Chapter 537 Father and Son Meet

   In other words, Ding Mu took the four Tianying under his command and asked them to go to Guo Pingfan. In the war-prone Diamond Kingdom, he has organized an army that has withstood the test of blood and fire. This army is the reserve force for future wars.

  Ding Mu thanked the Great China Army for its support, and brought his family to a large villa on the coast of California, USA.

  His son Ding Yan is here.

  Ding Mu came to the United States this time mainly to see his son. Ding Yan is going to elementary school soon, and Ding Mu is going to bring him back to Dahua from the United States. The reason is simple, the basic education of Dahua is obviously better than that of the United States.

   "Dad, Dad!" A handsome young man jumped up to Ding Mu's side, opened his hands, and rushed over.

  Although the father and son have never met each other, Ding Mu often communicates with him through video. Ding Yan already knew a lot of things. He knew that his father was a great scientist. Everyone around him adores him.

Cheng Qianzhan, Yunliu's old friends, are also so-called Tuogu loyal ministers, who have always told Ding Yan about Ding Mu's glorious deeds, and established Ding Mu as an indomitable man. Under their influence, men should be Such.

   In addition, the United States is also a country with strong individual heroism, and Ding Yan has also been influenced by this since childhood, thinking that his father is a great scientist.

  So, although Ding Yan has no contact with Ding Mu, he admires him very much. In his small heart, he feels that his father is an extremely great person.

   This time, when he heard that his father was coming to see him, Ding Yan was so excited that he didn't sleep well last night.

  Ding Mu picked up Ding Yan, and said with a smile, "Yan'er, I've grown so big before I hugged her. Dad likes Yan'er the most."

  Ding Yan kissed Ding Mu's cheek, and then said: "Yan'er also likes Dad. Dad, is your research successful?"

  Ding Mu nodded with a smile and said: "Well, it has succeeded in stages."

   "Yeah, that's great." Ding Yan smiled from the bottom of his heart, "Dad, can you tell me the story of the earth and aliens?"

  Ding Mu nodded and said, "Okay. Dad can tell you stories."

  Just when Ding Mu wanted to start the conversation, Cheng Qianzhan walked in and said, "Young master, young master has a basketball class in the afternoon, and we are leaving soon."

   "Grandpa Cheng, I don't want to go to basketball class. I want Dad to tell me stories. Dad, can I not go to basketball class?" Ding Yan looked at Ding Mu anxiously, his eyes full of prayers.

  How could Ding Mu refuse this kind of look, he said: "Cheng Bo, our father and son finally met, let's forget it today."

  Of course Cheng Qianzhan would not disobey what Ding Mu said, so he nodded and retreated.

Seeing Cheng Qianzhan gone, Ding Yan felt very happy to spend an afternoon with his father. He raised his beautiful phoenix eyes and asked like a cannonball: "Dad, are there any aliens? What do people look like? Will aliens come to attack the earth? If aliens come, can we win?"

Ding Mu smiled. It is not surprising that Ding Yan asked such a question. Children always like to explore the unknown, especially children who grew up in the United States. They have a strong atmosphere, such things as alien civilizations and aliens. , always of particular interest.

  Ding Mu said: "Yan'er, let's sit down and talk slowly, you ask Dad so many questions at once, Dad has to talk slowly."

"Okay, okay." Ding Yan smiled and moved the small bench and took two bottles of mineral water, and handed one to Ding Mu: "Father sat on the sofa drinking water, Yan'er sat on the small bench and listened to stories. "

  Ding Mu also narrowed his eyes seeing Ding Yan's cute appearance.

   After taking a sip of water, Ding Mu said affirmatively: "Whether there are aliens, the answer is relatively clear. There are aliens."

   "Yeah. I knew that there must be aliens." Ding Yan was encouraged.

  Of course Ding Mu knows that there are aliens, and his real-life beautification system is left by aliens. He said: "The universe is too big. In such a large range, human beings cannot be alone."

   "Dad, how big is the universe?" Ding Yan asked curiously.

Ding Mu picked up a pen, and while writing and drawing on Ding Yan's usual graffiti notebook, he said: "Contemporary astronomical research results show that the universe has a hierarchical structure, is constantly expanding, and has various forms of matter. A celestial system in constant motion.

  The earth we are on is in the solar system. The planets, asteroids, comets and meteoroids here all revolve around the central celestial body, the sun, and together constitute the solar system.

   There are other planetary systems outside our solar system. About 250 billion sun-like stars and interstellar matter constitute a larger celestial system - the Milky Way.

  The diameter of the Milky Way is about 100,000 light-years, and the solar system is located in a spiral arm of the Milky Way, about 30,000 light-years away from the center of the Milky Way. "

   "Dad, what is light year?" Ding Yan asked curiously, "Is this a unit of distance?"

"Well, that's right." Ding Mu said, "A light year is a unit of distance, which is the distance that light travels along a straight line in the vacuum of the universe for one year. The speed of light is about 300,000 kilometers per second, specifically 299 kilometers per second. , 792,458 meters."

  Ding Yan calculated in his mind, and said: "1 light year is 9460730472580800 meters."

  Ding Mu shrugged and said, "Son, you are good at mental arithmetic."

  Ding Yan smiled and said: "I learned this from Grandpa Sun. Dad, let's go on, what is outside the Milky Way?"

