A Man of Science and Engineering in Troubled Times Wandering in the Late Qing Dynasty

Chapter 581 Aurora

Several papers on astronomy that Li Yu had previously published in Europe were also reprinted in the American "Science", causing considerable reaction in the American astronomical community.

At present, the scientific research strength of the United States is not very good compared to Europe as a whole, but astronomy is relatively easy to develop, so it pays more attention to it.

Li Yu received an invitation from Hale from the American Astronomical Society to go to the Wilson Observatory he had just established, where an astronomy symposium was to be held.

The American Astronomical Society intends to build Wilson Observatory into a huge observatory to enhance astronomical research capabilities. It has invested a lot of money and has spent nearly ten years on construction.

Ordinarily, the construction period would not have lasted that long, mainly because an earthquake occurred during the period, which caused serious damage to the precision observation equipment, and it took a lot of time to re-manufacture it.

Haer is an old acquaintance of Li Yu, having met Li Yu many years ago when he first came to the American Astronomical Society.

The Wilson Observatory is located in Los Angeles, and Li Yu took a train to the western United States.

Haier also invited some professors from the University of California, Los Angeles (to be precise, it is not called UCLA yet, because the University of California at Berkeley in San Francisco is unwilling) and the California Institute of Technology.

These two universities will be the top universities in the United States for many years. Friends in China should be more familiar with Caltech. The protagonist Sheldon and others in "The Big Bang Theory" are supposed to be from Caltech.

Li Yu said: "Now that Mr. Haer has discovered the sunspot magnetic field, it is enough to show that the birth of sunspots is closely related to the solar magnetic field."

Haier brought the principals of the two universities and many members of the Astronomical Society to welcome Li Yu, which was enough to show the importance he attached to Li Yu.

Haier said: "This involves physical issues, so I'd better ask Mr. Li Yu to answer."

After entering the observatory, Haer first introduced his recent work, mainly about sunspots, flares, etc.

Li Yu said: "The sun is a star after all, so it is naturally different. The material movement on the surface of the sun is extremely violent, and its heat conduction mainly relies on thermal convection. It is not surprising that strong convection produces a strong magnetic field. It can also cause temperature changes, that is, it is expressed as Sunspots in Astronomical Phenomena.”

"It's hard for me to answer this question yet," Haier said, and then said to Li Yu, "Mr. Academician, you are an outstanding scholar who is good at both astronomy and physics. Maybe you can give an answer."

Haier said: "Mr. Li Yu published an article about cosmic rays just before. We found that the material ejected in solar flares contains a large number of high-energy cosmic rays, such as X-rays, gamma rays, etc."

It's just that these two universities are not well-known in the United States at present, and they both want to rely on the American Astronomical Society to increase their reputation and promote enrollment.

Someone else asked: "How big is it?"

When called sunspots, it superficially means that this area is about 1000 degrees Celsius cooler than other parts of the sun, but the temperature is still very high, at least 4000 degrees. If the other parts of the sun are covered, leaving only sunspots, they will still be very bright.

Schmidt asked: "There are also times when solar activity is intense?"

Flares are the opposite of sunspots, which are the brighter parts of the sun.

Haer said: "After many years of observation, this is definitely the case, and when sunspots are discovered, flares on the sun are often discovered, and flares eject a large amount of matter."

"This theory can be explained," Hale said. "In addition, we also found that sunspots seem to indicate the intensity of solar activity."

Haer said: "It's just that these sneezes are quite deadly. According to calculations, they can easily destroy all living things on the earth."

Schmidt asked: "What material was ejected?"

"After years of persistent research, we can be sure that sunspots have cycles and have extremely strong magnetic fields. In addition, when studying the spectrum of sunspots, we found that they overlap with the bright lines characteristic of the spectrum of iron elements, and we can conclude that the sun's There’s iron in the atmosphere.”

For Li Yu, these are almost common sense, so he said: "According to the size of the sun, it is easy to spray out hundreds of millions or even tens of billions of high-energy plasma at a time, just like we sneeze casually."

“The success is caused by the magnetic field, and the failure is caused by the magnetic field,” Li Yu said. “Solar flares, sunspots, etc. all originate from the solar magnetic field. Fortunately, the earth also has a magnetic field, which can prevent these terrible high-energy cosmic rays from entering the earth’s atmosphere. In the end, they can only It’s just auroras forming in the polar regions.”

