Inter-galaxy migration

What is the universe? As early as the Spring and Autumn Period and the Warring States Period, the word "universe" appeared in Zhuangzi, in which "Yu" refers to all the spaces, such as up, down, left and right, and "Zhou" refers to all the time through the ages.

The later universe refers to infinite time and space, indicating that the ancients had already known the universe at that time.

In modern astronomy, in addition to the infinite space-time above, the universe also has various energies such as dark energy and radiation rays, and the laws that affect these energies and substances.

In the past, humans could only observe with the naked eye, even before telescopes appeared. The ancients of our country discovered many stars around the ecliptic plane through "night-watching astrology" and divided them into 28 stars in order to better observe the sun, the moon and the five planets named after the five elements.

Now we know more about what the universe is, but due to the level of science and technology, we can't go deep into it and get more real mysteries. At present, according to the current level of human technology, the diameter of the universe we can observe is about 93 billion light years.

Maybe just saying this, we don't have a more intuitive concept. Then, through conversion, 1 light-year is about 9,460.7 billion kilometers, which is the distance of 1 year at the speed of light. If people walk at the speed of 1 meter per second, it will take about 300 million years to complete this distance, which is enough to imagine how big the universe is.

In such an infinite universe, the sun in our solar system is actually just a very ordinary star. If you zoom in on the whole galaxy, there are150 billion to 400 billion stars like the sun. In a galaxy, the naked eye can't see the sun at all, just like throwing a grain of sand on the beach, and then it's hard to find out where the sand has gone.

However, even the Milky Way, a galaxy with hundreds of billions of stars, is very common in the universe. In the observable universe alone, there are 654.38+025 billion galaxies similar to the Milky Way.

That is to say, if there are 200 billion stars in the Milky Way and125 billion galaxies in the universe, there are 25 trillion stars in total, which is only a rough estimate. In fact, there are more stars in the universe.

Are there aliens in such a terrible number of stars?

Physicist Hawking once said that according to the number of galaxies and stars in the universe, it can almost be judged that there must be alien life, but there may also be some microorganisms. But it is undeniable that there will be higher organisms that pose a serious threat to the earth.

If you are interested in extraterrestrial life, you may have heard of a paradox called Fermi Paradox, which asks, if there is no extraterrestrial intelligent life, why is there an earth civilization? If there is extraterrestrial intelligent life, why have we never found any signs of the existence of aliens?

1 1 years later, on the basis of Fermi paradox, the scientist Drake proposed two solutions to the equation, also known as Drake equation, to estimate the number of planetary civilizations outside the Earth in the Milky Way, but because there are three uncertain variables in the equation, the conclusion is unstable, so it is no longer trusted by future generations.

In 1975, Hart put forward four hypotheses to explain Fermi's paradox, that is, alien civilization cannot travel across galaxies, alien civilization does not intend to communicate with earth civilization, alien civilization has just been born and cannot communicate with earth civilization, and alien civilization has been to earth, but we have not found them yet.

However, Hart analyzed and denied all the above assumptions and concluded that alien civilization did not exist.

In fact, the essence of Fermi paradox is that there is no alien civilization in the universe, and in order to find evidence to crack it, human beings have also carried out various experiments.

In the 1960s, the United States and the Soviet Union began to develop space technology one after another because they obtained advanced rocket technology from Germany. At that time, the two countries were in the Cold War. In order to compete for their respective positions in the space field, a competition in the technical field came into being.

196 1 year, Soviet astronaut Gagarin reached the altitude of 330 kilometers on the earth's surface in the east 1 year, becoming the first human to enter space and the first human to see the whole picture of the earth in space.

Not to be outdone, the United States turned to develop a manned moon landing program, and successfully set foot on the first human footprint on the moon surface in July 1969.

In addition, more and more detectors are launched into the universe, and countless sensitive radio telescopes and other modern high-end astronomical equipment are monitoring distant signals every day, but no exact trace of alien life has been found.

