civilized planets in the galaxy is far more than that. It can be seen that human beings are not the only civilization in the galaxy. So why haven’t we found life or aliens in the galaxy yet?
This is mainly because the science and technology of human civilization is still very backward, and our understanding of the universe is still very little. Human civilization has not really entered the interstellar civilization. Take spaceship for example, human beings have not really entered the space at present. The most spaceship that can enter the space is to carry a man to the moon, and the farthest is Mars.
The real spaceship, first of all, must have a gravity system. The environment inside the spaceship must be the same as that on the earth. The gravity environment and the ecosystem must be the same. Only in this way can people survive in the spaceship for a long time. Another is speed. The spaceship must have a very fast speed. The distance in the universe is calculated in light years. If there is no speed, the spaceship can’t survive To explore the depths of the universe. This is also the main reason why human civilization has not yet discovered alien civilization.
The solar system is located at the edge of the galaxy, which is equivalent to a small mountain village. The closer it is to the center of the galaxy, the more resources it has, and the more civilization it has. Only in the future, when human beings really enter the interstellar civilization and have long-distance spaceships, they can leave the solar system and explore outside the system. Maybe they will find that there are too many living planets in the solar system, There are many kinds and forms of life, and there are many civilized planets. At that time, human beings will find many alien civilizations, some are more developed than the earth, some are still in primitive society, feudal society and so on.