Great Country Academician

Chapter 868: One-tenth of the speed of light

Standing on the ground and looking up at the stars is the only way for every advanced intelligent civilization to develop.

If there are other intelligent civilizations similar to humans in the universe, perhaps the vast space is also a headache for them at this moment.

The universe is so vast that even if it flies at the speed of light, it will take at least 93 billion years to fly out of the observable universe.

And no one knows how vast the space is outside the observable universe.

Let alone the entire universe, even the tiny solar system in the Milky Way is a long distance that humans cannot cross at present.

The farthest probe launched by human civilization, Voyager 1, has only traveled 25 billion kilometers and reached the edge of the Kuiper Belt.

It still has at least 17,000 years to go to the frontier of the solar system, the Oort Cloud.

This time is enough for the development of human civilization to go back at least twice.

Speed ​​is undoubtedly the core key for any intelligent civilization in the initial stage of exploring the space universe.

Therefore, Xu Chuan still attaches great importance to the electromagnetic propulsion technology of magnetic reconnection.

One tenth of the speed of light is undoubtedly the maximum speed that can be reached for an intelligent civilization that has just entered space.

Unfortunately, the entire physics and astrophysics communities do not know much about the phenomenon of magnetic reconnection.

Most of the observable magnetic reconnection phenomena come from the sun, the star closest to the earth.

For example, the phenomenon of post-flare rings, that is, the magnetic arch after the flare, sometimes has an obvious sharp corner at the top, which comes from the magnetic reconnection phenomenon.

But knowing that it comes from magnetic reconnection does not mean that all the mechanisms behind why the magnetic reconnection phenomenon is formed have been figured out.

Just like the solar flare eruption is divided into two forms of "slow reconnection" and "fast reconnection", no one knows the reason behind this.

At present, this is a very promising theory, which not only involves the dynamics of the electric field, but also is related to the corresponding magnetic field.

If the "truth" behind it can be figured out, human control of the "electromagnetic field" will be further improved.

Really control lightning!

In the office, after chatting for a while, Xu Chuan also stood up and said goodbye.

In the office, Chang Huaxiang picked up two papers from the tea table, flipped through them, stood up and put the planning documents of the manned Mars landing project into the drawer of the desk.

After thinking for a while, he took another paper related to magnetic reconnection theory to the School of Physics at the Gulou Campus of Nanjing University.

With his physics level, it is not easy to understand this kind of paper.

However, he has an old classmate at Nanjing University who happens to be a professor in the field of astrophysics.

No matter from which aspect, it is right to find someone to understand the magnetic reconnection theory first.

As for the paper, it must have been approved by Xu Chuan.

Although he has no way to judge the value of this paper, he still knows the importance of this kind of thing.

In the office building of the Department of Astrophysics, School of Physics, Nanjing University.

After knocking on the open door, Chang Huaxiang smiled and called out, "Long time no see, Lao Miao."

Miao Jianguo, who was in his office, drinking tea and reading newspapers leisurely, suddenly heard a familiar voice.

Turning his head, he saw his old friend standing by the door.

"Hey, Lao Chang, what brings you here? My humble abode is so bright." Miao Jianguo quickly stood up and greeted him with a smile.

Chang Huaxiang looked around the office and said with a smile, "You are so leisurely, reading newspapers and drinking tea, and your life is so comfortable."

Miao Jianguo smiled and said, "There are not many things that can be done in the astrophysics community, not as good as those of you who are engaged in aerospace. If you want, you can also come here. I welcome you anytime."

"Forget it, I'm not doing astrophysics research, why do I come here."

Miao Jianguo glanced at Chang Huaxiang, and said with a smile while making tea, "Look at you, you say that my life is comfortable here, but you don't come when I ask you to come. Aren't you just looking for trouble with me?"

"What's wrong? I'm drinking tea and reading a newspaper here. Did that offend you? Are you going to come over and criticize me?"

Chang Huaxiang smiled and said, "Don't put a accusation on me. I came here today to talk to you about something."

"Oh?"