   Ding Mu said: "There are many similar celestial systems outside the Milky Way, called extragalactic galaxies, often referred to as galaxies. At present, 100 billion galaxies have been observed.

   Galaxies are gathered into large and small groups, called galaxy clusters. On average, there are about a hundred galaxies in each galaxy cluster, with a diameter of tens of millions of light-years. Tens of thousands of galaxy clusters have been discovered. A small cluster of galaxies consisting of about 40 galaxies, including the Milky Way, is called the Local Group of galaxies.

  I personally study the latest statistics, there are at least 2 trillion galaxies in the universe. In such a large scale, logically speaking, the probability of aliens is very high. "

   "But where are they?" Ding Yan asked.

"Hahaha." Ding Mu smiled and said, "My dear son, someone asked you this question seventy years ago. That person was a famous physicist and a Nobel Prize winner. He Fermi, we call this problem the Fermi Paradox."

   "Oh..." Ding Yan seemed a little disappointed that Ding Mu said that, and continued to ask, "Then what does the Fermi Paradox mean?"

Ding Mu explained: "The Fermi paradox may be a bit complicated for you. He is talking about the contradiction between arguments about scale and probability and the scarcity of evidence. The remarkable size and age of the universe means that advanced extraterrestrial civilizations should exists. However, this hypothesis is not supported by sufficient evidence.

  The first point of the Fermi paradox, namely the scale problem, is an order of magnitude estimate: there are about 250 billion (2.5x10^11) stars in the Milky Way, and 700 billion (7x10^22) stars in the observable universe. Even if intelligent life is present in planets around these stars with a small probability, there should be a considerable number of civilizations in the Milky Way alone. This is also in line with the view of the principle of mediocrity, that is, the earth is not special, but just a typical planet with the same laws and phenomena as other stars.

The second point of the Fermi paradox is the answer to the view of scale: considering the ability of intelligent life to overcome the scarcity of resources and the tendency to expand outward, any advanced civilization is likely to search for new resources and develop their star systems, Then there's forays into neighboring galaxies. Because 13.7 billion years after the birth of the universe, we have not found reliable evidence of the existence of other intelligent life on the earth or elsewhere in the observable universe; it can be considered that intelligent life is very rare, or our general behavior of intelligent life understanding is wrong. "

Unexpectedly, Ding Yan understood all of this at once, and said: "Then I know, this is a theoretical and logical discussion about whether there are aliens. I think it can be divided into three situations. 1. There are no other civilizations in the universe. Second, alien civilizations exist, but they have not been able to contact us so far. Third, alien civilizations have come to Earth, but we don’t know it.”

Ding Mu said: "It's great, you summed it up perfectly. Son, but more and more facts tend to prove that alien civilizations exist and have come to Earth, but the vast majority of people have not yet been able to contact them. In other words, even if you have contacted them, you don’t know their alien identities. Maybe there is an alien behind you.”

   "Father, I'm afraid." Ding Yan suddenly felt a little scared, stood up from the small bench, and snuggled into Ding Mu's arms.

Ding Mu smiled, rubbed Ding Yan's head, and said: "Man, don't be afraid. Dad told you that the energy required for a real interstellar travel across galaxies is extremely huge. At least a second-level civilization can be compared. Easy to do."

  Ding Yan asked: "Father, what is a second-level civilization, and what level are we?"

  Ding Mu was very patient, and slowly replied: "The level of civilization I am talking about is called the Kardashev level.

  Based on how much energy a civilization can use to communicate with exoplanets. That is to say, planets that can use a lot of energy to communicate with the outside world can be counted in the Kardashev level.

   is based on a first-level civilization: the science and technology mastered by this level of civilization can completely control all available resources and everything on their planet. He is the absolute ruler of the planet, and he can control the weather, rivers, land, other creatures, oceans, and even the changes, rise and fall of substances in the crust as he wants. It can be said that they are omnipotent on their planet.

  Level 2 Civilization: Can make full use of the energy of their stars and bring their solar system under control. You can freely live and shuttle on various planets in the solar system, and don't worry about energy issues. Because you know how to efficiently use the endless energy emitted from the stars, the society is already highly developed, and the development tends to be highly accelerated.

   It should be mentioned that if a civilization reaches the second type, then it is almost indestructible. At least all natural and man-made means known to mankind cannot touch a hair on them. Even a supernova explosion in their vicinity cannot make them perish. They could shift their galaxies away from the exploding star, or simply harness the energy of the explosion.

  Third-level civilization: It is no longer limited to their solar system, but the entire galaxy where it is located, such as our Milky Way. The energy of all stars in the galaxy can be used. Such civilizations are beyond our imagination, and we can only guess at how they survived. According to Einstein's theory of relativity, exceeding the speed of light is theoretically impossible. A galaxy is very large, and it takes millions of years to fly from one end to the other even at a speed close to the speed of light. Therefore, the third type of civilization does not drive a huge spaceship to shuttle between the stars like in science fiction films. among. They should have the ability to artificially develop wormholes. "

   "Dad, what level of civilization are we?"

Ding Mu said: "Five years ago, the human index was 0.73 (2×1013 watts per second), an increase of 0.1 index means a 10-fold increase in energy, and an increase of 0.01 index means the 10th root of 10, which is 1.259 times of growth, human beings must increase the existing energy generation by thousands of times to reach the first level of civilization. However, this does not include the few technologies I have developed recently. The greatest contribution of your father is to make this human index, improved to nearly 8."

  (end of this chapter)