Schmidt, a professor at Caltech, asked: "What is the mechanism by which sunspots appear?"

Haer said: "Unfortunately, we are not yet able to study the magnetic field of the entire sun. We have no way of knowing how the sunspot magnetic field is related to the solar magnetic field. Based on the study of the earth's magnetic field and analogy to the sun, we will find that there is no correspondence at all."

In fact, Li Yu confused solar flares and coronal mass ejections to a certain extent, but even if he said it, the current level of astronomical observation is not easy to distinguish, and it will not have much impact.

Schmidt suddenly thought: "The Carrington event half a century ago was also caused by the magnetic field of the sun."

Li Yu nodded: "That should be the most intense solar flare phenomenon. Not only the polar regions, but also the whole world can see the aurora. Fortunately, there were not many telegrams at that time, otherwise the disaster consequences would be unimaginable."

If the Carrington Incident of 1859 had occurred in the era of artificial satellites, it would have been quite devastating.

Haer asked again: "You mentioned the aurora phenomenon. This is also a problem that has been troubled for a long time. I wonder if Mr. Academician can give an explanation?"

The English word for aurora is "aurora", which is transliterated as Aurora, which means the goddess of dawn in Roman mythology.

It was Galileo who later gave the word the meaning of aurora.

It's just that as a very beautiful atmospheric physical phenomenon, humans have been unable to explain the cause of the aurora for so many years, causing it to be shrouded in mystery.

But since you asked sincerely, I will tell you mercifully.

Li Yu said word by word: "Stimulated radiation, this is the latest research result of quantum physics."

There were almost no quantum theory practitioners present, and none of them understood.

So Li Yu walked up to the podium, picked up the chalk and started talking to them:

"A large number of high-energy particles ejected by the sun are blocked by the geomagnetic field, and finally enter the atmosphere only in the polar regions where the magnetic field is relatively weak. Because of their high energy, when they collide with air particles, the air molecules will gain energy, thereby allowing them to atoms become excited states."

Li Yu drew a schematic diagram of Bohr's energy level theory on the blackboard and continued:

"After all, the excited state is not a stable state, so it will return to the ground state. This process is the conversion of energy levels, and the energy extreme difference will be reflected in the form of the release of photons. This is the physical mechanism of the aurora, which I call stimulated emission. .”

Not only auroras, but also lasers work on stimulated radiation.

Historically, stimulated emission of radiation was first proposed by Einstein two or three years later.

Li Yu now gives a richer explanation.

Li Yu continued: "It is because of stimulated radiation that the aurora is mainly green, because the oxygen content in the high altitude is higher and it is easier to be excited than nitrogen, and oxygen stimulated radiation emits green light of about 557 nanometers. .

"Of course, if the energy of the high-energy particles ejected by the sun is higher, the nitrogen will be excited and emit blue light; if the energy is higher, the oxygen atoms in the high altitude will also emit red light."

What Li Yu said can be published as an excellent paper.

Haer and the professors from Caltech and UCLA were stunned for a moment: "It turns out that the latest theories of physics will have such a fantastic linkage with astronomy!"

Others lamented: "The sun is so kind. It is its gift that we can live. Otherwise, just a small fluctuation would be enough to destroy the earth."

Li Yu said: "Not long ago, I published an article about the atmosphere of Mars in Nature magazine. If we add the explanation of solar flares, it should be more explainable." Haier has read Li Yu's article. : "Didn't you say that the atmosphere on Mars is very thin?"

Li Yu said: "The reason why the atmosphere of Mars is so thin may be because it does not have a magnetic field like the Earth. I guess that many years ago, there was a dense atmosphere on Mars, but due to planetary collisions and other reasons, the internal flow of Mars stopped , causing the magnetic field to disappear, and then the Martian atmosphere was blown away by the solar wind."

Hale said: "If there hadn't been that collision, maybe there would have been life on Mars?"

Li Yu said: "I can only say it is possible."

Everyone in the audience stood up and applauded after listening to Li Yu's explanation.

Haier praised: "Mr. Li Yu is indeed the best astronomer in the world today. You made us enlightened with just a few words. My achievements in the observatory for decades are not as good as your several wonderful papers."

Li Yu modestly said: "Your observation data are necessary for the development of theory."

Hale said: "You are like the great Kepler, and we are just Tycho responsible for the observations."