Hearing this, Miao Jianguo looked over in surprise and said, "Academician Chang, who is famous for being in charge of several super aerospace projects, comes to me, an unknown person? How can I help?"

After leaving Beihang University and joining Xinghai Research Institute, the projects and things that Chang Huaxiang is responsible for are enviable not only in the aerospace industry, but also in the outside world.

The development of the space shuttle, the success of the manned lunar landing project, and the construction of the lunar surface scientific research base.

Each of them can be said to make any aerospace person envious to death.

Even he, who drinks tea and reads newspapers in the office every day, feels that this old classmate from decades ago has taken off in his later years.

Chang Huaxiang smiled and shook his head, saying, "Don't be so funny, I really have something serious to ask you."

"No problem." Miao Jianguo said with a smile, "You can ask me for help, but it won't work without a few meals."

"Okay, if you can solve it, let alone a month, you can eat for a year." Chang Huaxiang said with a smile.

"It seems that your meal is not delicious."

Miao Jianguo glanced at Chang Huaxiang, handed him a cup of tea, and said, "Tell me, what's the situation? You left thousands of researchers at Xinghai Research Institute and came to me."

When talking about business, Chang Huaxiang also restrained the smile on his face. After taking the tea, he said seriously: "How much do you know about magnetic reconnection theory?"

"Magnetic reconnection?"

Hearing this term, Miao Jianguo looked at his old friend curiously and was a little surprised: "This is something in the field of astrophysics. When did you study this?"

"Tell me first, I will tell you the details later." Chang Huaxiang picked up the tea and took a sip.

"Okay."

Nodding, Miao Jianguo thought for a while, and said: "The magnetic reconnection mechanism was proposed very early. In the 1950s, someone proposed a related theory."

"However, it took several decades to make a relatively complete explanation of the mechanism and find observational evidence to support it. It did not appear until the 1990s."

"In short, it is a very important rapid energy release process in astrophysics, and it is also a mechanism for converting magnetic energy into kinetic energy, thermal energy and radiation energy of particles."

"Academically speaking, there is a significant connection between the magnetic reconnection effect and plasma fluctuations, among which quasi-static fluctuations, shock waves and the eigenmodes of dynamic Alfvén waves are important components of the magnetic reconnection structure."

"Its high-frequency fluctuations can not only absorb the free energy of particles, but also cause the heating of particles and the generation of anomalous resistance. These multi-scale fluctuation processes reveal the multi-scale nature of energy conversion in magnetic reconnection"

After a brief introduction to the theory related to magnetic reconnection, Miao Jianguo picked up the cup of water on the tea table, took a sip of tea to moisten his throat, and then said:

"The specific mechanism of magnetic reconnection is unclear at present, but in the astrophysics community, it is generally believed that the energy release of stars is caused by the magnetic reconnection mechanism."

"In terms of manifestation, the observed ones can be divided into two types."

"One is the activity on stars, such as flares and coronal activities on the sun."

"The other is the plasma instability and asymmetric reconnection formed by planets, such as the Earth and Venus, which have some magnetic fields, when they encounter external erosion such as cosmic radiation and solar wind."

"This is the simple situation. If you want to know more, I can recommend two textbooks and several papers to you."

After listening to his old friend's description, Academician Chang Huaxiang nodded, thought for a while and asked: "What about the application of magnetic reconnection phenomenon and theory?"

"Has there been any in recent years?"

With Miao Jianguo's explanation, he has more or less a deep understanding of the magnetic reconnection mechanism.

Aerospace is still linked to physics. Although he will not go deep into it, it is not a big problem for him to understand these basic theories.

If the magnetic reconnection mechanism does have potential, then what he cares most about is undoubtedly the applicability of this theory.

Before this, whether there are scientific research results in other directions, whether the magnetic reconnection mechanism can be applied to aerospace engines, there is still a lot of reference value.

Miao Jianguo nodded and said, "Although not much, there are still some."