But this does not mean that there is really no alien civilization in the universe. It may be because they are too far away from each other, or it may be because the other party has not developed civilization, so they can't wear a signal. It may even be because they are so civilized that they can completely hide their information and prevent their position from being exposed.

This is actually similar to the "dark forest law" mentioned in Liu's "Three-body". The law of dark forest in the novel tells that in the universe, every civilization is a hunter hiding in the forest.

Because the fixed resources of the universe are limited, once the higher civilization finds the coordinates of the lower civilization, it will choose to remove them to prevent the waste of resources.

Therefore, the civilization of the universe will hide itself from being discovered by other civilizations. Even the three-body civilization in the novel, whose scientific and technological level is higher than that of the earth civilization, will expose the position of the three-body planet to the universe for fear of Luo Ji holding the idea of mutually assured destruction, and thus dare not lay hands on the earth.

Hawking also warned against responding to signals from aliens. After all, no one can guarantee that those alien creatures will not do all kinds of endless things to plunder resources like European colonists who came to North America.

Although most scientists believe that there must be an alien civilization in the universe, some scientists insist that the possibility of the existence of an alien civilization is very low.

From June 2065438 to June 2009, some scientists cracked Fermi's paradox by using the probability distribution method, and finally found that the uniqueness probability of the earth civilization in the Milky Way reached 53% to 99.6%, and that in hubble volume with the level of human science and technology reached 39% to 85%.

Professor Langrich, a British scientist, also said that the possibility of the existence of alien civilization is almost 0%, that is to say, human beings are probably the only civilization in the universe. He believes that intelligent human beings on the earth actually have many accidents, and they are all unique accidents.

For example, since the birth of the earth, it took 65.438+0.5 billion years for photosynthesis to appear on this planet. In the past 65.438+0.2 billion years, the first cell was born, and it took 65.438+0.3 billion years for animals to appear on the earth.

He said, assuming that the probability of organism structure evolution is 1%, then if we want to evolve Homo sapiens, the ancestor of human beings, we need at least1000000000000 kinds of creatures on the earth, so that Homo sapiens can be born and eventually develop into a human with higher intelligence. Therefore, Professor Longlich thinks that there may be no alien civilization except human beings in the universe.

If this is true, does it mean that human beings can make full use of such vast cosmic resources and we will have the whole universe?

This discovery is very surprising at first glance, because it means that the so-called "dark forest law" does not exist in reality. We don't need to be alert to the threat of alien civilization to the earth, nor do we need to be timid in the process of exploring the universe.

But in fact, only human civilization in the universe is not a good thing. There may be no place in the universe suitable for the survival and development of life except the solar system. Even if human beings develop the means of transportation for interstellar travel, they will not be able to realize interstellar migration in the future, or even find a suitable foothold.

Imagine that when our spacecraft has been able to develop to the speed of light, or beyond the speed of light, and come to the infinite depths of the universe, it must be very disappointing to find that almost all galaxies are desolate, and they are all planets with harsh and extreme environments such as Mars and Mercury.

Of course, this is just speculation, and there is no actual evidence to prove that the level of human science and technology is not enough to explore the universe, and it is impossible to find the real mystery of the universe.

In fact, it is only about 60 years since the development of human space technology in the 1960s. It's just in its infancy, and man has just stepped on a footprint on the moon.

Although the United States is the only country that has manned the moon at present, in the future, there will inevitably be more space powers that can realize manned technology, and even the nearest moon can set foot on Mars and Jupiter. , slowly moving towards the space age.

The universe is too big, and human existence itself is very small, just like a bacterium on the earth.

In fact, whether there is an alien civilization in the universe is not important to us now, because our existing technology means that human beings can do nothing whether they find an alien civilization or not.

But we believe that with the development of science and technology, human beings will be able to rush out of the solar system sooner or later. Even after 100, 1000 and 10000, it is possible for human beings to come to the edge of the universe, explore the mysteries of the universe and uncover the problems that have puzzled scientists for countless years.