His words gave Li Yu a lot of respect and even admiration. Li Yu smiled and said: "If you reward me, please reward me."

In the past few days, Li Yu took the opportunity to compile the contents of his speeches into papers at the Wilson Observatory, divided into one article dedicated to stimulated radiation, and another article on sunspots and the atmosphere of Mars.

At the same time, he also took time to visit Caltech and UCLA.

Haier accompanied the tour. He was in a good mood. After the visit, he said to Li Yu: "Does Mr. Li Yu like to watch movies?"

"I like it," Li Yu said, "There should be many film companies in Los Angeles, right?"

"There are so many, and there are many movie theaters," Haier said. "There is a new movie released today. It is a comedy star who has just debuted. Why don't we go and watch it together."

In his previous life, Li Yu would never have agreed to go to the cinema with a man, but in this era there were not many entertainment activities even in the United States, so Li Yu immediately agreed: "Let's go!"

Entering the cinema, Li Yu discovered that the film being shown was Charlie Chaplin's first film "Making a Living."

The film is a typical early comedy and is very short, only fifteen minutes.

Chaplin plays a con man in the film. He got acquainted with a well-known family and pursued the girl of this family desperately. However, one day, the young lady's fiancé came back, and it happened that he had been blackmailed by this liar. So the scam was finally exposed. But the liar Chaplin did not repent. He disguised himself as a journalist and started a new fraud.

Overall, this film is nothing new.

Fortunately, comedy films mainly focus on the acting skills of actors, and they are easy to shoot and require low investment. Other films will soon be produced.

After walking out of the theater, Li Yu, who was used to watching movies of at least 90 minutes, felt that he still had more to say, so he asked Haier: "Is this place close to the film shooting factory?"

Haier guessed that Li Yu might want to buy some copies of the movie to play back in China, so he said, "It's not far. How about we go to Keystone Film Company where the British comedian works?"

Chaplin was originally from the United Kingdom. In recent years, he toured the United States with the theater troupe and stayed in the United States to develop.

Li Yu said: "It's just what I want."

Haer also seems to like watching comedies: "This young actor first performed in a theater troupe. I liked it very much after watching it. At that time, I felt that this funny British actor would one day make everyone fall in love with him."

Li Yu smiled and said, "Mr. Haer is still a talent scout."

Haier said: "I don't know much about movies, and I don't have much research on filming and acting. I just think watching movies is more interesting."

Today's Los Angeles is not big, and Hollywood is even smaller. It didn't take long for them to arrive at Keystone Film Company.

This film company was established only two years ago and has grown rapidly.

As a businessman buying movie copies, Li Yu easily met Senat, the boss of the film company.

"It turns out they are Chinese." Senat was surprised.

Haer introduced him: "He is the great scientist Li Yu, the author of Star Wars."

Senat was in awe and quickly welcomed him in: "Li, please sit inside! Why do you come to a small place like Hollywood?"

Li Yu said smoothly: "I want to buy some movie copies and take them to China to play."

"Take it to China?" Senat asked in surprise. He really didn't expect that his movie could already go overseas without even fully opening up the US market.

Li Yu laughed and said, "Aren't all movies silent? There's no language barrier."

Senat asked, "How many copies would you like to buy?"

Li Yu took the time to say, "I bought 10 copies of each of the recently released films, and I will continue to buy future films."

Senat suddenly became energetic and said excitedly: "Li, you are really generous!"

At present, the most direct way for Hollywood film studios to make money is by selling film copies.

Keystone Film Company releases an average of 20 copies of each film, and it would be quite remarkable if it releases 30 copies.

Li Yu is definitely a big customer among big customers if he buys so much.

Film at this time was quite expensive, and the price of each copy was high, depending on the length of the movie and the effect of the stars.

——As early as the beginning of the 20th century when movies were just born, the concept of movie stars already existed.

If a movie studio can create a movie star, the movie it makes can even sell hundreds of copies of the movie, and fetch a high price.

Star-making also has considerable commercial considerations for film companies.

Li Yu added: "I like the films of this new actor named Chaplin very much. I will buy copies of his subsequent films."

Senat said flatteringly: "You are so discerning! He is the best comedian in our company."

Li Yu asked casually: "Can I take a look at your company's studio shooting?"

Senat immediately said: "No problem!"

Large customer requirements must be met as much as possible.

(End of this chapter)