"For example, the acceleration mechanism of cold ions, satellite in-situ observation of turbulent magnetic reconnection, and research on the conformation of biological macromolecules. The development of these theories and technologies are all related to magnetic reconnection."

Hearing this, Academician Chang Huaxiang's eyes moved, and he quickly asked: "What is the cold ion acceleration mechanism?"

Miao Jianguo thought for a while and said, "This may be complicated to explain."

After thinking for a while, he organized his words and continued: "To put it simply, it is the process of using plasma fluctuations to affect the magnetic reconnection mechanism."

"I think you are very clear about the controlled nuclear fusion technology. It is hot plasma The control of the daughter body. The cold plasma acceleration mechanism is another application. "

"Cold plasma plumes are generally composed of ions and electrons with energy below 100eV, with the characteristics of low speed and high density. The excitation characteristics of electron cyclotron whistle waves and left-polarized ion cyclotron whistle waves (L waves) in the magnetic reconnection mechanism can be used to excite quasi-parallel and anti-parallel whistle waves, thereby increasing the cyclotron radius of cold ions to a certain extent. "

"When the cyclotron radius of cold ions increases, their speed will also increase to a certain extent, which is the so-called acceleration mechanism. "

Hearing this, Chang Huaxiang's expression was a little touched, and his breathing became two points faster.

"In other words, using the magnetic reconnection mechanism, can plasma be accelerated?"

He really didn't expect to get this answer here today.

If the current technology can achieve a certain degree of ionization acceleration of cold ions, then the current application of thermoelectric ion acceleration in aerospace engines is also feasible.

One tenth of the speed of light.

For any intelligent civilization that has just entered space, this is an irresistible technology.

Even if they can't do this now, they can still improve the performance of the existing electric propulsion engine.

In terms of speed, it's no problem to double it, right?

According to Xu Chuan's calculations, it only takes half a month to travel from Earth to Mars. Compared with the moon, Mars is more suitable for immigration, and it will undoubtedly become a distant territory of China!

Miao Jianguo didn't think so much, or he didn't have the conditions to think about it.

Nodding, he said: "In theory, the magnetic reconnection mechanism can indeed be applied to the acceleration of plasma."

"But."

"But what?"

Miao Jianguo shook his head and continued: "But I don't know whether it can be done."

"Strictly speaking, the cold ion acceleration mechanism is just a theory, not an application. The physics community has observed this phenomenon in the laboratory and simulated the magnetic reconnection process through the 2.5DPIC (Particle-in-Cell) method."

"But this replication experiment is difficult to control the cold ion plume. It can only use weak magnetic fields to affect small-mass plasma and electrons to a certain extent."

"And more importantly, the physics community has not yet had a complete set of theories to explain this magnetic field. The excitation characteristics of whistling waves in reconnection and the acceleration mechanism of cold ions. "

"Not to mention the acceleration and manipulation of heavy ions with large mass."

"So."

He sighed and continued: "It is not so easy to make a breakthrough in this area of ​​research."

"Not only is it being studied in China, but also abroad."

"If I remember correctly, NASA, Nivea, and DENSO in the United States have all conducted research in this area."

"But there has been no breakthrough so far, let alone application. I haven't seen many theoretical papers related to the magnetic reconnection mechanism."

Although astrophysics is a relatively leisurely field, it generally refers to traditional astrophysics that studies the physical properties of the universe and stars (luminosity, density, temperature, chemical composition, etc.), as well as the interactions between stars.

In fact, astrophysicists usually need to apply many different academic fields to date.

Classical mechanics, electromagnetism, statistical mechanics, quantum mechanics, relativity, particle physics, etc. are all research objects for astrophysicists.

Although he seemed to be drinking tea and reading newspapers all day long, as a professor of astrophysics at Nanjing University, he was still quite interested in research related to astrophysics.

If not, Chang Huaxiang would not have come here to discuss the magnetic reconnection mechanism with him.

"Don't you have any theory?"

Chang Huaxiang frowned slightly, thought for a while, and took out the paper Xu Chuan gave him from his arms and handed it over: "Take a look at this."