After dinner, Ding Yan first felt a little sleepy. Although he is smart, he is a child after all, and he didn't even sleep in the afternoon when he was excited today, and he was already very sleepy at this time.

Gongsun Xiao was careful, and when he saw Ding Yan's sleepy expression, he said, "Ding Mu, your Yanjun is sleepy, why don't you rest in my room." I brought him a new set of toiletries. Our apartment is out of the ordinary, and there is no good hotel on the side. ”

Ding Mu and the second daughter haven't seen each other for a long time, and there are a lot of things they want to talk about, all of which are inappropriate for children, so I wish he would go to bed quickly, so he said, "Okay, then I'll trouble you." ”

Ding Yan was very well-behaved, brushed his teeth and washed his face, then lay on Gongsun Xiao's bed, smelled the fragrant quilt, and soon fell asleep.

After his son fell asleep, Ding Mu gently closed the door and chatted with his second daughter on the sofa in the living room.

Ding Mu especially told them about the best black technologies he had researched over the years, one by one, and showed off his achievements over the years in front of his old classmates. You must know that wealth does not return to the hometown, just like a night walk in brocade. Ding Mu is also eager to share his results. It's just that there are so many things in it that are really top secret and sensational, and he can only say the most insignificant things.

"I've been developing ultra-high-speed aircraft lately. You know the triple barrier to airplane speed, right?"

Gongsun Xiao and Xue Lingyun shook their heads in unison.

Gongsun Xiao said: "I don't know. ”

Xue Lingyun teased: "It seems that neither of us knows. We are studying medicine, and we know that pain, infection and blood loss are the three major difficulties in clinical surgery. ”

Ding Mu was a little embarrassed, but he still reluctantly said: "The triple barrier to the speed of the plane is the sound barrier, the heat barrier and the black barrier. This is also known as the three obstacles of aviation. Before me, humans had largely overcome the sound barrier and initially overcome the thermal barrier. But black obstacles are always inevitable, but I have solved the problem of black obstacles. ”

"Awesome. I like to listen to this, you can talk about it specifically. ”

Ding Mu said: "Sound barrier, you should know, sound barrier is a physical phenomenon, when the speed of an object is close to the speed of sound, it will gradually catch up with the sound waves emitted by itself. As a result of the superposition and accumulation of sound waves, shock waves will be generated, which in turn will cause obstacles to the acceleration of the aircraft, and this obstacle to the speed of increase due to the speed of sound is called sound barrier. Breaking the sound barrier creates a sonic boom. ”

"You've seen the old man in the park who gets up in the morning, and some people can shake the sonic boom when they make a whip. The strong sonic boom of the aircraft not only causes damage to the surrounding area, but also to the parts of the aircraft itself that extend beyond the impact surface. It's still a tough one. We've already gotten through it, though. ”

"Oh! It's true that we have been abroad for so many years, but we haven't seen that kind of old man who exercises early for many years. It's all early in the morning in the 24-hour gym on the treadmill. ”

"Cultural differences. Ding Mu continued: "The heat barrier is actually very difficult to break through. In fact, before me, Dahua Kingdom had never broken through the thermal barrier. ”

"What is a heat barrier, is it so difficult?" Gongsun Xiao said curiously.

"To put it simply, it is high-temperature friction heat, and when the frictional heat between the aircraft shell and the air reaches a certain temperature, the body has no strength. The aviation community refers to the high temperature encountered by aircraft when flying at high speed as a thermal barrier. Specifically, if it is more than 2.5 times the speed of sound, it is necessary to consider the thermal barrier. Above 3 times the speed of sound, aluminum alloy has little strength. It must be made of titanium alloy or high-temperature resistant steel plate. It's just that these two have their own shortcomings, titanium alloy is expensive, and it is difficult to process, and the high-temperature resistant steel plate is too heavy, and there are also limitations. ”

Xue Lingyun said: "This is definitely not difficult for you, aren't you an authority in materials science?"

"Hey, hey. Ding Mu smiled, "You're right." The aircraft materials I am researching are resistant to high temperatures and lightweight, which can make the aircraft challenge the black barrier. ”

"What is a black barrier. Gongsun Xiao still looked very curious and asked.

"As I said earlier, the friction between the plane and the air generates heat. But this example would be more appropriate with a satellite return capsule. This problem is often encountered in satellite return capsules, where the gas in the high-temperature region and the molecules of the material on the surface of the return capsule are broken down and ionized, forming a plasma region. It wrapped around the return capsule like a sheath. Because plasma can absorb and reflect radio waves, it will attenuate or even interrupt radio communication between the re-entry capsule and the outside world. This phenomenon is known as black barriers. For astronauts, it is very dangerous to encounter a black barrier, and there is no solution on the current earth. But I solved it. Not only to solve it, but I also have two solutions. The earthen method is the special material fenestration method, which can form a cooling area to transmit the signal. There is also a more high-end and high-end way to use other means of communication. This has been successfully tested, but it is not yet suitable for promotion......"

Of course he can solve it, Sir Matiha of Namerid Star is best at planetary login, and many of Ding Mu's black technologies are spaceflight-related. All this information has been left behind.

Looking at Ding Mukou, although Xue Lingyun and Gongsun Xiao didn't understand everything, the two of them listened to it with relish, and the more they drank wine. Slowly, the conversation turned to the side of private life.

Gongsun Xiao said: "Old classmate, I haven't seen you for so many years, you don't seem to have changed much, but you have become a father." ”

"How are you guys?" Ding Mu asked intentionally, "After so many years, haven't you talked about love?"

Gongsun Xiao shook his head and said: "I don't have time, the pressure of studying abroad is too great, I only slept four hours a day for two years to read all the books required by the teacher." It's Xue's family, many people are chasing her, didn't someone send her flowers just now? It's just that there must be someone else in her heart. It's been unpretentious. ”

"Oh?" Ding Mu looked at Xue Lingyun with meaningful eyes, seeing that her hair was straight, he couldn't help but say, "Why are you looking at me with that kind of look." ”

Ding Mu's eyes were blazing, and he was interested: "I'm curious, the person in your heart." Isn't it me?"

Xue Lingyun brushed it, and a red glow flew on her face, and the roots of her ears were red, and this Ding Mu was too naked. Moreover, this is in front of his best friend, Gongsun Xiao. She could feel that Gongsun Xiao also liked Ding Mu, and when the two of them chatted, they often mentioned this character who crossed their lives like a meteor.

She has long known that there are many women around him, and she has long known that Ding Mu's identity has become higher and higher, his achievements have become greater and greater, and he is getting farther and farther away from herself. No matter how hard he tries, he may not have any intersection with him again, so he can only silently be on the ground, watching him shine in the sky.

Unexpectedly, just today, in a foreign country overseas, this star-like legend actually came to them again, returned to their lives, and even ate his own cooking. It's a pity that he has a son. Moreover, carved out of a blank, the temperament is the same.

In a thought, Xue Lingyun thought a lot, and couldn't help but stop talking. But Ding Mu didn't give up: "Is it me?" ”

Gongsun Xiao spread his hands and said speechlessly: "Although, you may be telling the truth, but you are too narcissistic." Tut-tut, you have not changed after so many years. ”

"Hahaha. Ding Mu smiled heartily, "I'm looking for the feeling when I was a child." Xue everyone, everyone is now an adult, if you have something to say, don't hide it, just tell me, which aspect of me attracts you the most?"

Xue Lingyun also borrowed the strength of the wine, his head was hot, and said, "Okay, I'll make you proud once." The first time I saw you, I wanted to sleep with you. ”